ALBERT

Description: In high-speed electric trains, a pantograph is mounted on the roof the train to collect power through contact with an overhead catenary wire. The effect of fast harmonic and parametric excitation on a stochastically driven pantograph-catenary system is studied in this paper. A single-degree-of-freedom model of the pantograph-catenary system is adopted, wherein the stiffness of the nonlinear spring has a time-varying component characterized by both low and high frequencies. Using perturbation and harmonic averaging, a Fokker-Planck-Kolmogorov equation governing the stationary response of the pantograph-catenary system is set up. Based on the transition probability density of the stationary response, it is found that even small high-frequency parametric excitation has an appreciable effect on the system response. Among other things, it shifts the resonant frequency and often changes the response characteristics markedly. Content Type Journal Article Pages - DOI 10.3233/SAV-130818 Authors R.H. Huan, Department of Mechanics, Zhejiang University, Hangzhou, Zhejiang, China W.Q. Zhu, Department of Mechanics, Zhejiang University, Hangzhou, Zhejiang, China F. Ma, Department of Mechanical Engineering, University of California, Berkeley, CA, USA Z.H. Liu, Department of Civil Engineering, Xiamen University, Xiamen, Fujian, China Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622

Description: Predicting the degradation process of bearings before they reach the failure threshold is extremely important in industry. This paper proposed a novel method based on the support vector machine (SVM), and the Markov model to achieve this goal. Firstly, the features are extracted by time and time-frequency domain methods. However, the extracted original features still with high dimensional and include superfluous information, the nonlinear multi-features fusion technique LTSA is used to merge the features and reduce the dimension. Then, based on the extracted features, the SVM model is used to predict the bearings degradation process, the CAO method is used to determine the embedding dimension of the SVM model. After the bearing degradation process is predicted by SVM model, the Markov model is used to improve the prediction accuracy. The proposed method was validated by two bearing run-to-failure experiments, the results proved the effectiveness of the methodology. Content Type Journal Article Pages - DOI 10.3233/SAV-130817 Authors Shaojiang Dong, School of Mechatronics and Automotive Engineering, Chongqing Jiaotong University, Chongqing, China Shirong Yin, School of Mechatronics and Automotive Engineering, Chongqing Jiaotong University, Chongqing, China Baoping Tang, The State Key Laboratory of Mechanical Transmission, Chongqing University, Chongqing, China Lili Chen, School of Mechatronics and Automotive Engineering, Chongqing Jiaotong University, Chongqing, China Jun Li Tianhong Luo, School of Mechatronics and Automotive Engineering, Chongqing Jiaotong University, Chongqing, China Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622

Description: A methodology is presented to study resonances and stability for a single-degree-of-freedom (SDOF) system with piecewise linear-nonlinear stiffness terms (i.e. one piece is linear and the other is weakly nonlinear). Firstly, the exact response of the linear governing equation is obtained, and a modified perturbation method is applied to finding the approximate solution of the weakly nonlinear equation. Then, the primary and 1/2 subharmonic resonances are obtained by imposing continuity conditions and periodicity conditions. Furthermore, Jacobian matrix is derived to investigate the stability of resonance responses. Finally, the results of theoretical study are compared with numerical results, and a good agreement is observed. Content Type Journal Article Pages - DOI 10.3233/SAV-130819 Authors X. Gao, State Key Laboratory of Mechanics and Control of Mechanical Structures, Nanjing University of Aeronautics and Astronautics, Nanjing, Jiangsu, China Q. Chen, State Key Laboratory of Mechanics and Control of Mechanical Structures, Nanjing University of Aeronautics and Astronautics, Nanjing, Jiangsu, China Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622

Description: The dynamics of a system and its safety can be considerably affected by the presence of cracks. Health monitoring strategies attract so a great deal of interest from industry. Cracks detection methods based on modal parameters variation are particularly efficient in the case of large cracks but are difficult to implement in the case of small cracks due to measurement difficulties in the case of small parameters variation. Therefore the present study proposes a new method to detect small cracks based on active modal damping and piezoelectric components. This method uses the active damping variation identificated with the Rational Fraction Polynomial algorithm as an indicator of cracks detection. The efficiency of the proposed method is demonstrated through numerical simulations corresponding to different crack depth and locations in the case of a finite element model of a clamped-clamped beam including four piezoelectric transducers. Content Type Journal Article Pages - DOI 10.3233/SAV-130772 Authors B. Chomette, Institut d'Alembert, UMR, CNRS, Paris, France A. Fernandes, Institut d'Alembert, UMR, CNRS, Paris, France J.-J. Sinou, Laboratoire de Tribologie et Dynamique des Systèmes UMR-CNRS, Ècole Centrale de Lyon, Ecully, France Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622

Description: In this paper four semi-active dynamic vibration absorbers (DVAs) are analytically studied, where the time delay induced by measurement and execution in control procedure is included in the system. The first-order approximate analytical solutions of the four semi-active DVAs are established by the averaging method, based on the illustrated phase difference of the motion parameters. The comparisons between the analytical and the numerical solutions are carried out, which verify the correctness and satisfactory precision of the approximate analytical solutions. Then the effects of the time delay on the dynamical responses are analyzed, and it is found that the stability conditions for the steady-state responses of the primary systems are all periodic functions of time delay, with the same period as the excitation one. At last the effects of time delay on control performance are discussed. Content Type Journal Article Pages - DOI 10.3233/SAV-130774 Authors Yongjun Shen, Department of Mechanical Engineering, Shijiazhuang Tiedao University, Shijiazhuang, Hebei, China Mehdi Ahmadian, Center for Vehicle Systems and Safety, Department of Mechanical Engineering, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622

Description: The traditional beam element was improved to consider the variable axial parameters. The variable axial parameters were formulated in terms of a power series, and the general forms of elementary mass and stiffness matrices which depend on the power order were derived. The mass and stiffness matrices of the improved beam element were obtained in terms of an elementary matrix series. The beam elements for various tapered beams and a beam under linearly axial temperature distribution were derived. The vibrations of the beams with various taper shapes were studied and the variations of natural frequencies and modal shapes were investigated. A uniform beam under linearly axial temperature distribution was modeled and studied. The influences of axial temperature difference on the natural frequencies and modal shapes were investigated. Results show that the improved beam element could consider the variable axial parameters of beam conveniently. Content Type Journal Article Pages - DOI 10.3233/SAV-130771 Authors Peng He, School of Energy Science and Engineering, Harbin Institute of Technology, Harbin, Heilongjiang, China Zhansheng Liu, School of Energy Science and Engineering, Harbin Institute of Technology, Harbin, Heilongjiang, China Chun Li, School of Energy Science and Engineering, Harbin Institute of Technology, Harbin, Heilongjiang, China Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622

Description: The dynamic response of a Timoshenko beam with immovable ends resting on a nonlinear viscoelastic foundation and subjected to motion of a traveling mass moving with a constant velocity is studied. Primarily, the beam's nonlinear governing coupled PDEs of motion for the lateral and longitudinal displacements as well as the beam's cross-sectional rotation are derived using Hamilton's principle. On deriving these nonlinear coupled PDEs the stretching effect of the beam's neutral axis due to the beam's fixed end conditions in conjunction with the von-Karman strain-displacement relations are considered. To obtain the dynamic responses of the beam under the act of a moving mass, derived nonlinear coupled PDEs of motion are solved by applying the Galerkin's method. Then the beam's dynamic responses are obtained using mode summation technique. Furthermore, after verification of our results with other sources in the literature a parametric study on the dynamic response of the beam is conducted by changing the velocity of the moving mass, damping coefficient and stiffnesses of the foundation including linear and cubic nonlinear parts, respectively. It is observed that the inclusion of geometrical and foundation stiffness nonlinearities into the system in presence of the foundation damping will produce significant effect in the beam's dynamic response. Content Type Journal Article Pages - DOI 10.3233/SAV-130830 Authors Ahmad Mamandi, Department of Mechanical Engineering, Parand Branch, Islamic Azad University, Tehran, Iran Mohammad H. Kargarnovin, Department of Mechanical Engineering, Sharif University of Technology, Tehran, Iran Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622

Description: This contribution investigates the influence of parametric excitation on the dynamic stability of a microelectromechanical system. In systems with just a single degree of freedom, parametric excitation causes the oscillator to exhibit unstable behavior within certain intervals of the parametric excitation frequency. In multi-degree of freedom systems on the other hand, unstable behavior is caused within a wider range of intervals of the parametric excitation frequency. Moreover, such systems show frequency intervals of enhanced stability, an effect known as anti-resonance phenomenon. Both types of phenomena, the parametric resonance and anti-resonance, are modeled and studied for a microelectromechanical system with two degrees of freedom and some novel results are discussed. Content Type Journal Article Pages - DOI 10.3233/SAV-130826 Authors Johannes Welte, Rail Systems, Infrastructure and Cities, Siemens AG Austria, Vienna, Austria Till Kniffka, Institute of Mechanics and Mechatronics, Vienna University of Technology, Vienna, Austria Horst Ecker, Institute of Mechanics and Mechatronics, Vienna University of Technology, Vienna, Austria Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622

Description: The paper presents vibration analysis of a simply supported beam with a fractional order viscoelastic material model. The Bernoulli-Euler beam model is considered. The beam is excited by the supports movement. The Riemann – Liouville fractional derivative of order 0 α ⩽ 1 is applied. In the first stage, the steady-state vibrations of the beam are analyzed and therefore the Riemann – Liouville fractional derivative with lower terminal at −∞ is assumed. This assumption simplifies solution of the fractional differential equations and enables us to directly obtain amplitude-frequency characteristics of the examined system. The characteristics are obtained for various values of fractional derivative of order α and values of the Voigt material model parameters. The studies show that the selection of appropriate damping coefficients and fractional derivative order of damping model enables us to fit more accurately dynamic characteristic of the beam in comparison with using integer order derivative damping model. Content Type Journal Article Pages - DOI 10.3233/SAV-130825 Authors Jan Freundlich, Faculty of Automotive and Construction Machinery Engineering, Warsaw University of Technology, Narbutta 84, 02-524 Warsaw, Poland. Tel.: +48 22 2348459; Fax: +48 22 2348286; E-mail: jfr@simr.pw.edu.pl Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622

Description: The main problem in damage assessment is to ascertain the presence, location and severity of structural damage given the structure's dynamic characteristics. The most successful applications of vibration-based damage assessment are model updating methods based on global optimization algorithms. However, these algorithms run quite slowly, and the damage assessment process is achieved via a costly and time-consuming inverse process, which presents an obstacle for real-time health monitoring applications. Artificial Neural Networks (ANN) have recently been introduced as an alternative to model updating methods. Once a neural network has been properly trained, it can potentially detect, locate and quantify structural damage in a short period of time and can therefore be applied for real-time damage assessment. The primary contribution of this research is the development of a real-time damage assessment algorithm using ANN and anti-resonant frequencies. Anti-resonant frequencies can be identified more easily and more accurately than mode shapes, and they provide the same information. This research addresses the set-up of the neural network parameters and provides guidelines for the selection of these parameters in similar damage assessment problems. Two experimental cases validate this approach: an 8-DOF mass-spring system and a beam with multiple damage scenarios. Content Type Journal Article Pages - DOI 10.3233/SAV-130827 Authors V. Meruane, Department of Mechanical Engineering, Universidad de Chile, Beauchef, Santiago, Chile J. Mahu, Department of Mechanical Engineering, Universidad de Chile, Beauchef, Santiago, Chile Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622

Description: The nonlinear response of a three degree of freedom autoparametric system with a double pendulum, including the magnetorheological (MR) damper when the excitation comes from a DC motor which works with limited power supply, has been examined. The non-ideal source of power adds one degree of freedom which makes the system have four degrees of freedom. The influence of damping force in MR damper on the phenomenon of energy transfer has been studied numerically. Near the internal and external resonance region, except periodic vibration also chaotic vibration has been observed. Results show that MR damper can be used to change the dynamic behavior of the autoparametric system. Content Type Journal Article Pages - DOI 10.3233/SAV-130822 Authors Danuta Sado, Institute of Machine Design Fundamentals, Warsaw University of Technology, 84 Narbutta Street, 02-524 Warsaw, Poland. E-mail: dsa@simr.pw.edu.pl Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622

Description: A novel optimization technique for optimizing the damper top mount characteristics to improve vehicle ride comfort and harshness is developed. The proposed optimization technique employs a new combined objective function based on ride comfort, harshness and impact harshness evaluation. A detailed and accurate damper top mount mathematical model is implemented inside a validated quarter vehicle model to provide a realistic simulation environment for the optimization study. The ride comfort and harshness of the quarter vehicle are evaluated by analyzing the body acceleration in different frequency ranges. In addition, the top mount deformation is considered as a penalty factor for the system performance. The influence of the ride comfort and harshness weighting parameters of the proposed objective function on the optimal damper top mount characteristics is studied. The dynamic stiffness of the damper top mount is used to describe the optimum damper top mount characteristics for different optimization case studies. The proposed optimization routine is able to find the optimum characteristics of the damper top mount which improve the ride comfort and the harshness performances together. Content Type Journal Article Pages - DOI 10.3233/SAV-130828 Authors Mina M.S. Kaldas, Institute of Automotive Engineering, TU Braunschweig, Germany Kemal Çalı Şkan, Institute of Automotive Engineering, TU Braunschweig, Germany Roman Henze and, Institute of Automotive Engineering, TU Braunschweig, Germany Ferit Küçükay, Institute of Automotive Engineering, TU Braunschweig, Germany Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622

Description: Aiming at the economy and security of the positioning system in semi-submersible platform, the paper presents a new scheme based on the mooring line switching strategy. Considering the input delay in switching process, H_{∞} control with time-varying input delay is designed to calculate the control forces to resist disturbing forces. In order to reduce the conservativeness, the information of the lower bound of delay is taken into account, and a Lyapunov function which contains the range of delay is constructed. Besides, the input constraint is considered to avoid breakage of mooring lines. The sufficient conditions for delay-range-dependent stabilization are derived in terms of LMI, and the controller is also obtained. The effectiveness of the proposed approach is illustrated by a realistic design example. Content Type Journal Article Pages - DOI 10.3233/SAV-130829 Authors Xiaoyu Su, College of Automation, Harbin Engineering University, Harbin, Heilongjiang, China Hongzhang Jin, College of Automation, Harbin Engineering University, Harbin, Heilongjiang, China Wei Shen, School of Mechatronics Engineering, Harbin Institute of Technology, Harbin, Heilongjiang, China Yunbiao Gu, Tianjin Navigation Instrument Research Institute, Tianjin, China Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622

Description: This paper presents a nonlinear dynamic analysis of a flexible portal frame subjected to support excitation, which is provided by an electro-dynamical shaker. The main goal of this study is to investigate the dynamic interactions between a flexible portal frame and a nonlinear electrical support excitation. The numerical analysis shows a complex behavior of the system, which can be observed by phase spaces, Poincaré sections and bifurcation diagrams. Content Type Journal Article Pages - DOI 10.3233/SAV-130824 Authors Aline Souza de Paula, Department of Mechanical Engineering, Universidade de Brasília, Brasília, DF, Brazil José Manoel Balthazar, Departamento de Estatística, Instituto de Geociências e Ciências Exatas, Universidade Estadual Paulista, Matemática Aplicada e Computação-UNESP, Rio Claro, SP, Brasil Jorge Luis Palacios Felix, Depto de Engenharias, Universidade Federal do Pampa, Campus Alegrete, RS, Brasil Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622

Description: In this paper an inextensible cantilever beam subject to a concentrated axial load and a lateral harmonic excitation is investigated. Special attention is given to the effect of the axial load on the frequency-amplitude relation, bifurcations and instabilities of the beam. To this aim, the nonlinear integro-differential equations describing the flexural-flexural-torsional coupling of the beam are used, together with the Galerkin method, to obtain a set of discretized equations of motion, which are in turn solved by using the Runge-Kutta method. Both inertial and geometric nonlinearities are considered in the present analysis. Due to symmetries of the beam cross section, the beam exhibits a 1:1 internal resonance which has an important role on the nonlinear oscillations and bifurcation scenario. The results show that the axial load influences the stiffness of the beam changing its nonlinear behavior from hardening to softening. A detailed parametric analysis using several tools of nonlinear dynamics unveils the complex dynamic behavior of the beam in the parametric and external resonance regions. Bifurcations leading to multiple coexisting solutions are observed. Content Type Journal Article Pages - DOI 10.3233/SAV-130823 Authors Eulher C. Carvalho, Pontifical Catholic University of Rio de Janeiro, Rua Marquês de São Vicente, Rio de Janeiro, RJ, Brazil Paulo B. Gonçalves, Pontifical Catholic University of Rio de Janeiro, Rua Marquês de São Vicente, Rio de Janeiro, RJ, Brazil Giuseppe Rega, Sapienza University of Rome, Rome, Italy Zenón J.G.N. Del Prado, Federal University of Goiás, Goiânia, GO, Brazil Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622

Description: An application of the nonlinear saturation control (NSC) algorithm for a self-excited strongly nonlinear beam structure driven by an external force is presented in the paper. The mathematical model accounts for an Euler-Bernoulli beam with nonlinear curvature, reduced to first mode oscillations. It is assumed that the beam vibrates in the presence of a harmonic excitation close to the first natural frequency of the beam, and additionally the beam is self-excited by fluid flow, which is modelled by a nonlinear Rayleigh term for self-excitation. The self- and externally excited vibrations have been reduced by the application of an active, saturation-based controller. The approximate analytical solutions for a full structure have been found by the multiple time scales method, up to the first-order approximation. The analytical solutions have been compared with numerical results obtained from direct integration of the ordinary differential equations of motion. Finally, the influence of a negative damping term and the controller's parameters for effective vibrations suppression are presented. Content Type Journal Article Pages - DOI 10.3233/SAV-130821 Authors J. Warminski, Department of Applied Mechanics, Lublin University of Technology, Lublin, Poland M.P. Cartmell, Department of Mechanical Engineering, University of Sheffield, England, UK A. Mitura, Department of Applied Mechanics, Lublin University of Technology, Lublin, Poland M. Bochenski, Department of Applied Mechanics, Lublin University of Technology, Lublin, Poland Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622

Description: Content Type Journal Article Category Editorial Pages - DOI 10.3233/SAV-130816 Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622

Description: The dynamic response of laminated composite beams subjected to distributed moving masses is investigated using the finite element method (FEM) based on the both first-order shear deformation theory (FSDT) and the classical beam theory (CLT). Six and ten degrees of freedom beam elements are used to discretize the CLT and FSDT equations of motion, respectively. The resulting spatially discretized beam governing equations including of the effect of inertials, Coriolis and centrifugal forces due to moving distributed mass are evaluated in time domain by applying the Newmark's scheme. The presented approach is first validated by studying its convergence behavior and comparing the results with that of existing solutions in the literature. Then, the effect of incline angle, mass and velocity of moving body, layer orientation, load length, inertials, Coriolis and centrifugal forces due to the moving distributed mass and friction force between the beam and the moving distributed mass on the dynamic behavior of inclined laminated composite beams are investigated. Content Type Journal Article Pages - DOI 10.3233/SAV-130806 Authors E. Bahmyari, Department of Mechanical Engineering, Persian Gulf University, Bushehr, Iran S.R. Mohebpour, Department of Mechanical Engineering, Persian Gulf University, Bushehr, Iran P. Malekzadeh, Department of Mechanical Engineering, Persian Gulf University, Bushehr, Iran Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622

Description: Most of the civil structures exhibit nonlinear hysteresis behavior during earthquakes. However, detection of damage in these structures is a challenging issue due to successive change in structural characteristics during a seismic excitation. The current paper presents a promising approach for damage detection of nonlinear moment frames. First, several instantaneous time-frequency methods including: Hilbert-Huang transform, direct quadrature, Teager energy operator and higher-order energy operator are investigated as signal processing tools and the most appropriate method is selected using an outlier analysis. Next, a procedure is proposed based on time-frequency analysis in conjunction with clustering to find damage extension in moment frames under a seismic excitation using frequency, amplitude and energy damage measures. A probabilistic approach is implemented to investigate capability of the procedure for different ground motion records using incremental dynamic analysis. Results show that frequency is not an appropriate feature to detect damage in nonlinear structures. Content Type Journal Article Pages - DOI 10.3233/SAV-130807 Authors Ehsan Darvishan, Center of Excellence for Fundamental Studies in Structural Engineering, School of Civil Engineering, Iran University of Science and Technology, Narmak, Tehran, Iran Gholamreza Ghodrati Amiri, Center of Excellence for Fundamental Studies in Structural Engineering, School of Civil Engineering, Iran University of Science and Technology, Narmak, Tehran, Iran Ali Khodam, Center of Excellence for Fundamental Studies in Structural Engineering, School of Civil Engineering, Iran University of Science and Technology, Narmak, Tehran, Iran Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622

Description: This paper proposes a methodology to automatically choose the measurement locations of a nonlinear structure/equipment that needs to be monitored while operating. The response of the computational model (or experimental data) is used to construct the proper orthogonal modes applying the proper orthogonal decomposition (POD), and the effective independence distribution vector (EIDV) procedure is employed to eliminate, iteratively, locations that contribute less for the independence of the target proper orthogonal modes. Content Type Journal Article Pages - DOI 10.3233/SAV-130808 Authors T. G. Ritto, Federal University of Rio de Janeiro, Department of Mechanical Engineering, Centro de Tecnologia, Ilha do Fundão, 21945-970, Rio de Janeiro, Brazil. E-mail: tritto@mecanica.ufrj.br Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622

Description: The concept of fibre-reinforced plate elastomeric isolator (FRPEI) is introduced firstly in this paper. Three FRPEI specimens have been constructed to evaluate the mechanical performance of the isolators by performing vertical and horizontal tests. The research focuses on the compression stiffness, the shear stiffness, the hysteretic characteristic and the vertical bearing capacity of the isolators. The experimental results show that the mechanical performance of FRPEIs can meet the requirements of bridge rubber bearings and the energy dissipation capacity is better than that of general laminated rubber bearings. Therefore, it is feasible to use FRPEIs in seismic isolation of short span bridges in low seismic regions. Theoretical and finite element methods have also been employed and the deformation assumptions applied in the theoretical method are also verified by FEM. By comparing the differences of the results of different methods, the effectivenesses of the theoretical and finite element methods are evaluated and some considerations on isolator design are proposed. Content Type Journal Article Pages - DOI 10.3233/SAV-130780 Authors H. Zhang, Department of Bridge Engineering, Tongji University, Shanghai, China J. Li, Department of Bridge Engineering, Tongji University, Shanghai, China T. Peng, Department of Bridge Engineering, Tongji University, Shanghai, China Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622

Description: Due to the presence of system flexibility, impact can excite severe large amplitude vibration responses of the flexible robotic manipulator. This impact vibration exhibits characteristics of remarkable nonlinearity and strong energy. The main goal of this study is to put forward an energy-based control method to absorb and attenuate large amplitude impact vibration of the flexible robotic manipulator. The method takes advantage of internal resonance and is implemented through a vibration absorber based on the transfer and dissipation of energy. The addition of the vibration absorber to the flexible arm generates a coupling effect between vibration modes of the system. By means of analysis on 2:1 internal resonance, the exchange of energy is proven to be existent. The impact vibrational energy can be transferred from the arm to the absorber and dissipated through the damping of the absorber. The results of numerical simulations are promising and preliminarily verify that the method is feasible and can be used to combat large amplitude impact vibration of the flexible manipulator undergoing rigid motion. Content Type Journal Article Pages - DOI 10.3233/SAV-130775 Authors Yushu Bian, School of Mechanical Engineering and Automation, Beihang University, Beijing, China Zhihui Gao, School of Mechanical Engineering and Automation, Beihang University, Beijing, China Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622

Description: Shock induced vibration can be more crucial in the mid frequency range where the dynamic couplings with structural parts and components play important roles. To estimate the behavior of structures in this frequency range where conventional analytical schemes, such as statistical energy analysis (SEA) and finite element analysis (FEA) methods may become inaccurate, many alternative methodologies have been tried up to date. This study presents an effective and practical method to accurately predict transient responses in the mid frequency range without having to resort to the large computational efforts. Specifically, the present study employs the more realistic frequency response functions (FRFs) from the energy flow method (EFM) which is a hybrid method combining the pseudo SEA equation (or SEA-Like equation) and modal information obtained by the finite element analysis (FEA). Furthermore, to obtain the time responses synthesized with modal characteristics, a time domain correction is practiced with the input force signal and the reference FRF on a position of the response subsystem. A numerical simulation is performed for a simple five plate model to show its suitability and effectiveness over the standard analytical schemes. Content Type Journal Article Pages - DOI 10.3233/SAV-130789 Authors Sung-Hyun Woo, KOMPSAT-5 System Engineering and Integration Team, Korea Aerospace Research Institute, Daejeon, Korea Jae-Hung Han, Department of Aerospace Engineering, Korea Advanced Institute of Science and Technology, Daejeon, Korea Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622

Description: This study is concerned with the thermal vibration analysis of a short single-walled carbon nanotube embedded in an elastic medium based on nonlocal Timoshenko beam model. A Winkler- and Pasternak-type elastic foundation is employed to model the interaction of short carbon nanotubes and the surrounding elastic medium. Influence of all parameters such as nonlocal small-scale effects, high temperature change, Winkler modulus parameter, Pasternak shear parameter, vibration mode and aspect ratio of short carbon nanotubes on the vibration frequency are analyzed and discussed. The present study shows that for high temperature changes, the effect of Winkler constant in different nonlocal parameters on nonlocal frequency is negligible. Furthermore, for all temperatures, the nonlocal frequencies are always smaller than the local frequencies in short carbon nanotubes. In addition, for high Pasternak modulus, by increasing the aspect ratio, the nonlocal frequency decreases. It is concluded that short carbon nanotubes have the higher frequencies as compared with long carbon nanotubes. Content Type Journal Article Pages - DOI 10.3233/SAV-130787 Authors B. Amirian, Department of Mechanical Engineering, Isfahan University of Technology, Isfahan, Iran R. Hosseini-Ara, Department of Engineering, Payame Noor University, Tehran, Iran H. Moosavi, Department of Mechanical Engineering, Isfahan University of Technology, Isfahan, Iran Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622

Description: Water-jet cavitation peening (WCP) is a new technology for the surface modification of metallic materials. The cavitation behavior in this process involves complex and changeable physics phenomena, such as high speed, high pressure, multiple phases, phase transition, turbulence, and unstable features. Thus, the cavitation behavior and impact-pressure distribution in WCP have always been key problems in this field. Numerous factors affect the occurrence of cavitation. These factors include flow-boundary conditions, absolute pressure, flow velocity, flow viscosity, surface tension, and so on. Among these factors, pressure and vapor fraction are the most significant. Numerical simulations are performed to determine the flow-field characteristics of both inside and outside the cavitating nozzle of a submerged water jet. The factors that influence the cavitation intensity of pressure are simulated. Fujifilm pressure-sensitive paper is used to measure the distribution of impact pressure along the jet direction during the WCP process. The results show that submerged cavitation jets can induce cavitation both inside and outside a conical nozzle and a convergent-divergent nozzle when the inlet pressure is 32 MPa. Moreover, the shock wave pressure induced by the collapse of the bubble group reaches up to 300 MPa. Content Type Journal Article Pages - DOI 10.3233/SAV-130792 Authors H. Zhang, School of Mechanical Engineering and Automation, University of Science and Technology Liaoning, Anshan, Liaoning, China B. Han, School of Mechanical Engineering and Automation, University of Science and Technology Liaoning, Anshan, Liaoning, China X.G. Yu, School of Mechanical Engineering and Automation, University of Science and Technology Liaoning, Anshan, Liaoning, China D.Y. Ju, Department of Material Science and Engineering, Saitama Institute of Technology, Fukaya, Saitama, Japan Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622

Description: The present work analyses the buckling and vibration behaviour of non-homogeneous rectangular plates of uniform thickness on the basis of classical plate theory when the two opposite edges are simply supported and are subjected to linearly varying in-plane force. For non-homogeneity of the plate material it is assumed that young's modulus and density of the plate material vary exponentially along axial direction. The governing partial differential equation of motion of such plates has been reduced to an ordinary differential equation using the sine function for mode shapes between the simply supported edges. This resulting equation has been solved numerically employing differential quadrature method for three different combinations of clamped, simply supported and free boundary conditions at the other two edges. The effect of various parameters has been studied on the natural frequencies for the first three modes of vibration. Critical buckling loads have been computed. Three dimensional mode shapes have been presented. Comparison has been made with the known results. Content Type Journal Article Pages - DOI 10.3233/SAV-130791 Authors Roshan Lal, Department of Mathematics, Indian Institute of Technology Roorkee, Roorkee, India Renu Saini, Department of Mathematics, Indian Institute of Technology Roorkee, Roorkee, India Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622

Description: The formulation and solution of the inverse problem of damage identification based on a one-dimensional wave propagation approach are presented in this paper. Time history responses, obtained from pulse-echo synthetic experiments, are used to damage identification. The identification process is built on the minimization of the squared residue between the synthetic experimental echo, obtained by using a sequential algebraic algorithm, and the corresponding analytical one. Five different hybrid optimization methods are investigated. The hybridization is performed combining the deterministic Levenberg-Marquardt method and each one of the following stochastic techniques: The Particle Swarm Optimization; the Luus-Jaakola optimization method; the Simulated Annealing method; the Particle Collision method; and a Genetic Algorithm. A performance comparison of the five hybrid techniques is presented. Different damage scenarios are considered and, in order to account for noise corrupted data, signals with 10 dB of signal to noise ratio are also considered. It is shown that the damage identification procedure built on the Sequential Algebraic Algorithm yielded to very fast and successful solutions. In the performance comparison, it is also shown that the hybrid technique combining the Luus-Jaakola and the Levenberg-Marquardt optimization methods provides the faster damage recovery. Content Type Journal Article Pages - DOI 10.3233/SAV-130790 Authors R.A. Tenenbaum, Graduate Program in Computational Modeling, Polytechnic Institute, State University of Rio de Janeiro, Nova Friburgo, RJ, Brazil L.T. Stutz, Graduate Program in Computational Modeling, Polytechnic Institute, State University of Rio de Janeiro, Nova Friburgo, RJ, Brazil K.M. Fernandes, Instituto de Ciências Ambientais e Desenvolvimento Sustentável, Federal University of Bahia, Salvador, Brazil Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622

Description: The idea of safety region was introduced into the rolling bearing condition monitoring. The safety region estimation and the state identification of the rolling bearing operational were performed by the comprehensive utilization of Empirical Mode Decomposition (EMD), Principal Component Analysis (PCA), and the Least Square Support Vector Machine (LSSVM). The collected vibration data was segmented according to a certain time interval, and then the Intrinsic Mode Functions (IMFs) of each piece of the data were obtained by EMD. The control limits of two statistical variables extracted by PCA were presented as state characteristics. The safety region estimation for the rolling bearing operational status was performed by two-class LSSVM. The states of normal bearing, ball fault, inner race fault, and outer race fault were identified by the multi-class LSSVM. The results show that the estimation accuracy for both the safety region and the states identification reached 95%, and that the validity of the proposed method was verified. Content Type Journal Article Pages - DOI 10.3233/SAV-130788 Authors Yuan Zhang, School of Traffic and Transportation, Beijing Jiaotong University, Beijing, China Yong Qin, State Key Laboratory of Rail Traffic Control and Safety, Beijing Jiaotong University, Beijing, China Zongyi Xing, School of Mechanical Engineering, Nanjing University of Science and Technology, Nanjing, Jiangsu, China Limin Jia, State Key Laboratory of Rail Traffic Control and Safety, Beijing Jiaotong University, Beijing, China Xiaoqing Cheng, State Key Laboratory of Rail Traffic Control and Safety, Beijing Jiaotong University, Beijing, China Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622

Description: The potential of using topology optimization as a tool to optimize the passive constrained layer damping (PCLD) layouts with partial coverage on flat plates is investigated. The objective function is defined as a combination of several modal loss factors solved by finite element-modal strain energy (FE-MSE) method. An interface finite element is introduced to modeling the viscoelastic core of PCLD patch to save the computational space and time in the optimization procedure. Solid isotropic material with penalization (SIMP) method is used as the material interpolation scheme and the parameters are well selected to avoid local pseudo modes. Then, the method of moving asymptote (MMA) is employed as an optimizer to search the optimal topologies of PCLD patch on plates. Applications of two flat plates with different shapes have been applied to demonstrate the validation of the proposed approach. The results show that the objective function is in a steady convergence process and the damping effect of the plates can be enhanced by the optimized PCLD layouts. Content Type Journal Article Pages 199-211 DOI 10.3233/SAV-2012-00738 Authors Weiguang Zheng, State Key Laboratory of Digital Manufacturing Equipment and Technology, Huazhong University of Science and Technology, Wuhan, China Yingfeng Lei, State Key Lab of Vehicle NVH and Safety Technology, Chongqing, China Shande Li, State Key Laboratory of Digital Manufacturing Equipment and Technology, Huazhong University of Science and Technology, Wuhan, China Qibai Huang, State Key Laboratory of Digital Manufacturing Equipment and Technology, Huazhong University of Science and Technology, Wuhan, China Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622 Journal Volume Volume 20 Journal Issue Volume 20, Number 2 / 2013

Description: A numerical study is conducted to investigate the capability of the flux-limiter TVD schemes in capturing sharp discontinuities like shock waves. For this purpose, four classical test problems are considered such as slowly moving shock, gas Riemann problem with high density and pressure ratios, shock wave interaction with a density disturbance and shock-acoustic interaction. The governing equations consist of one-dimensional and quasi-one-dimensional Euler equations solved using an in-house numerical code. In order to validate the solution, the obtained results are compared with other results found in the literature. Content Type Journal Article Pages 287-296 DOI 10.3233/SAV-2012-0744 Authors Iman Harimi, Department of Mechanical Engineering, Isfahan University of Technology, Isfahan, Iran Ahmad Reza Pishevar, Department of Mechanical Engineering, Isfahan University of Technology, Isfahan, Iran Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622 Journal Volume Volume 20 Journal Issue Volume 20, Number 2 / 2013

Description: This works presents an investigation of the dynamics of micromachined arches resonators and their potential to be utilized as band-pass filters. The arches are actuated by a DC electrostatic load superimposed to an AC harmonic load. The dynamic response of the arch is studied analytically using a Galerkin-based reduced-order model when excited near its fundamental and third natural frequencies. Several simulation results are presented demonstrating interesting jumps and snap-through behavior of the arches and their attractive features for uses as band-pass filters, such as their sharp roll-off from pass bands to stop bands and their flat response. Content Type Journal Article Pages - DOI 10.3233/SAV-130786 Authors Hassen M. Ouakad, Department of Mechanical Engineering, King Fahd University of Petroleum and Minerals 31261, Dhahran, Kingdom of Saudi Arabia. E-mail: houakad@kfupm.edu.sa Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622

Description: The theory of singuarity functions is introduced to present an analytical approach for the natural properties of a unidirectional vibrating steel strip with two opposite edges simply supported and other two free, partially submerged in fluid and under tension. The velocity potential and Bernoulli's equation are used to describe the fluid pressure acting on the steel strip. The effect of fluid on vibrations of the strip may be equivalent to added mass of the strip. The math formula of added mass can be obtained from kinematic boundary conditions of the strip-fluid interfaces. Singularity functions are adopted to solve problems of the strip with discontinuous characteristics. By applying Laplace transforms, analytical solutions for inherent properties of the vibrating steel strip in contact with fluid are finally acquired. An example is given to illustrate that the proposed method matches the numerical solution using the finite element method (FEM) very closely. The results show that fluid has strong effect on natural frequencies and mode shapes of vibrating steel strips partially dipped into a liquid. The influences such as tension, the submergence depth, the position of strip in the container and the dimension of the container on the dynamic behavior of the strip are also investigated. Moreover, the presented method can also be used to study vertical or angled plates with discontinuous characteristics as well as different types of pressure fields around. Content Type Journal Article Pages - DOI 10.3233/SAV-130785 Authors J. Li, Institute of Applied Mechanics, College of Science, Northeastern University, Shenyang, Liaoning, China X.H. Guo, Institute of Applied Mechanics, College of Science, Northeastern University, Shenyang, Liaoning, China J. Luo, Institute of Applied Mechanics, College of Science, Northeastern University, Shenyang, Liaoning, China H.Y. Li, Institute of Applied Mechanics, College of Science, Northeastern University, Shenyang, Liaoning, China Y.Q. Wang, Institute of Applied Mechanics, College of Science, Northeastern University, Shenyang, Liaoning, China Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622

Description: During the last decade the chaotic behavior in MEMS resonators have been reported in a number of works. Here, the chaotic behavior of a micro-mechanical resonator is suppressed. The aim is to control the system forcing it to an orbit of the analytical solution obtained by the multiple scales method. The State Dependent Riccati Equation (SDRE) and the Optimal Linear Feedback Control (OLFC) strategies are used for controlling the trajectory of the system. Additionally, the SDRE technique is used in the state estimator design. The state estimation and the control techniques proved to be effective in controlling the trajectory of the system. Additionally, the robustness of the control strategies are tested considering parametric errors and measurement noise in the control loop. Content Type Journal Article Pages - DOI 10.3233/SAV-130782 Authors Angelo Marcelo Tusset, Departamento de Engenharia Eletrônica, Universidade Tecnológica Federal do Paraná, Ponta Grossa, Paraná, Brasil Átila Madureira Bueno, Departamento de Engenharia Eletrônica, Universidade Tecnológica Federal do Paraná, Ponta Grossa, Paraná, Brasil Claudinor Bitencourt Nascimento, Departamento de Engenharia Eletrônica, Universidade Tecnológica Federal do Paraná, Ponta Grossa, Paraná, Brasil Mauricio dos Santos Kaster, Departamento de Engenharia Eletrônica, Universidade Tecnológica Federal do Paraná, Ponta Grossa, Paraná, Brasil José Manoel Balthazar, Matemática Aplicada e Computação, Departamento de Estatística, Instituto de Geociências e Ciências Exatas, Rio Claro, Rio de Janeiro, Brasil Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622

Description: A gear transmission system is a complex non-stationary and nonlinear time-varying coupling system. When faults occur on gear system, it is difficult to extract the fault feature. This paper researches the threshold principle in the process of using the wavelet transform to de-noise the system, and combines EMD (empirical mode decomposition) with wavelet threshold de-noising to solve the problem. The wavelet threshold de-noising is acts on the high-frequency IMF (Intrinsic Mode Function) component of the signal, and does overcome the defect by simply highlighting the fault feature. On this basis, the pre-processed signal is analyzed by the method of time-frequency analysis to extract the feature of the signal. The result shows that the SNR (signal-noise ratio) of the signal was largely improved, and the fault feature of the signal can therefore be effectively extracted. Combined with time-frequency analyses in the different running conditions (300 rpm, 900 rpm), various faults such as tooth root crack, tooth wear and multi-fault can be identified effectively. Based on this theory and combining the merits of MATLAB and VC++, a multi-functional gear fault diagnosis software system is successfully exploited. Content Type Journal Article Pages - DOI 10.3233/SAV-130783 Authors Renping Shao, School of Mechatronics, Northwestern Polytechnical University, Xi'an, Shaanxi, China Wentao Hu, School of Mechatronics, Northwestern Polytechnical University, Xi'an, Shaanxi, China Jing Li, School of Mechatronics, Northwestern Polytechnical University, Xi'an, Shaanxi, China Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622

Description: Promptly and accurately dealing with the equipment breakdown is very important in terms of enhancing reliability and decreasing downtime. A novel fault diagnosis method PSO-RVM based on relevance vector machines (RVM) with particle swarm optimization (PSO) algorithm for plunger pump in truck crane is proposed. The particle swarm optimization algorithm is utilized to determine the kernel width parameter of the kernel function in RVM, and the five two-class RVMs with binary tree architecture are trained to recognize the condition of mechanism. The proposed method is employed in the diagnosis of plunger pump in truck crane. The six states, including normal state, bearing inner race fault, bearing roller fault, plunger wear fault, thrust plate wear fault, and swash plate wear fault, are used to test the classification performance of the proposed PSO-RVM model, which compared with the classical models, such as back-propagation artificial neural network (BP-ANN), ant colony optimization artificial neural network (ANT-ANN), RVM, and support vector machines with particle swarm optimization (PSO-SVM), respectively. The experimental results show that the PSO-RVM is superior to the first three classical models, and has a comparative performance to the PSO-SVM, the corresponding diagnostic accuracy achieving as high as 99.17% and 99.58%, respectively. But the number of relevance vectors is far fewer than that of support vector, and the former is about 1/12–1/3 of the latter, which indicates that the proposed PSO-RVM model is more suitable for applications that require low complexity and real-time monitoring. Content Type Journal Article Pages - DOI 10.3233/SAV-130784 Authors Wenliao Du, State Key Laboratory of Mechanical System and Vibration, Shanghai Jiao Tong University, Shanghai, China Ansheng Li, School of Mechanical and Electronic Engineering, Zhengzhou University of Light Industry, Zhengzhou, Henan, China Pengfei Ye, State Key Laboratory of Mechanical System and Vibration, Shanghai Jiao Tong University, Shanghai, China Chengliang Liu, State Key Laboratory of Mechanical System and Vibration, Shanghai Jiao Tong University, Shanghai, China Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622

Description: The viscous damping force in the mixed form as f_d \left( \dot {x} \right) = c_1 \dot {x} + c_2 \left| \dot {x} \right|\dot {x} can well describe damping characteristics of isolators and dampers in many cases. In this paper, performance characteristics of single-degree-of-freedom (SDOF) linear-stiffness isolators with mixed and piecewise mixed viscous damping are analytically examined under harmonic base excitation. Based on the first-order harmonic balance method (HBM), both relative and absolute displacement transmissibility expressions with the equivalent linear damping coefficient (ELDC) are given. And the analytical calculations show good agreement with the numerical results. Also, the influence of nonlinear damping on the response characteristics is investigated by comparing the transmissibility of linear and nonlinear systems. The resonant frequency always shifts to a lower value as the nonlinear damping component of the force f_d \left( \dot {x} \right) = c_1 \dot {x} + c_2 \left| \dot {x} \right|\dot {x} becomes stronger, and when the damping ratio in the corresponding linear model is relatively high, the relative transmissibility decreases at frequencies higher than the resonance frequency of the corresponding linear damping system and the absolute one increases for the frequency ratios above \sqrt 2 . Finally, the displacement transmissibility of a nonlinear isolator with piecewise mixed viscous damping is discussed and the process shows research similarity with the non-piecewise case. Content Type Journal Article Pages - DOI 10.3233/SAV-130794 Authors Xiaojuan Sun, School of Mechanical Engineering, Southeast University, Nanjing, Jiangsu, China Jianrun Zhang, School of Mechanical Engineering, Southeast University, Nanjing, Jiangsu, China Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622

Description: Impact causes shock waves that may be unexpected and damaging. A computationally efficient impact model with a generic beam which is discrete in time and continuous in space was undertaken; an Euler-Bernoulli beam with adjustable boundary conditions and variable contact location is numerically studied under a pulse loading. Experiments on a cantilever beam were carried out to verify the effects of influential parameters. A half-sine pulse excitation was applied through a mechanical shaker, and the deflection was captured by a high speed camera. Numerous test cases were conducted that varied pulse duration, pulse amplitude, and clearance. Decreasing the pulse duration lowers all deflection amplitudes, but the time in contact is insensitive. No gap causes minimal beam response, and increasing gap generates greater deflection. Representative test cases were selected for validating the theoretical model. When comparing numerical simulation with experimental results, satisfactory agreement for amplitude and duration can be reached even with raw input parameters. The contribution of this study is the incorporation of unique pulse loading, changeable boundary conditions, adjustable contact/impact situations, comprehensive parameter studies, and high speed photography. Content Type Journal Article Pages - DOI 10.3233/SAV-130793 Authors Weiping Xu, Key Laboratory of Transportation Tunnel Engineering, Ministry of Education, School of Civil Engineering, Southwest Jiaotong University, Chengdu, SiChuan, China Elizabeth K. Ervin, Civil Engineering, The University of Mississippi, MS, USA Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622

Description: In this paper, a damage imaging algorithm based on fractal dimension is developed for quantitative damage detection of composite structures. Box-counting dimension, a typical fractal dimension, is employed to analyze the difference of Lamb wave signals, extract damage feature and define damage index. An enhanced reconstruction algorithm for probabilistic inspection of damage is developed for damage imaging. Experimental investigation in a composite laminate and a stiffened composite panel shows that the developed algorithm could quantitatively predict the location and size of not only single but also multiple damages. The influence of parameters in the developed algorithm on the imaging quality and accuracy is studied, and reference values for parameters are presented. Content Type Journal Article Pages - DOI 10.3233/SAV-130798 Authors Li Zhou, State Key Laboratory of Mechanics and Control of Mechanical Structures, Nanjing University of Aeronautics and Astronautics, Nanjing, Jiangsu, China Hu Sun, State Key Laboratory of Mechanics and Control of Mechanical Structures, Nanjing University of Aeronautics and Astronautics, Nanjing, Jiangsu, China Zhiquan He, State Key Laboratory of Mechanics and Control of Mechanical Structures, Nanjing University of Aeronautics and Astronautics, Nanjing, Jiangsu, China Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622

Description: A limit state function is developed for the estimation of structural reliability in shock environments. This limit state function uses peak modal strain energies to characterize environmental severity and modal strain energies at failure to characterize the structural capacity. The Hasofer-Lind reliability index is briefly reviewed and its computation for the energy-based limit state function is discussed. Applications to two degree of freedom mass-spring systems and to a simple finite element model are considered. For these examples, computation of the reliability index requires little effort beyond a modal analysis, but still accounts for relevant uncertainties in both the structure and environment. For both examples, the reliability index is observed to agree well with the results of Monte Carlo analysis. In situations where fast, qualitative comparison of several candidate designs is required, the reliability index based on the proposed limit state function provides an attractive metric which can be used to compare and control reliability. Content Type Journal Article Pages - DOI 10.3233/SAV-130795 Authors Michael A. Guthrie, Analytical Structural Dynamics, Org. 1523, Sandia National Laboratories, MS 0346, P.O. Box 5800, Albuquerque, NM 87185, USA. Tel.: +1 505 284 1357; E-mail: maguthr@sandia.gov Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622

Description: The problem of fault tolerant vibration-attenuation controller design for uncertain linear structural systems with control input time-delay and saturation is investigated in this paper. The objective of designing controllers is to guarantee the asymptotic stability of closed-loop systems while attenuate disturbance from earthquake excitation. Firstly, based on matrix transformation, the structural system is described as state-space model, which contains actuator fault, input signal time-delay and saturation at the same time. Based on the obtained model, an LMIs-based condition for the system to be stabilizable is deduced. By solving these LMIs, the controller is established for the closed-loop system to be stable with a prescribed level of disturbance attenuation. The condition is also extended to the uncertain case. Finally, an example is included to demonstrate the effectiveness of the proposed theorems. Content Type Journal Article Pages - DOI 10.3233/SAV-130797 Authors Falu Weng, Faculty of Electrical Engineering and Automation, Jiangxi University of Science and Technology, Ganzhou, Jiangxi, China Yuanchun Ding, School of Resources and Environmental Engineering, Jiangxi University of Science and Technology, Ganzhou, Jiangxi, China Liming Liang, Faculty of Electrical Engineering and Automation, Jiangxi University of Science and Technology, Ganzhou, Jiangxi, China Guoliang Yang, Faculty of Electrical Engineering and Automation, Jiangxi University of Science and Technology, Ganzhou, Jiangxi, China Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622

Description: A 5-DOF dynamic model of vehicle shimmy system with clearance in universal joint of steering handling mechanism is presented. The sub model of cross shaft universal joint with clearance is built based on Hertz' theory, and two-state model is applied to describe the contact force. The sub model of the universal joint is combined with the simplified dynamic model of steering system, and a 5-DOF dynamic model of vehicle shimmy system with consideration of assembling clearance in universal joint of steering handling mechanism is presented. Based on this model, numerical analysis is carried out to evaluate the influence of clearance in universal joint on the dynamic behavior of the vehicle shimmy system. The results show that the clearance and some other parameters, such as vehicle speed, have coupled contribution to the dynamic behavior of the vehicle shimmy system. The conclusions provide theoretical basis for effective attenuation of vehicle shimmy, especially for those in-service vehicles. Content Type Journal Article Pages - DOI 10.3233/SAV-130796 Authors Jianwei Lu, School of Mechanical and Automotive Engineering, Hefei University of Technology, Hefei, Anhui, China Yi Xu, School of Mechanical and Automotive Engineering, Hefei University of Technology, Hefei, Anhui, China Chen Hu, School of Mechanical and Automotive Engineering, Hefei University of Technology, Hefei, Anhui, China Alexander F. Vakakis, Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, USA Lawrence A. Bergman, Department of Aerospace Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, USA Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622

Description: This paper describes the use of a structural/acoustic model of a section of a large aircraft to help define the sensor/actuator architecture that was used in a hardware demonstration of adaptive noise cancellation. Disturbances considered were representative of propeller-induced disturbances from an open fan aircraft. Controller on and controller off results from a hardware demonstration on a portion of a large aircraft are also included. The use of the model has facilitated the development of a new testing technique, closely related to modal testing, that can be used to find good structural actuator locations for adaptive noise cancellation. Content Type Journal Article Pages - DOI 10.3233/SAV-130799 Authors Steven Griffin, Boeing Company, San Francisco, WA, USA Adam Weston, Boeing Company, San Francisco, WA, USA Jeff Anderson, Boeing Company, San Francisco, WA, USA Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622

Description: Among various non-smooth dynamic systems, the periodically forced oscillation system with impact is perhaps the most common in engineering applications. The dynamical study becomes complicated due to the impact. This paper presents a systematic study on the periodically forced oscillation system with impact. A simplified model of the escapement mechanism is introduced. Impulsive differential equation and Poincare map are applied to describe the model and study the stability of the system. Numerical examples are given and the results show that the model is highly accurate in describing/predicting their dynamics. Content Type Journal Article Pages - DOI 10.3233/SAV-130800 Authors Jian Mao, Shanghai University of Engineering Science, Shanghai, China Yu Fu, Tianjin Seagull Watch Co. Ltd, Tianjin, China Peichao Li, Shanghai University of Engineering Science, Shanghai, China Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622

Description: Two improved analytical methods of calculations for natural frequencies and mode shapes of a uniform cantilever beam carrying a tip-mass under base excitation are presented based on forced vibration theory and the method of separation of variables, respectively. The cantilever model is simplified in detail by replacing the tip-mass with an equivalent inertial force and inertial moment acting at the free end of the cantilever based on D'Alembert's principle. The concentrated equivalent inertial force and inertial moment are further represented as distributed loads using Dirac Delta Function. In this case, some typical natural frequencies and mode shapes of the cantilever model are calculated by the improved and unimproved analytical methods. The comparing results show that, after improvement, these two methods are in extremely good agreement with each other even the offset distance between the gravity center of the tip-mass and the attachment point is large. As further verifications, the transient and steady displacement responses of the cantilever system under a sine base excitation are presented in which two improved methods are separately utilized. Finally, an experimental cantilever system is fabricated and the theoretical displacement responses are validated by the experimental measurements successfully. Content Type Journal Article Pages - DOI 10.3233/SAV-130804 Authors Hongjin Wang, Theory of Lubrication and Bearing Institute, Xi'an Jiaotong University, Xi'an, Shaanxi, China Qingfeng Meng, Theory of Lubrication and Bearing Institute, Xi'an Jiaotong University, Xi'an, Shaanxi, China Wuwei Feng, School of Ship and Ocean Engineering, Zhejiang Ocean University, Zhoushan, Zhejiang, China Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622

Description: In this paper, we applied an approach to obtain the natural frequency of the generalized Duffing oscillator ü + u + α_{3} u^{3} + α _{5} u^{5} + α _{7} u^{7} + … + α _n u^n =0 and a nonlinear oscillator with a restoring force which is the function of a non-integer power exponent of deflection ü+ α u| u |^{n - {1}} = 0. This approach is based on involved parameters, initial conditions and collocation points. For any arbitrary power of n, the approximate frequency analysis is carried out between the natural frequency and amplitude. The solution procedure is simple, and the results obtained are valid for the whole solution domain. Content Type Journal Article Pages - DOI 10.3233/SAV-130802 Authors Najeeb Alam Khan, Department of Mathematical Sciences, University of Karachi, Karachi, Pakistan Fatima Riaz, Department of Mathematical Sciences, University of Karachi, Karachi, Pakistan Nadeem Alam Khan, Department of Mathematical Sciences, University of Karachi, Karachi, Pakistan Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622

Description: Current trends in design of pump-turbines have lead into higher rotor-stator interaction (RSI) loads over impeller-runner. These dynamic loads are of special interest having produced catastrophic failures in pump-turbines. Determining RSI characteristics facilitate the proposal of actions that will prevent these failures. Pressure measurements in all around the perimeter of the impeller-runner are appropriate to monitor and detect RSI characteristics. Unfortunately most installed pump-turbines are not manufactured with in-built pressure sensors in appropriate positions to monitor RSI. For this reason, vibration measurements are the preferred method to monitor RSI in industry. Usually vibrations are measured in two perpendicular radial directions in bearings where valuable information could be lost due to bearing response. In this work, in order to avoid the effect of bearing response on measurement, two vibration sensors are installed rotating with the shaft. The RSI characteristics obtained with pressure measurements were compared to those determined using vibration measurements. The RSI characteristics obtained with pressure measurements were also determined using vibrations measured rotating with shaft. These RSI characteristics were not possible to be determined using the vibrations measured in guide bearing. Finally, it is recommended to measure vibrations rotating with shaft to detect RSI characteristics in installed pump-turbines as a more practical and reliable method to monitor RSI characteristics. Content Type Journal Article Pages - DOI 10.3233/SAV-130803 Authors Cristian G. Rodriguez, Department of Mechanical Engineering, University of Concepcion, Concepcion, Chile Borja Mateos-Prieto, Centre of Industrial Diagnostics and Fluid Dynamics, Technical University of Catalonia, Barcelona, Spain Eduard Egusquiza, Centre of Industrial Diagnostics and Fluid Dynamics, Technical University of Catalonia, Barcelona, Spain Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622

Description: In this paper, we focus on the vibration and acoustic response of a rectangular sandwich plate which is subjected to a concentrated harmonic force under thermal environment. The critical buckling temperature is obtained to decide the thermal load. The natural frequencies and modes as well as dynamic responses are acquired by using the analytical formulations based on equivalent non-classical theory, in which the effects of shear deformation and rotational inertia are taken into account. The rise of thermal load decreases the natural frequencies and moves response peaks to the low-frequency range. The specific features of sandwich plates with different formations are discussed subsequently. As the thickness ratio of facing to core increases, the natural frequencies are enlarged, and the response peaks float to the high-frequency region. Raising the Young's modulus of the core can cause the similar trends. The accuracy of the theoretical method is verified by comparing its results with those computed by the FEM/BEM. Content Type Journal Article Pages - DOI 10.3233/SAV-130801 Authors Yuan Liu, State Key Laboratory for Strength and Vibration of Mechanical Structures, Xi'an Jiaotong University, Xi'an, Shaanxi, China Yueming Li, State Key Laboratory for Strength and Vibration of Mechanical Structures, Xi'an Jiaotong University, Xi'an, Shaanxi, China Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622

Description: This paper presents a low frequency fiber optic accelerometer for application in high temperature environments of civil engineering structures. The reflection-based extrinsic fiber optic accelerometer developed in this study consists of a transmissive grating panel, reflective mirror, and two optical fiber collimators as the transceiver whose function can be maintained up to 130°C. In order to operate at high temperature, the sensor case and components were fabricated and assembled using invar and ceramic adhesive. The dynamic characteristics of the sensor probe were investigated and the correlation between the natural frequency of the sensor probe and temperature variation was described and discussed. Furthermore, high-temperature simulation equipment was designed for the verification test setup of the developed accelerometer for high temperature. This study was limited to consideration of 130°C applied temperature to the proposed fiber optic accelerometer due to an operational temperature limitation of commercial optical fiber collimator. The sinusoidal low frequency accelerations measured from the developed fiber optic accelerometer at 130°C demonstrated good agreement with those of an MEMS accelerometer measured at room temperature. The developed fiber optic accelerometer can be used in frequency ranges below 5.1 Hz up to 130°C with a margin of error that is less than 10% and a high sensitivity of 0.18 (m/s^2)/rad. Content Type Journal Article Pages - DOI 10.3233/SAV-130845 Authors Yeon-Gwan Lee, Agency for Defense Development, Daejeon, Korea Jin-Hyuk Kim, Department of Aerospace Engineering, Korea Advanced Institute of Science and Technology, Daejeon, Korea Chun-Gon Kim, Department of Aerospace Engineering, Korea Advanced Institute of Science and Technology, Daejeon, Korea Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622

Description: The applications of electromagnetic (EM)-wave-absorbers are being expanded for commercial and military purposes. For military applications in particular, EM-wave-absorbers (EMWAs) could minimize RCS (Radar Cross Section) of structures, which could reduce the possibility of detection by radar. In this study, EMWA composite structure containing a square periodic patterned layer is presented. It was found that control of the pattern geometry and surface resistance, induced EMWA characteristics which can create multi-resonance for wide-band absorption in composite structures. Content Type Journal Article Pages - DOI 10.3233/SAV-130846 Authors Won-Jun Lee, Agency for Defense Development, Daejeon, Korea Chun-Gon Kim, Department of Aerospace Engineering, School of Mechanical, Aerospace and System Engineering, KAIST, Daejeon, Korea Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622

Description: This study presents a non-contact sensing technique with ultrasonic wave propagation imaging algorithm, for damage visualization of liquid-immersed structures. An aluminum plate specimen (400 mm × 400 mm × 3 mm) with a 12 mm slit was immersed in water, and in glycerin. A 532 nm Q-switched continuous wave laser is used at an energy level of 1.2 mJ to scan an area of 100 mm × 100 mm. A Laser Doppler vibrometer is used as a non-contact ultrasonic sensor, which measures guided wave displacement at a fixed point. The tests are performed with two different cases of specimen: without water; and filled with water, and with glycerin. Lamb wave dispersion curves for the respective cases are calculated, to investigate the velocity-frequency relationship of each wave mode. Experimental propagation velocities of Lamb waves for different cases are compared with the theoretical dispersion curves. This study shows that the dispersion and attenuation of the Lamb wave is affected by the surrounding liquid, and the comparative experimental results are presented to verify it. In addition, it is demonstrated that the developed fully noncontact ultrasonic propagation imaging system is capable of damage sizing in submerged structures. Content Type Journal Article Pages - DOI 10.3233/SAV-130844 Authors Jung-Ryul Lee, Department of Aerospace Engineering and LANL-CBNU Engineering Institute Korea, Chonbuk National University, Chonbuk, Korea Jae-Kyeong Jang, Department of Aerospace Engineering and LANL-CBNU Engineering Institute Korea, Chonbuk National University, Chonbuk, Korea Cheol-Won Kong, Structures and Materials Department, Korea Aerospace Research Institute, Daejeon, Korea Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622

Description: The Naval Undersea Warfare Center has funded a project to investigate the accuracy of various bolt models used to represent actual shipboard bolted connections within an analytical shock survivability assessment. The ultimate goal within this project is to develop finite element bolt representations that are not only computationally efficient, but also accurate. A significant task within this effort involved the development of highly detailed finite element models of bolted connections under various load configurations. Accordingly, high-resolution bolt models were developed and incorporated into simulations of four bolted connection test arrangements: static shear, static tension, dynamic shear, and dynamic tension. These simulation results are validated against experimental data from physical testing of each configuration. Future research will focus on exploring simplified finite element bolt representations and comparing these against the high-resolution results. Content Type Journal Article Pages - DOI 10.3233/SAV-130769 Authors Kevin Behan, US Naval Undersea Warfare Center, Division Newport (NUWCDIVNPT), Newport, RI, USA Emily Guzas, US Naval Undersea Warfare Center, Division Newport (NUWCDIVNPT), Newport, RI, USA Jeffrey Milburn, US Naval Undersea Warfare Center, Division Newport (NUWCDIVNPT), Newport, RI, USA Stacy Moss, US Naval Undersea Warfare Center, Division Newport (NUWCDIVNPT), Newport, RI, USA Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622

Description: Condition monitoring of rolling element bearing is paramount for predicting the lifetime and performing effective maintenance of the mechanical equipment. To overcome the drawbacks of the hidden Markov model (HMM) and improve the diagnosis accuracy, conditional random field (CRF) model based classifier is proposed. In this model, the feature vectors sequences and the fault categories are linked by an undirected graphical model in which their relationship is represented by a global conditional probability distribution. In comparison with the HMM, the main advantage of the CRF model is that it can depict the temporal dynamic information between the observation sequences and state sequences without assuming the independence of the input feature vectors. Therefore, the interrelationship between the adjacent observation vectors can also be depicted and integrated into the model, which makes the classifier more robust and accurate than the HMM. To evaluate the effectiveness of the proposed method, four kinds of bearing vibration signals which correspond to normal, inner race pit, outer race pit and roller pit respectively are collected from the test rig. And the CRF and HMM models are built respectively to perform fault classification by taking the sub band energy features of wavelet packet decomposition (WPD) as the observation sequences. Moreover, K-fold cross validation method is adopted to improve the evaluation accuracy of the classifier. The analysis and comparison under different fold times show that the accuracy rate of classification using the CRF model is higher than the HMM. This method brings some new lights on the accurate classification of the bearing faults. Content Type Journal Article Pages - DOI 10.3233/SAV-130770 Authors Guofeng Wang, Key Laboratory of Mechanism Theory and Equipment Design of Ministry of Education, Tianjin University, Tianjin, China Xiaoliang Feng, Key Laboratory of Mechanism Theory and Equipment Design of Ministry of Education, Tianjin University, Tianjin, China Chang Liu, Key Laboratory of Mechanism Theory and Equipment Design of Ministry of Education, Tianjin University, Tianjin, China Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622

Description: This paper presents a detailed study on the impact source identification of a plate structure using time-reversal (T-R) method. Prior to impact monitoring, the plate is calibrated (or characterized) by transfer functions at discrete locations on the plate surface. Both impact location and impact loading time-history are identified using T-R technique and associated signal processing algorithms. Numerical verification for finite-size isotropic plates under low velocity impacts is performed to demonstrate the versatility of T-R method for impact source identification. The tradeoff between accuracy of the impact location detection and calibration spacing is studied in detail. In particular, the effect of plate thickness on calibration spacing has been examined. A number of parameters selected for determining the impact location, approximated transfer functions and steps taken for reconstructing the impact loading time-history are also examined. Two types of noise with various intensities contaminated in strain response and/or transfer functions are investigated for demonstrating the stability and reliability of the T-R method. The results show that T-R method is robust against noise in impact location detection and force reconstruction in circumventing the inherent ill-conditioned inverse problem. Only transfer functions are needed to be calibrated and four sensors are requested in T-R method for impact identification. Content Type Journal Article Pages - DOI 10.3233/SAV-130768 Authors Chunlin Chen, School of Aeronautics, Northwestern Polytechnical University, Xi'an, Shaanxi, China Yulong Li, School of Aeronautics, Northwestern Polytechnical University, Xi'an, Shaanxi, China Fuh-Gwo Yuan, Department of Mechanical and Aerospace Engineering, North Carolina State University, Raleigh, NC, USA Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622

Description: This article presents an analytical study for forced vibration of a cylindrical shell which is composed of a functionally graded piezoelectric material (FGPM). The cylindrical shell is assumed to have two-constituent material distributions through the thickness of the structure, and material properties of the cylindrical shell are assumed to vary according to a power-law distribution in terms of the volume fractions for constituent materials, the exact solution for the forced vibration problem is presented. Numerical results are presented to show the effect of electric excitation, thermal load, mechanical load and volume exponent on the static and force vibration of the FGPM cylindrical shell. The goal of this investigation is to optimize the FGPM cylindrical shell in engineering, also the present solution can be used in the forced vibration analysis of cylindrical smart elements. Content Type Journal Article Pages - DOI 10.3233/SAV-130766 Authors Hong-Liang Dai, State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body, Hunan University, Changsha, Hunan, China Hao-Jie Jiang, State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body, Hunan University, Changsha, Hunan, China Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622

Description: Taking Wigner-Ville distribution of gear fault signal as a picture, Sobel operator was applied for edge detection of picture and then Hough transform was used to extract signal feature. Some simulated and measured signals have been processed to demonstrate the effectiveness of new method, which was compared with traditional Wigner-Hough transform and SPWD-Hough transform. The results show that the proposed method can suppress cross term which is produced from using Wigner-Ville distribution to analyze multi-component signal, especially under the condition of low signal to noise ratio. The improved Wigner-Hough transform can effectively suppress the influence of noise and has a good real-time performance because its algorithm is fast. The proposed method provides an effective method to determine the state of gear accurately. Content Type Journal Article Pages - DOI 10.3233/SAV-130767 Authors Jian-Hua Cai, Department of Physics and Electronics, Hunan University of Arts and Science, Changde, Hunan, China Wei-Wen Hu, Department of Physics and Electronics, Hunan University of Arts and Science, Changde, Hunan, China Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622

Description: Vibration signals extracted from rotating parts of machinery carry a lot of useful information about the condition of operating machine. Due to the strong non-linear, complex and non-stationary characteristics of vibration signals from working bearings, an accurate and reliable health assessment method for bearing is necessary. This paper proposes to utilize the selected chaotic characteristics of vibration signal for health assessment of a bearing by using self-organizing map (SOM). Both Grassberger-Procaccia algorithm and Takens' theory are employed to calculate the characteristic vector which includes three chaotic characteristics, such as correlation dimension, largest Lyapunov exponent and Kolmogorov entropy. After that, SOM is used to map the three corresponding characteristics into a confidence value (CV) which represents the health state of the bearing. Finally, a case study based on vibration datasets of a group of testing bearings was conducted to demonstrate that the proposed method can reliably assess the health state of bearing. Content Type Journal Article Pages - DOI 10.3233/SAV-130765 Authors Chen Lu, School of Reliability and Systems Engineering, Beihang University, Beijing, China Qian Sun, School of Reliability and Systems Engineering, Beihang University, Beijing, China Laifa Tao, School of Reliability and Systems Engineering, Beihang University, Beijing, China Hongmei Liu, School of Reliability and Systems Engineering, Beihang University, Beijing, China Chuan Lu, School of Reliability and Systems Engineering, Beihang University, Beijing, China Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622

Description: Self-deploying structures seek to provide a compact launch package for large, lightweight satellite booms. One self-deploying method is a foldable tape spring. This paper examines the large scale behavior of a boom attached by a tape spring hinge during mock deployments. A boom attached by tape spring to a rigid stand was released and the boom bounced up to 60° before coming to rest (as opposed to snap-through behavior). These large amplitude bounces can cause the boom to collide with sensors, other booms or arrays causing damage or preventing full deployment. Results show the first bounce of deployment is nearly bounded by a four parameter ellipse. The ellipses of similar folds are similar also, suggesting that a model can be developed. Free-fall tests simulating the free-free condition found in microgravity also show similar elliptical motion. Envelopes that bound the extents of the boom motion allow for collisions to be prevented by adjustment of the design. Content Type Journal Article Pages - DOI 10.3233/SAV-130764 Authors A.L. Jennings, Department of Aeronautics and Astronautics, Air Force Institute of Technology, WPAFB, OH, USA J. Black, Department of Aeronautics and Astronautics, Air Force Institute of Technology, WPAFB, OH, USA C. Allen, Department of Aeronautics and Astronautics, Air Force Institute of Technology, WPAFB, OH, USA Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622

Description: In this paper, a novel damage detection algorithm is developed based on blind source separation in conjunction with time-series analysis. Blind source separation (BSS), is a powerful signal processing tool that is used to identify the modal responses and mode shapes of a vibrating structure using only the knowledge of responses. In the proposed method, BSS is first employed to estimate the modal response using the vibration measurements. Time-series analysis is then performed to characterize the mono-component modal responses and successively the resulting time-series models are utilized for one-step ahead prediction of the modal response. With the occurrence of newer measurements containing the signature of damaged system, a variance-based damage index is used to identify the damage instant. Once the damage instant is identified, the damaged and undamaged modal parameters of the system are estimated in an adaptive fashion. The proposed method solves classical damage detection issues including the identification of damage instant, location as well as the severity of damage. The proposed damage detection algorithm is verified using extensive numerical simulations followed by the full scale study of UCLA Factor building using the measured responses under Parkfield earthquake. Content Type Journal Article Pages - DOI 10.3233/SAV-120759 Authors A. Sadhu, Department of Civil and Environmental Engineering, University of Waterloo, Waterloo, ON, Canada B. Hazra, Department of Civil and Environmental Engineering, University of Waterloo, Waterloo, ON, Canada Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622

Description: The thermo-mechanical nonlinear vibrations and stability of a hinged-hinged axially moving beam, additionally supported by a nonlinear spring-mass support are examined via two numerical techniques. The system is subjected to a transverse harmonic excitation force as well as a thermal loading. Hamilton's principle is employed to derive the equations of motion; it is discretized into a multi-degree-freedom system by means of the Galerkin method. The steady state resonant response of the system for both cases with and without an internal resonance between the first two modes is examined via the pseudo-arclength continuation technique. In the second method, direct time integration is employed to construct bifurcation diagrams of Poincaré maps of the system. Content Type Journal Article Pages - DOI 10.3233/SAV-120752 Authors Siavash Kazemirad, Department of Mechanical Engineering, McGill University, Montreal, QC, Canada Mergen H. Ghayesh, Department of Mechanical Engineering, McGill University, Montreal, QC, Canada Marco Amabili, Department of Mechanical Engineering, McGill University, Montreal, QC, Canada Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622

Description: A modified Karhunen-Loève Decomposition/Proper Orthogonal Decomposition method, named Smooth Decomposition (SD) (also named smooth Karhunen-Loève decomposition), was recently introduced to analyze stationary random signal. It is based on a generalized eigenproblem defined from the covariance matrix of the random process and the covariance matrix of the associated time-derivative random process. The SD appears to be an interesting tool in terms of modal analysis. In this paper, the SD will be described in case of stationary random processes and extended also to stationary random fields. The main properties will be discussed and illustrated on a randomly excited clamped-free beam. Content Type Journal Article Pages - DOI 10.3233/SAV-120763 Authors Sergio Bellizzi, LMA, CNRS, Aix-Marseille University, Marseille, France Rubens Sampaio, Department of Mechanical Engineering, PUC-Rio, Rio de Janeiro, Brazil Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622

Description: A suitable dynamic model of rotor system is of great significance not only for supplying knowledge of the fault mechanism, but also for assisting in machine health monitoring research. Many techniques have been developed for properly modeling the radial vibration of large hydro-turbine generator units. However, an applicable dynamic model has not yet been reported in literature due to the complexity of the boundary conditions and exciting forces. In this paper, a finite element (FE) rotor dynamic model of radial vibration taking account of operating conditions is proposed. A brief and practical database method is employed to model the guide bearing. Taking advantage of the method, rotating speed and bearing clearance can be considered in the model. A novel algorithm, which can take account of both transient and steady-state analysis, is proposed to solve the model. Dynamic response for rotor model of 125 MW hydro-turbine generator units in Gezhouba Power Station is simulated. Field data from Optimal Maintenance Information System for Hydro power plants (HOMIS) are analyzed compared with the simulation. Results illustrate the application value of the model in providing knowledge of the fault mechanism and in failure diagnosis. Content Type Journal Article Pages - DOI 10.3233/SAV-120758 Authors Yong Xu, College of Water Resource {and} Hydropower, Sichuan University, Chengdu, Sichuan, China Zhaohui Li, School of Hydropower {and} Information Engineering, Huazhong University of Science and Technology, Wuhan, Hubei, China Xide Lai, School of Energy and Environment, Xihua University, Chengdu, Sichuan, China Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622

Description: The Soft Catch Gun at Picatinny Arsenal is regularly used for component testing. Most shots contain accelerometers which record accelerations as a function of time. Statistics of accelerometer data indicate that the muzzle exit accelerations are, on average, higher than tactical firings. For that reason, Soft Catch Gun tests with unusually high accelerations may not be scored for Lot Acceptance Tests (LAT) by some customers. The 95/50 Normal Tolerance Limit (NTL) is proposed as a means of determining which test results should be scored. This paper presents comparisons of Shock Response Spectra (SRS) used for the 95/50 scoring criteria. The paper also provides a Discussion Section outlining some concerns with scoring LAT results based on test results outside of the proposed 95/50 criteria. Content Type Journal Article Pages - DOI 10.3233/SAV-120762 Authors J.A. Cordes, U.S. Army ARDEC, Fuze and Precision Armaments Technology (RDAR-MEF-E), Picatinny Arsenal, NJ, USA P. Vo, Raytheon Missile Systems, Tucson, AZ, USA J. Lee, U.S. Army ARDEC, Fuze and Precision Armaments Technology (RDAR-MEF-E), Picatinny Arsenal, NJ, USA D. Geissler, U.S. Army ARDEC, Fuze and Precision Armaments Technology (RDAR-MEF-E), Picatinny Arsenal, NJ, USA J. Metz, U.S. Army ARDEC, Fuze and Precision Armaments Technology (RDAR-MEF-E), Picatinny Arsenal, NJ, USA D. Troast, U.S. Army ARDEC, Fuze and Precision Armaments Technology (RDAR-MEF-E), Picatinny Arsenal, NJ, USA A. Totten, U.S. Army ARDEC, Fuze and Precision Armaments Technology (RDAR-MEF-E), Picatinny Arsenal, NJ, USA Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622

Description: Structural spectral elements are formulated using the analytical solution of the applicable elastodynamic equations and, therefore, mesh refinement is not needed to analyze high frequency behavior provided the elastodynamic equations used remain valid. However,~for modeling complex structures, standard spectral elements require long and cumbersome analytical formulation. In this work, a method to build spectral finite elements from a finite element model of a slice of a structural waveguide (a structure with one dimension much larger than the other two) is proposed. First, the transfer matrix of the structural waveguide is obtained from the finite element model of a thin slice. Then, the wavenumbers and wave propagation modes are obtained from the transfer matrix and used to build the spectral element matrix. These spectral elements can be used to model homogeneous waveguides with constant cross section over long spans without the need of refining the finite element mesh along the waveguide. As an illustrating example, spectral elements are derived for straight uniform rods and beams and used to calculate the forced response in the longitudinal and transverse directions. Results obtained with the spectral element formulation are shown to agree well with results obtained with a finite element model of the whole beam. The proposed approach can be used to generate spectral elements of waveguides of arbitrary cross section and, potentially, of arbitrary order. Content Type Journal Article Pages - DOI 10.3233/SAV-120760 Authors P.B. Silva, Departamento de Mecânica Computacional, FEM, Universidade Estadual de Campinas R. Mendeleyev, Campinas – SP, Brazil A.L. Goldstein, Departamento de Mecânica Computacional, FEM, Universidade Estadual de Campinas R. Mendeleyev, Campinas – SP, Brazil J.R.F. Arruda, Departamento de Mecânica Computacional, FEM, Universidade Estadual de Campinas R. Mendeleyev, Campinas – SP, Brazil Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622

Description: In this study, free vibration analysis of beams carrying a number of various concentrated elements including point masses, rotary inertias, linear springs, rotational springs and spring-mass systems subjected to the axial load was performed. All analyses were performed using an Euler beam assumption and the Finite Element Method. The beam used in the analyses is accepted as pinned-pinned. The axial load applied to the beam from the free ends is either compressive or tensile. The effects of parameters such as the number of spring-mass systems on the beam, their locations and the axial load on the natural frequencies were investigated. The mode shapes of beams under axial load were also obtained. Content Type Journal Article Pages - DOI 10.3233/SAV-120750 Authors Gürkan Şakar, Department of Mechanical Engineering, Atatürk University, 25240 Erzurum, Turkey. E-mail: gsakar@atauni.edu.tr Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622

Description: When designing critical structures such as long-span structures and high-rise buildings, earthquake excitation in the vertical direction, in addition to the horizontal direction, should also be taken into consideration. Study on new devices that can mitigate and isolate multi-dimensional (including both horizontal and vertical) earthquake actions has a remarkable significance. A new kind of multi-dimensional earthquake isolation and mitigation device was recently developed, and experimental study on vertical performances of the device under different excitation frequencies and amplitudes has been carried out in this paper. The characteristics of the vertical properties including the initial stiffness, the energy dissipation stiffness, the energy dissipation per cycle and the vertical damping ratio changing with excitation frequency and amplitude were studied, and the formulas describing the characteristics were proposed. It can be concluded that the initial stiffness and the energy dissipation stiffness increase slightly with increasing frequency, while the energy dissipation per cycle and the damping ratio decrease slightly with increasing frequency, the initial stiffness, the energy dissipation stiffness and the damping ratio will decrease slightly with increasing excitation amplitudes, and the proposed formulas can describe the vertical properties of the multi-dimensional earthquake isolation and mitigation device changing with excitation frequency and amplitude. Content Type Journal Article Pages - DOI 10.3233/SAV-120753 Authors Zhaodong Xu, Key Laboratory of Concrete and Prestressed Concrete Structures of the Ministry of Education, Southeast University, Nanjing, Jiangsu, China Liheng Lu, Key Laboratory of Concrete and Prestressed Concrete Structures of the Ministry of Education, Southeast University, Nanjing, Jiangsu, China Benqiang Shi, Guangdong Country Garden Holdings Limited Company, Foshan, Guangdong, China Fuhgwo Yuan, Department of Mechanical Engineering, North Carolina State University, Raleigh, NC, USA Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622

Description: Wave based method which can be recognized as a semi-analytical and semi-numerical method is presented to analyze the free vibration characteristics of ring stiffened cylindrical shell with intermediate large frame ribs for arbitrary boundary conditions. According to the structure type and the positions of discontinuities, the model is divided into different substructures whose vibration field is expanded by wave functions which are exactly analytical solutions to the governing equations of the motions of corresponding structure type. Boundary conditions and continuity equations between different substructures are used to form the final matrix to be solved. Natural frequencies and vibration mode shapes are calculated by wave based method and the results show good agreement with finite element method for clamped-clamped, shear diaphragm – shear diaphragm and free-free boundary conditions. Free vibration characteristics of ring stiffened cylindrical shells with intermediate large frame ribs are compared with those with bulkheads and those with all ordinary ribs. Effects of the size, the number and the distribution of intermediate large frame rib are investigated. The frame rib which is large enough is playing a role as bulkhead, which can be considered imposing simply supported and clamped constraints at one end of the cabin and dividing the cylindrical shell into several cabins vibrating separately at their own natural frequencies. Content Type Journal Article Pages - DOI 10.3233/SAV-120761 Authors Meixia Chen, School of Naval Architecture and Ocean Engineering, Huazhong University of Science and Technology, Wuhan, Hubei, China Jianhui Wei, School of Naval Architecture and Ocean Engineering, Huazhong University of Science and Technology, Wuhan, Hubei, China Kun Xie, School of Naval Architecture and Ocean Engineering, Huazhong University of Science and Technology, Wuhan, Hubei, China Naiqi Deng, School of Naval Architecture and Ocean Engineering, Huazhong University of Science and Technology, Wuhan, Hubei, China Guoxiang Hou, School of Naval Architecture and Ocean Engineering, Huazhong University of Science and Technology, Wuhan, Hubei, China Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622

Description: The flexible beams carrying attachments often appear in engineering structures, modal analysis of those structures is important and necessary in structural design. This manuscript develops a proposed analytical method as a general tool for solving the free vibration of beams carrying various types of attachments with different distributions and arbitrary boundary conditions. In current practice, the natural frequencies of beam carrying lumped and uniform sprung mass and resting on Pasternak soil are calculated and compared with those in references to verify the methodology firstly. Then, the natural frequencies of beam carrying non-uniform spring-mass systems and stepped beam on Pasternak soil are calculated by the proposed method to study free vibration of beam carrying attachments with non-uniform cross section or distribution. Finally, some important conclusions are derived from results, which reveal that distribution density of spring-mass system at peaks of the mode shape makes dominate effects on the change of the natural frequencies at that mode and the natural frequencies of the stepped beam resting on elastic foundation are more sensitive to the increase of soil parameters. Content Type Journal Article Pages - DOI 10.3233/SAV-120751 Authors Heye Xiao, College of Marine, Northwestern Polytechnical University, Xi'an, Shaanxi, China Meiping sheng, College of Marine, Northwestern Polytechnical University, Xi'an, Shaanxi, China Zhihong Liu, College of Marine, Northwestern Polytechnical University, Xi'an, Shaanxi, China Zhaoyu Wei, School of Naval Architecture and Ocean Engineering, Jiangsu University of Science and Technology, Zhenjiang, Jiangsu, China Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622

Description: The work shows the use of a scaled roller rig to validate a real time wheel-rail contact code developed to study the wheel rail adhesion and the wear evolution. The code allows the profiles to change at each time step in order to take into account the material loss due to the wear process. The contact code replicates a testing machine composed of a roller rig with a prototype of a single suspended wheelset pressed onto it with a variable load. In order to generate the tangential forces, responsible for the wear process during the tests, the roller rig has independent rollers powered by electric motors and a dedicated control. The first motor is moved at the reference speed, while the second one produces a traction/braking torque that generates a specific longitudinal creepage that is controlled during the test. The system also allows measurement of specific kinematical quantities and forces that are elaborated by the real-time code in order to produce numerical results for comparison with the experimental ones. In this way the contact algorithm can be validated and optimized referring to experimental data directly measured in real time. This approach can be applied both to the determination of wheel-rail adhesion and to the wear process. The test rig is also equipped with a laser profilometer that allows measurement of the wheel and rail profiles with a very high accuracy. The initial profiles measured on the rig are used by the contact algorithm, where the wear model, based on Archard's method, is implemented, to estimate the profile evolution during the test. After a certain period of time the profiles are re-scanned and compared with the results of the simulation in order to adjust the wear rate. Content Type Journal Article Pages - DOI 10.3233/SAV-130820 Authors Nicola Bosso, Politecnico di Torino, C.so Duca degli Abruzzi 24, Torino, Italy Nicolò Zampieri, Politecnico di Torino, C.so Duca degli Abruzzi 24, Torino, Italy Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622

Description: The development of large scale Liquid Natural Gas (LNG) and high pressure Carbon Dioxide (CO_2) reinjection increases the need of technology to improve, predict and evaluate the stability of turbomachinery. In this paper, a system identification method for rotating machinery stability evaluation is investigated based on sine-sweep excitation testing with electromagnetic actuator. The least square method is applied to estimate the FRF to improve the data accuracy in frequency domain. Additionally, Smooth processing method is used to restrain the high-frequency noise to obtain clear characteristics of the frequency responses. Then, the traditional MIMO FRF is transformed into dFRF from real number field to complex field with a transformation matrix, eliminating the influence of forward and backward modal overlap and providing higher accuracy to identify rotor's first forward modal parameters using the rational polynomial method. Finally, the modal parameters are acquired for stability estimation by applying rational polynomial method to fit and identify the traditional MIMO FRF and dFRF. Furthermore, two sets of bearing with preload of 0.1 and 0.3 under both Load-On-Pad (LOP) and Load-Between-Pad (LBP) conditions are investigated. Additonally, the effect of oil inlet pressure (1.0 bar–1.75 bar) and temperature (43°C–51°C) on the stability of rotor are investigated in detail. Results indicate that the stability of rotor will be improved by increase the oil inlet temperature and pressure. It is found that the rotor is more stable on bearing with 0.1 preload than that of 0.3 preload. Load-on-Pad provides more damping to rotor than load-between-pad. The method and outcomes of this paper can provide both theory basis and technology foundation for improving the rotor stability of centrifugal compressors. Content Type Journal Article Pages - DOI 10.3233/SAV-130814 Authors Weimin Wang, Beijing Key Laboratory of Health Monitoring and Self-recovery for High-end Mechanical Equipment, Beijing University of Chemical Technology, Beijing, China Qihang Li, Beijing Key Laboratory of Health Monitoring and Self-recovery for High-end Mechanical Equipment, Beijing University of Chemical Technology, Beijing, China Jinji Gao, Beijing Key Laboratory of Health Monitoring and Self-recovery for High-end Mechanical Equipment, Beijing University of Chemical Technology, Beijing, China Feng He, ROMAC, Mechanical and Aerospace Engineering, University of Virginia, Charlottesville, VA, USA Tim Diamond, ROMAC, Mechanical and Aerospace Engineering, University of Virginia, Charlottesville, VA, USA Paul Allaire, ROMAC, Mechanical and Aerospace Engineering, University of Virginia, Charlottesville, VA, USA Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622

Description: The submarine experiences longitudinal vibration in the propulsion shafting system throughout most of run. With the intent to understand this type of vibration, the analytical study is carried out. In view of chained characteristic of propulsion shafting system, the transfer matrix model has been established to describe the dynamic behavior. This modular description facilitates greater flexibility for modeling and manipulating design modifications. As rotor-bearing system, the dynamic characteristics of lubricant oil film between thrust collar and tilting pads within thrust bearing are considered. Using hydrodynamic lubrication theory and small perturbation method, the axial stiffness and damping of oil film are deduced in great detail. Since the foundation contributes to axial rigidity of thrust bearing greatly, numerical estimation is made of the foundation stiffness with the finite element method. Based upon these values of dynamic parameters, the Campbell diagram describing natural frequencies in terms of shafting rotating speeds is available. The effect on natural frequencies and vibratory response of considerable variations in thrust bearing stiffness is next investigated. To alter natural frequency and reduce off-resonance response without drastic changes in structural configuration of thrust bearing foundation, the measure of moving thrust bearing backward is also examined. The longitudinal vibration transmission through the propulsion shafting system results in subsequent axial excitation of hull, the thrust load acting on the hull is particularly concerned. It is observed that the measures of structural modification are of little benefit to minimize thrust load transmitted to hull. The work will aid in understanding of the problem of propulsion shafting longitudinal vibration in submarine and provide reference for vibration control in future. Content Type Journal Article Pages - DOI 10.3233/SAV-130815 Authors Ganbo Zhang, School of Naval Architecture and Ocean Engineering, Huazhong University of Science and Technology, Wuhan, Hubei, China Yao Zhao, School of Naval Architecture and Ocean Engineering, Huazhong University of Science and Technology, Wuhan, Hubei, China Tianyun Li, School of Naval Architecture and Ocean Engineering, Huazhong University of Science and Technology, Wuhan, Hubei, China Xiang Zhu, School of Naval Architecture and Ocean Engineering, Huazhong University of Science and Technology, Wuhan, Hubei, China Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622

Description: The analysis of cylindrical shells using an improved version of the differential quadrature method is presented. The generalized differential quadrature (GDQ) method has computational advantages over the existing differential quadrature method. The GDQ method has been applied in solutions to fluid dynamics and plate problems and has shown superb accuracy, efficiency, convenience, and great potential in solving differential equations. The present article attempts to apply the method to the solutions of cylindrical shell problems. To illustrate the implementation of the GDQ method, the frequencies and fundamental frequencies for simply supported-simply supported, clamped-clamped, and clamped-simply supported boundary conditions are determined. Results obtained are validated by comparing them with those in the literature. Content Type Journal Article Pages 193-198 DOI 10.3233/SAV-1997-4305 Authors C.T. Loy, Department of Mechanical and Production Engineering, National University of Singapore, 10 Kent Ridge Crescent, Singapore 0511 K.Y. Lam, Department of Mechanical and Production Engineering, National University of Singapore, 10 Kent Ridge Crescent, Singapore 0511 C. Shu, Department of Mechanical and Production Engineering, National University of Singapore, 10 Kent Ridge Crescent, Singapore 0511 Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622 Journal Volume Volume 4 Journal Issue Volume 4, Number 3 / 1997

Description: During fatigue damage accumulation, cracks propagate through the material leading to catastrophic failure. As the cracks propagate, the natural frequency lowers, leading to a changing stress state. A new method has been developed where the damage accumulation rate is computed in the frequency domain using Linear Elastic Fracture Mechanics (LEFM), stress intensity and the natural frequency. A finite element model was developed to predict the stress intensity and natural frequency during damage accumulation. Validation of the LEFM technique was done through comparison to experimental data. Reasonably good correlation between the FEM and the analytic model were achieved for the stress intensity and natural frequency. Content Type Journal Article Pages - DOI 10.3233/SAV-130813 Authors Ed Habtour, Vehicle Technology Directorate, U.S. Army Research Laboratory, Aberdeen Proving Ground, MD, USA Mark Paulus, Naval Undersea Warfare Center Division, Keyport, WA, USA Abhijit Dasgupta, Department of Mechanical Engineering, College Park, University of Maryland, MD, USA Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622

Description: The stationary response of smooth and bilinear hysteretic systems to narrow-band random excitations is investigated by using the quasistatic method and digital simulation. It is shown that the response is qualitatively different in different ranges of values of the ratio of the excitation central frequency to the natural frequency of the system. In the resonant zone, the response is essentially non-Gaussian. For bilinear hysteretic systems with strong yielding, stochastic jumps may occur for a range of values of the ratio between nonresonant and resonant zones. Content Type Journal Article Pages 241-250 DOI 10.3233/SAV-1997-4404 Authors W.Q. Zhu, Department of Mechanics, Zhejiang University, Hangzhau 310027, China C.D. Huang, Canton/Seinuk Group 219, East 42nd St., New York, NY 10017-5736, USA T.T. Soong, Department of Civil Engineering, State University of New York, at Buffalo, Buffalo, NY 14260, USA Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622 Journal Volume Volume 4 Journal Issue Volume 4, Number 4 / 1997

Description: When a material is subjected to an alternating stress field, there are temperature fluctuations throughout its volume due to the thermoelastic effect. The resulting irreversible heat conduction leads to entropy production that in turn is the cause of thermoelastic damping. An analytical investigation of the entropy produced during a vibration cycle due to the reciprocity of temperature rise and strain yielded the change of the material damping factor as a function of the porosity of the material. A homogeneous, isotropic, elastic bar of cylindrical shape is considered with uniformly distributed spherical cavities under alternating uniform axial stress. The analytical calculation of the dynamic characteristics of the porous structure yielded the damping factor of the bar and the material damping factor. Exsperimental results on porous metals are in good correlation with an analysis. Content Type Journal Article Pages 261-268 DOI 10.3233/SAV-1997-4406 Authors Sofia D. Panteliou, Department of Mechanical Engineering, University of Patras, Patras 26110, Greece Andrew D. Dimarogonas, Department of Mechanical Design, Washington University, St. Louis, MO 63 130, USA Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622 Journal Volume Volume 4 Journal Issue Volume 4, Number 4 / 1997

Description: An in situ full-scale test is conducted to measure the dynamic response of a long cantilever wall that retains backfill soil. The recorded modal parameters of this retaining wall exhibited significant similarity to those of a clamped cantilever plate (rather than those of a cantilever beam or plane-strain analysis). Such a three-dimensional (3-D) response pattern is not accounted for by current analysis procedures. A simple 3-D finite element model is employed to further analyze the observed resonant configurations. The results indicate that such configurations play an important role in the seismic response of wall backfill soil systems of variable height, such as wing walls supporting highway approach ramps. Content Type Journal Article Pages 251-259 DOI 10.3233/SAV-1997-4405 Authors Sreenivas Alampalli, Transportation Research & Development Bureau, New York State Department of Transportation, 1220, Washington Avenue, Albany, NY 12232-0869, USA. E-mail: salampalli@gw.dot.state.ny.us Ahmed-W. Elgamal, University of California at San Diego, San Diego, CA 92093-0085, USA. E-mail: elgamal@ucsd.edu Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622 Journal Volume Volume 4 Journal Issue Volume 4, Number 4 / 1997

Description: A statistically generated weighting function for a second-order polynomial curve fit of residual functions has been developed. The residual flexibility test method, from which a residual function is generated, is a procedure to modal test large structures in a free-free environment to measure the effects of higher order modes and stiffness at distinct degree of freedom interfaces. Due to the present damping estimate limitations in the modal parameter evaluation (natural frequencies and mode shapes) of test data, the residual function has regions of irregular data, which should be a smooth curve in a second-order polynomial form. A weighting function of the data is generated by examining the variances between neighboring data points. From a weighted second-order polynomial curve fit, an accurate residual flexibility value can be obtained. The residual flexibility value and free-free modes from testing are used to improve a mathematical model of the structure, which is used to predict constrained mode shapes. Content Type Journal Article Pages 211-222 DOI 10.3233/SAV-1997-4401 Authors Paul Stanley Bookout, Marshall Space Flight Center (MSFC), Structural Analysis Division, ED23, AL 35812, USA Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622 Journal Volume Volume 4 Journal Issue Volume 4, Number 4 / 1997

Description: Two extensions of the force reconstruction method, the sum of weighted accelerations technique (SWAT), are presented in this article. SWAT requires the use of the structure's elastic mode shapes for reconstruction of the applied force. Although based on the same theory, the two new techniques do not rely on mode shapes to reconstruct the applied force and may be applied to structures whose mode shapes are not available. One technique uses the measured force and acceleration responses with the rigid body mode shapes to calculate the scalar weighting vector, so the technique is called SWAT-CAL (SWAT using a calibrated force input). The second technique uses the free-decay time response of the structure with the rigid body mode shapes to calculate the scalar weighting vector and is called SWAT-TEEM (SWAT using time eliminated elastic modes). All three methods are used to reconstruct forces for a simple structure. Content Type Journal Article Pages 231-239 DOI 10.3233/SAV-1997-4403 Authors Vesta I. Bateman, Sandia National Laboratories, Albuquerque, NM 87185-0555, USA Randall L. Mayes, Sandia National Laboratories, Albuquerque, NM 87185-0555, USA Thomas G. Carne, Sandia National Laboratories, Albuquerque, NM 87185-0555, USA Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622 Journal Volume Volume 4 Journal Issue Volume 4, Number 4 / 1997

Description: By using the Poincaré-like cell-to-cell mapping method and shooting method, the global characteristics of a planetary gear train is studied based on the torsional vibration model with errors of transmission, time varying meshing stiffness and multiple gear backlashes. The study results reveal that the planetary with a certain set of parameters has four coexisting periodic orbits, which is P-1, P-2, P-4, P-8 respectively. P-1 and P-2 motion aren't of long-term stability, P-8 motion is of local stability, and P-4 motion is of global stability; Shooting method doesn't have the capacity of searching coexisting periodic orbits in a global scope, and is easy to omit some periodic orbits which are far away from the main gropes of periodic orbits. Content Type Journal Article Pages - DOI 10.3233/SAV-130812 Authors T.J. Li, College of Mechanical and Electrical Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing, Jiangsu, China R.P. Zhu, College of Mechanical and Electrical Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing, Jiangsu, China Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622

Description: A lot of research on the properties of a panel-enclosure coupled system which consists of an enclosure with a simply supported flexible wall was conducted. However, an enclosure with clamped flexible walls is commonly encountered. The properties of a panel-enclosure system, with one clamped flexible wall, are different from that of a simply supported one, and there are only a few studies on it. Thus, this paper is dedicated to the study of the effect of structural-acoustic coupling on the properties of a panel-enclosure system, which consists of an enclosure with a clamped panel. The resonance frequencies and the decay times of the coupled system are obtained using the classical modal coupling theory. The effect of enclosure and its flexible boundary on the resonance frequencies and the modal decay times of the coupled system are then analyzed. It is shown that when panel thickness is changed, coupling strength is determined by the difference between the resonance frequencies of the panel and the enclosure modes. However, for the variation of enclosure depth, the factor which determines the coupling strength between panel and enclosure modes is the enclosure depth or the difference between their resonance frequencies. Content Type Journal Article Pages - DOI 10.3233/SAV-130811 Authors Yuan Wang, College of Mechanical Engineering, Southeast University, Nanjing, Jiangsu, China Jianrun Zhang, College of Mechanical Engineering, Southeast University, Nanjing, Jiangsu, China Vanquynh Le, College of Mechanical Engineering, Southeast University, Nanjing, Jiangsu, China Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622

Description: A diagnostic method, which uses the two-sided directional power spectra of complex-valued engine vibration signals, is presented and tested with four-cylinder compression and spark ignition engines for the diagnosis of cylinder power faults. As spectral estimators, the maximum likelihood and FFT methods are compared, and the multi-layer neural network is employed for pattern recognition. Experimental results show that the success rate for identifying the misfired cylinder is much higher with the use of two-sided directional power spectra than conventional one-sided power spectra. Content Type Journal Article Pages 391-401 DOI 10.3233/SAV-1997-45-609 Authors Chong-Won Lee, Center for Noise and Vibration Control (NOVIC), Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology, Science Town, Taejon 305-701, South Korea Yun-Sik Han, Center for Noise and Vibration Control (NOVIC), Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology, Science Town, Taejon 305-701, South Korea Jong-Po Park, Vibration Research Team, Research and Development Center, Korea Heavy Industries and Construction Co., Ltd., P.O. Box 77, Changwon 641-792, South Korea Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622 Journal Volume Volume 4 Journal Issue Volume 4, Number 5-6 / 1997

Description: This paper deals with measurement of a strong shock pressure like an imploding detonation of over 1 GPa which cannot be measured directly with currently available commercial pressure transducers. After the transfer functions of three kinds of materials were measured using a shock tube, Teflon was selected as a shock absorber. As an example of pressure beyond the limit of the pressure transducer, we tried to measure pressure at the center of an imploding detonation. From this measurement, we could estimate the pressure peak of about 1.7 GPa. Content Type Journal Article Pages 403-409 DOI 10.3233/SAV-1997-45-610 Authors Hajime Takada, Yokohama National University, Department of Mechanical Engineering and Materials Science, Japan Daisuke Fujimaki, Mitsubishi Motor Co. Ltd., Japan Takao Tsuboi, Yokohama National University, Japan Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622 Journal Volume Volume 4 Journal Issue Volume 4, Number 5-6 / 1997

Description: A first-principles-based model is presented for calculating the hole diameter resulting from the normal hypervelocity impact of a spherical aluminum projectile on a thin aluminum plate. One-dimensional shock theory is used to predict the creation and attenuation of Hugoniot pressures along the plate surface. Pressures are translated into the plate thickness by calculating intersecting positions of advancing shock fronts and centered-fan rarefaction waves. The radial position at which the shock pressure equals a predetermined value is defined to be the hole diameter. The model was calibrated by determining this critical value for aluminum-an-aluminum impacts using several hundred data points. A residuals analysis indicated some inherent problems with the model. Two empirical factors were added to account for thin plate and two-dimensional shock dissipation effects. The predictions of the adjusted model are shown to compare well with predictions of several empirical hole diameter models. Content Type Journal Article Pages 379-390 DOI 10.3233/SAV-1997-45-608 Authors William H. Jolly, Civil & Environmental Engineering Department, The University of Alabama in Huntsville, Huntsville, AL 35899, USA William P. Schonberg, Civil & Environmental Engineering Department, The University of Alabama in Huntsville, Huntsville, AL 35899, USA Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622 Journal Volume Volume 4 Journal Issue Volume 4, Number 5-6 / 1997

Description: The paper reviews several methods for the generation of stationary realizations of sampled time histories with non-Gaussian distributions and introduces a new method which can be used to control the cross-spectral density matrix and the probability density functions (pdfs) of the multiple input problem. Discussed first are two methods for the specialized case of matching the auto (power) spectrum, the skewness, and kurtosis using generalized shot noise and using polynomial functions. It is then shown that the skewness and kurtosis can also be controlled by the phase of a complex frequency domain description of the random process. The general case of matching a target probability density function using a zero memory nonlinear (ZMNL) function is then covered. Next methods for generating vectors of random variables with a specified covariance matrix for a class of spherically invariant random vectors (SIRV) are discussed. Finally the general case of matching the cross-spectral density matrix of a vector of inputs with non-Gaussian marginal distributions is presented. Content Type Journal Article Pages 361-377 DOI 10.3233/SAV-1997-45-607 Authors David O. Smallwood, Mechanical and Thermal Environments Department, Sandia National Laboratories, P.O. Box 5800, MS-0865 Albuquerque, NM 87185-0865, USA Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622 Journal Volume Volume 4 Journal Issue Volume 4, Number 5-6 / 1997

Description: In this article the synchronization of two eccentric rotors driven by hydraulic motors (TERDHM) in one vibrating system is studied. The differential equations of TERDHM motion are derived, and the synchronous and stable rotating conditions of TERDHM are established. It is found from the analysis and simulation that the angular velocities of TERDHM act on each other and both vary in a small range approaching their mean value. The synchronous rotation speed is equal to the average angular velocity of TERDHM, and the phase difference between them depends on the difference of the flow rates of the two hydraulic motors. Content Type Journal Article Pages 305-310 DOI 10.3233/SAV-1997-45-602 Authors Tianxia Zhang, Department of Mechanical Engineering, Northeastern University, Shenyang, Liaoning, 110006 China Bangchun Wen, Department of Mechanical Engineering, Northeastern University, Shenyang, Liaoning, 110006 China Jian Fan, Department of Mechanical Engineering, Northeastern University, Shenyang, Liaoning, 110006 China Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622 Journal Volume Volume 4 Journal Issue Volume 4, Number 5-6 / 1997

Description: The Toeplitz Jacobian matrix method is an efficient algorithm for computing the steady state solutions of nonlinear periodic vibration. In this paper, the method is generalized by using multiple time scales to double-periodic solutions in a multi-frequency excited system. The method is combined with a standard multi-dimensional FFT algorithm to accurately simulate the nonlinear oscillators with widely separated frequencies. The continuation technique can also be incorporated with the Newton–Raphson iteration to further increase its efficiency, and to achieve the complete frequency response characteristics. Content Type Journal Article Pages 351-359 DOI 10.3233/SAV-1997-45-606 Authors T. Ge, School of Engineering, University of Manchester, M13 9PL, UK A.Y.T. Leung, School of Engineering, University of Manchester, M13 9PL, UK Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622 Journal Volume Volume 4 Journal Issue Volume 4, Number 5-6 / 1997

Description: A fluid surface damping (FSD) technique for vibration suppression of beamlikestructures is proposed. The technique is a modification of the surface layer damping method. Two viscoelastic surface layers containing fluid-filled cavities are attached symmetrically to the opposite surfaces of the beam. The cavities on one side are attached to the corresponding cavities on the other side via connection passages. As the beam vibrates, the fluid is pumped back and forth through the connecting passages. Therefore, in addition to the viscoelastic damping provided by the surface layers, the technique offers viscous damping due to the fluid flow through the passage. A mathematical model for the proposed technique is developed, normalized, and solved in the frequency domain to investigate the effect of various parameters on the vibration suppression of a cantilever beam. The steady-state frequency response for a base white-noise excitation is calculated at the beam's free tip and over a frequency range containing the first five resonant frequencies. The parameters investigated are the flow-through passage viscous resistance, the length and location of the layers, the hydraulic capacitance of the fluid-filled cavities, and inertia of the moving fluid (hydraulic inertance). Results indicate that the proposed technique has promising potential in the field of vibration suppression of beamlike structures. With two FSD elements, all peak vibration amplitudes can be well suppressed over the entire frequency spectrum studied. Content Type Journal Article Pages 295-304 DOI 10.3233/SAV-1997-45-601 Authors Hany Ghoneim, Department of Mechanical and Industrial Engineering, Kuwait University, PO Box 5969, Safat 13060, Kuwait Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622 Journal Volume Volume 4 Journal Issue Volume 4, Number 5-6 / 1997

Description: In this article a procedure is presented for the analytical synthesis of optimal vibration isolation for a hand-arm system subjected to stochastic excitation. A general approach is discussed for a selected vibration isolation criterion. The general procedure is illustrated by analytical examples for different hand-arm systems described by their driving-point impedances. The influence of particular forms of excitation and the structure of the vibroisolated hand-arm systems on the resultant vibration isolation is then discussed. Some numerical examples illustrating the procedure have also been included. Content Type Journal Article Pages 281-291 DOI 10.3233/SAV-1997-4408 Authors Marek Ksi\c{a}żek, Institute of Mechanics and Machine Design, Cracow University of Technology, Al. Jana Pawła II 37, 31-864 Kraków, Poland Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622 Journal Volume Volume 4 Journal Issue Volume 4, Number 4 / 1997

Description: A uniform description is given of a method of measurement using a Michelson interferometer for measuring the linear motion quantities acceleration, velocity and displacement, and a diffraction grating interferometer for measuring the circular motion quantities angular acceleration, angular velocity and rotation angle. The paper focusses on an analysis of the dynamic behaviour of an interferometric measurement system based on the counting technique with regard to the measurement errors due to deterministic and stochastic disturbing quantities. The error analysis and description presented are aimed at giving some rules, mathematical expressions and graphical presentations that have proved to be helpful in recognizing the errors in interferometric measurements of motion quantities, optimizing the measurement conditions (e.g., filter settings), obtaining corrections and estimating the uncertainty of measurement. Content Type Journal Article Pages 327-340 DOI 10.3233/SAV-1997-45-604 Authors Hans-Jürgen von Martens, Physikalisch-Technische Bundesanstalt (PTB), Fürstenwalder Damm 388, 12587 Berlin, Germany Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622 Journal Volume Volume 4 Journal Issue Volume 4, Number 5-6 / 1997

Description: An eigenvalue sensitivity formula for a combined beam structure due to the variation of its shape or joint coordinates is proposed based on the Lagrange multiplier technique for a free vibration equation of the structure. The shape variation is decomposed into the length and the orientation variation of each beam to obtain individual effects on the total sensitivity. The sensitivity equations due to the length and the orientation variations are expressed as an energy density form and the cross product of joint forces and displacements respectively. Several numerical examples are also presented to validate the proposed formulation and to show how to implement the idea. Content Type Journal Article Pages 341-350 DOI 10.3233/SAV-1997-45-605 Authors Kwang-Min Won, Korea Advanced Institute of Science, and Technology, Taejon 305-701, Korea Youn-sik Park, Korea Advanced Institute of Science, and Technology, Taejon 305-701, Korea Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622 Journal Volume Volume 4 Journal Issue Volume 4, Number 5-6 / 1997

Description: Substructuring and component mode synthesis (CMS), is a very popular method of model reduction for large structural dynamics problems. Starting from the pioneering works on this technique in the early 1960s, many researchers have studied and used this technique in a variety of applications. Besides model reduction, CMS offers several other crucial advantages. The present work aims to provide a review of the available literature on this important technique. Content Type Journal Article Category Review Pages 199-210 DOI 10.3233/SAV-1997-4306 Authors P. Seshu, Dept. of Mechanical Engineering, Indian Institute of Technology, Powai, Bombay 400 076, India Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622 Journal Volume Volume 4 Journal Issue Volume 4, Number 3 / 1997

Description: A nonlinear three dimensional (3D) single rack model and a nonlinear 3D whole pool multi-rack model are developed for the spent fuel storage racks of a nuclear power plant (NPP) to determine impacts and frictional motion responses when subjected to 3D excitations from the supporting building floor. The submerged free standing rack system and surrounding water are coupled due to hydrodynamic fluid-structure interaction (FSI) using potential theory. The models developed have features that allow consideration of geometric and material nonlinearities including (1) the impacts of fuel assemblies to rack cells, a rack to adjacent racks or pool walls, and rack support legs to the pool floor; (2) the hydrodynamic coupling of fuel assemblies with their storing racks, and of a rack with adjacent racks, pool walls, and the pool floor; and (3) the dynamic motion behavior of rocking, twisting, and frictional sliding of rack modules. Using these models 3D nonlinear time history dynamic analyses are performed per the U.S. Nuclear Regulatory Commission (USNRC) criteria. Since few such modeling, analyses, and results using both the 3D single and whole pool multiple rack models are available in the literature, this paper emphasizes description of modeling and analysis techniques using the SOLVIA general purpose nonlinear finite element code. Typical response results with different Coulomb friction coefficients are presented and discussed. Content Type Journal Article Pages 311-325 DOI 10.3233/SAV-1997-45-603 Authors Yong Zhao, Engineering Mechanics Group Battelle, 505 King Avenue, Columbus, OH 43201, USA Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622 Journal Volume Volume 4 Journal Issue Volume 4, Number 5-6 / 1997

Description: Simple models representing a shaker and a test object are used to illustrate changes in test object response due to shaker dynamics and differences between the test and service environment. The degree of coupling is quantified in terms of ratios of the natural frequencies and the masses. Regions of overstress can depend on reproducing absolute rather than relative motion in a test. Shaker tests reprodusing output spectra observed in service, when shakerlji.xture impedance is higher than the impedance in service, is shown to cause overtest at frequencies below natural frequencies of the service environment. Content Type Journal Article Pages 269-280 DOI 10.3233/SAV-1997-4407 Authors Craig C. Smith, Department of Mechanical Engineering, Brigham Young University, Provo, UT 84602-4102, USA Forrest L. Staffanson, Department of Mechanical Engineering, Brigham Young University, Provo, UT 84602-4102, USA Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622 Journal Volume Volume 4 Journal Issue Volume 4, Number 4 / 1997

Description: High speed rotary motion of complex joints were quantified with triaxial angular rate sensors. Angular rate sensors were mounted to rigid links on either side of a joint to measure angular velocities about three orthogonal sensor axes. After collecting the data, the angular velocity vector of each sensor was transformed to local link axes and integrated to obtain the incremental change in angular position for each time step. Using the angular position time histories, a transformation matrix between the reference frame of each link was calculated. Incremental Eulerian rotations from the transformation matrix were calculated using an axis system defined for the joint. Summation of the incremental Eulerian rotations produced the angular position of the joint in terms of the standard axes. This procedure is illustrated by applying it to joint motion of the ankle, the spine, and the neck of crash dummies during impact tests. The methodology exhibited an accuracy of less than 5% error, improved flexibility over photographic techniques, and the ability to examine 3-dimensional motion. Content Type Journal Article Pages 223-229 DOI 10.3233/SAV-1997-4402 Authors Gregory W. Hall, Department of Mechanical, Aerospace, and Nuclear Engineering, Automobile Safety Laboratory, University of Virginia, 1011 Linden Avenue, Charlottesville, VA 22902, USA Jeff R. Crandall, Department of Mechanical, Aerospace, and Nuclear Engineering, Automobile Safety Laboratory, University of Virginia, 1011 Linden Avenue, Charlottesville, VA 22902, USA Gregory S. Klopp, Department of Mechanical, Aerospace, and Nuclear Engineering, Automobile Safety Laboratory, University of Virginia, 1011 Linden Avenue, Charlottesville, VA 22902, USA Walter D. Pilkey, Department of Mechanical, Aerospace, and Nuclear Engineering, Automobile Safety Laboratory, University of Virginia, 1011 Linden Avenue, Charlottesville, VA 22902, USA Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622 Journal Volume Volume 4 Journal Issue Volume 4, Number 4 / 1997

Description: In this paper the author investigates the angular position and vibration control of a nonlinear rigid-flexible two link robotic manipulator considering fast angular maneuvers. The nonlinear control technique named State-Dependent Riccati Equation (SDRE) is used here to achieve these aims. In a more realistic approach, it is considered that some states can be measured and some states cannot be measured. The states not measured are estimated in order to be used for the SDRE control. These states are all the angular velocities and the velocity of deformation of the flexible link. A SDRE-based estimator is used here. Not only different initial conditions between the system to be controlled (here named "real" system) and the estimator but also a different mathematical model is considered as the estimation model in order to verify the limitations of the proposed state estimation and control techniques. The mathematical model that emulates the real system to be controlled considers two modes expansion and the estimation model considers only one mode expansion. The results for the different approaches are compared and discussed. Content Type Journal Article Pages - DOI 10.3233/SAV-130778 Authors André Fenili, Universidade Federal do ABC (UFABC), CECS/Aerospace Engineering Av. dos Estados, 5001 – Bloco B, Sala 936 – Santo André/SP – CEP 09210 580, Brazil. Tel.: +55 11 49960134; E-mail: andre.fenili@ufabc.edu.br Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622

Description: The present paper aims to explore damage assessment methodology based on the changes in dynamic parameters properties of vibration of a structural system. The finite-element model is used to apply at an element level. Reduction of the element stiffness is considered for structural damage. A procedure for locating and quantifying damaged areas of the structure based on the innovative Big Bang-Big Crunch (BB-BC) optimization method is developed for continuous variable optimization. For verifying the method a number of damage scenarios for simulated structures have been considered. For the purpose of damage location and severity assessment the approach is applied in three examples by using complete and incomplete modal data. The effect of noise on the accuracy of the results is investigated in some cases. A great unbraced frame with a lot of damaged element is considered to prove the ability of proposed method. More over BB-BC optimization method in damage detection is compared with particle swarm optimizer with passive congregation (PSOPC) algorithm. This work shows that BB-BC optimization method is a feasible methodology to detect damage location and severity while introducing numerous advantages compared to referred method. Content Type Journal Article Pages - DOI 10.3233/SAV-130773 Authors Zahra Tabrizian, College of Civil Engineering, Babol Noshirvani University of Technology, Babol, Iran Ehsan Afshari, School of Civil Engineering, Iran University of Science and Technology, Narmak, Tehran, Iran Gholamreza Ghodrati Amiri, Centre of Excellence for Fundamental Studies in Structural Engineering, Iran University of Science and Technology, Narmak, Tehran, Iran Morteza Hossein Ali Beigy, College of Civil Engineering, Babol Noshirvani University of Technology, Babol, Iran Seyed Mohammad Pourhoseini Nejad, Department of Civil Engineering, Yazd University, Yazd, Iran Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622

Description: Statistical Energy Analysis (SEA) has been usefully applied in the prediction of the vibro-acoustic dynamic behavior of built-up structures at high frequencies. However, although SEA is the representative alternative of established prediction tools in the high frequency ranges, it has various weaknesses such as the uncertainty of prediction result due to the ambiguous standards of defining the subsystem and the impossibility of local treatments within one subsystem. Energy flow analysis (EFA) is a promising method that can overcome the weak points of the traditional finite element analysis (FEA), traditional boundary element analysis (BEA), and SEA in the high frequency ranges. Energy flow finite element analysis (EFFEA) is a numerical tool that applies finite element technique to EFA for solving arbitrary boundary value problems. EFADS (Energy Flow Analysis Design System), EFFEA software, has been developed for the effective prediction of acoustic and vibrational responses of built-up structures at high frequencies. The most recent version of EFADS can cover the general coupled plate and beam structures including not only various kinds of rigid joints among beams and plates but also special joints such as the spring-damper junction and rigid bar connection. For effective maintenance, EFADS is composed of three main modules: the translator, model-converter, and main solver. Additionally, EFADS supports some utility modules which afford various functions for users. Finally, for the validation of developed software, the vibrational analysis using EFADS and experiment of one part of a real automobile were performed and these results were compared with successful results. Content Type Journal Article Pages - DOI 10.3233/SAV-130805 Authors Young-Ho Park, Department of Naval Architecture and Marine Engineering, Changwon National University, Sarim-dong, Changwon-si, Gyeongsangnam-do, 641–773, Korea. Tel.: +82 552 133 684; Fax: +82 552 133 689; E-mail: parkyh@changwon.ac.kr Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622

Description: Pyrotechnic devices have been employed in satellite launch vehicle missions, generally for the separation of structural subsystems such as stage and satellite separation. Expanding tubes are linear explosives enclosed by an oval steel tube, and have been widely used for pyrotechnic joint separation systems. A numerical model is proposed for the prediction of the proper load of an expanding tube using a nonlinear dynamic analysis code, AUTODYN 2D and 3D. To compute a proper core load, numerical models of the open-ended steel tube and mild detonating tube encasing a high explosive were developed and compared with experimental results. 2D and 3D computational results showed good correlation with ballistic test results. The model will provide more flexibility in expanding tube design, leading to economic benefits in the overall expanding tube development procedure. Content Type Journal Article Pages - DOI 10.3233/BEN-130837 Authors Mijin Choi, Department of Aerospace Engineering and LANL-CBNU Engineering Institute Korea, Chonbuk National University, Jeonju, Korea Jung-Ryul Lee, Department of Aerospace Engineering and LANL-CBNU Engineering Institute Korea, Chonbuk National University, Jeonju, Korea Cheol-Won Kong, Structures and Material Department, Korea Aerospace Research Institute, Daejeon, Korea Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622

Description: Extensive researches have recently been performed to study structural integrity using structural vibration data measured by in-structure sensors. A fiber optic sensor is one of candidates for the in-structure sensors because it is low in cost, light in weight, small in size, resistant to EM interference, long in service life, etc. Especially, an interferometric fiber optic sensor is very useful to measure vibrations with high resolution and accuracy. In this paper, a dual-cavity fiber Fabry-Perot interferometer was proposed with a phase-compensating algorithm for measuring micro-vibration. The interferometer has structurally two arbitrary cavities; therefore the initial phase difference between two sinusoidal signals induced from the interferometer was also arbitrary. In order to do signal processing including an arc-tangent method, a random value of the initial phase difference is automatically adjusted to the exact 90~degree in the phase-compensating algorithm part. For the verification of the performance of the interferometer, a simple vibration-test was performed to measure micro-vibration caused by Piezo-electric transducer (PZT). As an experimental result, the interferometer attached on the PZT successfully measured the 50 Hz-vibration of which the absolute displacement oscillated between −424 nm and +424 nm. Content Type Journal Article Pages - DOI 10.3233/SAV-130838 Authors Dae-Hyun Kim, Department of Mechanical and Automotive Engineering, Seoul National University of Science and Technology, Seoul, Korea Byung-Jun Ahn, Graduate School of NID Fusion Technology, Seoul National University of Science and Technology, Seoul, Korea Jin-Hyuk Lee, Graduate School of Energy and Environment, Seoul National University of Science and Technology, Seoul, Korea Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622

Description: An analysis method is proposed for the vibration analysis of the Mindlin rectangular plates with general elastically restrained edges, in which the vibration displacements and the cross-sectional rotations of the mid-plane are expressed as the linear combination of a double Fourier cosine series and four one-dimensional Fourier series. The use of these supplementary functions is to solve the possible discontinuities with first derivatives at each edge. So this method can be applied to get the exact solution for vibration of plates with general elastic boundary conditions. The matrix eigenvalue equation which is equivalent to governing differential equations of the plate can be derived through using the boundary conditions and the governing equations based on Mindlin plate theory. The natural frequencies can be got through solving the matrix equation. Finally the numerical results are presented to validate the accuracy of the method. Content Type Journal Article Pages - DOI 10.3233/BEN-130832 Authors Kai Xue, College of Mechanical and Electrical Engineering, Harbin Engineering University, Harbin, Heilongjiang, China Jiufa Wang, College of Mechanical and Electrical Engineering, Harbin Engineering University, Harbin, Heilongjiang, China Qiuhong Li, College of Mechanical and Electrical Engineering, Harbin Engineering University, Harbin, Heilongjiang, China Weiyuan Wang, College of Mechanical and Electrical Engineering, Harbin Engineering University, Harbin, Heilongjiang, China Ping Wang, College of Mechanical and Electrical Engineering, Harbin Engineering University, Harbin, Heilongjiang, China Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622

Description: This paper presents an experimental investigation into the dynamic response of three free floating stiffened metal boxes with protective coatings subjected to underwater explosion (UNDEX). One box kept intact while the other two were respectively covered with monolithic coatings and chiral honeycomb coatings. Three groups of live fire tests with different attack angles and stand-off distances were conducted. The free field water pressure and wall pressure near the bottom hull were monitored. The acceleration and strain peaks recorded at representative locations on the inner structure were selected as the major comparative criterions. Detailed discussion on the test results shows that the impulse transmitted to the structure at the initial stage can be reduced, owing to the coating flexibility and fluid-structure interaction (FSI) mechanism. Consequently, the acceleration peaks on the stiffeners induced by both shock wave and bubble pulse were reduced. The shock environment can be more effectively improved by honeycomb coating when compared with monolithic coating. Most of the strain peaks on the bottom hull decreased to a certain extent, but some of them were notably manifested, especially for honeycomb coating. The test affirms the fact that soft coating can cause stress concentration on the shell that is in direct contact with the coating due to the impedance mismatch between the interfaces of materials. A softer rubber coating induces a greater magnitude of strain. Content Type Journal Article Pages - DOI 10.3233/SAV-130831 Authors Feng Xiao, Institute of Vibration, Shock and Noise, State Key Laboratory of Mechanical System and Vibration, School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai, China Yong Chen, Institute of Vibration, Shock and Noise, State Key Laboratory of Mechanical System and Vibration, School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai, China Zhipeng Du, Naval Research Center, Beijing, China Hongxing Hua, Institute of Vibration, Shock and Noise, State Key Laboratory of Mechanical System and Vibration, School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai, China Dawei Zhu, Naval Research Center, Beijing, China Journal Shock and Vibration Online ISSN 1875-9203 Print ISSN 1070-9622