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  • STRUCTURAL MECHANICS  (2,702)
  • 1980-1984  (1,192)
  • 1970-1974  (1,510)
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  • 1
    Publication Date: 2005-11-27
    Description: Fatigue crack length relationship with aircraft inspection intervals and structural reinforcement, high strength materials, and aircraft usage effects
    Keywords: STRUCTURAL MECHANICS
    Type: NASA AIRCRAFT SAFETY AND OPERATING PROBL., VOL. 1 1971; P 391-401
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  • 2
    Publication Date: 2005-11-27
    Description: Vibration design and test criteria considerations for space shuttle
    Keywords: STRUCTURAL MECHANICS
    Type: NASA SPACE SHUTTLE TECHNOL. CONF., VOL. 3 APR. 1971; P 423-450
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  • 3
    Publication Date: 2005-11-27
    Description: Optimization of payload for space shuttle by reducing structural loading and weight
    Keywords: STRUCTURAL MECHANICS
    Type: NASA SPACE SHUTTLE TECHNOL. CONF., VOL. 3 APR. 1971; P 315-332
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  • 4
    Publication Date: 2005-11-27
    Description: Buffet response of straight wing and delta wing model of space shuttle launch configuration
    Keywords: STRUCTURAL MECHANICS
    Type: NASA SPACE SHUTTLE TECHNOL. CONF., VOL. 3 APR. 1971; P 265-291
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  • 5
    Publication Date: 2005-11-27
    Description: Transonic wind tunnel investigation of flow characteristics and pressure fluctuation of space shuttle launch and reentry configurations
    Keywords: STRUCTURAL MECHANICS
    Type: NASA SPACE SHUTTLE TECHNOL. CONF., VOL. 3 APR. 1971; P 293-314
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  • 6
    Publication Date: 2005-11-27
    Description: Parameters contributing to aeroelastic problems in thermal protection of space shuttle
    Keywords: STRUCTURAL MECHANICS
    Type: NASA SPACE SHUTTLE TECHNOL. CONF., VOL. 3 APR. 1971; P 247-264
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  • 7
    Publication Date: 2005-11-27
    Description: Application of research in panel flutter and boundary layer thickness to space shuttle
    Keywords: STRUCTURAL MECHANICS
    Type: NASA SPACE SHUTTLE TECHNOL. CONF., VOL. 3 APR. 1971; P 231-245
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  • 8
    Publication Date: 2005-11-27
    Description: Transonic flutter and buffeting for elastic wind tunnel models of straight wing proposed for space shuttles
    Keywords: STRUCTURAL MECHANICS
    Type: NASA SPACE SHUTTLE TECHNOL. CONF., VOL. 3 APR. 1971; P 201-229
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  • 9
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    In:  CASI
    Publication Date: 2005-11-27
    Description: Problems in propellant dynamics including pipeline dynamics, effect of bubble location, turbulent flow, and effect of tilting tank on liquid oscillation frequency
    Keywords: STRUCTURAL MECHANICS
    Type: NASA SPACE SHUTTLE TECHNOL. CONF., VOL. 3 APR. 1971; P 95-120
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  • 10
    Publication Date: 2005-11-27
    Description: Dynamic response of thermal protection system panel for space shuttle
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. LANGLEY RES. CENTER NASA SPACE SHUTTLE TECHNOL. CONF., VOL. 3 APR. 1971; P 49-93
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  • 11
    Publication Date: 2005-11-27
    Description: Vibration tests of space shuttle panels at room temperature
    Keywords: STRUCTURAL MECHANICS
    Type: NASA SPACE SHUTTLE TECHNOL. CONF., VOL. 3 APR. 1971; P 27-48
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  • 12
    Publication Date: 2005-11-27
    Description: Vibration studies of dynamic scale model of space shuttle
    Keywords: STRUCTURAL MECHANICS
    Type: NASA SPACE SHUTTLE TECHNOL. CONF., VOL. 3 APR. 1971; P 1-25
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  • 13
    Publication Date: 2005-11-27
    Description: Theoretical calculations and holographic measurements on transverse deflections of astronomical mirror blank
    Keywords: STRUCTURAL MECHANICS
    Type: NASA, WASHINGTON OPT. TELESCOPE TECHNOL. 1970; P 287-270
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  • 14
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    In:  CASI
    Publication Date: 2005-11-27
    Description: Dynamic analysis to predict space vehicle response to atmospheric disturbances with reference to space shuttle
    Keywords: STRUCTURAL MECHANICS
    Type: SPACE TRANSPORTATION SYSTEM TECHNOL. SYMP., VOL. 2 JUL. 1970; P 331-348
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  • 15
    Publication Date: 2005-11-27
    Description: Load alleviation and structural mode control potential for space shuttle vehicle
    Keywords: STRUCTURAL MECHANICS
    Type: SPACE TRANSPORTATION SYSTEM TECHNOL. SYMP., VOL. 2 JUL. 1970; P 349-363
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  • 16
    Publication Date: 2005-11-27
    Description: Basic vibration characteristics and random response in thin panels
    Keywords: STRUCTURAL MECHANICS
    Type: SPACE TRANSPORTATION SYSTEM TECHNOL. SYMP., VOL. 2 JUL. 1970; P 43-57
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  • 17
    Publication Date: 2005-11-27
    Description: Communications satellite antenna structure dynamic response to random loads in launch environment
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. LEWIS RES. CENTER SPACE TRANSPORTATION SYSTEM TECHNOL. SYMP., VOL. 2 JUL. 1970; P 301-329
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  • 18
    Publication Date: 2005-11-27
    Description: Staging dynamics for piggyback space shuttles
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. LEWIS RES. CENTER SPACE TRANSPORTATION SYSTEM TECHNOL. SYMP., VOL. 2 JUL. 1970; P 123-142
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  • 19
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    In:  CASI
    Publication Date: 2005-11-27
    Description: Lifting and control surface flutter on space shuttles
    Keywords: STRUCTURAL MECHANICS
    Type: SPACE TRANSPORTATION SYSTEM TECHNOL. SYMP., VOL. 2 JUL. 1970; P 177-198
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  • 20
    Publication Date: 2005-11-27
    Description: Control systems for vibration isolation of large structures and vacuum chambers
    Keywords: STRUCTURAL MECHANICS
    Type: NASA, WASHINGTON OPT. TELESCOPES TECHNOL. 1970; P 733-749
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  • 21
    Publication Date: 2005-11-27
    Description: Thermal environment effects on alignment behavior of structural joints and assemblies of reentry vehicle and Mars landing module
    Keywords: STRUCTURAL MECHANICS
    Type: OPT. TELESCOPE TECHNOL. 1970; P 335-349
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  • 22
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    In:  CASI
    Publication Date: 2005-11-27
    Description: Vibration response and acoustic fatigue characteristics of space shuttle thermal protection system design concepts
    Keywords: STRUCTURAL MECHANICS
    Type: SPACE TRANSPORTATION SYSTEM TECHNOL. SYMP., VOL. 2 JUL. 1970; P 273-284
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  • 23
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    In:  CASI
    Publication Date: 2005-11-27
    Description: Dynamic model for obtaining response data for space shuttle
    Keywords: STRUCTURAL MECHANICS
    Type: SPACE TRANSPORTATION SYSTEM TECHNOL. SYMP., VOL. 2 JUL. 1970; P 29-42
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  • 24
    Publication Date: 2005-11-27
    Description: Pogo effect influence on aerodynamic phenomena in rocket afterbody
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. LEWIS RES. CENTER SPACE TRANSPORTATION SYSTEM TECHNOL. SYMP., VOL. 2 JUL. 1970; P 263-265
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  • 25
    Publication Date: 2005-11-30
    Description: The latest technology for structural analysis in relation to the design tasks that lie ahead for the space shuttle is reviewed. For shell-of-revolution structures, the analysis can be formulated as a one-dimensional problem which is readily solved by using finite-difference or numerical-integration techniques. For more general asymmetric shells, a two-dimensional formulation is required. However, the governing equations are readily formulated and are amenable to solution by finite-difference techniques. For a completely general structural arrangement, such as structural frameworks, recourse is usually made to discretized formulations using finite elements. Of course, the finite-element programs could be used for shell structures, but at a loss in accuracy and increase in computer time compared with the special purpose programs.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA Space Shuttle Technol. Conf.; p 685-725
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  • 26
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    In:  CASI
    Publication Date: 2005-11-27
    Description: Ring reinforcements for damping structural deformation in orthotropic mirror design
    Keywords: STRUCTURAL MECHANICS
    Type: NASA, WASHINGTON OPT. TELESCOPE TECHNOL. 1970; P 283-286
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  • 27
    Publication Date: 2005-11-27
    Description: Finite element method for structural design of astronomical mirrors
    Keywords: STRUCTURAL MECHANICS
    Type: NASA, WASHINGTON OPT. TELESCOPE TECHNOL. 1970; P 249-255
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  • 28
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    In:  CASI
    Publication Date: 2005-11-27
    Description: Transient loading considerations for shuttle design
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. LEWIS RES. CENTER SPACE TRANSPORTATION SYSTEM TECHNOL. SYMP., VOL. 2 JUL. 1970; P 79-100
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  • 29
    Publication Date: 2005-11-27
    Description: Assessment of techniques for determining eigenvalues of large systems
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. LEWIS RES. CENTER SPACE TRANSPORTATION SYSTEM TECHNOL. SYMP., VOL. 2 JUL. 1970; P 4-27
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  • 30
    Publication Date: 2005-11-27
    Description: Using finite element method in analysis and design of optical space telescopes
    Keywords: STRUCTURAL MECHANICS
    Type: OPT. TELESCOPE TECHNOL. 1970; P 401-415
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  • 31
    Publication Date: 2005-11-27
    Description: Structural analysis for optimal load carrying substrate members of lightweight astronomical mirror
    Keywords: STRUCTURAL MECHANICS
    Type: NASA, WASHINGTON OPT. TELESCOPE TECHNOL. 1970; P 257-280
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  • 32
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    In:  CASI
    Publication Date: 2005-11-27
    Description: User checklist for spacecraft boom selection with review of structural, electrical and mechanical properties
    Keywords: STRUCTURAL MECHANICS
    Type: JPL PROC. OF THE 4TH AEROSPACE MECH. SYMP. 15 JAN. 1970; P 51-54
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  • 33
    Publication Date: 2005-11-27
    Description: Acoustic, vibration, and shock environments in designing orbital telescopes
    Keywords: STRUCTURAL MECHANICS
    Type: OPT. TELESCOPE TECHNOL. 1970; P 389-400
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  • 34
    Publication Date: 2005-11-27
    Description: Coupled structure-propulsion system instability /POGO/ prevention on space shuttle
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. LEWIS RES. CENTER SPACE TRANSPORTATION SYSTEM TECHNOL. SYMP., VOL. 2 JUL. 1970; P 249-262
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  • 35
    Publication Date: 2005-11-27
    Description: Supersonic panel flutter of space shuttle heat shields with flexible supports
    Keywords: STRUCTURAL MECHANICS
    Type: SPACE TRANSPORTATION SYSTEM TECHNOL. SYMP., VOL. 2 JUL. 1970; P 199-221
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  • 36
    Publication Date: 2005-11-27
    Description: Design and development of deployment fixture for simulated zero gravity testing of large area solar array
    Keywords: STRUCTURAL MECHANICS
    Type: JPL PROC. OF THE 4TH AEROSPACE MECH. SYMP. 15 JAN. 1970; P 83-89
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  • 37
    Publication Date: 2005-11-27
    Description: Mechanical and thermal properties of materials for five spacecraft boom designs
    Keywords: STRUCTURAL MECHANICS
    Type: JPL PROC. OF THE 4TH AEROSPACE MECH. SYMP. 15 JAN. 1970; P 43-45
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  • 38
    Publication Date: 2005-11-27
    Description: Customer opinion of design of aerospace mechanisms
    Keywords: STRUCTURAL MECHANICS
    Type: JPL PROC. OF THE 4TH AEROSPACE MECH. SYMP. 15 JAN. 1970; P 91-94
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  • 39
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    Publication Date: 2005-11-27
    Description: Performance summary and spacecraft applications of booms with future trends
    Keywords: STRUCTURAL MECHANICS
    Type: JPL PROC. OF THE 4TH AEROSPACE MECH. SYMP. 15 JAN. 1970; P 55-72
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  • 40
    Publication Date: 2005-03-28
    Description: In many structures the final stress states are dependent on the sequence of construction or the stress states at various stages of construction are of interest. Such problems can be analyzed using finite element programs that have the capability of adding (birthing) elements to simulate the progress of construction. However, the usual procedure of assembling elements may lead to numerical instabilities or stress states that are unrealistic. Both problems are demonstrated in the analysis of a structure using the program ADINA. A technique which combines application of a preload with element birthing to overcome these problems is described and illustrated.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. Langley Research Center Res. in Struct. and Dyn., 1984; p 395-404
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  • 41
    Publication Date: 2005-03-28
    Description: A technique utilizing finite element analysis, liquid impact kinematics, and momentum theory is described and compared to single-drop impact test data performed on various configurations of coated ceramic material. The method correlates well with test data and is useful in predicting the single-drop impact damage velocity threshold for low-density, coated ceramic materials.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. Langley Research Center Res. in Struct. and Dyn., 1984; p 385-393
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  • 42
    Publication Date: 2005-03-28
    Description: An algorithm is outlined for simulating the contact surface erosion for impact problems. The algorithm dynamically relocates the contact surface as projectile and target materials exceed their failure criterion. Example computations of axisymmetric and oblique impacts are compared with experimental data.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. Langley Research Center Res. in Struct. and Dyn., 1984; p 315-324
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  • 43
    Publication Date: 2005-03-28
    Description: A study of the dynamic characteristics of a coupled translational-rotational system is given. The formulation of the problem considers the soil-structure interaction effects by utilizing the impedance functions at the foundation of a structure. Due to the fact that the coefficient matrix in the characteristic equation is frequency dependent in nature, iterations have to be performed to find the nature frequencies of the system. Examples and discussions are presented. Comparisons of the analytical results from various approaches are also given.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. Langley Research Center Res. in Struct. and Dyn., 1984; p 289-296
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  • 44
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    Publication Date: 2005-03-28
    Description: Two analytical techniques applicable to large deflection dynamic response calculations for pressure loaded composite sandwich panels are demonstrated. One technique utilizes finite element modeling with a single equivalent layer representing the face sheets and core. The other technique utilizes the modal analysis computer code DEPROP which was recently modified to include transverse shear deformation in a core layer. The example problem consists of a simply supported rectangular sandwich panel. Included are comparisons of linear and nonlinear static response calculations, in addition to dynamic response calculations.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. Langley Research Center Res. in Struct. and Dyn., 1984; p 251-268
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  • 45
    Publication Date: 2005-03-28
    Description: The design of thin shell structures with respect to elastoplastic buckling requires an extended analysis of the influence of initial imperfections. For conservative design, the most critical defect should be assumed with the maximum allowable magnitude. This defect is closely related to the initial postbuckling behavior. An algorithm is given for the quasi-static analysis of the postbuckling behavior of structures that exhibit multiple buckling points. the algorithm based upon an energy criterion allows the computation of the critical perturbation which will be employed for the definition of the critical defect. For computational efficiency, the algorithm uses the reduced basis technique with automatic update of the modal basis. The method is applied to the axisymmetric buckling of cylindrical shells under axial compression, and conclusions are given for future research.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. Langley Research Center Res. in Struct. and Dyn., 1984; p 237-250
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  • 46
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    Publication Date: 2005-03-28
    Description: A general approach is required for describing matter of behavior when the failure is likely to involve growth and coalescence of a large number of fractures. Failures of this kind appear frequently in rapid dynamic processes, particularly in the formation of spall fragments. An approach to formulating constitutive relations that accounts for the opening, shear and growth of an ensemble of cracks is discussed. The approach accounts for plastic flow accompanying fragmentation. The resulting constitutive relations were incorporated into a Lagrangian computer program. A theoretical approach to coalescence is described. The simplest formulation uses a linear Liouville equation, with crack growth limited by the mean free path of cracks, assumed constant. This approach allows for an anisotropic distribution of cracks. An alternative approach in which the decrease of the mean free path with increasing crack size is accounted for, but the crack distribution is assumed isotropic is described. A reduction of the governing Liouville equation to an ordinary differential equation of third order is possible, and the result can be used to determine how mean free path decreases with increasing crack size.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. Langley Research Center Res. in Struct. and Dyn., 1984; p 185-195
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  • 47
    Publication Date: 2005-03-28
    Description: The design of a composite panel requires some way of finding the minimum thickness laminate which will withstand the load requirements without failure. The mathematical complexity of this problem dictates the use of nonlinear optimization techniques. Specialized laminate optimization programs were developed which are compact and efficient enough to run on microcomputers. Only stresses at a point and inplane loads and deflections are considered. The programs are simple to use and require no knowledge of optimization. Techniques are developed which find minimum thickness laminates with either ply ratios or ply angles as design variables. A method is presented for finding the optimum orientation for the axis of symmetry of an orthotropic laminate. The orthotropic laminate program uses an approximate failure theory, which speed up computations dramatically.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. Langley Research Center Res. in Struct. and Dyn., 1984; p 181-183
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  • 48
    Publication Date: 2005-03-28
    Description: The evaluation of the total probability of a plastic collapse failure P sub f for a highly redundant structure of random interdependent plastic moments acted on by random interdepedent loads is a difficult and computationally very costly process. The evaluation of reasonable bounds to this probability requires the use of second moment algebra which involves man statistical parameters. A computer program which selects the best strategy for minimizing the interval between upper and lower bounds of P sub f is now in its final stage of development. The relative importance of various uncertainties involved in the computational process on the resulting bounds of P sub f, sensitivity is analyzed. Response sensitivities for both mode and system reliability of an ideal plastic portal frame are shown.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. Langley Research Center Res. in Struct. and Dyn., 1984; p 159-179
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  • 49
    Publication Date: 2005-03-28
    Description: A finite element modeling technique which utilizes a triangular element called TSHEL with 45 degrees of freedom and seven point integration was tested for analysis of thin plate and shell structures. The element formulation is based on the degenerate solid shell concept and the mixed formulation with assumed independent inplane and transverse shear strains. The effectiveness of the present modeling technique which features combined use of elements with kinematic modes and those without kinematic modes to eliminate both locking and spurious kinematic modes at the global structural levels are shown.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. Langley Research Center Res. in Struct. and Dyn., 1984; p 123-142
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  • 50
    Publication Date: 2005-03-28
    Description: The stress derivative technique for control of keystoning deformation in under-integrated finte elements is based on expansion of the stress in a Taylor series about the element center and retention of additional terms beyond the constant stress term. It has the advantage over other control techniques that keystoning resistance is provided by actual rather than artificial material properties. Application of this technique to the quadrilateral ring elements used for modelling solids of revolution subjected to axisymmetric loads is described. In a cylindrical coordinate system additional terms appear in the formulation which must be dealt with in arriving at a workable keystoning control scheme.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. Langley Research Center Res. in Struct. and Dyn., 1984; p 111-122
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  • 51
    Publication Date: 2005-03-28
    Description: An existing program is currently being adapted to perform finite element analysis by distributing substructures over a network of four Apple IIe microcomputers connected to a shared disk. In this network, one microcomputer controls the entire process while the others perform the analysis on each substructure in parallel. This substructure analysis is used in an iterative, fully stressed, structural resizing procedure. This procedure allows experimentatation with resizing in which all analyses are not completed during a single iteration. This research gives some insight on how to configure multidiscriplinary analysis and optimization procedures for decomposable engineering systems using either high performance engineering workstations or a parallel processor supercomputer. In addition, the operational experience gained facilitates the implementation of analysis programs on these new computers when they become available in an engineering environment.
    Keywords: STRUCTURAL MECHANICS
    Type: Res. in Struct. and Dyn., 1984; p 45-54
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  • 52
    Publication Date: 2005-03-28
    Description: Described are the experiences gained from solving for the dynamic response of two simple structures on an experimental Multiple Instruction Multiple Data (MIMD) computer called the finite element machine. Introduced are MIMD computing concepts, describing how the concurrent algorithmic techniques implemented and giving results for the two example problems. The results show computational speedups of up to 7.83 using eight of the finite element machine processors and indicate that significant computational speedups are possible for large order structural computations.
    Keywords: STRUCTURAL MECHANICS
    Type: Res. in Struct. and Dyn., 1984; p 31-44
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  • 53
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    In:  CASI
    Publication Date: 2005-03-28
    Description: The FLEX/32 Multicomputer is a generic environment for cooperating multiple processors. The FLEX/32 supports a number of different processors, making it heterogeneous in terms of the instruction sets it supports, and homogeneous in its ability to provide consistent storage and input/output facilities to its differing processors. These facilities are accessed through standard 32-bit VMEbus connections. The FLEX/32 supports the full UNIX System V Operating System and languages associated with it, plus the extended ConCurrent C and Concurrent FORTRAN 77 languages that allow programming of concurrent software at a high level. Direct programming support at all levels is provided by the environment hardware for concurrent software execution and optimization, including hardware support for shared resource access arbitration, conditional critical region arbitration, and interprocessor messages.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. Langley Research Center Res. in Struct. and Dyn., 1984; p 1-14
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  • 54
    Publication Date: 2005-03-28
    Description: Research aimed at faster, more cost effective parallel machines and algorithms for improving designer productivity with finite element computations is discussed. A set of 8 boards, containing 4 nearest neighbor connected arrays of commercially available floating point chips and substantial memory, are inserted into a commercially available machine. One-tenth Mflop (64 bit operation) processors provide an 89% efficiency when solving the equations arising in a finite element problem for a single variable regular grid of size 40 by 40 by 40. This is approximately 15 to 20 times faster than a much more expensive machine such as a VAX 11/780 used in double precision. The efficiency falls off as faster or more processors are envisaged because communication times become dominant. A novel successive overrelaxation algorithm which uses cyclic reduction in order to permit data transfer and computation to overlap in time is proposed.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. Langley Research Center Res. in Struct. and Dyn., 1984; p 15-29
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  • 55
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    In:  CASI
    Publication Date: 2004-10-30
    Description: Space shuttle liftoff dynamics
    Keywords: STRUCTURAL MECHANICS
    Type: SPACE TRANSPORTATION SYSTEM TECNOL. SYMP., VOL. 2 JUL. 1970; P 101-122
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  • 56
    Publication Date: 2006-03-28
    Description: Cybernetics diagnostics of machines and mechanisms using the spectral approach is discussed. The problem of establishing the accuracy of determination of the spectral composition is investigated. In systems with rectilinear or rotary movement, the vibrations appear in the form of movement rate vibrations, which are equivalent to frequency modulation of the signal, in proportion to the mean movement rate of the body. The case of a harmonic signal which reproduces and analyzes the characteristics of the frequency modulated signal is discussed. Mathematical models are developed to show the relationships of the parameters.
    Keywords: STRUCTURAL MECHANICS
    Type: Cybernetic Diagnostics of Mech. Systems with Vibro-acoustic Phenomena (NASA-TT-F-14899); p 275-278
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  • 57
    Publication Date: 2006-03-28
    Description: Free vibrations of a system and vibrations which are multiples of them in frequency are discussed. The corresponding periodic forced vibrations of the type n/m (n is the number of periods of disturbance between periods of movement and m is the number of periods of movement in one period of disturbance), generated by a harmonic or close to harmonic disturbance, are propagated close to the corresponding curves of the free vibrations and their frequency multiples. It has been proposed that investigation of transitional modes of motion and capture regions be carried out by precise methods in phase space, with the least number of coordinates. Thus, for example, for nonautonomous second order equations (for example, the Duffing equations), in place of three variables (coordinates, velocity, phases), it is proposed to use two: velocity during transition of the coordinate through zero and phase.
    Keywords: STRUCTURAL MECHANICS
    Type: Cybernetic Diagnostics of Mech. Systems with Vibro-acoustic Phenomena (NASA-TT-F-14899); p 256-259
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  • 58
    Publication Date: 2006-03-28
    Description: A numerical analysis of the transitional modes of motion for a vibroshock system was conducted. The capture regions of the system are emphasized. The three initial parameters for a nonautonomous vibroshock system with one degree of freedom are identified as: (1) coordinates, (2) velocity, and (3) time. Mathematical models are developed to show the relationship of the parameters. Graphs are included to show the nature of the capture regions and to portray the trajectory of motion of mass with time, by solution of differential equations during increase and decrease in time.
    Keywords: STRUCTURAL MECHANICS
    Type: Cybernetic Diagnostics of Mech. Systems with Vibro-acoustic Phenomena (NASA-TT-F-14899); p 250-255
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  • 59
    Publication Date: 2006-03-28
    Description: A solution is given to the problem of a transient vibration process in a fastened plate, during a sudden displacement of the edge. Some partial cases of excitation are examined in which the packing can be calculated and the explicit type of change in a deformation over time can be found. Some examples are presented.
    Keywords: STRUCTURAL MECHANICS
    Type: Cybernetic Diagnostics of Mech. Systems with Vibro-acoustic Phenomena (NASA-TT-F-14899); p 204-207
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  • 60
    Publication Date: 2006-03-28
    Description: The method of automatic identification of acoustical signals, by means of the segmentation was used to investigate noises and vibrations in machines and mechanisms, for cybernetic diagnostics. The structural analysis consists of presentation of a noise or vibroacoustical signal as a sequence of segments, determined by the time quantization, in which each segment is characterized by specific spectral characteristics. The structural spectrum is plotted as a histogram of the segments, also as a relation of the probability density of appearance of a segment to the segment type. It is assumed that the conditions of ergodic processes are maintained.
    Keywords: STRUCTURAL MECHANICS
    Type: Cybernetic Diagnostics of Mech. Systems with Vibro-acoustic Phenomena (NASA-TT-F-14899); p 179-180
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  • 61
    Publication Date: 2006-03-28
    Description: An experimental investigation for estimating the nonlinearity of a diagnostic object was carried out on a single-stage, spur gear reducer. The linearity of the properties of spur gearing (including the linearity of its mode of operation) was tested. Torsional vibrations of the driven wheel and transverse (to the meshing plane) vibrations of the drive wheel on its support were taken as the two outputs of the object to be analyzed. The results of the investigation showed that the degree of nonlinearity of a reducing gear is essentially connected with its operating mode, so that different mathematical models of it can correspond to different values of the system parameters.
    Keywords: STRUCTURAL MECHANICS
    Type: Cybernetic Diagnostics of Mech. Systems with Vibro-acoustic Phenomena (NASA-TT-F-14899); p 157-159
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  • 62
    Publication Date: 2006-03-01
    Description: The stability of equilibrium shapes of elastic systems is examined. Stability loss in the case of similar equilibrium shapes, the disappearance of stable equilibrium shapes, and the disappearance of any forms of equilibrium are discussed. The error made by Euler in analyzing stability loss is pointed out, and Mises' truss is used as an example of stability loss in the case of similar equilibrium shapes.
    Keywords: STRUCTURAL MECHANICS
    Type: Stability and Oscillation of Elastic Systems: Mod. Concepts, Paradoxes and Errors (NASA-TT-F-751); p 1-183
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  • 63
    facet.materialart.
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    In:  CASI
    Publication Date: 2006-03-01
    Description: Problems of oscillations of linear systems are discussed, including systems with a fractional number of degrees of freedom as well as free oscillations of a cantilever in the field of centrifugal forces. Four methods of solving the problem of the action of periodic instantaneous impulses are presented. The Tacoma catastrophe is analyzed and used as an example of aeroelastic oscillations. Problems of nonlinear system oscillations include the vibration maintenance of rotation, the Sommerfeld effect, and self-oscillations of a quasi-system with dry friction.
    Keywords: STRUCTURAL MECHANICS
    Type: Stability and Oscillation of Elastic Systems: Mod. Concepts, Paradoxes and Errors NASA-TT-F-751); p 184-418
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  • 64
    facet.materialart.
    Unknown
    In:  CASI
    Publication Date: 2006-02-14
    Description: The design, manufacture, and testing of an isolation system placed under a bench which simulates a space platform during testing in a hard vacuum are described. A low natural frequency isolation system is used to decouple ground vibrations from the bench. The materials used are vacuum compatible and do not introduce unwanted matter which would contaminate the payload optics and/or the testing environment. The system accommodates payloads of varying weights and envelopes.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. Goddard Space Flight Center 13th Space Simulation Conf.; p 320-339
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  • 65
    facet.materialart.
    Unknown
    In:  CASI
    Publication Date: 2006-02-14
    Description: The potential cost and performance advantages of welding was understood but ignored by solar panel manufacturers in the U.S. Although NASA, DOD and COMSAT have supported welding development efforts, soldering remains the only U.S. space qualified method for interconnecting solar cells. The reason is that no U.S. satellite prime contractor found it necessary, due to mission requirements, to abandon the space proven soldering process. It appears that the proposed NASA space station program will provide an array requirement, a 10 year operation in a low Earth orbital environment, that mandates welding. The status of welding technology in the U.S. is assessed.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. Lewis Research Center Space Photovoltaic Res. and Technol. 1983; p 220-222
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  • 66
    Publication Date: 2006-02-14
    Description: Solid rocket booster cavity collapse flight measurements included external pressures on the motor case and aft skirt, internal motor case pressures, accelerometers located in the forward skirt, mid-body area, and aft skirt, as well as strain gages located on the skin of the motor case. This flight data yielded applied pressure longitudinal and circumferential distributions which compare well with model test predictions. The internal motor case ullage pressure, which is below atmospheric due to the rapid cooling of the hot internal gas, was more severe (lower) than anticipated due to the ullage gas being hotter than predicted. The structural dynamic response characteristics were as expected. Structural ring and wall damage are detailed and are considered to be attributable to the direct application of cavity collapse pressure combined with the structurally destabilizing, low internal motor case pressure.
    Keywords: STRUCTURAL MECHANICS
    Type: Shock and Vibration Inform. Center The Shock and Vibration Bull., No. 52. Part 2; p 21-26
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  • 67
    Publication Date: 2006-04-25
    Description: NASA computer program for dynamic structural analysis in stress and thermal deformation problems
    Keywords: STRUCTURAL MECHANICS
    Type: NIFICANT ACCOMPLISHMENTS IN SCI. AND TECHNOL. AT GODDARD SPACE FLIGHT CENTER 1970; P 221-224
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  • 68
    Publication Date: 2006-02-14
    Description: Researchers define damage-tolerant structural systems as those systems which not only have adeqate intact strength to withstand initial failure but also adequate residual strength to minimize the possibility of, and hence the consequences of, further failure. The incorporation of damage tolerance cannot be done in total isolation of the function being required of the system and the costs associated with obtaining improved damage tolerance. The approach, therefore, is to formulate multiple-objective, multi-level decision support problems (DSP), the solutions of which represent a compromise between higher costs and higher damage tolerance. Mulitple-objective decision support problems are easily solved in the linear domain. These formulations, however, include both linear and nonlinear constraints and goals, which in the past, have not been considered due to the resulting complexity. Here, researchers: (1) present a complete discussion and description of decision support problems; (2) identify what further research needs to be done in order to obtain information that is required but not known for solving problems using these models; and (3) identify what needs to be done to implement this prototype method in practice.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. Langley Research Center Recent Experiences in Multidisciplinary Analysis and Optimization, Part 2; 36 p
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  • 69
    Publication Date: 2006-02-14
    Description: Ocean-going vehicles and platforms are among the largest structures in the world and are subjected to relatively harsh conditions of motions and loads. Some of them, such as semi-submersible platforms, are a relatively new type of structure and hence there is no formal, well evolved and established structural design code as there is for more traditional structures. More recently, efforts have also been made to develop a design method of this type for ships and other ocean structures. One of the many advantages of a rationally based design method is versatility; it can be used for structures that have widely differing purposes, measures of merit, shapes and sizes. The purpose is to describe a rationally based design method that has been developed within the field of ocean structures, in order that persons dealing with other types of structure can judge whether and to what extent its various features may be useful for those other types. Also, even though some features may not be applicable they might stimulate some useful ideas.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. Langley Research Center Recent Experiences in Multidisciplinary Analysis and Optimization, Part 2; 18 p
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  • 70
    Publication Date: 2006-02-14
    Description: The random vibration of the components of the space shuttle causing internal cargo bay acoustic impingement on the payload was investigated. The import factors to be considered in the design of acoustically loaded structures are the prediction of acoustic environment, prediction of structural response to this environment, and to determine the effect of the response on the structural strength requirements. Two basic responses were analyzed. The primary structure response due to random vibration is first analyzed. The output of primary structure response is used as an input to the secondary structure to calculate the component response.
    Keywords: STRUCTURAL MECHANICS
    Type: Alabama Univ. in Huntsville The 1981 NASA(ASEE Summer Fac. Fellowship Program; 12 p
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  • 71
    Publication Date: 2006-02-14
    Description: The elastic membrane equations which describe the deflection of a biaxially tensioned reflective mesh from an idealized surface were developed and solved. The conditions of equilibrium of the forces acting on a membrane element furnish equations which may be used to solve a variety of problems. Configurations considered include continuous, as well as incremental mesh attachment to structural members to form shapes which are approximately parabolic or spherical.
    Keywords: STRUCTURAL MECHANICS
    Type: Alabama Univ. in Huntsville The 1981 NASA(ASEE summer Fac. Fellowship Program; 11 p
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  • 72
    Publication Date: 2006-01-11
    Description: One of the most important methods of reducing the noise and vibration level is the damping of the secondary sources, such as metal plates, often used in vehicle structures, by means of covering materials with high internal viscosity. Damping layers are chosen at an optimum thickness corresponding to the frequency and temperature range in which a certain structure works. The structure's response corresponding to various real situations is analyzed by means of a measuring chain including electroacoustical or electromechanical transducers. The experimental results provide the dependence of the loss factor and damping transmission coefficient as a function of the damping layer thickness or of the frequency for various viscoelastic covering materials.
    Keywords: STRUCTURAL MECHANICS
    Type: The 4th Natl. Conf. on Acoustics, Vol. 1A (NASA-TT-F-15375); p 246-253
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  • 73
    Publication Date: 2006-01-11
    Description: Vibration sources are described for pneumatic hammers used in the mining industry (pick hammers), in boiler shops (riveting hammers), etc., bringing to light the fact that the principal vibration source is the variation in air pressure inside the cylinder. The present state of the art of vibration control of pneumatic hammers as it is practiced abroad, and the solutions adopted for this purpose, are discussed. A new type of pneumatic hammer with a low noise and vibration level is presented.
    Keywords: STRUCTURAL MECHANICS
    Type: The 4th Natl. Conf. on Acoustics, Vol. 1A (NASA-TT-F-15375); p 79-84
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  • 74
    facet.materialart.
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    In:  CASI
    Publication Date: 2006-01-11
    Description: Special measures are discussed for calculating, designing and executing a forge hammer foundation, so that the vibrations that occur during its working will not be transmitted to neighboring machinery, workrooms and offices. These vibrations are harmful to the workers near the forge hammer.
    Keywords: STRUCTURAL MECHANICS
    Type: The 4th Natl. Conf. on Acoustics, Vol. 1A (NASA-TT-F-15375); p 73-78
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  • 75
    Publication Date: 2006-01-11
    Description: Because of the high vibration level occurring during the running of electric locomotives, mechanical defects occur in the control mechanisms of auxiliary services. This fact has given rise to the necessity of determining the values of these vibrations in electric locomotives during their running. Measurements were conducted on the Craiova-Drobeta-Turnu Severin line, and measures to reduce the vibration level in electric locomotives were instituted.
    Keywords: STRUCTURAL MECHANICS
    Type: The 4th Natl. Conf. on Acoustics, Vol. 1A (NASA-TT-F-15375); p 50-54
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  • 76
    Publication Date: 2006-01-11
    Description: A method is presented of determining the mean square transversal deflection of an isotropic and homogeneous linear viscoelastic beam having a certain number of lengthwise distributed lumped masses. It is assumed that the beam is acted upon by a stationary random process uniformly distributed along the beam. The method is useful in vibration level control by means of additional lumped masses.
    Keywords: STRUCTURAL MECHANICS
    Type: The 4th Natl. Conf. on Acoustics, Vol. 1A (NASA-TT-F-15375); p 36-42
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  • 77
    facet.materialart.
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    In:  CASI
    Publication Date: 2006-01-11
    Description: An oscillating system with quadratic damping subjected to white noise excitation is replaced by a nonlinear, statistically equivalent system for which the associated Fokker-Planck equation can be exactly solved. The mean square responses are calculated and the optimum damping coefficient is determined with respect to the minimum mean square acceleration criteria. An application of these results to the optimization of automobile suspension damping is given.
    Keywords: STRUCTURAL MECHANICS
    Type: The 4th Natl. Conf. on Acoustics, Vol. 1A (NASA-TT-F-15375); p 29-35
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  • 78
    Publication Date: 2006-01-11
    Description: A seismic action which is characterized by the acceleration function of the seismic motion is analyzed. The equations of motion in the direction of the seismic action are determined for a completely rigid ground and for a ground with linear deformability characteristics (rotation deformability). The equation for the rotation motion is derived by considering elastic and viscoelastic properties of the foundation ground. The differential equations are written by treating the mechanical model of a many-storied structure as a fixed vertical beam with a uniformly distributed mass as well as with concentrated masses on each floor.
    Keywords: STRUCTURAL MECHANICS
    Type: The 4th Natl. Conf. on Acoustics, Vol. 1A (NASA-TT-F-15375); p 43-49
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  • 79
    Publication Date: 2006-01-11
    Description: The insulation of nonlinear and random vibrations is considered for some ore preparing and sorting implements: rotary crushers, resonance screens, hammer mills, etc. The appearance of subharmonic vibrations is analyzed, and the conditions for their appearance are determined. A method is given for calculating the insulation of these vibrations by means of elastic elements made of rubber. The insulation of the random vibrations produced by Symons crushers is calculated by determining the transmissability and deformation of the insulation system for a narrow band random response.
    Keywords: STRUCTURAL MECHANICS
    Type: The 4th Natl. Conf. on Acoustics, Vol. 1A (NASA-TT-F-15375); p 22-28
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  • 80
    Publication Date: 2006-01-11
    Description: Expressions are derived for the displacements of a many storied building subjected to the action of classical weaving looms located at different levels of the building. The building is regarded as a vertical fixed beam with a uniformly distributed mass as well as concentrated masses at each level. The calculation relations are obtained on the assumption of harmonic variation of the forces acting at each level as well as the assumption of narrow band stationary random excitatory forces.
    Keywords: STRUCTURAL MECHANICS
    Type: The 4th Natl. Conf. on Acoustics, Vol. 1A (NASA-TT-F-15375); p 15-21
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  • 81
    Publication Date: 2006-01-11
    Description: For compacting concretes in building, vibrating beams are used. The vibrations are generated by inertial vibrators, and the beam is normally displaced by the operator by means of a handle that is elastically fastened to the beam by means of rubber pads. Considered are vibrations transmitted to the operator, taking into account the beam's shock vibration motions. The steady state motion of a dynamic beam pattern is studied, and results of experimental tests with existing equipment are presented.
    Keywords: STRUCTURAL MECHANICS
    Type: The 4th Natl. Conf. on Acoustics, Vol. 1A (NASA-TT-F-15375); p 9-14
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  • 82
    Publication Date: 2006-04-02
    Description: Asymptotic solutions of Novozhilov's equations of shells of revolution are derived for axisymmetric and first harmonic loadings. The solutions obtained are valid throughout the shallow and nonshallow regions. Stresses in dome shaped shells of revolution with a discontinuity in the form of a circular hole, a circular rigid insert, or a nozzle at the apex have been investigated. Numerical results are obtained for spheres, ellipsoids, and paraboloids, containing a discontinuity under a internal pressure and moment. Curves depicting stress distributions are given. The influence of three types of discontinuity on the stresses of the shells is also given.
    Keywords: STRUCTURAL MECHANICS
    Type: Multivariant Function Model Generation; 118 p
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  • 83
    Publication Date: 2006-03-28
    Description: The problem is discussed of identification of a linear object of known structure, the movement of which is described by a system of differential equations of the type y = Ay + Bu, where y is an n-dimensional output vector, u is an m-dimensional vector of stationary, random disturbances (inputs), A and B are matrices of unknown parameters of the dimension, n x n and n x m, respectively. The spectral and reciprocal spectral densities of the inputs and outputs are used as the initial information on the object.
    Keywords: STRUCTURAL MECHANICS
    Type: Cybernetic Diagnostics of Mech. Systems with Vibro-acoustic Phenomena (NASA-TT-F-14899); p 139-141
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  • 84
    Publication Date: 2006-03-28
    Description: Radial and axial vibration measurements on the scanning disk and the data storage board of an optical-mechanical scanner are evaluated. Statistical processing of the observational data establishes the excitation source and determines the effect of disk torsional vibrations on the data storage board.
    Keywords: STRUCTURAL MECHANICS
    Type: Cybernetic Diagnostics of Mech. Systems with Vibro-acoustic Phenomena (NASA-TT-F-14899); p 105-106
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  • 85
    Publication Date: 2006-03-28
    Description: The torque of a drive shaft in a magnetic recording device was studied by oscillographic recordings. Statistical evaluation of the dynamic spectral densities showed that the principle source of disturbing forces is loading in the drive shaft radial play.
    Keywords: STRUCTURAL MECHANICS
    Type: Cybernetic Diagnostics of Mech. Systems with Vibro-acoustic Phenomena (NASA-TT-F-14899); p 103-104
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  • 86
    Publication Date: 2006-03-28
    Description: The equation of motion was used to examine the problem of vibrations of a thin elastic plate covered with a thin viscous layer. Mathematical formulation and the solution of the problem are given.
    Keywords: STRUCTURAL MECHANICS
    Type: Cybernetic Diagnostics of Mech. Systems with Vibro-acoustic Phenomena (NASA-TT-F-14899); p 89-90
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  • 87
    Publication Date: 2006-03-28
    Description: The statistical characteristics of complex variation amplitudes of shells excited by harmonic force sources in the sound frequency range are examined. Vibrations were measured with a multichannel unit, permitting the component values of a complex vibration amplitude for the i-th measurement point to be obtained at each measured point. An estimation was also made of the nature of the vibration field structure.
    Keywords: STRUCTURAL MECHANICS
    Type: Cybernetic Diagnostics of Mech. Systems with Vibro-acoustic Phenomena (NASA-TT-F-14899); p 68-73
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  • 88
    Publication Date: 2006-03-28
    Description: A traveling wave unit was built to process measurement data on spatial damping parameters and to simplify statistical treatment of the results. Mean values of the loss coefficient, lengths of flexual waves, and wave propagation velocities for a given set of discrete functions were determined. Results are given in a table.
    Keywords: STRUCTURAL MECHANICS
    Type: Cybernetic Diagnostics of Mech. Systems with Vibro-acoustic Phenomena (NASA-TT-F-14899); p 81-82
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  • 89
    Publication Date: 2006-03-28
    Description: A method is proposed for determining vibroacoustic characteristics from the results of measurements of the distribution of vibrational energy in a structure. The method is based on an energy model of a structure studied earlier. Equations are written to describe the distribution of vibrational energy in a hypothetical diffuse energy state in structural elements.
    Keywords: STRUCTURAL MECHANICS
    Type: Cybernetic Diagnostics of Mech. Systems with Vibro-acoustic Phenomena (NASA-TT-F-14899); p 74-77
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  • 90
    Publication Date: 2006-03-28
    Description: The distribution pattern of the amplitudes of vibrations, measured at various points on the surface of a shell, stimulated by a point source of harmonic force in the sound frequency range was studied experimentally. This pattern permits a valid spacing estimate to be carried out of the average structural characteristics of the vibrations, which are used for both estimation of the vibration excitability of the structure and for estimation of the effectiveness of use of a vibration-absorbing covering.
    Keywords: STRUCTURAL MECHANICS
    Type: Cybernetic Diagnostics of Mech. Systems with Vibro-acoustic Phenomena (NASA-TT-F-14899); p 61-67
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  • 91
    Publication Date: 2006-03-28
    Description: A method, developed for making measurements in reverberation chambers in the steady state mode, is reported. Spatial distribution patterns of the square of the sound pressure vs type of exciting signal were produced theoretically and checked experimentally in a reverberation chamber. Results of measurements of spatial irregularities of the field with pure tones and with noise bands in the 200 to 2,000 Hz frequency range were used for calculating statistical parameters of the reverbation fields by computer. The calculation program included determination of density probability function, integral distribution pattern, mathematical expectation, normalized dispersion of the mean square of the pressure.
    Keywords: STRUCTURAL MECHANICS
    Type: Cybernetic Diagnostics of Mech. Systems with Vibro-acoustic Phenomena (NASA-TT-F-14899); p 57-60
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  • 92
    Publication Date: 2006-03-28
    Description: Research was begun into the dynamic characteristics of wires, including the self-damping properties. A series of wire insulator fastenings, with and without dampers, was also developed.
    Keywords: STRUCTURAL MECHANICS
    Type: Cybernetic Diagnostics of Mech. Systems with Vibro-acoustic Phenomena (NASA-TT-F-14899); p 48-49
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  • 93
    Publication Date: 2006-03-28
    Description: Various calculation schemes were proposed for describing vibrations in a piping system with pulsating flow. Methods were selected and applied according to the type of irregularities examined: concentrated ones, extended ones, or complex ones. The selection of a method also depends on comparability of the extent of the irregularities with the pressure wavelength and velocity in the flow. Relations were found which permit a description of the interaction of a pulsating flow with any irregularity in the system. For complex systems with varying temperatures and some irregularities, relations were obtained, which reflect the varying phase displacement of the forces in these irregularities. The effect of the frictional torque on pipeline supports, in the presence of flexural and torsional vibrations was investigated, on the assumption that the frictional torque depends linearly on the angular velocity.
    Keywords: STRUCTURAL MECHANICS
    Type: Cybernetic Diagnostics of Mech. Systems with Vibro-acoustic Phenomena (NASA-TT-F-14899); p 51-52
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  • 94
    Publication Date: 2006-03-28
    Description: Certain characteristics of the reactions of typical skin panels of a passenger aircraft to acoustical loading are being investigated, for development of an objective method of diagnostics for skin condition, under the operations and maintenance sections of civil aviation. There are a number of difficulties connected with the solution of this problem. The reactions of skin panels exposed to the noises of the exhaust jets are dependent on the aircraft operating conditions, the geometric parameters and limiting conditions of the panels.
    Keywords: STRUCTURAL MECHANICS
    Type: Cybernetic Diagnostics of Mech. Systems with Vibro-acoustic Phenomena (NASA-TT-F-14899); p 41-43
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  • 95
    Publication Date: 2006-03-28
    Description: A program was compiled for calculating acoustical pressure levels, which might be created by vibrations of complex structures (an assembly of shells and rods), under the influence of a given force, for cases when these fields cannot be measured directly. The acoustical field is determined according to transition frequency and pulse characteristics of the structure in the projection mode. Projection characteristics are equal to the reception characteristics, for vibrating systems in which the reciprocity principle holds true. Characteristics in the receiving mode are calculated on the basis of experimental data on a point pulse space velocity source (input signal) and vibration response of the structure (output signal). The space velocity of a pulse source, set at a point in space r, where it is necessary to calculate the sound field of the structure p(r,t), is determined by measurements of acoustic pressure, created by a point source at a distance R. The vibration response is measured at the point where the forces F and f exciting the system should act.
    Keywords: STRUCTURAL MECHANICS
    Type: Cybernetic Diagnostics of Mech. Systems with Vibro-acoustic Phenomena (NASA-TT-F-14899); p 53-56
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  • 96
    Publication Date: 2006-02-14
    Description: The use of microcomputers in the design of a cable catenary large space antenna system is discussed. The development of a system design capability, data base utilization, systems integration, program structure and logic, and integrated graphics output are discussed.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. Langley Research Center Recent Experiences in Multidisciplinary Analysis and Optimization, Part 2; 14 p
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  • 97
    Publication Date: 2006-02-14
    Description: An exceptionally elegant method for structural optimization with constraints on the static response presented by Shield and Prager is discussed. Their derivation of the optimality condition was facilitated by a reformulation of the structural elasticity equations in terms of what was then a new variational principle, the principle of stationary mutual potential energy. Their optimality condition relates the design variable to an appropriately defined mutual strain energy. An alternative but related approach, based upon the principle of stationary mutual complementary energy, presented by N. C. Haung, is also discussed. The simplicity of these principles lies in the facts that the energy functionals are stationary at the solution to the field equations and that their stationary value is proportional to the quantity to be optimized.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. Langley Research Center Recent Experiences in Multidisciplinary Analysis and Optimization, Part 2; 11 p
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  • 98
    Publication Date: 2006-04-03
    Description: The effects of space environments on damping materials and damping designs on flexible structures were investigated. The following items were examined: damping of flexible spacecraft appendages; composite loss factor (n sub s) vs. time in high vacuum for damped test beams and damping of flexible structures. The STEP experiments show inherent damping of flexible structures in space effective possible damping design configurations for space structures, effects of passively damped components on the system loss factor of flexible structures and the effect of space environment on properties of damping materials.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. Langley Research Center STEP Expt. Requirements; p 79-102
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  • 99
    Publication Date: 2006-03-28
    Description: Endless structures are realized in practice, in the presence of loss and to an adequate extent, owing to which, reflections from the edges to the center part of the structure can be disregarded. In the absence of losses, reflections from the boundary frequently have to be taken into account. In this case, besides compensation for waves passing through the boundary, the reciprocal connection system can be used for compensation of the total field ahead of the boundary. In these cases, the system converters can be located in a different manner relative to the boundary and to one another. Each of the locations has inherent peculiarities, which must be taken into account in solving specific problems.
    Keywords: STRUCTURAL MECHANICS
    Type: Cybernetic Diagnostics of Mech. Systems with Vibro-acoustic Phenomena (NASA-TT-F-14899); p 222-228
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  • 100
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    In:  CASI
    Publication Date: 2006-03-28
    Description: The vibration characteristics of an unidimensional structure are discussed. The cases considered are: (1) a rigid pipe in which a wave propagates, (2) an infinite string along which a transverse wave propagates, (3) a rod along which longitudinal or torsional columns propagate, and (4) generally a unidimensional propagation of some one mode of vibrations which is nondegenerating with distance. Mathematical models are developed to show the performance of the mechanical devices under various damping conditions.
    Keywords: STRUCTURAL MECHANICS
    Type: Cybernetic Diagnostics of Mech. Systems with Vibro-acoustic Phenomena (NASA-TT-F-14899); p 216-221
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