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  • Other Sources  (4,035)
  • STRUCTURAL MECHANICS  (2,235)
  • AIRCRAFT DESIGN, TESTING AND PERFORMANCE  (1,800)
  • Chemistry
  • Physics
  • 1980-1984  (2,044)
  • 1975-1979  (1,991)
  • 1925-1929
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  • 1
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    Finite element modelling of buried structures (1984)
    In:  CASI
    Details
    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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  • 2
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    Single-drop impact damage prediction for low density, coated ceramic materials (1984)
    In:  CASI
    Details
    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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  • 3
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    Simulation of contact surface erosion for impact problems (1984)
    In:  CASI
    Details
    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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  • 4
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    Analysis of a transport fuselage section drop test (1984)
    In:  CASI
    Details
    Publication Date: 2005-03-28
    Description: Transport fuselage section drop tests provided useful information about the crash behavior of metal aircraft in preparation for a full-scale Boeing 720 controlled impact demonstration (CID). The fuselage sections have also provided an operational test environment for the data acquisition system designed for the CID test, and data for analysis and correlation with the DYCAST nonlinear finite-element program. The correlation of the DYCAST section model predictions was quite good for the total fuselage crushing deflection (22 to 24 inches predicted versus 24 to 26 inches measured), floor deformation, and accelerations for the floor and fuselage. The DYCAST seat and occupant model was adequate to approximate dynamic loading to the floor, but a more sophisticated model would be required for good correlation with dummy accelerations. Although a full-section model using only finite elements for the subfloor was desirable, constraints of time and computer resources limited the finite-element subfloor model to a two-frame model. Results from the two-frame model indicate that DYCAST can provide excellent correlation with experimental crash behavior of fuselage structure with a minimum of empirical force-deflection data representing structure in the analytical model.
    Keywords: AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Type: Res. in Struct. and Dyn., 1984; p 347-368
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  • 5
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    Crashworthiness of light aircraft fuselage structures: A numerical and experimental investigation (1984)
    In:  CASI
    Details
    Publication Date: 2005-03-28
    Description: The dynamic behavior of aircraft fuselage structures subject to various impact conditions was investigated. An analytical model was developed based on a self-consistent finite element (CFE) formulation utilizing shell, curved beam, and stringer type elements. Equations of motion were formulated and linearized (i.e., for small displacements), although material nonlinearity was retained to treat local plastic deformation. The equations were solved using the implicit Newmark-Beta method with a frontal solver routine. Stiffened aluminum fuselage models were also tested in free flight using the UTIAS pendulum crash test facility. Data were obtained on dynamic strains, g-loads, and transient deformations (using high speed photography in the latter case) during the impact process. Correlations between tests and predicted results are presented, together with computer graphics, based on the CFE model. These results include level and oblique angle impacts as well as the free-flight crash test. Comparisons with a hybrid, lumped mass finite element computer model demonstrate that the CFE formulation provides the test overall agreement with impact test data for comparable computing costs.
    Keywords: AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA. Langley Research Center Res. in Struct. and Dyn., 1984; p 325-346
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  • 6
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    Response and characteristics of structures subjected to S-H waves (1984)
    In:  CASI
    Details
    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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  • 7
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    Nonlinear dynamic analysis of sandwich panels (1984)
    In:  CASI
    Details
    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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  • 8
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    Initial postbuckling analysis of elastoplastic thin-shear structures (1984)
    In:  CASI
    Details
    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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  • 9
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    Fracture, failure, and fragmentation (1984)
    In:  CASI
    Details
    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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  • 10
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    Composite laminate optimization program suitable for microcomputers (1984)
    In:  CASI
    Details
    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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  • 11
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    Sensitivity analysis of limit state functions for probability-based plastic design (1984)
    In:  CASI
    Details
    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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  • 12
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    A triangular finite element for thin plates and shells (1984)
    In:  CASI
    Details
    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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  • 13
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    Stress-derivative control of keystoning deformation in finite element codes (1984)
    In:  CASI
    Details
    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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  • 14
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    Initial experience with distributing structural calculations among computers operating in parallel (1984)
    In:  CASI
    Details
    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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  • 15
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    Application of concurrent processing to structural dynamic response computations (1984)
    In:  CASI
    Details
    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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  • 16
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    The FLEX/32 multicomputing environment (1984)
    In:  CASI
    Details
    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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  • 17
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    Finite element computation on nearest neighbor connected machines (1984)
    In:  CASI
    Details
    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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  • 18
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    Application of numerical optimization techniques to high speed inlet bleed system design (1977)
    In:  CASI
    Details
    Publication Date: 2006-01-10
    Keywords: AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Type: Inlet Workshop; p 280-287
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  • 19
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    Rapid interface flaw extension with friction (1976)
    In:  CASI
    Details
    Publication Date: 2006-08-09
    Description: An idealized two-dimensional example of rapid interface flow extension is described. Initially undisturbed dissimilar isotropic, homogeneous, linearly elastic half-spaces are perfectly bonded along the interface y=0. Quantities associated with the half-space or = to 0 are denoted by the prime superscript or the subscripts 3 or 4 while those in y or = to 0 carry the subscripts 1 or 2. At time t=0 adjacent material points at x=0, y= + or - 0 are forced apart horizontally with a constant relative velocity delta v. This results in a zone of bond failure which extends symmetrically along the interface at a constant rate c. The newly created flaw surfaces are in sliding contact resisted by Coulomb friction. The friction coefficient is gamma.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. Langley Res. Center Advan. in Eng. Sci., Vol. 1; p 239-246
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  • 20
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    Tests of beaded and tubular structural panels (1978)
    In:  CASI
    Details
    Publication Date: 2006-06-12
    Description: Two efficient concepts built from curved elements were identified, and a data base for tubular panels was developed. The tubular panel failure modes were understood, and the data base for these panels indicated that their performance can be predicted. The concepts are currently being tested in a realistic builtup structure; 157 room temperature tests and 67 hot tests were made with no structural failures, although all of these tests were not at the design load of the structure.
    Keywords: STRUCTURAL MECHANICS
    Type: Recent Advan. in Structures for Hypersonic Flight, Pt. 2; p 538-576
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  • 21
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    Recent advances in thermal-structural analysis and design (1978)
    In:  CASI
    Details
    Publication Date: 2006-06-13
    Description: A continuing effort to develop a comprehensive capability for thermal-structural analysis and automated design (sizing) is reviewed. A principal role in the activity is played by the finite element program SPAR which contains both an efficient structural and thermal analysis capability. The benefit of having thermal and structural analyses in the same finite element program is illustrated by the application of SPAR to design calculations for the National Transonic Facility - a cryogenic wind tunnel under construction at Langley. Some experience with large-scale thermal structural analysis problems, particularly the space shuttle orbiter, has led to the identification of some analysis needs. Those needs include automated model generation and data output for lumped parameter thermal analysis, faster solution methods for nonlinear transient heat transfer, automated interpolation of temperature data from a thermal finite element model to a dissimilar structural finite model, and automated techniques to identify the times at which the critical combinations of transient heating and loads occur on a structure.
    Keywords: STRUCTURAL MECHANICS
    Type: Recent Advan. in Structures for Hypersonic Flight, Pt.2; p 897-941
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  • 22
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    Recent advances in thermostructural finite element analysis (1978)
    In:  CASI
    Details
    Publication Date: 2006-06-13
    Description: A comparison study is described which has indicated that the finite element and lumped parameter methods are comparable for steady-state conduction/convection analyses. The finite element model was advantageous because of the ease of model verification with computer graphics. Some problems encountered in constructing compatible thermal and structural models have indicated the need for further methodology developments to automate the transition between thermal and structural analyses. The need for more efficient finite element nonlinear transient algorithms has been cited. With further development in the thermal analysis area, the finite element method offers high potential for an integrated thermal/structural analysis capability.
    Keywords: STRUCTURAL MECHANICS
    Type: Recent Advan. in Structures for Hypersonic Flight, Pt. 2; p 851-896
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  • 23
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    External insulator for liquid hydrogen tanks (1978)
    In:  CASI
    Details
    Publication Date: 2006-06-13
    Description: With optimized insulation thickness, tank temperatures were always below 311 K (100 F). This conclusion indicated that an aluminum tank could be used with an optimized insulation system if desired. The N2 purged systems were always lighter than CO2 purged systems. The lower condensation temperature was the controlling factor. Closed cell foam systems were lightest. Closed cell foams, in spite of their need for protective outer insulation, produced insulation systems which were lighter than systems which allowed cryodeposition. Foam system durability established for TMAX = 316 K (110 F). Tests for a subsonic application established this durability; higher temperature limit foam durability was unknown at this. An increase in foam TMAX from 316 K (110 F) to 450 K (350 F) potentially decreased TPS mass by 25 percent.
    Keywords: STRUCTURAL MECHANICS
    Type: Recent Advan. in Structures for Hypersonic Flight, Pt. 2; p 807-847
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  • 24
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    Dryden Flight Research Center hot structures research (1978)
    In:  CASI
    Details
    Publication Date: 2006-06-13
    Description: The facilities, testing techniques, and design methods are described for NASA Dryden Flight Research Center. High temperature strain gage technology, realistic flight hardware fabrication, and structural analysis are discussed. A considerable amount of experimental work on hot structure concepts for hypersonic vehicles was performed; all the work is not complete, and there are still problem areas that need to be resolved.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. Langley Res. Center Recent Advan. in Structures for Hypersonic Flight, Pt. 2; p 707-750
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  • 25
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    Multiwall TPS (1978)
    In:  CASI
    Details
    Publication Date: 2006-06-13
    Description: A study of multiwall TPS as an alternative to LRSI for the space shuttle indicated that vented multiwall, with foil thicknesses limited to those used in multiwall fabricated to date, is some what heavier than LRSI. With reduced foil thicknesses, multiwall TPS may equal the weight of LRSI. Metallic conduction through multiwall TPS transfered less heat than gas conduction or radiation. Radiation heat transfer was greatest at high temperatures; however, the number of layers selected can significantly reduce radiation. At low-to-intermediate temperatures, gas conduction transfered the most heat through multiwall TPS. Gas conduction may be eliminated by evacuation of panels. Oxidation rates required a trade of foil thickness against life.
    Keywords: STRUCTURAL MECHANICS
    Type: Recent Advan. in Structures for Hypersonic Flight, Pt. 2; p 671-706
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  • 26
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    Structures and TPS for the NHFRF/HYTID (1978)
    In:  CASI
    Details
    Publication Date: 2006-06-13
    Description: The goal of HYTID was to provide a cost effective hypersonic vehicle constructed of near-state-of art systems and structure with sufficient margins to assure no vehicle flight development problems, and to permit concentration of flight operations on hypersonic research with a broad series of experiments carried in a dedicated payload bay or on the exposed surface of the lower aft fuselage.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. Langley Res. Center Recent Advan. in Structures for Hypersonic Flight, Pt. 2; p 601-627
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  • 27
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    Design and fabrication of a super alloy thermal protection system (1978)
    In:  CASI
    Details
    Publication Date: 2006-06-13
    Description: A lightweight metallic TPS was designed, and two test articles were fabricated, one from Haynes 188 and one from Rene 41. A baseline TPS concept, selected at the beginning of the program, consisted of a Haynes 25 corrugation-stiffened beaded skin surface panel, a specially designed support system, and an insulation system. By optimizing the structure for the design loads and by chem-milling to remove material not needed, the mass of the baseline surface panel was reduced 25%, and the mass of the support structure was reduced 50%. The insulation system mass was reduced 40% by using two types of insulation, each suited to its temperature range, and by eliminating a foul bag which encapsulated the baseline insulation system. These reductions resulted in an overall 35% reduction in mass of the Haynes 188 panel from the baseline Haynes 25 design. Similar reductions were achieved with the Rene 41 system.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. Langley Res. Center Recent Advan. in Structures for Hypersonic Flight, Pt. 2; p 629-669
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  • 28
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    Structures for hypersonic airbreathing tactical missiles (1978)
    In:  CASI
    Details
    Publication Date: 2006-06-13
    Description: The studies to date were encouraging and indicated that materials were available or could be developed to satisfy scramjet requirements. Some of the more promising materials for the critical components were indicated. This information is summarized as follows : (1) radome - Slip cast fused silica is the current candidate, but others are being investigated. One shortcoming of slip cast fused silica is its susceptability to rain damage. (2) inlet leading edges - A refractory metal with a good oxidation protective coating will be required. Tantalum T222 with a Hafnia coating looks promising. (3) inlet ducts - An uninsulated refractory alloy will be required. Columbium F-85 was the best of those considered for the noncircular ducts. (4) external body - The external body temperatures are sufficiently low to permit the use of super alloys. (5) combustor and nozzle - The pyrolytic graphite/silicon carbide coating is very attractive for use in the combustor and nozzle areas.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. Langley Res. Center Recent Advan. in Structures for Hypersonic Flight, Pt. 2; p 577-599
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  • 29
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    Influence of a circular hole under uniform normal pressure on the stresses around a line crack in an infinite plate (1976)
    In:  CASI
    Details
    Publication Date: 2006-08-09
    Description: Based on the two dimensional theory of elasticity and by the use of Muskhelishvili's technique, the influence of a circular hole, under uniform normal pressure, on the stresses around a line crack in an infinite plate subjected to tension is discussed. Numerical calculations were carried out, and the variation of the crack tip stress intensity factor due to the geometry was clarified.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. Langley Res. Center Advan. in Eng. Sci., Vol. 1; p 275-282
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  • 30
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    Combined vibration/temperature/sideload environmental testing of UHF blade antennas (1979)
    In:  CASI
    Details
    Publication Date: 2006-07-02
    Description: Service problems encountered on the F-4 aircraft showed that the environmental qualification requirements for the UHF blade antenna were not adequate. Although the individual environmental levels were stringent enough, only combined environmental testing could duplicate the conditions in which service problems occurred. Techniques for applying static side load simultaneously with vibration and temperature were developed. The combined environment testing was instrumental in the rapid assessment of antenna modifications and resulted in a final configuration which proved satisfactory in service. A need to include combined environmental testing for qualification of blade antennas was established.
    Keywords: STRUCTURAL MECHANICS
    Type: Shock and Vibration Inform. Center The Shock and Vibration Bull., Pt. 3; p 79-84
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  • 31
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    Selected topics from the structural acoustics program for the B-1 aircraft (1979)
    In:  CASI
    Details
    Publication Date: 2006-07-02
    Description: The major elements of the structural acoustics program for the B-1 aircraft are considered. Acoustic pressures measured at 280 sites on the surface of the vehicle were used to develop pressure models for a resizing of airframe components for aircraft No. 4 (A/C4). Acoustical fatigue design data for two dynamically complex structural configurations were acquired in laboratory programs, the conceptions for and executions of which detailed significant departures from the conventional. Design requirements for mechanical fasteners for configurations other than these two made use of analytical extensions of regrettably limited available information.
    Keywords: AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Type: Shock and Vibration Inform. Center The Shock and Vibration Bull., Pt. 3; p 55-68
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  • 32
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    Vibration investigation of a large transport helicopter (1977)
    In:  CASI
    Details
    Publication Date: 2004-11-29
    Keywords: AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Type: Shock and Vibration Inform. Center The Shock and Vibration Bull. Part 3 Sept. 1977; p 139-147
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  • 33
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    Multiobjective optimization techniques for structural design (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The multiobjective programming techniques are important in the design of complex structural systems whose quality depends generally on a number of different and often conflicting objective functions which cannot be combined into a single design objective. The applicability of multiobjective optimization techniques is studied with reference to simple design problems. Specifically, the parameter optimization of a cantilever beam with a tip mass and a three-degree-of-freedom vabration isolation system and the trajectory optimization of a cantilever beam are considered. The solutions of these multicriteria design problems are attempted by using global criterion, utility function, game theory, goal programming, goal attainment, bounded objective function, and lexicographic methods. It has been observed that the game theory approach required the maximum computational effort, but it yielded better optimum solutions with proper balance of the various objective functions in all the cases.
    Keywords: AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA. Langley Research Center Recent Experiences in Multidisciplinary Analysis and Optimization, Part 2; 8 p
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  • 34
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    Overview: Applications of numerical optimization methods to helicopter design problems (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: There are a number of helicopter design problems that are well suited to applications of numerical design optimization techniques. Adequate implementation of this technology will provide high pay-offs. There are a number of numerical optimization programs available, and there are many excellent response/performance analysis programs developed or being developed. But integration of these programs in a form that is usable in the design phase should be recognized as important. It is also necessary to attract the attention of engineers engaged in the development of analysis capabilities and to make them aware that analysis capabilities are much more powerful if integrated into design oriented codes. Frequently, the shortcoming of analysis capabilities are revealed by coupling them with an optimization code. Most of the published work has addressed problems in preliminary system design, rotor system/blade design or airframe design. Very few published results were found in acoustics, aerodynamics and control system design. Currently major efforts are focused on vibration reduction, and aerodynamics/acoustics applications appear to be growing fast. The development of a computer program system to integrate the multiple disciplines required in helicopter design with numerical optimization technique is needed. Activities in Britain, Germany and Poland are identified, but no published results from France, Italy, the USSR or Japan were found.
    Keywords: AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA. Langley Research Center Recent Experiences in Multidisciplinary Analysis and Optimization, Part 2; 13 p
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  • 35
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    The structural optimization of a spreader bar for twin lift helicopter operations (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: An optimization study was performed to develop a minimum weight spreader bar to allow two helicopters to lift the same payload. With this arrangement, the maximum payload that can be lifted is almost doubled without the expense of designing and building a new helicopter. The concept has had some limited use by civil helicopter operators using small helicopters and has been demonstrated in large scale by two CH-54's which successfully lifted a total load of 20 ton. To this point, rather heavy available beams or tower structures have been used for the spreader bar. Since the weight of the bar not only detracts from payload but also adds to the logistics problem, there are more than the usual incentives to minimize weight. Since the design requirement is for classic beam column with uniform side loads resulting from bar weight and aerodynamic drag, the design problem is particularly amenable to optimization. A study has been performed at Sikorsky to establish the minimum weight for a spreader bar sized to carry a load equal to the capacity of two Army BLACK HAWK helicopters. Toward this end, a computer program was written to analyze the spreader bar deflections and stresses and coupled to the NASA developed CONMIN optimization routines.
    Keywords: AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA. Langley Research Center Recent Experiences in Multidisciplinary Analysis and Optimization, Part 2; 12 p
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  • 36
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    Optimization of helicopter rotor blade design for minimum vibration (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The optimization approach discussed is part of an ongoing effort to develop a general automated procedure for rotor blade design. This procedure can be used to determine the necessary geometric, structural, and material properties of a rotor system to achieve desired objectives relating to vibration, stress, and aerodynamic performance. The approach used for helicopter vibration is emphasized. Based on analytical studies performed at the United Technologies Research Center (UTRC), a simplified vibration analysis was developed to be used in conjunction with a forced response analysis in the optimization process. This simplified analysis improves the efficiency of the design process significantly. Results of applying this approach to the design of an existing rotor blade model are presented.
    Keywords: AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA. Langley Research Center Recent Experiences in Multidisciplinary Analysis and Optimization, Part 2; 17 p
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  • 37
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    Attack helicopter (AH-1T) cockpit systems integration (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: This discussion summarizes the effort conducted by the BHTI Human Factors and Cockpit Arrangement group for a study and design of the integration of a cockpit control system for the AH 1T (TOW). The resulting design is a culmination of studies that were conducted using the existing configuration as a baseline and complementing it with new equipment and subsystems that fulfill the attack helicopter requirements for the foreseeable future. Of primary concern was the requirement to add a missile control system, with secondary considerations for improved NOE and night operations. In addition, growth capabilities for improved target acquisition, weapons delivery, and precise navigation was considered. Along with the addition of new equipment, the aircraft was assumed to have a central multiplex data bus system for information transfer throughout the aircraft and its subsystems.
    Keywords: AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA. Ames Research Center Technical Workshop: Advanced Helicopter Cockpit Design Concepts; p 271-316
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  • 38
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    Operational requirements - system concepts (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: Nine research areas that are most critical to the issue of cockpits for the single pilot are discussed. Helicopter are addressed in this report. They are as follows: (1) automation priority issues; (2) increased complexity of systems; (3) cockpit workload highest in navigation; (4) auto hover and flight trim controls; (5) voice technology in integrated form; (6) systems must have visual and auditory declutter modes; (7) cockpit should be designed to be NBC resistant; and (8) considerations for spillover to civilian public service.
    Keywords: AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Type: Technical Workshop: Advanced Helicopter Cockpit Design Concepts; p 229-238
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  • 39
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    HH-60D night hawk helicopter (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: Fundamental development issues, system requirements and improvements are reported for the HH-60D night hawk helicopter. The HH-60D mission requirements are for combat search and rescue (aerospace rescue and recovery service user based at Scott AFB) and special operations (special operations forces based at Hurlburt AFB). Cockpit design, computer architecture and software are described in detail.
    Keywords: AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA. Ames Research Center Technical Workshop: Advanced Helicopter Cockpit Design Concepts; p 145-164
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  • 40
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    Vibration isolation system for testing in a vacuum (1984)
    In:  CASI
    Details
    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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  • 41
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    The NASA welding assessment program (1984)
    In:  CASI
    Details
    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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  • 42
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    EET theoretical design techniques (1981)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: As a part of the EET aerodynamics program an out-of-house program was developed and monitored to provide theoretical procedures useful in the design of transport aircraft. The focus of the effort was to provide tools valid in the nonlinear transonic speed range. The effort was divided into two basic areas, inviscid configuration analysis and design procedures and viscous correction procedures.
    Keywords: AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Type: Advan. Aerodyn.: Selected NASA Res.; p 79-94
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  • 43
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    F-111 TACT natural laminar flow glove flight results (1981)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: Improvements in cruise efficiency on the order of 15 to 40% are obtained by increasing the extent of laminar flow over lifting surfaces. Two methods of achieving laminar flow are being considered, natural laminar flow and laminar flow control. Natural laminar flow (NLF) relies primarily on airfoil shape while laminar flow control involves boundary layer suction or blowing with mechanical devices. The extent of natural laminar flow that could be achieved with consistency in a real flight environment at chord Reynolds numbers in the range of 30 x 10(6) power was evaluated. Nineteen flights were conducted on the F-111 TACT airplane having a NLF airfoil glove section. The section consists of a supercritical airfoil providing favorable pressure gradients over extensive portions of the upper and lower surfaces of the wing. Boundary layer measurements were obtained over a range of wing leading edge sweep angles at Mach numbers from 0.80 to 0.85. Data were obtained for natural transition and for a range of forced transition locations over the test airfoil.
    Keywords: AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA. Langley Research Center Advan. Aerodyn.: Selected NASA Res.; p 11-20
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  • 44
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    Space shuttle solid rocket booster water entry cavity collapse loads (1982)
    In:  CASI
    Details
    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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  • 45
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    Analysis of fuel system technology for broad property fuels (1984)
    In:  CASI
    Details
    Publication Date: 2006-04-09
    Description: An analytical study was performed in order to assess relative performance and economic factors involved with alternative advanced fuel systems for future commercial aircraft operating with broad property fuels. Significant results, with emphasis on design practicality from the engine manufacturer' standpoint, are highlighted. Several advanced fuel systems were modeled to determine as accurately as possible the relative merits of each system from the standpoint of compatibility with broad property fuel. Freezing point, thermal stability, and lubricity were key property issues. A computer model was formulated to determine the investment incentive for each system. Results are given.
    Keywords: AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA. Lewis Research Center Assessment of Alternative Aircraft Fuels; p 141-158
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  • 46
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    A new formulation for the epsilon method applied to the minimum-time-to-climb problem (1978)
    In:  CASI
    Details
    Publication Date: 2006-03-02
    Description: Balakrishnan's epsilon technique is used to compute minimum-time profiles for the F-104 airplane. This technique differs from the classical gradient method in that a quadratic penalty on the error in satisfying the equation of motion is included in the cost function to be minimized as a means of eliminating the requirement of satisfying the equations of motion. Although the number of unknown independent functions is increased to include the state variables, the evaluation of the gradient of the cost function is simplified, resulting in considerable computational savings, thereby making it appear feasible to use the epsilon method for real-time application.
    Keywords: AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA, Washington Fourth Inter-Center Control Systems Conf.; p 423-434
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  • 47
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    In-flight three-dimensional boundary layer and wake measurements from a swept supercritical wing (1978)
    In:  CASI
    Details
    Publication Date: 2006-02-22
    Description: Three-dimensional boundary layer and wake velocity profiles were measured in flight on the supercritical wing of the F-111 transonic aircraft technology aircraft. These data, along with pressure distributions, were obtained to establish a data base with which data obtained by three-dimensional analytical techniques could be correlated. Only a brief summary of the total data base is given. The data presented represented one chord station at a wing leading-edge sweep angle of 26 deg. They cover an angle of attack range from 6 degs to 9 degs at free-stream Mach numbers from 0.85 to 0.90. A brief discussion of the techniques used to obtain the boundary layer and wake profiles is included.
    Keywords: AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA. Langley Res. Center Advanced Technol. Airfoil Res., Vol. 1, Pt. 2; p 643-655
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  • 48
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    A conceptual basis for the design of damage-tolerant structural systems (1984)
    In:  CASI
    Details
    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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  • 49
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    Aeroelastic-aerodynamic optimization of high speed helicopter-compound rotor (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: Several problems related to the aeroelastic/aerodynamic optimization of a high speed helicopter compound rotor are discussed. The helicopter fuselage vibration problem, the effects of fuselage vibrations, the source of external and periodic air loads, typical airfoil environments and configurations, rotor dynamics, vibration reduction, and requirements for the rotor design optimization analysis are among the topics covered.
    Keywords: AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA. Langley Research Center Recent Experiences in Multidisciplinary Analysis and Optimization, Part 2; 20 p
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  • 50
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    Helicopter rotor blade aerodynamic optimization by mathematical programming (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: Formal mathematical programing was applied to the aerodynamic rotor blade design process. The approach is to couple hover and forward flight analysis programs with the general-purpose optimization program CONMIN to determine the blade taper ratio, percent taper, twist distribution, and solidity which minimize the horsepower required at hover while meeting constraints on forward flight performance. Designs obtained using this approach for the blade of a representative Army helicopter compare well with those obtained using a conventional approach involving personnel-intensive parametric studies. Results from the present method can be obtained in 2 days as compared to 5 weeks required by the conventional procedure. Also the systematic manipulation of the design variables by the optimization procedure minimizes the need for the researcher to have a vast body of past experience and data in determining the influence of a design change on the performance.
    Keywords: AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Type: Recent Experiences in Multidisciplinary Analysis and Optimization, Part 2; 12 p
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  • 51
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    Structural optimization of large ocean-going structures (1984)
    In:  CASI
    Details
    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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  • 52
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    Integrated cockpit design for the Army helicopter improvement program (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The main Army Helicopter Improvement Program (AHIP) mission is to navigate precisely, locate targets accurately, communicate their position to other battlefield elements, and to designate them for laser guided weapons. The onboard navigation and mast-mounted sight (MMS) avionics enable accurate tracking of current aircraft position and subsequent target location. The AHIP crewstation development was based on extensive mission/task analysis, function allocation, total system design, and test and verification. The avionics requirements to meet the mission was limited by the existing aircraft structural and performance characteristics and resultant space, weight, and power restrictions. These limitations and night operations requirement led to the use of night vision goggles. The combination of these requirements and limitations dictated an integrated control/display approach using multifunction displays and controls.
    Keywords: AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA. Ames Research Center Technical Workshop: Advanced Helicopter Cockpit Design Concepts; p 121-144
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  • 53
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    A study of component design loads due to dynamic environment (1982)
    In:  CASI
    Details
    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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  • 54
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    Effect of heavy rain on aircraft (1981)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: A summary on heavy rain effects on aircraft aerodynamics validation of research and some wind shear accidents in which heavy rain were an important factor. Frost formation and what frost does to the lift and drag curves for an airfoil was examined. If frost could cause severe aerodynamic problems for both general aviation and transport aircraft due to its roughness, then heavy rain produce a similar result. The influencing parameters of heavy rain on an aircraft are studied. Sources of aerodynamic roughness due to rain and wind shear and heavy rain accidents are outlined.
    Keywords: AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA. Marshall Space Flight Center Proc.: 5th Ann. Workshop on Meteorol. and Environ. Inputs to Aviation Systems 76-80 (SEE N82-21139 12-01)
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  • 55
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    Meteorology impact on future aircraft design (1981)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: Meteorology impact on future aircraft design is discussed. Upcoming changes in both design and operations that will be influenced by the meteorological environment are outlined. Future and more nonconventional designs and meteorological impact brought about by operational changes over the next few years are examined.
    Keywords: AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA. Marshall Space Flight Center Proc.: 5th Ann. Workshop on Meteorol. and Environ. Inputs to Aviation Systems; p 29-34
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  • 56
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    NASTRAN analysis of a wheel-rail loading on its foundation (1978)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: One type of azimuth bearing for a large ground antenna (100 m) will consist of steel wheels, mounted at four corners of the alidade, rolling on a circular flat rail which provides the vertical restraints; a radial constraining bearing at the center of the alidade provides the horizontal restraints. One important design feature is the compressive stresses in the grout or concrete foundation under the wheel-rail load. A finite element analysis check was made of a particular design that consists of a steel rail resting on a concrete foundation. Symmetry was assumed as much as possible in order to minimize the models, but meaningful element sizes were used. Recently developed isoparametric hexahedron elements available in the NASTRAN computing program, which minimizes the number of elements required while maintaining the accuracy of the computed stresses, were used with two versions of NASTRAN. Test cases to check with the analytical solutions were made. A side loading was also applied to calculate the increase in the concrete stresses.
    Keywords: STRUCTURAL MECHANICS
    Type: The Deep Space Network; p 204-215
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  • 57
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    Proportioning the airplane for lateral stability (1976)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: Proportioning for lateral aircraft control included: (1) directional stability (slope of curve of yawing moment coefficient against sideslip), and (2) effective dihedral factor (slope of curve of rolling moment coefficient against sideslip). Basic forces influencing the directional stability of aircraft are indicated. Propeller side force, basic fuselage yaw, and vertical tail side force contributed to yaw moment about center of gravity.
    Keywords: AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Type: Collected Works of Charles J. Donlan; 6 p
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  • 58
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    A simplified method of evaluating the stress wave environment of internal equipment (1979)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: A simplified method called the transfer function technique (TFT) was devised for evaluating the stress wave environment in a structure containing internal equipment. The TFT consists of following the initial in-plane stress wave that propagates through a structure subjected to a dynamic load and characterizing how the wave is altered as it is transmitted through intersections of structural members. As a basis for evaluating the TFT, impact experiments and detailed stress wave analyses were performed for structures with two or three, or more members. Transfer functions that relate the wave transmitted through an intersection to the incident wave were deduced from the predicted wave response. By sequentially applying these transfer functions to a structure with several intersections, it was found that the environment produced by the initial stress wave propagating through the structure can be approximated well. The TFT can be used as a design tool or as an analytical tool to determine whether a more detailed wave analysis is warranted.
    Keywords: STRUCTURAL MECHANICS
    Type: Shock and Vibration Inform. Center The Shock and Vibration Bull., Pt. 1; p 89-96
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  • 59
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    Status of cavity noise phenomena measurement and suppression on the B-1 aircraft (1979)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: During the B-1 aircraft development, an extensive program of weapons bay cavity noise measurement and suppression studies was performed using wind tunnel models, flight test measurements, and aircraft design modifications. Substantial cavity noise reduction was demonstrated during flight test operations. The unsuppressed cavity noise level of 170 dB was reduced to values less than 150 dB with external retractable spoilers upstream of the cavity opening.
    Keywords: AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Type: Shock and Vibration Inform. Center The Shock and Vibration Bull., Pt 1; p 59-66
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  • 60
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    High G pyrotechnic shock simulation using metal-to-metal impact (1979)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: A technique for simulating high g level pyrotechnic shocks is described and the results of applying the technique to obtain the MIL-STD-1540A shock spectrum with a maximum acceleration of 18,000g at 2,000 Hz are presented. Designing the resonant beam and plate on which the test unit is mounted, and generating a proper impulsive load on them, were the essentials of the technique. One dimensional stress wave and Euler equations were employed in the design. A metal pendulum hammer was used to generate the impulsive load.
    Keywords: STRUCTURAL MECHANICS
    Type: Shock and Vibration Inform. Center The Shock and Vibration Bull., Pt. 1; p 97-100
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  • 61
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    Probability of failure prediction for step-stress fatigue under sine or random stress (1979)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: A previously proposed cumulative fatigue damage law is extended to predict the probability of failure or fatigue life for structural materials with S-N fatigue curves represented as a scatterband of failure points. The proposed law applies to structures subjected to sinusoidal or random stresses and includes the effect of initial crack (i.e., flaw) sizes. The corrected cycle ratio damage function is shown to have physical significance.
    Keywords: STRUCTURAL MECHANICS
    Type: Shock and Vibration Inform. Center The Shock and Vibration Bull., Pt. 1; p 31-41
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  • 62
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    Spin tests of 1/16-scale models of the N3N-3 landplane and seaplane, 12 January 1940 (1976)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: The test program included the study of both the seaplane and landplane types. On both versions of the model, the effects of loading changes and control dispositions were examined, and on the seaplane, the effect of the cowled and uncowled engine was investigated.
    Keywords: AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Type: Collected Works of Charles J. Donlan; 37 p
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  • 63
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    Spin tests of a 1/20-scale model of the XF4U-1 airplane, 12 July 1939 (1976)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: These tests were performed to determine the spinning characteristics of the 1/20-scale model of the XF4U-1 airplane. Effects of loading changes and various control dispositions using both the original and modified vertical tail surfaces were studied. Subsequent tests were made to determine the effects of additional tail modifications.
    Keywords: AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Type: Collected Works of Charles J. Donlan; 47 p
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  • 64
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    Surface contour of a biaxially strained, doubly curved antenna reflective mesh (1982)
    In:  CASI
    Details
    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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  • 65
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    Meteorological impact on aviation fuel efficiency (1981)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The connection between fuel consumption and weather data is discussed. Fuel efficient flights creating adequate near real time weather information are examined. The lack of highly resolved real time and near real time wind and temperature data at flight altitudes is investigated. The existing systems, which is based on twice a day balloon observations, supplemented by pilot reports or other occasional data, is not adequate for optimum flight planning. The impacts of upper winds and temperatures on fuel efficiency and flight planning are not widely appreciated and developing new weather products are considered.
    Keywords: AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA. Marshall Space Flight Center Proc.: 5th Ann. Workshop on Meteorol. and Environ. Inputs to Aviation Systems; p 15-19
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  • 66
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    Spin tests of a 1/20-scale model of the XP-39 airplane, 15 March 1939 (1976)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: The tests were performed to determine the spinning characteristics of a 1/20-scale model of the Bell XP-39 airplane. Effects of loading changes and of various control dispositions were studied. Subsequent tests were performed to determine the effect of a change in wing dihedral.
    Keywords: AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Type: Collected Works of Charles J. Donlan; 23 p
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  • 67
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    Lateral stability and control tests of the XP-77 airplane in the NACA full-scale tunnel, 16 June 1944 (1976)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: Tests were made in the NACA full-scale tunnel to determine the lateral stability and control characteristics of the XP-77 airplane. Measurements were made of the forces and moments on the airplane at various angles of attack and angles of yaw. The measurements were made with the propeller removed and with the propeller installed and operating at various thrust coefficients, and with the landing flaps retracted and deflected. The effects of aileron, elevator, and rudder deflection on control surface effectiveness and hinge moments were determined. The tests were planned to obtain the data required to evaluate as completely as possible the Army Air Force requirements on lateral stability and control for pursuit-type airplanes.
    Keywords: AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Type: Collected Works of Charles J. Donlan; 84 p
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  • 68
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    Opportunities for aerodynamic-drag reduction (1975)
    In:  CASI
    Details
    Publication Date: 2006-01-11
    Description: Methods for reducing aerodynamic drag to improve aircraft performance and reduce fuel consumption are discussed. The techniques considered are: (1) pressure drag reduction, (2) supercritical airfoils, (3) subcritical airfoils, (4) induced drag reduction by over-the-wing blowing and increased aspect ratio, and (5) friction drag reduction by laminar flow control and slot injection. It is stated that a 50 percent reduction from current drag values is expected through the application of these techniques.
    Keywords: AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA/Univ. Conf. on Aeron.; p 323-352
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  • 69
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    Some trends in aircraft design: Structures (1975)
    In:  CASI
    Details
    Publication Date: 2006-01-11
    Description: Trends and programs currently underway on the national scene to improve the structural interface in the aircraft design process are discussed. The National Aeronautics and Space Administration shares a partnership with the educational and industrial community in the development of the tools, the criteria, and the data base essential to produce high-performance and cost-effective vehicles. Several thrusts to build the technology in materials, structural concepts, analytical programs, and integrated design procedures essential for performing the trade-offs required to fashion competitive vehicles are presented. The application of advanced fibrous composites, improved methods for structural analysis, and continued attention to important peripheral problems of aeroelastic and thermal stability are among the topics considered.
    Keywords: AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA/Univ. Conf. on Aeron.; p 213-272
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  • 70
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    Fuel system research and technology: An overview of the NASA program (1984)
    In:  CASI
    Details
    Publication Date: 2006-04-09
    Description: The interactions between the design and operation of aircraft fuel systems and the properties of alternative aircraft fuels are discussed. An overview of fuels system research and technology in terms of its rationale, its progress, and future plans is given. The measurement of ambient air temperatures for a wide range of seasonal and geographic variations, design studies on the use of fuels with increased as well as conventional freezing temperatures, the evaluation of fuel heating systems, and the low temperature behavior of fuels are among the topics discussed.
    Keywords: AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Type: Assessment of Alternative Aircraft Fuels; p 111-120
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  • 71
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    Flight test techniques for low speed airfoil evaluation (1978)
    In:  CASI
    Details
    Publication Date: 2006-02-21
    Description: Techniques for in-flight evaluation of new airfoils by modifying a single engine general aviation aircraft and measuring and recording airfoil surface pressures, airfoil wake pressures, and aircraft angle of attack and airspeed are presented. Included are descriptions of the aircraft modifications, instrumentation, data reduction techniques, illustrations of typical results and comments on new equipment for flight test applications.
    Keywords: AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA. Langley Res. Center Advanced Technol. Airfoil Res., Vol. 1, Pt. 2; p 623-642
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  • 72
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    Microcomputer design and analysis of the cable catenary large space antenna system (1984)
    In:  CASI
    Details
    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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  • 73
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    Multidisciplinary approach to the design of high pressure oxygen systems (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: Several examples of spacecraft systems fires are examined. Much of the design, manufacture, inspection, test, and operation of current high pressure oxygen components and systems has been driven by weight, cost, functional, and schedule requirements. As a result, little coordination has been expended on design for safe operation. While the number of oxygen related fires has not been large, their cost, including program losses and delays, has been very large. Most of these failures need not have occurred.
    Keywords: AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA. Langley Research Center Recent Experiences in Multidisciplinary Analysis and Optimization, Part 2; 13 p
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  • 74
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    Structural optimization with constraints on transients response (1984)
    In:  CASI
    Details
    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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  • 75
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    Fuel system design concepts for broad property fuels (1984)
    In:  CASI
    Details
    Publication Date: 2006-04-09
    Description: The results of a study assessing the impact of using jet fuel with relaxed specification properties on an aircraft fuel system are given. The study objectives were to identify credible values for specific fuel properties which might be relaxed, to evolve advanced fuel system designs for airframe and engines which would permit use of the specified relaxed properties fuels, and to evaluate performance of the candidate advanced fuel systems and the relaxed property fuels in a typical transport aircraft. The study used, as a baseline, the fuel system incorporated in the Lockheed Tristar. This aircraft is powered by three RB.211-524 Rolls-Royce engines and incorporates a Pratt and Whitney ST6C-421 auxiliary power unit for engine starting and inflight emergency electrical power. The fuel property limits examined are compared with commercial Jet A kerosene and the NASA RFP fuel properties. A screening of these properties established that a higher freezing point and a lower thermal stability would impact fuel system design more significantly than any of the other property changes. Three candidate fuel systems which combine the ability to operate with fuels having both a high freeze point and a low thermal stability are described. All candidates employ bleed air to melt fuel freeze-out prior to starting the APU or an inoperable engine. The effects of incorporating these systems on aircraft weight and engine specific fuel consumption are given.
    Keywords: AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA. Lewis Research Center Assessment of Alternative Aircraft Fuels; p 159-170
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  • 76
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    The effects of the space environment on damping materials and damping designs on flexible structures (1984)
    In:  CASI
    Details
    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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  • 77
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    Application of numerical optimization to rotor aerodynamic design (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: Based on initial results obtained from the performance optimization code, a number of observations can be made regarding the utility of optimization codes in supporting design of rotors for improved performance. (1) The primary objective of improving the productivity and responsiveness of current design methods can be met. (2) The use of optimization allows the designer to consider a wider range of design variables in a greatly compressed time period. (3) Optimization requires the user to carefully define his problem to avoid unproductive use of computer resources. (4) Optimization will increase the burden on the analyst to validate designs and to improve the accuracy of analysis methods. (5) Direct calculation of finite difference derivatives by the optimizer was not prohibitive for this application but was expensive. Approximate analysis in some form would be considered to improve program response time. (6) Program developement is not complete and will continue to evolve to integrate new analysis methods, design problems, and alternate optimizer options.
    Keywords: AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA. Langley Research Center Recent Experiences in Multidisciplinary Analysis and Optimization, Part 2; 15 p
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  • 78
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    Study of meteoroid impact craters on various materials (A0138-1) (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: Interplanetary dust particles (micrometeoroids) are expected to form well-defined craters upon impacting exposed material in space. Studying the frequency and features of these craters will provide data on the mass-flux distribution of micrometeoroids and, to a lesser extent, on the velocity magnitude and direction. This experiment will study impact craters produced by micrometeoroids on selected materials (metals and glasses in the form of thick targets) to obtain valuable technological and scientific data. Specifically, the studies will focus on determining micrometeoroid composition and mass-flux distribution. Analyses will also be made on the distribution of impact velocity vectors.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. Langley Research Center Long Duration Exposure Facility (LDEF); p 121-123
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  • 79
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    A study of the effect of subcritical crack growth on the geometry dependence on nonlinear fracture toughness parameters (1976)
    In:  CASI
    Details
    Publication Date: 2006-08-09
    Description: The effect of subcritical crack growth on the geometry dependence of nonlinear fracture toughness parameters was studied by comparing the toughness values for different specimen geometries at the onset of subcritical crack growth and at the initiation of unstable crack propagation. Center-cracked thin sheet specimens of 2024-T3 and 7075-T6 aluminum alloys were tested by varying the specimen length L, width w, and crack length-to-width ratio c/w. When the onset of unstable crack propagation was selected as the critical point, the nonlinear energy toughness and the R curve toughness increased with increasing w and decreasing L and c/w. However, when the onset of subcritical crack growth was taken as the critical point, energy toughness and the linear toughness values were independent of these geometrical variables.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. Langley Res. Center Advan. in Eng. Sci., Vol. 1; p 257-266
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  • 80
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    Influence of specimen boundary on the dynamic stress intensity factor (1976)
    In:  CASI
    Details
    Publication Date: 2006-08-09
    Description: The problem to be considered is the sudden appearance of a flaw or crack in a strip of material of finite height subjected to tensile loading. Stress waves are generated within the strip and are reflected from boundary to boundary. Of interest is the maximum value of the dynamic stress intensity factor at a given instance of time as the strip height to crack length ratio is varied.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. Langley Res. Center Advan. in Eng. Sci., Vol. 1; p 205-214
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  • 81
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    An investigation into the probabilistic combination of quasi-static and random accelerations (1984)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Keywords: STRUCTURAL MECHANICS
    Type: JPL, Proceedings of the Shuttle Payload Dynamic Environments and Loads Prediction Workshop, Volume 2; p 527-541
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  • 82
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    Propulsive effects due to flight through turbulence (1975)
    In:  Other Sources
    Details
    Publication Date: 2011-08-16
    Description: A simple and straightforward analysis is presented for evaluating the approximate magnitude of the propulsive effect for various types of airplane (soaring glider, light airplane, fighter, and transport). The airplane, subject to vertical gust disturbances, is assumed to be constrained to fly at constant airspeed and constant pitch angle. Changes in the magnitude and direction of the lift vector are taken into account. It is shown that the thrust effects due to turbulence vary as the square of the turbulence intensity and are quite small for moderate turbulence. Only for rather severe turbulence are the effects large enough to be given any consideration. The thrust coefficient is 10-20% of the drag coefficient of a soaring glider.
    Keywords: AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Type: Journal of Aircraft; 12; July 197
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  • 83
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    Fracture testing with surface crack specimens (1975)
    In:  Other Sources
    Details
    Publication Date: 2011-08-16
    Description: This paper is a report of ASTM Task Group E24.01.05 on Part-Through Crack Testing. It includes recommendations for the design, preparation, and static fracture testing of surface crack specimens based on the current state of the art. The recommendations are preceded by background information including discussions of stress intensity factors, crack opening displacements, and fracture toughness values associated with surface crack specimens. Cyclic-load and sustained-load tests are discussed briefly. Recommendations for further research are included.
    Keywords: STRUCTURAL MECHANICS
    Type: Journal of Testing and Evaluation; 3; Sept
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  • 84
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    Comparison of sonic boom minimization results in real and isothermal atmospheres (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: The method of Seebass and George (1972, 1974) for minimizing certain features of the pressure signature and yielding the corresponding F function and equivalent area distribution A in an isothermal atmosphere is modified to provide the same capability for a real atmosphere. The appropriate equations of George and Plotkin (1969) describing horizontal advance, ray tube area, and signature propagation are used.
    Keywords: AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Type: Journal of Aircraft; 12; May 1975
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  • 85
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    Structural reanalysis via a mixed method (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: A study is made of the approximate structural reanalysis technique based on the use of Taylor series expansion of response variables in terms of design variables in conjunction with the mixed method. In addition, comparisons are made with two reanalysis techniques based on the displacement method. These techniques are the Taylor series expansion and the modified reduced basis. It is shown that the use of the reciprocals of the sizing variables as design variables (which is the natural choice in the mixed method) can result in a substantial improvement in the accuracy of the reanalysis technique. Numerical results are presented for a space truss structure.
    Keywords: STRUCTURAL MECHANICS
    Type: Computers and Structures; 5; Apr. 197
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  • 86
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    An orthotropic sandwich plate containing a part-through crack under mixed mode deformation (1978)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Keywords: STRUCTURAL MECHANICS
    Type: Engineering Fracture Mechanics; 10; 1, 19; 1978
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  • 87
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    Toward scramjet aircraft (1978)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: The possibility for civil, military, and remotely-piloted aviation above Mach 5 is discussed with reference to the scramjet. Actively cooled aircraft structures of low weight are described, together with jet nozzle design and combustion parameters. The scramjet is seen as operating alone or in tandem with ramjet propulsion, which would power an aircraft up to scramjet speeds. Attention is given to the specific impulse of the scramjet engine, with hydrogen as the primary fuel. Applications include: advanced reconnaissance and interceptor aircraft, strategic cruise (both aircraft and missiles), highly-maneuverable interceptor missiles, transports, aircraft-type launch vehicles, first stages for Space Shuttle launching craft, and single-stage-to-orbit vehicles. Research has focused on increasing the propulsion power of the scramjet engine, while reducing drag on the accompanying airframe.
    Keywords: AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Type: Astronautics and Aeronautics; 16; Feb. 197
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  • 88
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    Finite element solution for beams using an element averaging technique (1978)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: The article investigates the error in the computation of natural frequency through finite element models of the structures when elements of unequal length are chosen and then goes on to suggest an averaging technique for unequal length elements, with different structural properties. Using the element averaging technique, a typical structure has been analysed for its natural frequencies and the results are described.
    Keywords: STRUCTURAL MECHANICS
    Type: Computers and Structures; 8; Feb. 197
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  • 89
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    Displacement coefficients along the inner boundaries of radially cracked ring segments subject to forces and couples (1978)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Displacement results of plane boundary collocation analysis are given for various locations on the inner boundaries of radially cracked ring segments (C-shaped specimens) subject to two complementary types of loading. Results are presented for ratios of outer to inner radius in the range of 1.1 to 2.5 and ratios a/W in the range 0.1 to 0.8, where a is the crack length for a specimen of wall thickness W. By combination of these results the resultant displacement coefficient or the corresponding influence coefficient can be obtained for any practical load line location of a pin-loaded specimen.
    Keywords: STRUCTURAL MECHANICS
    Type: Journal of Testing and Evaluation; 6; May 1978
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  • 90
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    Constitutive relationships for anisotropic high-temperature alloys (1983)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A constitutive theory is presented for representing the anisotropic viscoplastic behavior of high-temperature alloys that possess directional properties resulting from controlled grain growth or solidification. The theory is an extension of a viscoplastic model that has been applied in structural analyses involving isotropic metals. Anisotropy is introduced through the definition of a vector field that identifies a preferential (solidification) direction at each material point. Following the development of a full multiaxial theory, application is made to homogeneously stressed elements in pure shear and to a uniaxially stressed rectangular block in plane stress with the stress direction oriented at an arbitrary angle with the material direction. It is shown that an additional material parameter introduced to characterize the degree of anisotropy can be determined on the basis of simple creep tests.
    Keywords: STRUCTURAL MECHANICS
    Type: Nuclear Engineering and Design (ISSN 0029-5493); 83; 389-396
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  • 91
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    Computer control for automated flight test maneuvering (1984)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The application of an experimental flight test maneuver autopilot test technique for collecting aerodynamic and structural flight research data on a highly maneuverable aircraft is described in this paper. This technique, which was developed to increase the quality and quantity of data obtained during flight test, was applied to the highly maneuverable aircraft technology (HiMAT) vehicle. A primary flight experiment was to verify the design techniques used to develop the HiMAT aerodynamics and structures. This required the performance of maneuvers for collection of large quantities of high-quality pressure distribution, loads, and wing and canard deflection data. Flight data obtained while executing these research maneuvers are presented to demonstrate the effectiveness of this new technique.
    Keywords: AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Type: Journal of Aircraft (ISSN 0021-8669); 21; 776-782
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  • 92
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    Status review of a supersonically biased fighter wing design study (1984)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Keywords: AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Type: Journal of Aircraft (ISSN 0021-8669); 21; 767-775
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  • 93
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    Geometrically nonlinear analysis of adhesively bonded joints (1984)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A geometrically nonlinear finite element analysis of cohesive failure in typical joints is presented. Cracked-lap-shear joints were chosen for analysis. Results obtained from linear and nonlinear analysis show that nonlinear effects, due to large rotations, significantly affect the calculated mode 1, crack opening, and mode 2, inplane shear, strain-energy-release rates. The ratio of the mode 1 to mode 2 strain-energy-release rates (G1/G2) was found to be strongly affected by the adhesive modulus and the adherend thickness. The ratios between 0.2 and 0.8 can be obtained by varying adherend thickness and using either a single or double cracked-lap-shear specimen configuration. Debond growth rate data, together with the analysis, indicate that mode 1 strain-energy-release rate governs debond growth. Results from the present analysis agree well with experimentally measured joint opening displacements. Previously announced in STAR as N83-13497
    Keywords: STRUCTURAL MECHANICS
    Type: ASME, Transactions, Journal of Engineering Materials and Technology (ISSN 0094-4289); 106; 59-65
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  • 94
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    Creating competitive rotorcraft noise technology (1984)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Rotorcraft noise includes turbofan engine noise components, as well as noise from the main and tail rotors that is conditioned by the aircraft's various operational modes. Both of the rotors generate loading noise and broadband noise. Another noise contributor is blade/vortex interaction noise, which results when shed vortices are encountered by a following blade, releasing impulsive acoustic energy. Attention is presently given to the experimental and developmental initiatives to be made by a NASA/industry five-year program that began in 1983. Aeroacoustic data acquired from experiments conducted in NASA facilities can be used in the development of empirical noise prediction methods, in the improvement of existing noise prediction methodology, in the evaluation of proposed reduced noise designs, and in the establishment of useful scaling relationships for selected noise-generating mechanisms.
    Keywords: AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Type: Aerospace America (ISSN 0740-722X); 22; 60-63
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  • 95
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    A study of altitude and flight path angle dynamics for a singularly perturbed fuel optimization problem (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: This short paper will demonstrate that the separation of altitude and flight path angle dynamics using singular perturbation techniques for a transport fuel optimization problem results in an unacceptable oscillation in altitude. A technique for damping this oscillation by adding a penalty term to the cost function for the optimization problem will be discussed. This technique will be compared with a different approach that linearizes the altitude and flight path angle boundary layers.
    Keywords: AIRCRAFT DESIGN, TESTING AND PERFORMANCE
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  • 96
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    The input mobility of an infinite circular cylindrical elastic shell filled with fluid (1983)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: The force input mobility of an infinite elastic circular cylindrical shell filled with fluid is derived by using the spectral equations of motion. Mobilities are evaluated and their physical interpretations are discussed for a steel shell of thickness h/a = 0.05 filled with water and vibrating in the n = 0, 1 and 2 circumferential modes. The results are subsequently used to analyze the related situations of wave transmission through a radial ring constraint and the far field vibrational energy distributions between the contained fluid and the shell wall for line and point driving forces.
    Keywords: STRUCTURAL MECHANICS
    Type: Journal of Sound and Vibration (ISSN 0022-460X); 87; 409-427
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  • 97
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    An elastic-plastic finite element analysis of crack initiation, stable crack growth, and instability (1984)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: Studies have been conducted to develop efficient techniques to simulate crack extension and to examine various local and global fracture criteria. Of the considered criteria, the crack-tip-opening angle (CTOA) or displacement (CTOD) at a specified distance from the crack tip was shown to be most suited for modeling stable crack growth and instability during the fracture process. The results obtained in a number of studies show the necessity for studying different crack configurations when assessing the validity of any fracture criteria. One of the objectives of the present investigation is related to a critical evaluation of the CTOD growth criterion using an elastic-plastic finite element analysis under monotonic loading to failure. The analysis was found to predict three stages of crack growth behavior under monotonic loading to failure. Calculated CTOD values agreed well with experimental values for crack growth initiation.
    Keywords: STRUCTURAL MECHANICS
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  • 98
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    Analysis of an internally radially cracked ring segment subject to three-point radial loading (1983)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: The boundary collocation method was used to generate Mode 1 stress intensity and crack mouth opening displacement coefficients for externally radially cracked ring segments subjected to three point radial loading. Numerical results were obtained for ring segment outer-to-inner radius ratios (R sub o/R sub i) ranging from 1.10 to 2.50 and crack length to segment width ratios (a/W) ranging from 0.1 to 0.8. Stress intensity and crack mouth displacement coefficients were found to depend on the ratios R sub o/R sub i and a/W as well as the included angle between the directions of the reaction forces. Previously announced in STAR as N83-35413
    Keywords: STRUCTURAL MECHANICS
    Type: Journal of Testing and Evaluation (ISSN 0090-3973); 11; 357-359
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  • 99
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    On the determination of airplane model structure form flight data (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A procedure based on a modified stepwise regression and several selection criteria is presented for the determination of airplane model structure from flight data. The aerodynamic force and moment coefficients in an airplane model are expresed either as polynomials in output and input variables or as a combination of splines. The procedure is demonstrated in three examples by attempting to determine a local, extended and global model. Some of the resulting models are verified by using the maximum likelihood estimation or by examining model prediction capabilities.
    Keywords: AIRCRAFT DESIGN, TESTING AND PERFORMANCE
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  • 100
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    Analysis of electromagnetic fields on an F-106B aircraft during lightning strikes (1982)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Information on the exterior electromagnetic environment of an aircraft when it is struck by lightning has been obtained during thunderstorm penetrations with an F-106B aircraft. Electric and magnetic fields were observed, using mainly time-derivative type sensors, with bandwidths to 50 MHz. Lightning pulse lengths ranging from 25 ns to 7 microsec have been recorded. Sufficient high-frequency content was present to excite electromagnetic resonances of the aircraft, and peaks in the frequency spectra of the waveforms in the range 7 to 23 MHz are in agreement with the resonant frequencies determined in laboratory scale-model tests. Both positively and negatively charged strikes were experienced, and most of the data suggest low values of peak current.
    Keywords: AIRCRAFT DESIGN, TESTING AND PERFORMANCE
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