224
224

Jun 2, 2011
06/11

by
Cook, Sid; Harsanyi, Joseph; Faber, Vanc

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With EO-1 Hyperion in orbit NASA is showing their continued commitment to hyperspectral imaging (HSI). As HSI sensor technology continues to mature, the ever-increasing amounts of sensor data generated will result in a need for more cost effective communication and data handling systems. Lockheed Martin, with considerable experience in spacecraft design and developing special purpose onboard processors, has teamed with Applied Signal & Image Technology (ASIT), who has an extensive heritage...

Topics: STRUCTURAL MEMBERS, STRUCTURAL ENGINEERING, MODAL RESPONSE, SLENDER BODIES, SUPPORTS, STRUCTURAL...

237
237

Jun 21, 2010
06/10

by
Benson, H. E

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No Abstract Available

Topics: CONTROL SIMULATION, DYNAMIC CONTROL, MODAL RESPONSE, SATURN S-4B STAGE, BURNING TIME, MATRICES...

257
257

Jun 13, 2011
06/11

by
Singh, Upendra N.; Koch, Grady J.; Ismail, Syed; Kavaya, Michael; Yu, Jirong; Wood, Sidney A.; Emmitt, G. Davi

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A concept is explored for combining the Doppler and DIAL techniques into a single, multifunctional instrument. Wind, CO2 concentration, and aerosol density can all be measured. Technology to build this instrument is described, including the demonstration of a prototype lidar. Applications are described for use in the Earth science. The atmosphere of Mars can also be studied, and results from a recently-developed simulation model of performance in the Martian atmosphere are presented.

Topics: GAMMA RAY TELESCOPES, SATELLITE TRACKING, SCHEDULES, TDR SATELLITES, TELEMETRY, PREDICTIONS, MODAL...

A new method for component mode synthesis was developed for installation in NASTRAN level 17.5. Results obtained from the new method are presented, and these results are compared with existing modal synthesis methods.

Topics: NASA Technical Reports Server (NTRS), DYNAMIC MODELS, NASTRAN, MODAL RESPONSE, STRUCTURAL ANALYSIS,...

469
469

Jun 20, 2010
06/10

by
Hart, F. D.; Miller, D. K

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Vibration modal response of thin cylindrical shells

Topics: CYLINDRICAL SHELLS, MODAL RESPONSE, THIN WALLED SHELLS, VIBRATION MODE, MATHEMATICAL MODELS,...

A method to determine the modes of dynamical systems is described. The inputs and outputs of a system are Fourier transformed and averaged to reduce the error level. An instrumental variable method that estimates modal parameters from multiple correlations between responses of single input, multiple output systems is applied to estimate aircraft, spacecraft, and off-shore platform modal parameters.

Topics: NASA Technical Reports Server (NTRS), DYNAMIC CHARACTERISTICS, MODAL RESPONSE, SPECTRUM ANALYSIS,...

Vibration investigations of a model of the asymmetric multielement space shuttle were made. The influence on overall motions of local deformation in the vicinity of element interfaces, high modal density, low structural damping, and high responsiveness in the crew cabin are included in the findings. Mode frequencies generally increase with decreasing propellant masses and staging of elements.

Topics: NASA Technical Reports Server (NTRS), DYNAMIC STRUCTURAL ANALYSIS, SPACE SHUTTLES, STRUCTURAL...

Modal identification of seemingly simple structures, such as the generic truss is often surprisingly difficult in practice due to high modal density, nonlinearities, and other nonideal factors. Under these circumstances, different data analysis techniques can generate substantially different results. The initial application of a new hybrid-data method for studying the performance characteristics of various identification techniques with such data is summarized. This approach offers new pieces...

Topics: NASA Technical Reports Server (NTRS), DATA PROCESSING, MODAL RESPONSE, SYSTEM IDENTIFICATION,...

The possibility of modeling and controlling flexible manipulator arms was examined. A modal approach was used for obtaining the mathematical model and control techniques. The arm model was represented mathematically by a state space description defined in terms of joint angles and mode amplitudes obtained from truncation on the distributed systems, and included the motion of a two link two joint arm. Three basic techniques were used for controlling the system: pole allocation with gains...

Topics: NASA Technical Reports Server (NTRS), MANIPULATORS, MODAL RESPONSE, REMOTE CONTROL, ALGORITHMS,...

735
735

Jul 12, 2010
07/10

by
NON

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Abstracts are cited for 234 patents and patent applications introduced into the NASA scientific and technical information system during the period July 1982 through December 1982. Each entry consists of a citation, an abstract, and in most cases, a key illustration selected from the patent or patent application.

Topics: COMBUSTION CHAMBERS, SOUND WAVES, ENGINE NOISE, MODAL RESPONSE, PROPAGATION MODES, TURBOFAN...

286
286

Jul 11, 2010
07/10

by
CARL, H.; BOHM, H.; POH, F. A

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IT IS SHOWN THAT THE WC/C FUEL CELL OFFERS AN EXCELLENT ALTERNATIVE TO CONVENTIONAL POWER SOURCES FOR MANY APPLICATIONS. THREE DEMONSTRATION EXAMPLES ARE PRESENTED FOR ILLUSTRATION: (1) ELECTRIC TRUCKS FOR INDUSTRIAL WAREHOUSE AND PLANT APPLICATIONS; (2) FORK LIFT TRUCKS; AND (3) POWER SUPPLY FOR RADIO LINK STATIONS.

Topics: CORRELATION COEFFICIENTS, DYNAMIC MODELS, MODAL RESPONSE, VIKING ORBITER SPACECRAFT, COUPLING...

On November 23, 2011 International Space Station Guidance, Navigation, and Control reported unusual pitch rate disturbance. These disturbances were an order of magnitude greater than nominal rates. The Loads and Dynamics team was asked to review and analyze current accelerometer data to investigate this disturbance. This paper will cover the investigation process under taken by the Loads and Dynamics group. It will detail the accelerometers used and analysis performed. The analysis included...

Topics: NASA Technical Reports Server (NTRS), ACCELEROMETERS, INTERNATIONAL SPACE STATION, PITCHING...

199
199

Jun 27, 2010
06/10

by
Turk, R. R

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Production method for manufacturing porous tungsten bodies from tungsten powder particles

Topics: DYNAMIC STRUCTURAL ANALYSIS, ITERATIVE SOLUTION, MODAL RESPONSE, RAYLEIGH-RITZ METHOD, STATIC...

Analytical models of three structures were used to test mass matrix-reduction schemes. Accuracy of four mode shapes and frequencies was tracked through successive mass matrix-reductions with diminishing numbers of indicator degrees of freedom. Results were consistently disappointing. Two new procedures were developed in attempt to improve accuracy.

Topics: NASA Technical Reports Server (NTRS), EIGENVALUES, METHODOLOGY, MODAL RESPONSE, RAYLEIGH-RITZ...

309
309

May 31, 2011
05/11

by
Turner, Travis L

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This study presents results from an effort to fabricate a shape memory alloy hybrid composite (SMAHC) panel specimen and test the structure for dynamic response and noise transmission characteristics under the action of thermal and random acoustic loads. A method for fabricating a SMAHC laminate with bi-directional SMA reinforcement is described. Glass-epoxy unidirectional prepreg tape and Nitinol ribbon comprise the material system. Thermal activation of the Nitinol actuators was achieved...

Topics: IMPACT, MATHEMATICAL MODELS, DEFORMATION, NONLINEARITY, CYLINDRICAL BODIES, ALUMINUM, NUMERICAL...

Repeated or closely packed modal frequencies are common physical occurrences for vibrating structures which are complex or possess multi-planes of symmetry. The computation of the sensitivity to structural modifications for these frequencies and mode shapes is made difficult by the fact that the mode shapes are not unique, since any linear combination of eigenvectors corresponding to a repeated eigenvalue is also an eigenvector. The work of Chen and Pan is extended, who used modal expansion...

Topics: NASA Technical Reports Server (NTRS), EIGENVECTORS, MODAL RESPONSE, SENSITIVITY, STRUCTURAL...

How the presence of nonlinearities in structural test data can be detected when using modern linear modal data analysis methods is discussed. The extent to which linear algorithms can provide useful information on nonlinear systems was discussed. The modal data analysis method successfully identified the frequency components (but not damping) of the true solution of a nonlinear systems. It was found that the approximate modal parameters of the linear system can be identified by the modal method...

Topics: NASA Technical Reports Server (NTRS), DATA PROCESSING, DYNAMIC STRUCTURAL ANALYSIS, MODAL RESPONSE,...

With complex structures, comparison of independently derived sets of experimental modal parameters is an excellent way to increase confidence in the results. This paper presents modal identification results using the Eigensystem Realization Algorithm (ERA) on frequency response functions from the modal test of the Space Station Resource Node. The Resource Node is the first U.S.-built structure for the International Space Station. The modal test was conducted by the NASA Marshall Space Flight...

Topics: NASA Technical Reports Server (NTRS), INTERNATIONAL SPACE STATION, VIBRATION MODE, SPACECRAFT...

This paper presents analyses for the modal characteristics and impact response of an all-aluminum cylinder. The analyses were performed in preparation for impact tests of the cylinder at The Impact Dynamics Research Facility (IDRF) at the NASA Langley Research Center. Mode shapes and frequencies were computed using NASTRAN and compared with existing experimental data to assess the overall accuracy of the mass and stiffness of the finite element model. A series of non-linear impact analyses were...

Topics: NASA Technical Reports Server (NTRS), IMPACT, CYLINDRICAL BODIES, ALUMINUM, NUMERICAL ANALYSIS,...

A detailed dynamic analysis is performed of a vibrating beam with bending stiffness periodic in the spatial coordinate. The effects of system parameters on beam response are explored with a perturbation expansion technique. It is found that periodic stiffness acts to modulate the modal displacements from the characteristic shape of a simple sine wave. The results are verified by a finite element solution and through experimental testing.

Topics: NASA Technical Reports Server (NTRS), BEAMS (SUPPORTS), BENDING, BENDING VIBRATION, DYNAMIC...

A compendium is presented of orbital configuration test modal data, analytical test modal data, analytical test correlation modal data and analytical flight configuration 1.2 modal data. Section A presents tables showing the generalized mass contributions for each of the thirty test modes. Section B presents the two dimensional mode shape plots for the thirty test modes. Tables of GMC's for the test correlated analytical modes are presented in Section C. These analytical modes were generated...

Topics: NASA Technical Reports Server (NTRS), MODAL RESPONSE, SATELLITE ROTATION, SKYLAB PROGRAM,...

Statistical Energy Analysis (SEA) is defined by considering the asymptotic limit of Classical Modal Analysis, an approach called Asymptotic Modal Analysis (AMA). The general approach is described for both structural and acoustical systems. The theoretical foundation is presented for structural systems, and experimental verification is presented for a structural plate responding to a random force. Work accomplished subsequent to the grant initiation focusses on the acoustic response of an...

Topics: NASA Technical Reports Server (NTRS), ACOUSTICS, AIRCRAFT STRUCTURES, ASYMPTOTIC METHODS, MODAL...

In various problems in structural dynamics, the eigenvalues of a linear system depend on a characteristic parameter of the system. Under certain conditions, two eigenvalues of the system approach each other as the characteristic parameter is varied, leading to modal interaction. In a system with conservative coupling, the two eigenvalues eventually repel each other, leading to the curve veering effect. In a system with nonconservative coupling, the eigenvalues continue to attract each other,...

Topics: NASA Technical Reports Server (NTRS), CATASTROPHE THEORY, DYNAMIC STRUCTURAL ANALYSIS, EIGENVALUES,...

An acoustic modal decomposition of the measured pressure field in a full scale annular combustor installed in a ducted test rig is described. The modal analysis, utilizing a least squares optimization routine, is facilitated by the assumption of randomly occurring pressure disturbances which generate equal amplitude clockwise and counter-clockwise pressure waves, and the assumption of statistical independence between modes. These assumptions are fully justified by the measured cross spectral...

Topics: NASA Technical Reports Server (NTRS), COMBUSTION CHAMBERS, ENGINE NOISE, MODAL RESPONSE,...

Some techniques for comparing structural vibration data determined from test and analysis are discussed. Orthogonality is a general category of one group, correlation is a second, synthesis is a third and matrix improvement is a fourth. Advantages and short-comings of the methods are explored with suggestions as to how they can complement one another. The purpose for comparing vibration data from test and analysis for a given structure is to find out whether each is representing the dynamic...

Topics: NASA Technical Reports Server (NTRS), CORRELATION COEFFICIENTS, MATRICES (MATHEMATICS),...

An interactive digital computer program for modal analysis and gain estimation for eigensystem synthesis was written. Both mathematical and operation considerations are described; however, the mathematical presentation is limited to those concepts essential to the operational capability of the program. The program is capable of both modal and spectral synthesis of multi-input control systems. It is user friendly, has scratchpad capability and dynamic memory, and can be used to design either...

Topics: NASA Technical Reports Server (NTRS), COMPUTER GRAPHICS, EIGENVALUES, EIGENVECTORS, MODAL RESPONSE,...

A method is developed and illustrated which finds minimum changes in analytical mass and stiffness matrices to make them consistent with a set of measured normal modes and natural frequencies. The corrected model is an improved base for studies of physical changes, changes in boundary conditions, and for prediction of forced responses. Features of the method are: efficient procedures not requiring solutions of the eigenproblem; the model may have more degrees of freedom than the test data;...

Topics: NASA Technical Reports Server (NTRS), AIRCRAFT STRUCTURES, DYNAMIC STRUCTURAL ANALYSIS, MODAL...

The resonance testing of a structural specimen related to the space shuttle vehicle is described. The specimen consisted of a thin aluminum skin reinforced by hat-section stringers and supported by two ribs or bulkheads of corrugated web. A representative section of the space shuttle thermal protection system was bonded to the outer surface of the skin. The tests were completed by using miniature accelerometers to collect vibration data from locations forming a predetermined mesh over the tiles...

Topics: NASA Technical Reports Server (NTRS), RESONANCE TESTING, SPACE SHUTTLES, STRUCTURAL STABILITY,...

Special modeling techniques were developed to simulate an accurate mathematical model of the transporter/canister/payload system during ground transport of the Inertial Upper Stage/Tracking and Data Relay Satellite (IUS/TDRS) payload. The three finite element models - the transporter, the canister, and the IUS/TDRS payload - were merged into one model and used along with the NASTRAN normal mode analysis. Deficiencies were found in the NASTRAN program that make a total analysis using modal...

Topics: NASA Technical Reports Server (NTRS), GROUND HANDLING, MATHEMATICAL MODELS, NASTRAN, SPACE SHUTTLE...

A simplified cylindrical model of an aircraft fuselage is used to investigate the mechanisms of interior noise suppression using synchrophasing techniques. This investigation allows isolation of important parameters to define the characteristics of synchrophasing. The optimum synchrophase angle for maximum noise reduction is found for several interior microphone positions with pure tone source excitation. Noise reductions of up to 30 dB are shown for some microphone positions, however, overall...

Topics: NASA Technical Reports Server (NTRS), AIRCRAFT COMPARTMENTS, AIRCRAFT NOISE, NOISE REDUCTION,...

A computer program was developed to take a NASTRAN output file from a normal modes analysis and calculate the modal strain energies of selected elements. The FORTRAN program can determine the modal strain energies for CROD, CBAR, CELAS, CTRMEM, CQDMEM2, and CSHEAR elements. Modal strain energies are useful in estimating damping in structures.

Topics: NASA Technical Reports Server (NTRS), DAMPING, MODAL RESPONSE, NASTRAN, STRAIN ENERGY METHODS,...

This paper presents a technique for calculating the modal participation factors for base excitation problems using a DMAP alter to the NASTRAN real eigenvalue analysis Rigid Format. The DMAP program automates the generation of the seismic mass to add to the degrees of freedom representing the shaker input directions and calculates the modal participation factors. These are shown in the paper to be a good measure of the maximum acceleration expected at any point on the structure when the...

Topics: NASA Technical Reports Server (NTRS), COMPUTER PROGRAMS, EIGENVALUES, EIGENVECTORS, EXCITATION,...

The design and implementation of a vertical degree of freedom suspension system is described which provides a constant force off-load condition to counter gravity over large displacements. By accommodating motions up to one meter for structures weighing up to 100 pounds, the system is useful for experiments which simulate orbital construction events such as docking, multiple component assembly, or structural deployment. A unique aspect of this device is the combination of a large stroke passive...

Topics: NASA Technical Reports Server (NTRS), GROUND TESTS, SPACE MANUFACTURING, SUSPENDING (HANGING),...

An interactive steady state frequency response computer program with graphics is documented. Single or multiple forces may be applied to the structure using a modal superposition approach to calculate response. The method can be reapplied to linear, proportionally damped structures in which the damping may be viscous or structural. The theoretical approach and program organization are described. Example problems, user instructions, and a sample interactive session are given to demonstate the...

Topics: NASA Technical Reports Server (NTRS), COMPUTER PROGRAMS, DYNAMIC STRUCTURAL ANALYSIS, FREQUENCY...

An on line technique is presented for the identification of rotor blade modal damping and frequency from rotorcraft random response test data. The identification technique is based upon a recursive maximum likelihood (RML) algorithm, which is demonstrated to have excellent convergence characteristics in the presence of random measurement noise and random excitation. The RML technique requires virtually no user interaction, provides accurate confidence bands on the parameter estimates, and can...

Topics: NASA Technical Reports Server (NTRS), DAMPING, MODAL RESPONSE, PARAMETER IDENTIFICATION, ROTARY...

Developments in methodology and data analysis techniques for flutter testing in flight and on the ground are discussed.

Topics: NASA Technical Reports Server (NTRS), AERODYNAMIC NOISE, AEROELASTICITY, CONFERENCES, FLUTTER...

The application of reciprocal modal vectors to the analysis of structural response data is described. Reciprocal modal vectors are constructed using an existing experimental modal model and an existing frequency response matrix of a structure, and can be assembled into a matrix that effectively transforms the data from the physical space to a modal space within a particular frequency range. In other words, the weighting matrix necessary for modal vector orthogonality (typically the mass matrix)...

Topics: NASA Technical Reports Server (NTRS), CONTROL SYSTEMS DESIGN, FEEDBACK CONTROL, FLIGHT TESTS,...

The analytical techniques and computer program developed in the fully-coupled rotor vibration study are described. The rotor blade natural frequency and mode shape analysis was implemented in a digital computer program designated DF1758. The program computes collective, cyclic, and scissor modes for a single blade within a specified range of frequency for specified values of rotor RPM and collective angle. The analysis includes effects of blade twist, cg offset from reference axis, and shear...

Topics: NASA Technical Reports Server (NTRS), COMPUTER PROGRAMS, DIGITAL COMPUTERS, MODAL RESPONSE,...

Candidate autopilot control laws that control the engine failure transient sink rates by demonstrating the engineering application of modern state variable control theory were defined. The results of approximate modal analysis were compared to those derived from full state analyses provided from computer design solutions. The aircraft was described, and a state variable model of its longitudinal dynamic motion due to engine and control variations was defined. The classical fast and slow modes...

Topics: NASA Technical Reports Server (NTRS), AUTOMATIC FLIGHT CONTROL, AUTOMATIC PILOTS, ENGINE FAILURE,...

A multivariable synthesis procedure based on eigenvalue/eigenvector assignment is reviewed and is employed to develop a systematic design procedure to meet the lateral handling qualities design objectives of a fighter aircraft over a wide range of flight conditions. The closed loop modal characterization developed provides significant insight into the design process and plays a pivotal role in the synthesis of robust feedback systems. The simplicity of the synthesis algorithm yields an...

Topics: NASA Technical Reports Server (NTRS), AIRCRAFT DESIGN, CONTROL THEORY, CONTROLLABILITY,...

As part of an investigation to develop measurement techniques for structureborne noise, three modal surveys have been conducted on an OV-10A aircraft and the results have been presented. The purpose of the modal surveys was to identify suitable locations for mounting accelerometer and strain gages in subsequent tests in which transfer functions relating wing vibration to interior noise were to be determined. These surveys are as follows:(1) wing/fuselage modal survey utilizing one shaker under...

Topics: NASA Technical Reports Server (NTRS), ACOUSTIC MEASUREMENT, AIRCRAFT NOISE, AIRCRAFT STRUCTURES,...

The major accomplishments of this research are: (1) the refinement and documentation of a multi-input, multi-output modal parameter estimation algorithm which is applicable to general linear, time-invariant dynamic systems; (2) the development and testing of an unsymmetric block-Lanzcos algorithm for reduced-order modeling of linear systems with arbitrary damping; and (3) the development of a control-structure-interaction (CSI) test facility.

Topics: NASA Technical Reports Server (NTRS), ALGORITHMS, DYNAMIC STRUCTURAL ANALYSIS, FEEDBACK CONTROL,...

Procedures for improving the modal modeling of structures using test data and to determine appropriate analytical models based on substructure experimental data were explored. Two related research topics were considered in modal modeling: using several independently acquired columns of frequency response data, and modal modeling using simultaneous multi-point excitation. In component mode synthesis modeling, the emphasis is on determining the best way to employ complex modes and residuals.

Topics: NASA Technical Reports Server (NTRS), DAMPING, DYNAMIC RESPONSE, EXCITATION, MODAL RESPONSE,...

200
200

May 23, 2011
05/11

by
Hsu, K.-J.; DeMore, W. B

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Rate constants of 15 OH reactions with halogen-substituted alkanes, C1 to C3, were studied using a relative rate technique in the temperature range 283-403 K. Compounds studied were CHF2Cl (22), CHF2Br (22B), CH3F (41), CH2F2 (32), CHF3 (23), CHClFCCl2F (122a), CHCl2CF3 (123), CHClFCF3 (124), CH3CF3 (143a), CH3CH2F (161), CF3CHFCF3 (227ea), CF3CH2CF3 (236fa), CF3CHFCHF2 (236ea), and CHF2CF2CH2F (245ca). Using CH4, CH3CCl3, CF3CF2H, and C2H6 as primary reference standards (JPL 92-20 rate...

Topics: DYNAMIC STRUCTURAL ANALYSIS, FLAT PLATES, FREE VIBRATION, MODAL RESPONSE, NASTRAN, FLUID-SOLID...

The Dryden Flight Research Facility of NASA Ames Research Center conducted a ground vibration test on a modified U.S. Army U-8F airplane. Modifications included new engines, propellers, and engine-mounted truss assemblies. The ground vibration test was conducted using sine dwell, single-point random, and impact excitations. The test was performed to determine modal frequencies, mode shapes, and structural damping coefficients of the airframe and propeller with full and empty fuel tanks. The...

Topics: NASA Technical Reports Server (NTRS), GROUND TESTS, MODAL RESPONSE, RESEARCH AIRCRAFT, STRUCTURAL...

A controller design approach for large space structures is presented, which consists of a primary attitude controller and a secondary or damping enhancement controller. The secondary controller, which uses several Annular Momentum Control Device (AMCD's), is shown to make the closed loop system asymptotically stable under relatively simple conditions. The primary controller using torque actuators (or AMCD's) and colocated attitude and rate sensors is shown to be stable. It is shown that the...

Topics: NASA Technical Reports Server (NTRS), CONTROLLERS, DAMPING, LARGE SPACE STRUCTURES, MODAL RESPONSE,...

An investigation of the effects of small mistuning on the aeroelastic modes of bladed disk assemblies with aerodynamic coupling between blades is presented. The cornerstone of the approach is the use and development of perturbation methods that exhibit the crucial role of the interblade coupling and yield general findings regarding mistuning effects. It is shown that blade assemblies with weak aerodynamic interblade coupling are highly sensitive to small blade mistuning, and that their dynamics...

Topics: NASA Technical Reports Server (NTRS), AEROELASTICITY, EIGENVALUES, MODAL RESPONSE, PERTURBATION...

New methods were developed for efficient aeroservoelastic analysis and optimization. The main target was to develop a method for investigating large structural variations using a single set of modal coordinates. This task was accomplished by basing the structural modal coordinates on normal modes calculated with a set of fictitious masses loading the locations of anticipated structural changes. The following subject areas are covered: (1) modal coordinates for aeroelastic analysis with large...

Topics: NASA Technical Reports Server (NTRS), AERODYNAMIC LOADS, AEROELASTICITY, AEROSERVOELASTICITY,...

Despite its powerful analytical capabilities, COSMIC/NASTRAN lacks adequate post-processing adroitness. PATRAN, on the other hand is widely accepted for its graphical capabilities. A nonproprietary, public domain code mnemonically titled CPI (for COSMIC/NASTRAN-PATRAN Interface) is designed to manipulate a large number of files rapidly and efficiently between the two parent codes. In addition to PATRAN's results file preparation, CPI also prepares PATRAN's P/PLOT data files for xy plotting. The...

Topics: NASA Technical Reports Server (NTRS), COMPUTER GRAPHICS, FORMAT, INTERFACES, NASTRAN, TRANSLATING,...

This study consisted of four parallel efforts: (1) modal analyses of elastic continua for Liapunov stability analysis of flexible spacecraft; (2) development of general purpose simulation equations for arbitrary spacecraft; (3) evaluation of alternative mathematical models for elastic components of spacecraft; and (4) examination of the influence of vehicle flexibility on spacecraft attitude control system performance. A complete record is given of achievements under tasks (1) and (3), in the...

Topics: NASA Technical Reports Server (NTRS), ELASTIC BODIES, LIAPUNOV FUNCTIONS, MODAL RESPONSE, ROTATING...