| Development of Improved Modeling and Analysis Techniques for Dynamics of Shell Structures |
24 JUL 91 |
109 pages |
| Authors:
K. C. Park; C. Farhat; COLORADO UNIV AT BOULDER CENTER FOR SPACE STRUCTURES AND CONTROLS
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 | This report contains two related research thrusts: improved shell structural modeling for underwater acoustics and massively parallel computations of shell dynamics response. Improvements on the existing ANS shell elements have been made and implemented on a testbed software; the module was then delivered to NRL for their applications. In addition, the so-called frequency-window tailoring of finite element models has been developed so that very high- frequency components can be accurately ... |
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| Development of Nonlinear Transient Analysis Algorithms for Dynamics and Control of Large Space Structures |
MAY 91 |
299 pages |
| Authors:
K. C. Park; C. A. Felippa; COLORADO UNIV AT BOULDER CENTER FOR SPACE STRUCTURES AND CONTROLS
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| This is a final report on the research project supported by the Air Force Office of Scientific Research under Grant F49620-87-C-0074, entitled Development of Nonlinear Transient Analysis Algorithms for Dynamics and Control of Large Space Structures, which covered the period of 01 October 1987 to 31 December 1990. The objectives of the research have been: (1) the development of improved dynamic modeling techniques that can capture essential response components encompassing ... |
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| Development of Error Criteria for Discrete Modeling of Solids and Structures |
MAR 88 |
316 pages |
| Authors:
K. C. Park; C. A. Felippa; D. L. Flaggs; G. M. Stanley; D. S. Kang; LOCKHEED MISSILES AND SPACE CO INC PALO ALTO CA PALO ALTO RESEARCH LAB
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| The objectives of this research were two-fold. The first was the development of a-priori and a-posteriori error estimation techniques based upon symbolic Fourier analysis techniques. The second objective was to improve the accuracy of current finite elements being used in the analysis of shell and solid structures. Significant progress was made in both research areas. A brief summary is provided below with accompanying details in the appendices. (mjm) |
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| Wave Dispersion Mechanisms in Large Space Structures |
25 NOV 85 |
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| Authors:
K. C. Park; LOCKHEED MISSILES AND SPACE CO INC PALO ALTO CA PALO ALTO RESEARCH LAB
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 | This report describes an investigation into wave dispersion phenomena in large lattice space structures. Particular results were 1) That local member dynamic characteristics significantly influence global dynamic response; 2) That it is possible to increase dispersion of wave energy in lattice-truss structures by adopting a nonuniform lattice construction; and 3) That local member dynamics characteristics require detailed modeling techniques which are capable of capturing member bending behavior in order to ... |
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| Local-Global Interactions in the Transient Response of Lattice-Truss Plates |
AUG 84 |
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| Authors:
M. E. Regelbrugge; K. C. Park; LOCKHEED MISSILES AND SPACE CO INC PALO ALTO CA PALO ALTO RESEARCH LAB
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| The transient response of lattice truss plates is studied with emphasis on how the individual lattice members dynamic characteristics influence with transient response characteristics. When the lattic members are modeled as bars, the transient responses are dominated by the low frequency components that correspond to the continuum thick plate case. However, when the lattic members are modeled as slender beams to be more realistic, the dynamic characteristics of the individual ... |
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| STINT/CD: A Stand-Alone Explicit Time Integration Package for Structural Dynamics Analysis. |
JUN 1980 |
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| Authors:
Phillip G. Underwood; K. C. Park; LOCKHEED MISSILES AND SPACE CO INC PALO ALTO CA PALO ALTO RESEARCH LAB
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| This paper is a user's guide for the stand-alone explicit direct time integration package STINT/CD for structural dynamics analysis. STINT/CD uses an automatic variable time increment central difference method. The purpose, function, limitations, and usage of the package are described. A FORTRAN listing of STINT/CD is given along with a sample problem which illustrates its usage and performance. (Author) |
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| A Variable-Step Central Difference Method for Structural Dynamics Analysis. Part I. Theoretical Aspects. Part II. Implementation and Performance Evaluation, |
APR 1979 |
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| Authors:
K. C. Park; P. G. Underwood; LOCKHEED MISSILES AND SPACE CO INC PALO ALTO CALIF PALO ALTO RESEARCH LAB
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| Part I: Three major theoretical aspects of variable-step explicit integration procedures are proposed and analyzed. These include basic fixed-step integration formulas for no damping, diagonal damping and nondiagonal damping problems; the adjustment of the basic formulas to accommodate step changes; and, step size selection criteria. It is shown that the truncation error concept is not adequate to detect numerical instability for general structural dynamics analysis when low accuracy is requested. ... |
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| Partitioned Transient Analysis Procedures for Coupled-Field Problems. |
FEB 1979 |
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| Authors:
K. C. Park; LOCKHEED MISSILES AND SPACE CO INC PALO ALTO CALIF PALO ALTO RESEARCH LAB
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| A general partitioned transient analysis procedure is proposed, which is amenable to a unified stability analysis technique. The procedure embodies two existing inplicit-explicit procedures and one existing implicit-implicit procedure. A new implicit-explicit procedure is discovered, as a special case of the general procedure, that allows degree-by-degree implicit or explicit selections of the solution vector and can be implemented within the framework of the implicit integration packages. A new element-by-element implicit-implicit ... |
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| Staggered Solution Procedures for Doubly Asymptotic Fluid-Structure Interaction Analysis. |
28 FEB 1978 |
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| Authors:
K. C. Park; C. A. Felippa; J. A. DeRuntz; LOCKHEED MISSILES AND SPACE CO INC PALO ALTO CALIF PALO ALTO RESEARCH LAB
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| This report examines direct time integration techniques for the transient response analysis of fluid-structure interaction problems treated with the Doubly Asymptotic Approximation. Efficient solution of the equations of motion is achieved by a modular computer implementation in which separate fluid and structure analyzers are interfaced through extrapolation of the coupling terms. Because conventional realization of this technique is handicapped by severe time-increment limitations, a versatile formulation is developed that circumvents ... |
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| Computational Aspects of Time Integration Procedures in Structural Dynamics. Part I. Implementation. Part II. Error Propagation, |
JAN 1977 |
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| Authors:
K. C. Park; C. A. Felippa; LOCKHEED MISSILES AND SPACE CO INC PALO ALTO CALIF PALO ALTO RESEARCH LAB
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| A unified approach for the implementation of direct time integration procedures in structural dynamics is presented. Two key performance assessment factors are considered, viz., computational effort and error propagation. It is shown that these factors are strongly affected by details in the reduction of the second-order equations of motion to a system of first-order equations, and by the computational path followed at each time step. Part I is primarily devoted ... |
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| Development and Experimental Verification of Procedures to Determine Nonlinear Load-Deflection Characteristics of Helicopter Substructures Subjected to Crash Forces. Volume I. Development of Simplified Analytical Techniques to Predict Typical Helicopter A |
MAY 1974 |
252 pages |
| Authors:
G. Wittlin; K. C. Park; LOCKHEED-CALIFORNIA CO BURBANK
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| The results of a study to develop simplified design procedures for determining nonlinear load-deflection characteristics for helicopter airframe structures are presented in a two-volume report. Volume one describes 60 technical reports and papers with regard to their applicability to crashworthiness analysis and designer-oriented procedures. Studies were made using an existing 31 lumped mass model of the UH-1H helicopter to determine the sensitivity of responses to changes in load-deflection representations. Twelve ... |
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| Development and Experimental Verification of Procedures to Determine Nonlinear Load-Deflection Characteristics of Helicopter Substructures Subjected to Crash Forces. Volume II. Test Data and Description of Refined Program 'Krash', Including a User's Guide |
MAY 1974 |
245 pages |
| Authors:
G. Wittlin; K. C. Park; LOCKHEED-CALIFORNIA CO BURBANK
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| Volume two of a two-volume report continues the results of a study to develop simplified design procedures for determining nonlinear load-deflection characteristics for helicopter airframe structures. Program KRASH is refined to facilitate its use by designers. In particular, the input data is reordered, some imputs are standardized and more general load-deflection curve characteristics are possible. The analytical techniques are presented in the form of design charts, nomographs, curves, tables and ... |
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