Date of Award

Summer 1991

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Mechanical & Aerospace Engineering

Program/Concentration

Engineering Mechanics

Committee Director

Chuh Mei

Committee Member

Jean W. Hou

Committee Member

Jerrold M. Housner

Call Number for Print

Special Collections; LD4331.E57M34

Abstract

Test/analysis correlation is an important aspect of the verification of analysis models which are used to predict on-orbit response characteristics of large space structures. This thesis summarizes the study of using reduced analysis models for performing dynamic test/analysis correlation. The reduced test-analysis model (TAM) has the same number of degrees-of-freedom (DOF) as the number of test measurements. This allows the direct comparison of modal parameters between ground vibration test results and finite element model (FEM) analysis results. The TAM can also be used for pre-test analysis and to aid in the post-test mathematical model updating process.

Herein, four methods for model reduction are reviewed and compared, then two of these are selected for detailed evaluation and application to a simple model and to a realistic experimental structure. First, several criteria are defined to assess accuracy of the reduced models relative to the exact FEM. Degrees-of-freedom associated with various masses throughout the structure are eliminated to examine the subsequent impact on the prediction performance of the reduced model which results. Ultimately two reduction methods are applied to the test/analysis correlation of a laboratory truss structure. FEM analysis results for the truss are presented and used as the baseline to evaluate the accuracy of the reduced analysis models. Sets of retained DOF are studied with respect to the performance of each method. Finally, ground modal test results for the truss are used in the test/analysis correlation. Observations are made about method performance and conclusions are drawn concerning the selection of an appropriate reduction method.

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DOI

10.25777/3jmh-tj30

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