Perturbation Methods for the Eigencharacteristics of Symmetric and Asymmetric Systems

Dynamic analysis for a vibratory system typically begins with an evaluation of its eigencharacteristics. However, when design changes are introduced, the eigensolutions of the system change and thus must be recomputed. In this paper, three different methods based on the eigenvalue perturbation theor...

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Main Authors: Philip D. Cha, Austin Shin
Format: Article
Language:English
Published: Wiley 2018-01-01
Series:Shock and Vibration
Online Access:http://dx.doi.org/10.1155/2018/8609138
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author Philip D. Cha
Austin Shin
author_facet Philip D. Cha
Austin Shin
author_sort Philip D. Cha
collection DOAJ
description Dynamic analysis for a vibratory system typically begins with an evaluation of its eigencharacteristics. However, when design changes are introduced, the eigensolutions of the system change and thus must be recomputed. In this paper, three different methods based on the eigenvalue perturbation theory are introduced to analyze the effects of modifications without performing a potentially time-consuming and costly reanalysis. They will be referred to as the straightforward perturbation method, the incremental perturbation method, and the triple product method. In the straightforward perturbation method, the eigenvalue perturbation theory is used to formulate a first-order and a second-order approximation of the eigensolutions of symmetric and asymmetric systems. In the incremental perturbation method, the straightforward approach is extended to analyze systems with large perturbations using an iterative scheme. Finally, in the triple product method, the accuracy of the approximate eigenvalues is significantly improved by exploiting the orthogonality conditions of the perturbed eigenvectors. All three methods require only the eigensolutions of the nominal or unperturbed system, and in application, they involve simple matrix multiplications. Numerical experiments show that the proposed methods achieve accurate results for systems with and without damping and for systems with symmetric and asymmetric system matrices.
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spelling doaj-art-125d5f8a96d3403faba361e8b899b29a2025-02-03T01:31:58ZengWileyShock and Vibration1070-96221875-92032018-01-01201810.1155/2018/86091388609138Perturbation Methods for the Eigencharacteristics of Symmetric and Asymmetric SystemsPhilip D. Cha0Austin Shin1Department of Engineering, Harvey Mudd College, 301 Platt Blvd., Claremont, CA 91711, USADepartment of Engineering, Harvey Mudd College, 301 Platt Blvd., Claremont, CA 91711, USADynamic analysis for a vibratory system typically begins with an evaluation of its eigencharacteristics. However, when design changes are introduced, the eigensolutions of the system change and thus must be recomputed. In this paper, three different methods based on the eigenvalue perturbation theory are introduced to analyze the effects of modifications without performing a potentially time-consuming and costly reanalysis. They will be referred to as the straightforward perturbation method, the incremental perturbation method, and the triple product method. In the straightforward perturbation method, the eigenvalue perturbation theory is used to formulate a first-order and a second-order approximation of the eigensolutions of symmetric and asymmetric systems. In the incremental perturbation method, the straightforward approach is extended to analyze systems with large perturbations using an iterative scheme. Finally, in the triple product method, the accuracy of the approximate eigenvalues is significantly improved by exploiting the orthogonality conditions of the perturbed eigenvectors. All three methods require only the eigensolutions of the nominal or unperturbed system, and in application, they involve simple matrix multiplications. Numerical experiments show that the proposed methods achieve accurate results for systems with and without damping and for systems with symmetric and asymmetric system matrices.http://dx.doi.org/10.1155/2018/8609138
spellingShingle Philip D. Cha
Austin Shin
Perturbation Methods for the Eigencharacteristics of Symmetric and Asymmetric Systems
Shock and Vibration
title Perturbation Methods for the Eigencharacteristics of Symmetric and Asymmetric Systems
title_full Perturbation Methods for the Eigencharacteristics of Symmetric and Asymmetric Systems
title_fullStr Perturbation Methods for the Eigencharacteristics of Symmetric and Asymmetric Systems
title_full_unstemmed Perturbation Methods for the Eigencharacteristics of Symmetric and Asymmetric Systems
title_short Perturbation Methods for the Eigencharacteristics of Symmetric and Asymmetric Systems
title_sort perturbation methods for the eigencharacteristics of symmetric and asymmetric systems
url http://dx.doi.org/10.1155/2018/8609138
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AT austinshin perturbationmethodsfortheeigencharacteristicsofsymmetricandasymmetricsystems