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Dissertation/Thesis Abstract

Energy Transfer - Random Vibrations and CMS Analysis
by Hammoud, Kassem Reda, M.S., California State University, Long Beach, 2020, 170; 28153589
Abstract (Summary)

This thesis presents the results of a study on creating tools to be used for analyzing how energy is distributed and transferred from one subsystem to another using various engineering analysis techniques. Due to the complexity of the analysis and a large number of junctures with different input impedance and loss factors, the energy transfer of two subsystems can be understood using Component Mode Synthesis (CMS). CMS is a form of substructure coupling analysis and is frequently used in structural dynamics. CMS allows the derivation of the behavior of an entire assembly from its constituent components.

The dynamic behavior of each of the components is formulated by enforcing equilibrium and compatibility along with each component interface. CMS forms the dynamic characteristics of the full system model. The functions created by CMS span the required solution space of the problem. Natural modes and frequencies of structural systems are determined by utilizing the energy methods and mode functions applied to a complete system or a subsystem. The mode synthesis is analyzed by using equations of constraint and conditions of force equilibrium and deflection at different junctions. Analytical techniques to analyze how energy is distributed from one transverse system to another, such as beams, has not been clearly demonstrated in previous work.

Analytical solutions for beam are not readily available. Therefore, random vibrations were analytically analyzed, through CMS, and verified via finite element analysis (FEA) and small-scale experimentation. The test bed (beams) will be connected through a spring and excited with a force in this research. In the case of any dynamic computational analysis, the equation of motion holds important information about a system through its derivation. CMS attempts to piece the behavior of a system together by assemblies utilizing energy methods such as LaGrange, Extended Hamilton, Lagrange Multipliers, and Modal Analysis.

The results of this study verify that all methods are equally important and valuable in finding particular elements of a solution. The results of this research have direct application and provided a full analytical demonstration of using a known solution, such as the eigenmode of a cantilever beam, and applying the extended Hamilton principle to solve for a transverse system problem using CMS. The derived equations which approximated the theoretical solution developed from CMS and the analytical technique, were proved effective and accurate through comparison with NASTRAN and small-scale experimentation. This research further contributes to the understanding of random vibrations of transverse systems, particularly at high frequencies often impacted with limitations using FEA, by approximating solutions that would otherwise be unavailable.

Indexing (document details)
Advisor: Torabzadeh, Jalal
Commitee: Teagle, Allen, Marayong, Panadda
School: California State University, Long Beach
Department: Mechanical and Aerospace Engineering
School Location: United States -- California
Source: MAI 82/8(E), Masters Abstracts International
Subjects: Mechanical engineering, Physics, Energy
Keywords: Beam Analysis, Component Mode Synthesis, Data Acquisition System, Extended Hamilton Principle, Finite Element Analysis, Random Vibration
Publication Number: 28153589
ISBN: 9798582507680
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