Asymptotic Modal Analysis of Structural and Acoustical Systems (Synthesis Lectures on Mechanical Engineering)

This book describes the Asymptotic Modal Analysis (AMA) method to predict the high-frequency vibroacoustic response of structural and acoustical systems. The AMA method is based on taking the asymptotic limit of Classical Modal Analysis (CMA) as the number of modes in the structural system or acoustical system becomes large in a certain frequency bandwidth. While CMA requires both the computation of individual modes and a modal summation, AMA evaluates the averaged modal response only at a center frequency of the bandwidth and does not sum the individual contributions from each mode to obtain a final result. It is similar to Statistical Energy Analysis (SEA) in this respect. However, while SEA is limited to obtaining spatial averages or mean values (as it is a statistical method), AMA is derived systematically from CMA and can provide spatial information as well as estimates of the accuracy of the solution for a particular number of modes. A principal goal is to present the state-of-the-art of AMA and suggest where further developments may be possible. A short review of the CMA method as applied to structural and acoustical systems subjected to random excitation is first presented. Then the development of AMA is presented for an individual structural system and an individual acoustic cavity system, as well as a combined structural-acoustic system. The extension of AMA for treating coupled or multi-component systems is then described, followed by its application to nonlinear systems. Finally, the AMA method is summarized and potential further developments are discussed.

Dr. Shung H. Sung is a retired Staff Research Engineer from General Motors Research & Development Center where she was involved with the development of engine noise and vehicle structural-acoustic technologies. She received her Ph.D. in Aeronautical and Astronautical Engineering from Purdue University. She is an American Society of Mechanical Engineers (ASME) Fellow, holds several patents, and is actively involved in organizing ASME and Acoustical Society of America (ASA) technical programs.Dr. Dean R. Culver is a Research Fellow at the U.S. Army Research Laboratory. He received his Ph.D. in Mechanical Engineering and Material Science from Duke University. His interests include nonlinear dynamics, biophysics, and vibration analysis. His current research includes robotic design and nonlinear structural vibration in vehicles.Dr. Donald J. Nefske is a retired Technical Fellow from General Motors Research & Development Center. He received his Ph.D. in Engineering Mechanics from theUniversity of Michigan, and has over 35 years experience in developing Computer-Aided-Engineering (CAE) capabilities for automotive vehicle noise and vibration. He is an ASME Fellow and currently consults on CAE structural-acoustic applications.Dr. Earl H. Dowell is the William Holland Hall Professor at the Pratt School of Engineering at Duke University. He is the former Dean of the Pratt School of Engineering and an elected member of the National Academy of Engineering. He is a Fellow of the American Institute of Aeronautics and Astronautics (AIAA), the American Academy of Mechanics, and the American Society of Mechanical Engineers (ASME), and is the recipient of several other awards and honors.