Thursday, April 18, 2019
2:00 – 3:00 pm
Speaker: Dr. Weidong Zhu, Department of Mechanical Engineering, University of Maryland, Baltimore County
Some interesting results on vibration and stability of distributed structural systems, vibration-based damage detection, and infinitely variable transmission are reviewed. Vibration and stability of translating media with time-varying lengths and/or velocities are addressed. Two types of dynamic stability problems are considered: dynamic stability of translating media during extension and retraction, and parametric instabilities in distributed structural systems with periodically varying lengths and/or velocities. The incremental harmonic balance method is used and modified to handle periodic responses of high-dimensional nonlinear models and their stability and bifurcations, as well as quasi-periodic responses. A new spatial discretization and substructure method, which ensures that all matching conditions of distributed components are satisfied, and hence uniform convergence of solutions, are discussed. The method overcomes drawbacks of classical assumed modes and component mode synthesis methods. New formulations of flexible multibody dynamics are developed with application to elevator traveling cables. A minimal number of degrees of freedom are needed to achieve the same accuracy as those of finite element and absolute nodal coordinate formulation methods. Nonlinear wave propagation in phononic structures and elastic wave cloaking are discussed. New methodologies are applied to elevator and other systems. Two major challenges in model-based damage detection are addressed: accurate modeling of structures and development of a robustness algorithm for identifying locations and extent of damage. Non-model-based damage detection methods using scanning laser vibrometry are also be presented. Finally, design, analysis, and control of novel infinitely variable transmission are discussed.
Weidong Zhu is a Professor in the Department of Mechanical Engineering at the University of Maryland, Baltimore County, and the founder and director of its Dynamic Systems and Vibrations Laboratory and Laser Vibrometry Laboratory. He received his double major BS degree in Mechanical Engineering and Computational Science from Shanghai Jiao Tong University in 1986, and his MS and PhD degrees in Mechanical Engineering from Arizona State University and the University of California at Berkeley in 1988 and 1994, respectively. He is a recipient of the 2004 National Science Foundation CAREER Award, has been an ASME Fellow since 2010, was an Associate Editor of the ASME Journal of Vibration and Acoustics from 2007-2014, and is a Subject Editor of the Journal of Sound and Vibration. His research spans the fields of dynamics, vibration, control, applied mechanics, structural health monitoring, metamaterials, and wind energy, and involves analytical development, numerical simulation, experimental validation, and industrial application. He has published 140 archival journal papers in these areas and has five U.S. patents.