Li Cheng
The Hong Kong Polytechnic University
Presenting in Track 8: Dynamics, Vibration and Control
Presentation Title: Slow Wave Structures for Vibration and Noise Control
Abstract: Acoustic/elastic waves can be manipulated through proper structural design to produce the so-called slow wave phenomenon. In flexible structures undergoing bending vibrations, slow waves can be enabled by tailoring the structural thickness or material density according to a power-law relationship, leading to gradually reduced phase/group velocity of the flexural waves alongside a compression of the wavelength and enhancement of the energy density. This phenomenon, known as "Acoustic Black Hole" (ABH), can be leveraged in many engineering applications such as the design of lightweight and highly damped structures, sound-proofing structures, dynamic absorbers and energy harvesting devices etc. For sound waves, the counterpart of the ABH is the so-called "Sonic Black Hole" (SBH), which can be realized inside a conduit by means of a series of spacers with reducing inner diameters. Due to the combined effects of wave compression and energy concentration, slow waves within the SBH waveguide allow for efficient sound absorption with proper boundary treatment. This talk review some of the recent advances in both ABH and SBH research made by the research team led by the speaker. Modeling and analytical tools, salient phenomena, underlying physical principles, and potential applications of slow-wave-based vibration and noise control techniques will be showcased and discussed.
Biography: Dr. Li Cheng is a Chair Professor, Director of the Consortium for Sound and Vibration Research (CSVR) and Associate Dean (Research) of the Faculty of Engineering at the Hong Kong Polytechnic University. After obtaining his Ph.D. degree from the Institut National des Sciences Appliquées de Lyon (INSA-Lyon, France), he became a faculty member at Laval University (Canada) before joining Hong Kong PolyU in 2000. He was formerly the Head of the Department of Mechanical Engineering. He currently serves as Deputy Editor-in-Chief of the Journal of Sound and Vibration, Associate Editors of the Journal of the Acoustical Society of America, Structural Health Monitoring: An International Journal and Nonlinear Dynamics. Dr. Cheng is a Fellow of the Royal Society of Canada (Academy of Science), a Fellow of the Canadian Academy of Engineering, a Distinguished Fellow of the International Institute of Acoustics and Vibration, and a Fellow of five other societies. He served as President of the Hong Kong Society of Theoretical and Applied Mechanics. He is currently the President of the International Institute of Noise Control Engineering (I-INCE).