Woodruff School of Mechanical Engineering
Faculty Candidate Seminar
Engineering extreme acoustic parameters and its applications
Mr. Chengzhi Shi
University of California, Berkeley
Monday, December 11, 2017 at 11:00:00 AM
MRDC Building, Room 3515
Dr. Alper Erturk
Acoustics has captured the interest of mankind for centuries because of its broad applications in almost all aspects of the society including communications, biomedical imaging, and architectural designs. The control of acoustic wave propagation is essential for these applications. However, even after a long history of study, the control of sound propagation on demand is still a challenging task. Recent development of acoustic metamaterials with properties not existed in nature enables unconventional controls of acoustic wave propagation including asymmetric wave transport, invisibility cloaking, and virtual illusion. In this talk, I will discuss the design of an acoustic metamaterial whose density and inverse bulk modulus cover entire range from positive to zero to negative values, where the simultaneous zero density and inverse bulk modulus is realized for the first time in experiment. This zero index metamaterial enables the control of acoustic phase front at will, which is used to collimate cylindrical waves emitted by a point source and generate directional acoustic plane waves that are important for imaging and sensing. I will then show how the control of acoustic phase front can be used to generate acoustic waves with different orbital angular momentum (OAM), which we applied to demonstrate the first high-speed acoustic communication in experiment. Finally, I will present my vision on how the unconventional control of sound propagation can revolutionize the fundamental study of wave dynamics, on-chip devices, and health care applications.
Chengzhi Shi is currently a PhD candidate in the Department of Mechanical Engineering at the University of California, Berkeley. He has earned his MS and BS degrees both in mechanical engineering from the University of Michigan – Shanghai Jiao Tong University Joint Institute. During his PhD and MS studies, Chengzhi has over ten first and co-first authored papers published in high impact journals including Nature Communications and PNAS. Because of his distinguished achievements, Chengzhi has won prestigious awards including the Berkeley Fellowship. His research interests cover both theoretical and experimental studies of wave propagation, structural materials and metamaterials, dynamics and vibrations, and their broad applications including high-speed underwater communications and ultrasonic biomedical engineering.
Refreshments will be served.