The base research project is on two-dimensional phononic band gap materials whose characteristic stop band can be tuned by using an eccentric coating layer to the core scatterers. The host institution is the Polytechnic University of Valencia, Spain, whose 1995 article in the Nature magazine was considered by many as the article that started this field of endeavor. The visit coincided with an exciting period of time in phononic materials research: the concept of metamaterial that used in the successful demonstration of "cloaking device" for microwave had gained prominence, and the race to be the first to demonstrate the acoustic cloaking was on. Major accomplishments of the visit include: 1) Establishment of a computational procedure for analyzing the scattering of acoustic wave by general multi-layer scatterers. 2) Establishment of a general solution for acoustic wave propagating in a mass-orthotropic metamaterial. 3) Discovery of ultrasonic focusing effects by a grid of heated wires. 4) Semi-analytical analysis of the proposed acoustic cloak design. 5) Analysis for induced transparency in an acoustic metamaterial. The last component of a part of three-way collaborative effort initiated by the PI and involved the PI's institution, the host institution and the Naval Research Laboratory. The visit further enhanced the long-term collaboration between the PI and the host.

Liang-Wu Cai received the B.Sc. degree in Modern Mechanics from the University of Science and Technology of China in 1985, and his M.Eng. degree in Solid Mechanics from the Chinese Academy of Sciences in 1988. He received his Sc.D. degree in Applied Mechanics from the Massachusetts Institute of Technology in 1998. He was a post-doctoral fellow at MIT from 1998 to 2001. Since August 2001, he has been an Assistant Professor of Mechanical and Nuclear Engineering at Kansas State University. His research interests include wave mechanics, acoustic, non-destructive valuation of materials, and mechanics of composite materials.

NSF CMMI-0510940 Amendment 001

Researchers should cite this work as follows:

Liang-Wu Cai, "Tunable Two-Dimensional Phononic Materials Research", Trip report presented at the NSF IREE 2007 Grantees Conference, October 30 - November 1, 2007, Purdue University, West Lafayette, Indiana

• (2009), "Tunable Two-Dimensional Phononic Materials Research," http://globalhub.org/resources/907.

1. iree 2007 109
2. Spain 3
3. trip report 221