In recent years, Non-Hermitian physics has drawn considerable attention. Bender and Boettcher suggested that the parity(P) and time(T) symmetries can be responsible for purely real spectra of non-Hermitian operators[1]. Then, it was further developed and extended to optics and acoustics[2, 3]. The PT symmetric system experience PT phase transition at critical point. This kind of PT symmetric system can be used to design single mode lasers, coherent perfect absorb, isolators and invisible sensor. However, it is difficult to apply the PT symmetric system in elastic waves because of its multi-modes and the balance of the loss and gain. In addition, the gain materials are hard to be found in nature. In this work, we first use the mass-spring model to exhibit the PT symmetric system’s characteristics. Then we expand PT symmetric system to continuous model, and analyze a PT symmetric beam structure. We use piezoelectric patches based on active shunted circuit to control the critical point of PT symmetric beam successfully. Results show that this work is useful and has potential to be developed as non-disturbance sensors for nondestructive examination method based on guided waves.

Date Published: 1 April 2019
PDF
Proc. SPIE 10972, Health Monitoring of Structural and Biological Systems XIII, 109720S (1 April 2019); doi: 10.1117/12.2514260

Published in SPIE Proceedings Vol. 10972:
Health Monitoring of Structural and Biological Systems XIII
Paul Fromme; Zhongqing Su, Editor(s)