PHM 2021 Keynote Speech 10

Voltage Controlled Topologically Protected Wave Propagation in Dielectric Membrane-type Acoustic Metamaterials


Abstract


Topological acoustic metamaterials have attracted enormous research attention in recent years. A significant hallmark of these structures is that they can support interface modes that are robust to structural disturbance and protected by topology. However, most of the studies are often limited to the passive structures that manifest wave propagation at fixed frequency ranges.  In view of the shortage of non-passive topological acoustic metamaterials, this work has a primary motive to study the active control of topologically protected wave propagation in soft dielectric membrane-type metamaterials (MAM) based on quantum spin Hall effect (QSHE). The unit cell of the periodic structure is designed with C6v symmetry. Then, the plane wave expansion method is adopted to analytically capture the system dispersion properties. A finite element model is further developed and excellent convergence with the analytical result is presented.  By adjusting locations of spraying discs in the honeycomb unit cell, mode shape inversion is observed, separating the topologically trivial state from the nontrivial counterpart. Consequently, the topologically protected interface modes (TPIMs) are observed. Additionally, an electrical voltage that lies within the locking-up limit is applied to MAM to actively control the working frequency of the TPIM. Further, several waveguide paths are designed to control the robust wave propagation in the structure. Conclusively, a voltage-controlled topological metamaterial is designed to actively tune the working frequency range of the device.

Speaker


CW Lim avatar
Dr. CW Lim China

Professor

City University of Hong Kong, China


Dr. CW Lim is the Prof. City University of Hong Kong China. Currently a fellow of ASME, ASCE, EMI and HKIE. He is one of the editors for JoMMS, Assoc Editor for JVET, IJBC, JTS, subject editor for AMM, JSV, and on the editorial board of some top-ranked international journals. Professor Lim has expertise in theory of plates and shells, dynamics of smart piezoelectric structures, nonlinear dynamics, nanomechanics, symplectic elasticity and metamaterials.

He has published one very well-selling title “Symplectic Elasticity”, co-authored with other authers.  He has published more than 330 international journal papers, accumulated about 12,000 citations and has a Google Scholar H-index 56.  One of his papers has been cited more than 800 times since it was first published in JMPS in 2015.  It is also one of the most highly cited papers in the journal.  Another paper was granted the IJSS 2004-2008 most cited article award.  He was also awarded Top Referees in 2009, Proc. A, The Royal Society.  Professor Lim is a registered professional engineer in HK.  He holds one registered finite element software and three patents.  Recently Professor Lim was awarded the prestigious 2020 JN Reddy Medal1 as a recognition “for significant and original contributions to vibration of plates and shells, smart piezoelectric structures, nanomechanics, and symplectic elasticity”.