A postbuckling-based metamaterial for switching the propagation of surface acoustic waves

The use of periodic materials for wave control and signal processing has been a focus of intensive research over the past two decades and continues to garner significant attention. Common signal processing mechanisms like switches and rectifiers often depend on magnetic fields and/or logic gates for their activation. We propose a metamaterial that enables the control of mechanical waves—surface acoustic waves—through an ON–OFF mechanism that switches the propagation of the waves through a tunable platform of elastic beams. In the OFF configuration, the beams remain in their undeformed state and resonate at a specific frequency range, creating a bandgap that stops wave propagation. Conversely, in the ON configuration, the beams undergo buckling, redistributing the vibration energy across multiple modes and eliminating the bandgap, thus allowing wave propagation. Analytical and numerical findings demonstrate the significant potential of this mechanism for controlling wave propagation in nonlinear periodic materials. This switching mechanism relies purely on mechanical processes, thereby eliminating the need for external fields.