Ultra-compact metafence to block and channel mechanical waves

Abstract

Wave steering by artificial materials (for example, phononic crystals and acoustic metamaterials) is a fascinating frontier in modern physics and engineering, but suffers from bulky sizes and intractable challenges in fabrication. A sparse layer of identical tiny scatters, which we call metafence, is presented here in a non-destructive way to omnidirectionally block and arbitrarily channel flexural mechanical waves in plates. The underlying mechanism is that the restraining force and moment of the scatter are tuned simultaneously to counter-balance the incident wave. Both our experimental results and numerical analysis have demonstrated that broadband wave sources ranging from 3 to 7 kHz can be segregated from the protected area by the metafence. The metafence is also assembled into a waveguide routing with an arbitrary configuration. Compared with previous isolators and waveguides, our metafences exhibit absolute advantages in compact size, flexible configuration, and high structural strength. The current scenario sheds light on the design of lightweight-and-strong architectures for vibration control and energy harvesting with a high efficiency, and can be extended to microfluidics, acoustics, seismology and other fields.