Asymmetric full mode-converting transmission of elastic waves

Abstract

Asymmetric transmission in which wave energy propagates only in one direction attracts significant attention in various fields because of its rich physics and potential applications. In this work, we propose an elastic mode-converting metamaterial, which allows a full-power mode-converting transmission from longitudinal waves to transverse waves in the forward direction, while completely restricts the L wave transmission in the inverse direction. The metamaterial is designed by simply cutting two arrays of periodic silts on a matrix by exploring a straight design methodology, and thus very friendly for fabrication and application. Eigen-frequency analysis shows that the bilayer metamaterial exhibits two modes with significantly close natural frequencies around the working frequency, one for full-power mode-converting transmission, and the other for asymmetric transmission. Ultrasonic experiments are carried out to validate the proposed design. Our work offers a simple and efficient way for the realization of a complete one-way mode-converting transmission, and could be critically useful in designing diode-like meta-devices for novel wave manipulations.