All-passive nonlinear electromagnetic metastructure for simultaneous energy harvesting and earthquake mitigation

J. Mike Walker’ 66 Department of Mechanical Engineering, Texas A&M University - 202 Spencer St, College Station, TX, 77843, USA

^(a) ya.wang@tamu.edu

Received: 20 November 2019
Accepted: 27 March 2020

Abstract

Resonance-based metastructures have recently attracted increasing attention for earthquake mitigation. Their application is limited, however, by their narrow attenuation zone. In this letter, we report an all-passive metastructure consisting of an array of dual-functional nonlinear electromagnetic resonator units. Each resonator unit consists of two rotary oscillators and one rectilinear oscillator based on nonlinear magnet levitation. The nonlinearity and intrinsic frequency up-conversion allows a broadened frequency operation range for simultaneous earthquake mitigation and energy harvesting. An analytical model is developed to investigate the wave dispersion and dynamic response of a single nonlinear resonant unit and the results agree well with the experimental data and the finite element analysis (FEA). Experimental results show that a two-unit array maintains a high instantaneous output voltage from 2.5 to 4.5 Hz under base excitation of 0.5 g. Maximum power of 3.7 mW and harvesting efficiency of 22.26% are achieved under harmonic excitation of 0.5 g and 4 Hz. The FEA exhibits the displacement reduction over 6 dB from 3.5 to 7 Hz with the metastructure array of 1340 units (160 meters long).