Session: SYMP 7-1: Energy Harvesting with Metamaterials

Paper Number: 147923

147923 - Bistable Metamaterials for Impact Mitigation 

Metamaterials have shown promise in a number of applications, including energy harvesting and impact mitigation. Dissipation, local resonance, and scattering are some of the most common mechanisms utilized for the mitigation of impact loads in metamaterials. Recently, the phenomenon of bistability has gained interest as a new route to achieve unconventional mechanical and dynamical properties in metamaterials. Specifically, bistable lattices that support transition waves, i.e., solitary waves carrying strain energy and momentum that transform the state of a medium as they propagate, have been shown to enable frequency-independent energy harvesting and extreme input-output frequency conversion. In addition to these applications, bistable lattices can achieve impact mitigation by trapping some of the energy from the collision into a transition wave. Unlike former mechanisms, energy locking through bistability can be achieved regardless of the frequency of the input load or the size of the unit. Thus, bistable structures can efficiently mitigate (or even harvest energy from) impact loads, which consist of a broad range of frequencies.

The present study uses numerical simulations and experiments to demonstrate the impact damping capabilities of a metamaterial consisting of bistable units that are connected through linear inter-site springs.  An impact on the first bistable unit can trigger the propagation of a transition wave through the metamaterial up to a certain location, referred to as the depth of the transition wave. The strength of impact, measured by the initial velocity of the first unit of the metamaterial, influences the depth of the transition wave in a cyclic manner. This indicates that transition waves propagate through the bistable metamaterial, and thus, lock energy from the impact, only for certain ranges of impact strength. We show that these distinct ranges of impact strength are intricately linked to the collision of multiple compression and rarefaction transition waves generated due to the initial kinetic energy imparted by the impact. Furthermore, we explore how these ranges of impact strengths can be controlled by design parameters such as the onsite stiffness of the bistable unit cells. We quantify damping performance by measuring transmissibility, which is the ratio of the maximum magnitude of velocity of the last unit to that of the first unit of the metamaterial. We finalize our study by comparing the damping performance of the bistable metamaterial with its linear counterpart. When the impact triggers transition waves, the bistable metamaterial demonstrates significantly lower transmissibility, and thus better damping performance than the corresponding linear metamaterial.

Presenting Author: Sneha Srikanth Purdue University

Presenting Author Biography: Sneha Srikanth is a PhD student in the Department of Mechanical Engineering conducting research on bistable metamaterials in the Programmable Structures Lab, at Purdue University. She earned her bachelor's degree in Mechanical Engineering from the Indian Institute of Technology Madras in 2022. As part of her undergraduate research, she investigated the dynamics of coupled thermoacoustic oscillators.

Authors:

Sneha Srikanth
Andres Arrieta