Simultaneous All-Polarized Elastic Wave Energy Harvesting and Attenuation with Chiral Mechanical Metamaterials

We present a novel approach to address the challenge of simultaneously attenuating elastic waves across all polarizations and harvesting energy from these waves. Our research introduces an innovative chiral mechanical metamaterial design with defect structures (CMMD), overcoming the limitations of existing mechanical metamaterials that typically excel in either wave attenuation or energy harvesting, but not both.<br/>The CMMD demonstrates dual functionality by exploiting both complete bandgap and defect mode phenomena, enabling effective broadband wave attenuation and enhanced energy harvesting across the low-frequency spectrum. Through theoretical analysis and numerical simulations, we systematically develop a complete bandgap and strategically incorporated defect structures that induce modes for all wave polarizations within the bandgap region. Importantly, we design the defect structures with consideration to ensure they seamlessly integrate into the overall shape of the structure. Through numerical simulations, we confirm that our designed CMMD can acheive the desired vibration reduction and energy harvesting as intended. Experimental validation substantiates the CMMD's superior performance, demonstrating remarkable enhancements in electrical output power: up to 20.5 times for flexural waves and 511.4 times for longitudinal-torsional waves compared to defectless counterparts. These results underscore the CMMD's effectiveness in both attenuating and harvesting energy across various wave polarizations.<br/>Our findings open new possibilities for multifaceted applications in fields such as vibration control, energy-efficient structures, and smart structures, highlighting the potential of thoughtfully designed chiral mechanical metamaterials in addressing complex engineering challenges.