Hierarchical rotating-bending metamaterials for simultaneous mechanical vibration suppression and electricity generation

Abstract

triangular joints between dodecagon unit cells. The proposed structure is additively manufactured from thermoplastic polyurethane (TPU) and further analyzed through finite element analysis (FEA) to explore the deformation mechanisms. Under compression, the high-stiffness triangular joints rotate, inducing bending in adjacent walls, resulting in enhanced stability and quasi-zero-stiffness (QZS) features. Local deformation mechanisms include pure bending, bending combined with shear, and simultaneous shrinkage and expansion. To harness these local deformations, piezo elements integration strategies are proposed. A piezo bender (PB) is adhered to regions experiencing pure bending, lead zirconate titanate (PZT) patches are attached where bending and shear coexist, and piezo stacks are applied at locations with shrinkage and expansion. Experimental results show that before and after gluing piezo elements, the structure exhibits obvious vibration isolation performance, which is independent of the number of unit cells. From the frequency transfer functions, at 10 Hz, where vibration isolation arises, the PB and piezo stack generate power around 8.6 and 2.6 μWg , respectively, while PZT generates power around 11 nW/g. At a higher frequency of 200 Hz, the PB generates a power of 32 nW/g, piezo stack generates a power of 7.6 nW/g, and PZT generates a power of 2.9 nW/g. The proposed hierarchical metamaterials provides multifunctional capabilities, simultaneously isolating vibrations and generating electricity. They facilitate versatile solutions in vibration/stiffness control of engineering structures, like wearable devices, home appliances, vehicle parts, and civil infrastructures, by providing self-powered sensing and energy generation ability