Energy harvesting via wrinkling instabilities

Conventional vibratory energy harvesters, working based on linear resonance, suffer from narrow bandwidth and are very inefficient at small scale for low frequency harvesting. Here, to improve the harvesting effectiveness, we propose to exploit surface instability or in general instability in layered composites where intriguing morphological patterns with large strain are formed under compressive loads. The induced large strains, which are independent of the excitation frequency, could be exploited to give rise to large strains in an attached piezoelectric layer to generate charge and, hence, energy. In this study, we particularly focus on wrinkling of a stiff interfacial layer embedded within a soft matrix. We derive the governing dynamical equation of thin piezoelectric patches attached at the peaks and troughs of the wrinkles. Results show that wrinkling could help to increase the harvested power by more than an order of magnitude.