AbstractsEngineering

An increased amount of work is done towards opti- mizing the mechanical design of vibrational energy harvesters in order to cope with varying ambient conditions. Here the performance of a piezoelectric energy harvester with varying non-linear spring characteristics is modelled and experimentally veri- fied, determining the optimal non-linear motion for various operating conditions. A positive, bi-stable (negative) and balanced (zero) spring stiffness with end-of-stroke stiffening effect is achieved through static balancing of the energy harvesting device. Results show that a zero stiffness system generates a higher power output for a wide range of input conditions due to its increased range of motion without suffering from a minimal energy threshold typically seen in multi-stable energy harvesters. The numeric model accurately predicts key features of the harvester performance for different stiffness settings, providing a valuable tool in non-linear energy harvester design.