Design, modeling and testing of a new compressive amplifier structure for piezoelectric harvester

Abstract

In recent years, harnessing electrical energy from mechanical vibration by using a piezoelectric energy harvester (PEH) has attracted much attention from researchers. This sustainable energy harvester is useful for wireless sensor network, where a replacement or replenishment of an energy source such as a battery is impractical. From previous studies, the amount of energy generated by the PEH is very limited even in a high force environment. To solve this issue, mechanical amplifier structure such as Cymbal structure is implemented to amplify the tensile loading force towards the PEH. In terms of the material strength perspective, this performance can be further enhanced by using a compressive-type mechanical amplifier structure, as the compressive yield strength of piezoelectric material is much higher than its tensile yield strength. In this study, a compressive structural design which is named as Hull structure is proposed. Several techniques included analytical model analysis, finite element analysis (FEA), and experimental testing have been used to evaluate its performance. It shows a force amplification factor of 9.72 at 6° through the analytical model. From the FEA result, the proposed Hull structure shows great potential in enhancing the power output of 11.34 mW, which is 3.08 times larger than the benchmarking Tensile Cymbal structure. It also shows 5.28 times greater output voltage than the benchmark case in the experiment. Besides, it has a great advantage of providing a wider area for excitation loading force which increases the PEH’s load capacity and suitable for the vehicular excitation application.