Energy harvesting has become a popular topic for battery substitution in recent years. In particular, mechanical vibrational energy, one of the most common energy sources, has been intensely studied. Piezoelectric materials play a crucial role in vibrational energy harvesting as they can directly convert the mechanical energy to the desired electric energy. In particular these are attractive when they are made into a cantilever form allowing the harvester to harness larger energy. This project aimed at optimizing the performance of single-layered piezoelectric cantilevers, also known as the unimorphs, from the point of view of output power and operation lifetime with the use of a stroke limit stopper. \\
In this study, a cantilever beam consisting of PZT (PZT5A4) bonded to an elastic substrate (Pernifer 45) with a tip mass attached to the free end is used as the harvester. To reduce the cracks generated in the piezoelectric material and subsequently increase the lifetime, a limit stopper is introduced to constrain the deflection of the unimorph.The influence of the stroke on the lifetime and power output is shown by a series of vibration tests under different operation conditions with varied unimorph lengths, configurations, attached tip masses and stroke distances. The result confirms the possibility of the limit stopper to improve output energy of longer unimorphs in certain distance ranges. It also points out that current designs do not allow performance optimization in both output and lifetime simultaneously. One ought to choose one of the two, as the methods which increased the instant power output also resulted in a sharp reduction in lifetime as well as total power capacity.