Energy harvesting from vibrating cantilever beams with piezoelectric patches and performance enhancement by structural modifications

Piezoelectric energy harvesting from vibrating structures is an effective method for capturing dissipated mechanical energy and converting it into useful electrical power. However, power captured from them are in low-levels and needed to be increased. In this study, enhancing performance of piezoelectric energy harvesters was studied in two main parts, geometry modification and improvement of mechanical energy transfer. First, analytical and finite element methods for plain and tapered structures were given and verified through different cases including some literature studies. A parametric study on tapered structures was performed for increased power response using verified analytical method. Then, effectiveness of auxetic geometries on harvested power were investigated through Finite Element Method and some non-auxetic new shapes were introduced for increased power response. It was shown that the power gain from auxetic structures was very high compared to plain structures; however, this increase in power can also be achieved using a non-auxetic simple rectangular structure in some cases. On the other hand, new structures outperformed the plain structure in all cases and performed better than the auxetic geometry in most cases. In the last part of the study, the mechanical energy transfer between the substructure and piezoelectric patch was investigated. An analytical equation to predict mechanical energy transfer into the piezoelectric patch was proposed and validated by a study which includes tailoring stiffness of the beam to match with piezoelectric patches through numerical models and experiments. Finally, freeze casting method is proposed as an approach to produce piezoelectric composites with good piezoelectric properties and mechanical properties that can be easily adjusted to maximise the harvested power via mechanical energy transfer.