Piezoelectric Energy Harvesting from Macro-Fiber Composites with an Application to Morphing-Wing Aircrafts

摘要

The use of piezoelectric materials for low-power generation has been investigated by several researchers over the last decade. Typically, unimorph and bimorph cantilevers with conventionally poled monolithic piezoceramics have been implemented for this purpose. The experimental and modeling efforts in the literature are mostly limited to these monolithic configurations. However, there are several excitation conditions and operation environments where the monolithic piezoceramic configurations cannot be used due to their extremely brittle nature. The macro-fiber composite (MFC) piezoceramic configuration overcomes this issue owing to its flexible and robust nature. This paper investigates the MFC configuration for piezoelectric energy harvesting and presents a distributed-parameter electromechanical model. MFC unimorph configuration is modeled based on the Euler-Bernoulli beam theory and it is assumed to be excited by the translation of its base in the transverse direction with superimposed small rotation. A resistive load is considered in the electrical circuit for simplicity. After deriving the governing differential equations, closed-form solutions for the coupled vibration response and the voltage response are obtained for harmonic base excitations. Model predictions are first verified for an MFC unimorph with a brass substrate and then validations are given for MFC unimorphs with various substrate materials and thicknesses. For the same type of MFC with three different substrate materials (brass, aluminum and stainless steel), it is shown that the maximum peak power at resonance excitation is obtained for the aluminum substrate. Experimental results for different substrates are predicted successfully by using the coupled analytical model proposed here. Finally, results from the preliminary wind tunnel experiments are presented for piezoelectric energy harvesting from a flow-excited morphing airfoil with MFCs.