Finite element analysis of the electro-mechanical behaviors of piezocomposite bimorph energy harvesters under static and dynamic loadings

This study uses a finite element method to investigate electro-mechanical behaviors of bimorph cantilever beams composed of a steel substrate and two layers of a piezocomposite made of PZT-5H fiber/PVDF materials. The properties of the representative volume element of piezocomposites are determined by the numerical simulation based on the micromechanical homogenization method. Then, eigenfrequency and static analyses are performed, followed by a comprehensive dynamic study incorporating time-dependent analysis under sinusoidal harmonic loadings at two different excitation frequencies. A parametric study is performed to evaluate natural frequencies, mode shapes, displacement, strain, stress, electric potential, and electric field of the piezocomposite bimorph harvester for three different fiber volume fractions. The results demonstrate that increasing volume fraction leads to better electro-mechanical properties of piezocomposite bimorph harvesters, with resonance occurring at elevated frequencies. Additionally, an increased volume fraction results in reduced displacement and strain, while simultaneously amplifying the electric field and electric potential under static loadings. Dynamic loading analysis reveals that piezocomposite bimorph beams with a higher volume fraction exhibit higher electric potential and electric field, reaching equilibrium in a shorter duration. A frequency response analysis is conducted on the bimorph beam with varying cross-sections and volume fractions. The trapezoidal beam yields better electrical outputs as compared to the rectangular and triangular beams. The obtained mechanical behaviors by the present simulation are found to be in good agreement with those predicted through other researchers.