Composite Piezoelectric Energy Harvesters with Symmetric Angle-Ply Stacking Sequences and Variable Through-the-Thickness Poisson's Ratios

Herein, the effect of symmetric carbon fiber composites laminates with angle-ply stacking sequences ([±β/±θ]_S) in the design of composite piezoelectric energy harvesters (PEHs) is evaluated. Some of those specific stacking sequences also feature negative Poisson's ratio (NPR) or near zero Poisson's ratio (NZPR) through the thickness for ply angles θ < 45°. Six different architectures with similar in-plane elastic modulus E₁ and different positive Poisson's ratio and NPR v₁₃ values are considered here. Finite element models are developed to understand the distribution of the voltage density of the laminates with the different stacking sequences and their bending properties. Experimental tests (three-point bending and vibration) are also performed. Both the simulations and the experimental results show that the PEH with the stacking sequences of near zero v₁₃ generate the highest power compared with the other composite energy harvesters. The maximum voltage frequency response function (FRF) happens at the fundamental resonance, and the PEH with near zero v₁₃ has also the lowest resonance frequency compared with the other stacking sequences.