Electromechanical Modeling and Dimensionless Optimization of a Multilayer PZT-5H Energy Harvester for Vehicle Suspension Systems

Vehicle suspension systems dissipate substantial vibration energy, generated by tyre–road interactions, most of which is lost as heat through damping. Recovering this energy can provide a sustainable power source for self-powered sensing and intelligent vehicle monitoring. This study presents a coupled electromechanical model of a quarter-car suspension incorporating a multilayer PZT-5H stack in series configuration for vibration energy harvesting. The proposed arrangement preserves effective suspension stiffness while enhancing electrical output through cumulative voltage generation. The governing mechanical and electrical equations are reformulated into a dimensionless framework, enabling generalized evaluation of mass ratio, stiffness ratio, damping, electromechanical coupling, and electrical load. The analytical model is independently verified using a MATLAB-Simulink (R2025b) implementation, while available experimental data are used only as an external benchmark rather than as direct full-scale validation. Parametric analysis shows that harvested power peaks near the suspension-bounce resonance, while stiffness ratio and mass ratio significantly influence strain transfer and inertial energy exchange, respectively. Taguchi-based design of experiments and ANOVA reveal that load resistance is the dominant factor, contributing approximately 63.6% and 58.5% of the variance for the undamped and damped models, respectively, followed by stiffness ratio (19.6% and 17.9%) and mass ratio (14.0% and 12.5%). The proposed framework integrates the series-connected piezoelectric configuration, dimensionless modeling, analytical–numerical verification, and statistical optimization to provide a unified methodology for designing suspension-integrated piezoelectric energy harvesters.