Vibrational Energy Harvesting from Functionally Graded Nonprismatic Beams

Abstract

This study investigates the vibrational energy harvesting capabilities of axially functionally graded nonprismatic piezolaminated beams under combined thermal-mechanical loading conditions for automotive applications. A coupled multi-physics finite element model was developed to analyze the electromechanical response of tapered cantilever beams with varying width (cb) and height (ch) taper coefficients while maintaining a material gradient index (k=1) and power law exponent (np=4). Four geometric configurations with taper coefficients of 0.3 and 0.7 were subjected to both isolated mechanical impulses loading and combined thermal-mechanical loading with a 50°C temperature gradient. Results demonstrate that taper parameters significantly influence performance, with height tapering showing greater impact on displacement response than width tapering. Thermal loading increased displacement by 16.7-66.7% across configurations, highlighting complex thermal-mechanical coupling effects. Voltage generation was enhanced with increasing taper coefficients, reaching 340 V/mm in the optimized configuration (cb =0.7, ch =0.7) compared to 140 V/mm in the baseline configuration (cb=0.3, ch=0.3). Most notably, output power exhibited dramatic enhancement under combined loading conditions, with the optimized configuration achieving 0.15 W/mm², representing a 650% increase over mechanical loading alone. The findings suggest that axially functionally graded nonprismatic piezolaminated beams offer promising solutions for harvesting waste vibrational and thermal energy in automotive environments, with the potential to power various low-energy automotive sensors and monitoring systems.