Self-Powered Bridge Monitoring via Tri-Stable Piezoelectric Harvesters under Moving Traffic Excitation

This study examines the electromechanical response of a tri-stable piezoelectric cantilever energy harvester mounted on a simply supported beam under moving vehicle loads, representative of bridge health monitoring conditions. The tri-stable configuration is achieved through magnetic coupling, enabling broader potential wells for enhanced vibration energy harvesting compared to traditional linear or bi-stable systems. A comprehensive mathematical model is developed that incorporates Euler-Bernoulli beam theory, Galerkin discretization, and the harmonic balance method for analytical solutions. This is verified against numerical simulations, demonstrating the convergence between the analytical and numerical outcomes. The influence of key parameters such as moving mass, velocity, length, and density is analyzed through time responses, phase portraits, Poincaré maps, wavelet transforms, frequency spectra, and RMS voltage outputs. Results demonstrate that the tri-stable harvester outperforms bi-stable counterparts at higher velocities, achieving up to 30% higher cumulative power and broader bandwidth due to efficient inter-well transitions. However, bi-stable systems show advantages at lower velocities. These findings provide practical design guidelines for self-powered wireless sensor networks in intelligent transportation systems, identifying velocity-dependent operational regimes that maximize energy harvesting efficiency under realistic traffic-induced excitations.