树形分叉压电振动俘能结构设计及实验验证*

In harvesting wideband and weak vibration energy in practical environments, classical piezoe-lectric energy harvesters often can't give a high electric output. To overcome this limitation, we intro- duce a novel design of tree-like tri-fork vibration energy harvester with piezoelectric patches bonded to the clamped end. Under base excitations, the harvester is expected to be able to produce large ampli-tudes and electric outputs. Firstly, the mathematical model is established, and corresponding simula-tions are conducted. Then the prototype was fabricated and validation experiments are carried out. The experimental results prove that under wideband stochastic excitations, the harvester can oscillate with a large amplitude and produce large output. Based on the results, we upgrade the structure by adding a mass on the tip of middle beam, the inertial force produced by the tip mass under excitation can drive the tri-fork beam to generate large vibration and output. Corresponding experiments were carried out to ver-ify the improved structure. The results show that with the change in structure, the electric output increa-ses dramatically for the same excitation intensity. For the stochastic excitation of PSD=0.045g/Hz. across a piezoelectric patch featuring the size of 20mm×10mm×2mm, the structure with the middle tip mass can produce an output of RMS power of 61.72µW, about 2.32 times that without the tip mass.