Analysis of a cantilever beam type vibration energy harvester with a lever mechanism

This thesis focuses on the energy harvesting efficiency of piezoelectric-based cantilever beam type vibration energy harvesters. The aim is to increase efficiency by homogenizing the axial stress along the beam. For this purpose, a counter mass is attached to the beam via a simple lever mechanism. This way, an inertial force is applied on the beam, having a direction opposite of the inertia force of the tip mass, thereby obtaining a loading close to pure moment. This structure is investigated in two methods; a detailed analytical model and numerical model are constructed. The analytical model and finite element analysis are used to assess the effect of two design parameters on efficiency, which are ratio of counter and tip masses, and lever beam length ratio. Modal analysis and harmonic response analyses are performed for both methods and compared with each other. The obtained results are compared with the strain distribution in a standard cantilever beam. It is shown that efficiency increases by means of the proposed method. As a result of analytical work, strain distribution greater than 0.53 was obtained. As a result of the test, strain distributions over 0.74 were obtained in a certain frequency bandwidth by altering with different mass and leverage ratios.