Coupled static and dynamic FE analyses of a nonlinear electromechanical vibration energy harvester

The paper presents the coupled static and dynamic mechanical–electromagnetic finite element analyses of an electromechanical vibration energy harvesting converter with permanent–magnet excitation. The system consists of a small, milliwatt power range, linear–motion generator connected to a cantilever–beam spring element. The finite element equations derived for the mechanical part of the system according to the 1–D Timoshenko beam theory are coupled strongly with those describing the 2–D distribution of magnetic field in the generator and those associated with the electric circuit. The considered electromechanical coupling allows for prediction of static and dynamic response of the system subjected to action of externally applied force. The static displacement of the moving element is computed via solution of the nonlinear system of equations and is used as an initial solution in dynamic analysis. For computation of the dynamic response of the system the time–stepping procedure based on the Crank– Nicolson discretisation schema is applied. The models are positively validated against the measurements carried out on the laboratory test–stand.