Dynamic analysis of a bi-stable buckled structure for vibration energy harvester

Abstract

Vibration energy harvesting offers a viable alternative to batteries for powering sensors in remote locations. In the past decade, the energy harvesting community has turned to nonlinear structures as an effective means for creating high-performance devices. In particular, researchers have used buckled structures to improve vibration scavenging power production at low frequencies (<100 Hz) and to broaden device operational bandwidths. To achieve these ends, accurate structural models are needed. These models are critical for carrying out a systematic and quantitative device design process. Specifically, the models enable the user to optimize device geometries, arrive at meaningful estimates of power production, and estimate device lifetimes, etc. This work focuses on the dynamic behavior of a bi-stable switching energy harvester made from a buckled beam structure, coupled to two cantilever beams with tip masses via a torsional rod. Results from experimental testing of the energy harvesting structure under different forced vibration conditions are compared with a nonlinear model created of the structure. For the model, linear equations of motion for free vibration of each component have been derived using Hamilton’s principle, and shape functions for each individual component are determined by applying boundary conditions for the linear vibration. Nonlinear dynamic behavior effects are integrated through consideration of large deformation of the main beam. The effects of different parameters on the vibrational system, including the geometry of the structure, buckling load and natural frequency of the cantilever arms, have been investigated. These parameters can play an important role in the optimization process of energy harvesters. Finally, parametric results obtained from the presented method are compared with the experimental data in different aspects.