Vibrational energy harvesting in bistable systems and structures

Orateur : Grzegorz LITAK (Lublin University of Technology - Poland)

A common energy harvesting device uses a piezoelectric patch on a cantilever beam with a tip mass. The usual configuration exploits the linear resonance of th e system ; this works well for harmonic excitation and when the natural frequency is accurately tuned to the excitation frequency. Among various systems discussed, a cantilever beam with a tip mass that is mounted vertically and excited in the transverse direction at its base is considered. This device is highly non-linear with two potential wells for large tip masses, when the beam is buckled. The system dynamics may include multiple solutions and jumps between the potential wells, and these are exploited in the harvesting device. The electromechanical equations of motion for this system are developed, and its response for a range of parameters is investigated using phase portraits and bifurcation diagrams. The model is validated using an experimental device with three different tip masses, representing three interesting cases : a linear system ; a low natural frequency, non-buckled beam ; and a buckled beam. We examine the multiple solutions and associated power outputs.

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