Dynamics of a Shell-Type Amplified Piezoelectric Actuator

A dynamic model for a shell-type amplified piezoelectric actuator (APA) is proposed. The dimensions of the shell of a typical shell-type actuator allow one to model it as a set of connected beams. The contribution of the geometric nonlinearity in the axial direction of the beams due to bending is accounted for in the formulation. Subsequent nonlinear analysis using both analytical and numerical approaches reveals the presence of second harmonic in the response spectrum. This occurrence is also seen experimentally. A frequency regime is also identified within which the effect of quadratic nonlinearity is minimal and the actuator exhibits high fidelity. Dependence of the response spectrum on the actuator geometry has been studied. For a given forcing frequency, a certain geometric configuration is shown to exist, which maximizes the nonlinear effects. The effect of prestressing of the piezoelectric stack on the frequency spectrum is also studied. The obtained results are expected to lead to improved design of such actuators.