Vibration Analysis of Piezolaminated Plates for Sensing and Actuating Applications Under Dynamic Excitation

The vibration characteristics of piezolaminated plates under coupled electromechanical loading are investigated using the finite element method. Higher order shear deformation theory is adopted to incorporate the effect of shear in the formulation. In the finite element formulation, an isoperimetric eight-nodded rectangular element is employed with linear through-the-thickness electric potential distribution. In the parametric study, the influences of geometry and boundary conditions on the vibration characteristics of piezolaminated plates are evaluated. Numerical results are presented for the frequencies of simply supported, clamped plates fitted with piezoelectric patches at the top and bottom surfaces of the laminate. For this, a model simulating the effect of the electromechanical loading with control potential is developed. Studies are also performed for piezolaminated plates with various thickness-to-span ratios, along with convergence test. The effect of the provision of piezoelectric layers to improve the vibration response of plates is investigated. This analysis reveals that the electro-mechanical coupling can strengthen the plate’s resistance to vibration.

Delayed electromechanical instability of a viscoelastic dielectric elastomer balloon

When a dielectric elastomer (DE) balloon is subjected to electromechanical loading, instability may happen. In recent experiments, it has been shown that the instability configuration of a DE balloon under electromechanical loading can be very different from that only subjected to mechanical load. It has also been observed in the experiments that the electromechanical instability phenomena of a DE balloon can be highly time-dependent. In this article, we adopt a nonlinear viscoelastic model for the DE membrane to investigate the time-dependent electromechanical instability of a DE balloon. Using the model, we show that under a constant electromechanical loading, a DE balloon may gradually evolve from a convex shape to a non-convex shape with bulging out in the centre, and compressive hoop stress can also gradually develop the balloon, resulting in wrinkles as observed in the experiments. We have further shown that the snap-through instability phenomenon of the DE balloon also greatly depends on the ramping rate of the applied voltage.