Stretchable wavy structures on dielectric elastomeric substrates

Soft dielectric elastomers with high relative permittivity, very low modulus and high electric breakdown strength have emerged as promising materials for various applications as sensors, actuators and in energy harvesting. A bilayer material(consisting of a stiff thin film on a thick soft substrate), under large compression, exhibit mechanical instabilities like wrinkling and folding. We performed a linear perturbation analysis for the same, to get the first-order approximation curves for the primary and secondary deformed wavelength of the wrinkles due to an applied nominal compression to the system. We developed a fully coupled non-linear FEM code(UEL subroutine in Abaqus/Standard) to model the electromechanical behaviour of the soft substrate. The selection of initial dimensions of the sample for FE simulations is from the first-order approximation curves. The post bifurcation analysis of the system and the effect of applied electric potential, with buckled thin metal film as corrugated electrodes, are studied through FEA, considering Gent hyperelastic model for the substrate. The efficiency of the system(within the failure bounds) and the extent up to which the mechanical instability can be harnessed in this system, under an applied electric field, is studied in this work.