The rate dependence of the dielectric strength of dielectric elastomers

Elastomers are widely used in electronics and electrical devices, either as insulators or transducers. The insulation and actuation performance of elastomers are highly susceptible to their dielectric strength. Among the factors that influence the dielectric strength of elastomers, material viscoelasticity is an important factor that needs further investigation. Since the material viscoelasticity is often characterized by rate-dependent behaviors, we present two different sample configurations to experimentally examine the electrical and mechanical rate dependence of the dielectric strength of VHB 4905 elastomers. At pre-stretch ratio of 4, the improvement of the dielectric strength is about 30% from voltage ramp of 50 V/s to 800 V/s. Particularly, with an in-house biaxial test platform, the effect of the stretching rate on the dielectric strength is examined for the first time. The improvement of the dielectric strength is about 35% from stretching rate of 0.1 mm/s to 5 mm/s. Moreover, a dielectric strength predictor based on configurational stress is adopted to describe the experimental data. According to the predictor, the loading rate affects the dielectric strength of the elastomer mainly by influencing the evolution of the inelastic deformation.