Effect of Stress Relaxation on Insulating Properties of Dielectric Elastomers with Different Pre-strain Ratios

Dielectric elastomer (DE) has been considered as ideal artificial muscles due to its intrinsic softness and flexibility, large reversible deformation, high specific energy density as well as light quality. However, low modulus and large elastic deformation bring about electromechanical instability (EMI), resulting limited electrical breakdown strength. Pre-strain can efficiently eliminate EMI and improve DE's breakdown strength. Theoretically, stress relaxation will make the effect decline with the time subsequently. In this paper, we have investigated the influence of pre-strain ratio and time to DE's insulating properties. After stress relaxation, the electrical breakdown strength of dielectric elastomers does not constantly decay, and its variation is consistent with that of Young's modulus and dependent on the pre-strain ratios.