Effect of crosslinks, entanglements, and chain extensibilities on dynamic electromechanical instability of dielectric elastomers

State Key Laboratory for Strength and Vibration of Mechanical Structures, Xi'an Jiaotong University Xi'an, 710049, China and School of Mechanical Engineering, Xi'an Jiaotong University - Xi'an, 710049, China

^(a) hlchen@mail.xjtu.edu.cn

Received: 2 August 2018
Accepted: 29 October 2018

Abstract

Dynamic electromechanical instability (EMI) can affect the actuation performance of dielectric elastomers (DEs). This letter develops a theoretical framework to investigate the dynamic EMI of DEs with diverse crosslinks, entanglements, and chain extensibilities under a step voltage and equal biaxial pre-stresses. Based on the work-energy principle combining the EMI condition, the dynamic instability parameters at transition state between the stable and instable states are determined. At the small pre-stress, weak crosslinks or strong entanglements contribute to achieving a high actuation stretch ratio. When the pre-stress further increases, the DE with strong entanglements is prone to the dynamic EMI, and the variation in the dynamic instability actuation stretch ratio with the level of crosslinks is non-monotonic, which forms a peak. Moreover, as the level of chain extensibilities reduces, the dynamic instability actuation stretch ratio increases, and the enhancement effect can be significant at the large pre-stress. These results can help optimize the dynamic DE to obtain a stable oscillation without the dynamic EMI or utilize dynamic EMI to achieve a dramatic deformation.