Effects of variation of permittivity and the actuating voltage on the dynamic response of dielectric elastomer actuator

Dielectric elastomer(DE) has been recognized as one of the most promising materials that could be used as artificial muscle. Theoretical analyses on issues of DE mechanics, physics and material science in quasi-static state or small deformation have been widely carried out during the past few decades. When subjected to high voltage, the DE material exhibits complex dynamic behavior upon cyclic loading which is known as the viscoelasticity and electromechanical coupling. To understand the dynamic response of this viscoelastic material, a comprehensive model and quantitative research are required to be constituted. In this paper, a theoretical and experimental study is carried out to investigate the dynamic behavior based on experimental results of a rectangular DE actuator undergoing different actuating voltages. Firstly we build a comprehensive constitutive model, based on Gent energy function, by treating the permittivity as a strain-dependent variable. It is validated by experiments and, the ability to predict the behavior of the proposed model and the existed model is compared. The influence of the loading pattern of the applied voltage on the DE actuator performance is also studied. Experiments have been done to compare the maximum strains obtained while DE actuator is under a ramp signal and periodic signal respectively. The experimental results of the two types of strain exhibit the effects of loading pattern on the dynamic performance and inspire us to make an improvement to the constitutive model that can describe the dynamic performance better.

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