Instability has been recognized as one of the major issues restricting the full potential applications of dielectric elastomer (DE)-based devices. While great efforts have been devoted to investigating the instabilities of DE actuators, those studies are limited to using either hyperelastic material models or viscoelastic constitutive models with constant material viscosity. As observed in the experiments, the intrinsic material viscosity of elastomers varies with deformation, which becomes more manifest particularly for DE actuators undergoing large deformation. This work attempts to fill this knowledge gap by developing a finite element (FE) framework that combines the nonlinear field theory with the micro–macro constitutive model incorporating nonlinear material viscosity to investigate the electromechanical responses and the instability of DE actuators. A highly customized user-element subroutine (UEL) in Abaqus is developed for the FE implementation. The effects of the nonlinear material viscosity on a variety of instability modes of DE (VHB 4910) actuators with different configurations are numerically investigated, including electromechanical instability (EMI), buckling, wrinkling, and crumpling. The accuracy and robustness of the FE framework are validated by comparison with existing experimental data and analytical studies. This work provides a general approach for instability analysis of DE actuators with different configurations and can further function as a universal platform for numerical analysis on the electromechanical finite deformation of DE structures with complex configurations, leading to better design and applications of DE-based devices.

不稳定性已被认为是限制基于介电弹性体 (DE) 的设备的全部潜在应用的主要问题之一。虽然已经为研究 DE 致动器的不稳定性做出了巨大努力，但这些研究仅限于使用超弹性材料模型或具有恒定材料粘度的粘弹性本构模型。正如在实验中观察到的，弹性体的特性材料粘度随变形而变化，这对于经历大变形的 DE 致动器尤为明显。这项工作试图通过开发有限元 (FE) 框架来填补这一知识空白，该框架将非线性场理论与包含非线性材料粘度的微宏观本构模型相结合，以研究 DE 致动器的机电响应和不稳定性。Abaqus 中高度定制的用户元素子程序 (UEL) 是为 FE 实现开发的。非线性材料粘度对具有不同配置的 DE (VHB 4910) 执行器的各种不稳定模式的影响进行了数值研究，包括机电不稳定 (EMI)、屈曲、起皱和起皱。通过与现有的实验数据和分析研究进行比较，验证了有限元框架的准确性和稳健性。