Experimentally verified model of viscoelastic behavior of multilayer unimorph dielectric elastomer actuators

This work presents a linear viscoelastic model to describe the time-dependent actuation behavior of multilayer unimorph dielectric elastomer actuators (MUDEA), with experimental validation by actuators produced by a robotic dispenser system. MUDEA are a type of soft actuator which can produce large bending deformation without prestretch typically required by dielectric elastomer actuators. Current analytical and finite element models of MUDEA do not consider material viscoelasticity and cannot predict the change over time of performance metrics such as tip displacement and blocking force. The linear viscoelastic model presented in this work is based on a linear elastic model for the MUDEA extended to account for viscous effects by the elastic–viscoelastic correspondence principle. The model is easily implemented because it is based on explicit expressions which can be evaluated numerically by any computer algebra system. The model was used to predict the tip displacement and blocking force of MUDEAs consisting of two, four, six, eight, and ten layers of dielectric elastomer material. The model predictions agreed well with experimental data obtained from MUDEA produced by a robotic dispenser system, which was capable of producing multilayered structures of thin layers of dielectric elastomer and carbon nanotube based electrode material. (paper)