Modeling and Design Optimization of a Pre-stretched Rolled Dielectric Elastomer Actuator

Dielectric elastomer actuators (DEAs) possess characteristics closest to human muscles and have been rapidly developed. The rolled DEA is considered more suitable as a driving module due to its ability to output unidirectional deformation. This paper proposes a high-performance actuator, which is connected in series by a spring and a DEA, wherein the spring realizes the pre-stretching of the DEA. To predict the mechanical behavior of the structure, the rolled DEA is simplified into a single-layer tubular DEA, and a static model is established to predict the free displacement and blocking force under different input voltages, spring stiffness coefficients, and geometric parameters of the structure. The optimal pre-stretch effect was tailored by finding the optimal combination of spring stiffness and pre-stretch through a two-dimensional search, thereby maximizing the free displacement, blocking force, or equivalent work. Under the optimal parameter combination aimed at maximizing the equivalent work, the system achieves a free displacement of 0.43 mm and a blocking force of 0.57 N. These values are 3.6 times higher for free displacement and 1.54 times higher for blocking force compared to the springless structure. The effectiveness of the theoretical analysis model is verified by experiments, and relevant manufacturing processes are introduced. This study offers a promising approach to analyzing the effect of pre-stretch on the performance of rolled DEAs, opening up new possibilities for soft robotics applications.