Modeling the electromechanical behavior of fiber-like dielectric elastomer actuator

Due to their excellent electrode-dielectric interfaces, straightforward fabrication process, lightweight, and slender structure, fiber-like dielectric elastomer actuators (DEAs) with axial deformation have broader application prospects than classical sandwich-configuration DEAs in soft robotics and are receiving increasing attention. However, the corresponding theoretical work is far behind of experimental research. Herein, a coaxial fiber-like DEA consisting of electrode core-dielectric annulus-electrode shell layout is proposed, and a nonlinear thermodynamic model is established to elucidate its electromechanical coupling behavior. Meanwhile, the standard linear solid rheological model is used to characterize the dielectric elastomers’ viscoelastic behavior. Subsequently, the static and dynamic electromechanical responses of the fiber-like DEAs are analyzed numerically, and the effects of material and structural parameters on the electromechanical behaviors are demonstrated. Theoretical calculation results indicate that coaxial fiber-like architecture could effectively suppress the electromechanical instability and achieve higher axial strain than tube-like hollow counterparts under equivalent electric fields. Moreover, decreasing the viscoelasticity and the thickness of the dielectric layer can effectively increase actuation strain. Finally, to verify the validity of the theoretical framework, the actuation performance of the fiber-like DEAs fabricated through one-step co-extrusion technique is measured. The theoretical predictions show good agreement with the experimental results, conclusively validating the effectiveness of the proposed model. This research establishes a theoretical groundwork for the design and optimization of fiber-like DEAs and provides critical guidelines for developing high-performance fiber-like DEAs for applications in soft robotics.