Study On Multi-stable Grasping Structure Based On Dielectric Elastomer And Shape Memory Polymer

Dielectric elastomer is a typical smart soft material,with many advantages such as large deformation,fast response,high energy density,high fracture toughness and high electromechanical efficiency.The actuator made of dielectric elastomer is driven by the strain response of elastomeric polymer with flexible electrode under the action of electric field.It has the advantages of simple structure,light weight and low cost.These advantages make it show potential application value in many aspects.However,the traditional dielectric elastomer grasping structure has low grasping force.On this basis,using the variable stiffness characteristic of shape memory polymer,the grabbing force of the grabbing structure can be greatly increased,and the shape can be fixed without continuous electrification in the process of grabbing and releasing.In this paper,a multi-stable grasping structure based on dielectric elastomer and shape memory polymer is studied.Combining the advantages and characteristics of the two materials,the grasping structure has the advantages of simple structure,light weight and soft grasping.In addition,the electro-deformation characteristics of dielectric elastomer,shape memory effect and variable stiffness characteristics of shape memory polymer can be used to realize the automatic grasping and releasing process of the grasping structure.Firstly,starting from the study of mechanical properties of materials,the dynamic thermomechanical analysis,relaxation test and uniaxial tension test of shape memory polymer specimens were carried out,and the uniaxial tension test of dielectric elastomers was carried out.The material parameters were fitted to provide the necessary data for the subsequent theoretical and simulation calculations.Then,based on the energy method,the theoretical model of the actuator layer was established and calculated by using MATLAB.The effects of the prestretching ratio of dielectric elastomer film,the size of shape memory polymer frame,voltage and temperature on the structure performance of the actuator layer were analyzed,and the structural parameters were preliminarily determined.After that,the fitted material parameters were input into the constitutive model of the material.Then,ABAQUS is used to simulate the bending and unfolding process of the actuator.Finally,bending and unfolding experiments are carried out to test and record the bending angle and unfolding angle of the actuator.The structure is optimized and improved by combining theoretical and simulation results,and then applied to the grasping structure.