The Structure-efficiency Relationship Between Dielectric Elastomers And Devices

Compared with other smart materials,dielectric elastomer has faster electromechanical response,higher energy density and larger actuated strain after pre-stretching.It can be first choice of material for artificial muscle actuators.Dielectric elastomer actuator is mainly composed of dielectric elastomer and electrode.The intrinsic properties of the dielectric elastomer determine the theoretical size of the electromechanical coupling efficiency,while the electrodes affect the actual size of the electromechanical coupling efficiency.Therefore,the electromechanical coupling efficiency of dielectric elastomer actuator is closely related to dielectric elastomer and electrode.Based on thermodynamic theory,we studied the electromechanical coupling efficiency of ideal dielectric elastomer under constant voltage,constant electric field and constant charge.Then,we considered the non-linear mechanical behavior and electrostrictive effect of material,a non-linear electromechanical coupling model was constructed to calculate the electromechanical coupling efficiency of acrylate rubber(VHB4905)under different strain.Finally,the influence of flexible silicone rubber electrodes on the electromechanical coupling efficiency was studied.The electromechanical coupling efficiency of ideal linear elastic materials is different under three driving modes.Under constant charge,the electromechanical coupling efficiency is the highest,and the theoretical maximum of coupling efficiency can reach 100%.Under constant electric field,the theoretical maximum of coupling efficiency is 90%.Under constant voltage,the electromechanical coupling efficiency is the lowest,and the theoretical maximum of coupling efficiency is 50%.The theoretical electromechanical coupling efficiencies of VHB4905 are 31%,38%,42%,43%at 0%,50%,100%and 150%pre-stretching,respectively.The lower the modulus of electrodes,the greater the electromechanical coupling efficiency;the higher the conductivity of electrodes,the larger the electromechanical coupling efficiency;the smaller the area of electrodes,the higher the electromechanical coupling efficiency;the thinner the thickness of electrodes,and the higher the electromechanical coupling efficiency.