Design, Analysis And Optimization Of Flexible Actuators Based On Dielectric Elastomer

In order to enable robots to enter some extreme environments instead of human beings to perform military exploration and other tasks,in recent years,domestic and foreign scientific researchers are committed to the research of various functional soft materials and bioinspired soft robots.Although great progress has been made,the development of soft robots is still in the primary stage,and all aspects of performance need to be improved,so soft robots can’t be really put into practical application.As a kind of typical functional soft material,dielectric elastomer has the characteristics of soft,large electric deformation,fast response speed,high energy density and light weight.It has great application advantages in the fields of soft robot,actuators and so on.This dissertation aims to develop a kind of flexible actuators based on dielectric elastomer,systematically design them from the aspects of material,structure,geometric parameters and fabrication,then test their actuation performance,and then further focus on the optimization method.The purpose is to obtain a kind of flexible actuators with excellent performance,that is,they have high breakdown voltage,large deformation and output force,so as to lay a foundation for integration into soft robot in the future.Make it possible for flexible actuators to move from the laboratory to the field environment.The main research contents of this dissertation are as follows:(1)The method of establishing the constitutive equation of dielectric elastomer based on the framework model of thermodynamic theory is introduced.We will establish the material system with acrylate as the main component,plan the manufacturing process of spin coating,design geometric parameters based on the typical structure of dielectric elastomer actuator,and study the key parameter of actuator layer thickness from the perspectives of piezoelectric multi-layer cantilever model and experiment.Finally,it is determined to develop single-layer flexible actuators with three thicknesses.(2)Test the material characteristics of dielectric elastomer,analyze the relationship between stress,elastic modulus and strain under uniaxial tensile test,and monitor the variation law of dielectric loss with driving frequency.The electromechanical performance of actuators is tested,the maximum deformation that can be output,the maximum voltage that can be supported and the load weight that can be overcome are studied,and the causes of Breakdown Failure in the response process are discussed.According to the test results,the actuator of thickness is 200μm can realize 31° angular displacement,its deformation is relatively flexible,and all three actuators can lift mass blocks equivalent to their own weight.At the same time,based on the finite element software,two analysis methods are selected to simulate the maximum deformation of the actuator in theory.(3)A series of performance optimization tests of the developed actuators are carried out,focusing on the laminated structure optimization method based on single-layer actuator.The experimental results show that the two-layer actuator can output 16 mm vertical deformation displacement,and the three-layer actuator can lift 2500 mg end-load.In general,the laminated dielectric elastomer actuators have excellent actuation deformation and output force,and the breakdown voltage is also higher than that of single layer.At the same time,the displacement-frequency response of the laminated actuators is tested in the frequency band of 0.1～100 Hz,and their energy density and efficiency are estimated.Through calculation,it is known that the energy density of the three-layer actuator is higher than 0.36 m J/g and the energy efficiency is higher than 0.17%.In addition,the optimization methods of increasing spin coating times and changing the materials of electrode and passive layer are also tested,but the effect of optimization is not good.