Study On Electromechanical Coupling Characteristics Of Dielectric Elastomer Based On Finite Element Method

As a typical intelligent flexible material,dielectric elastomers(DE)can not only convert electric energy into mechanical energy as bionic driver,but also can be applied to the field of power generation in reverse direction,converting mechanical energy into electrical energy.The material has the characteristics of low mass density,high energy density,large deformation,good electromechanical conversion efficiency and low price,making it widely applied in bionics and power generation field.Based on the generation cycle of dielectric elastomer generator(DEG),the DEG was modeled and simulated,and its electromechanical coupling characteristics were studied.It will provide some reference value for the subsequent DEG design.The main research contents of this paper are as follows:(1)Study on constitutive model and parameters of DE material.DE is a kind of hyperelastic material with large deformation,whichhas nonlinear mechanical properties.The exact description of the constitutive relationship of DE materials is the key to the study of the electromechanical properties of DEG.And it is also the basis for subsequent electromechanical modeling and related simulation.Based on the four type hyperelastic constitutive models of Neo-Hooken、Mooney-Rivlin、Ogden and Yeoh,the mechanical constitutive model of DE was analyzed.The uniaxial tensile,pure shear tensile and biaxial tensile tests were designed.The proper constitutive model was selected through compound fitting and its constitutive parameters were determined.The Mooney-Rivlin hyperelastic model was selected by analysis and comparison,and was applied to the subsequent finite element modeling.(2)The study of DEG electrostatic model.As the bionic force in driving mode,Maxwell electrostatic force also exists in the DEG power generation mode,which affects its electromechanical characteristics.The DEG electrostatic model was established.The distribution of electrostatic force was studied from two aspects of theory and simulation,and its size and direction were determined.The relative dielectric constant,as fatal electrical parameters,plays an important role in the study of electromechanical properties.The relationship between the electrical parameters above and the tensile rate under three different tensile modes was measured,and the relation function was fitted.The relative dielectric constant and dielectric breakdown relation function were used for subsequent modeling and simulation to improve the accuracy of modeling.(3)The establishment of DEG mathematics and simulation model and experimental research.The electromechanical coupling theory model and the finite element simulation model of three kinds of tensile methods were established and compared with the experiments.The simulation model was based on the Mooney-Rivlin hyperelastic constitutive,and the relative permittivity was considered as a variable.The simulation model of DE film was constrained by the finite element physical field,and then the simulation of the tension,capacitance changes and boosting ability was carried out through steady state and transient solution.The experimental platform of three kinds of tensile methods was built and compared with the simulation data.And the results were basically the same.(4)Simulation analysis and Experimental Research on DEG prototype.A new type of inflatable DEG prototype was designed,and the simulation modeling and experimental research were carried out Based on the above Mooney-Rivlin hyperelastic model,combined with thin shell theory,a theoretical model of generator deformation was established,and the mechanical simulation was carried out under COMSOL finite element environment.The experiment platform was set up to carry on the related experimental research,and the simulation and the mechanics experiment were compared.Experimental research was carried out from three aspects of bias voltage,piston moving distance and frequency.The experimental results showed that the effect of this kind of generator is much better than the above three types of plane deformation,and the bias voltage and the moving distance of the piston have an obvious influence on the generator.The influence of the frequency has no obvious effect on the generator,and it can be used for reference for the design of the prototype of the generator.