Research On The Deformation Mechanism Characteristic And Constitutive Relation Of Dielectric Elastomer

Dieletric Elastomer(DE) is a kind of intelligent material which has special mechanical characteristics and mechanical properties. This thesis discusses the DE material’s deformation responsive characteristics and the stress-strain behaviors, as well as analyzes the deformation mechanism and the constitutive relation. During the research, theoretical and experimental methods have been used. The various characteristics’theoretical models, which has been mentioned in this thesis, have been tested by lots of experimental data. It will provide references in the application of DE in the future.According to the theory of superelasticity, DE’s viscoelastic and hyperelastic constitutive relation has been studied. The studies relating to DE’s viscoelastic properties includes:Design the uniaxial tensile test, establish DE’s viscoelasticity character model according to the three element model, process and analyze the test data, according to the regression model parameters, estimate the characteristic time constants. Using the characteristic time constants, measure the impact of deformation response which is caused by DE’s viscoelastic creep and relaxation properties. The study aimed at the DE’s hyperelastic properties includes:according to the material’s strain energy function constitutive equation, establish the DE’s constitutive model, corresponding to the result of uniaxial tensile test, using the method of numeric calculation, get the material parameters of the superelasticity model. By simulation experiment, verify the material parameters, the material parameters are the important reference data for establishing DE’s electromechanical coupling model, carrying out finite element simulation, as well as developing driving devices.The experimental schedule of the deformation mechanism test has been made on the basic of the Maxwell theory. The test has been carried out several times under various voltages, different preliminary drafts, different electrode thickness and different boundary conditions, in order to get the material’s deformation rate. When evaluating the impact of single factors, the preliminary drafts, voltage, the size of the plate and the thickness of the electrode have different impacts on the DE’s deformation; When evaluating the impact of comprehensive factors, by means of establishing regression equations, and optimal calculating the mentioned 4 factors in the range of their upper and lower limits, get the matching parameters of DE’s maximum deformation rate.Because DE has dual characteristics of material and geometric nonlinear, in order to master DE’s deformation mechanism and deformation regularity, besides studying the relating basic theories and carrying out tests, multi simulation methods has been used to describe material’s deformation mechanism and deformation regularity. Using the finite element analysis and the quadratic orthogonal regression testing method, establish the finite element model and mathematical model, develop the simulating program. By means of the simulation test, compare and verify the DE’s deformation mechanism and deformation regularity. It shows, that the method of simulation analyzing is an effective method to study the DE’s deformation mechanism characters.Under the action of electric field, the DE’s critical point can be reached or overstepped, the thin film will be destroyed, it will lead to instability of the DE’s Electro-mechanical Coupling System. In order to solve this problem, three Hyperelastic electromechanical coupling models have been established, by using the planar mechanical and electrical driving test to verify the impact of Elongation rate and material’s parameters on the instabilty of DE’s electromechanical coupling system.By researching the application of DE, the working principle of dram-type actuator has been analyzed,and the drum-type actuator has been developed. During the researching process, by changing the number of spring, the initial length of the spring and the stiffness coefficient of the spring, realize driving the DE devices with different degrees of freedom. The simulation test shows the developed push-pull drum-type actuator, bending drum-type actuator and corner drum-type actuator and so on are rational and feasible. It provides an important basis for the further study and design of the multidimensional composite driver.