Dielectric elastomer (DE) is the most promising electroactive polymer material for smart actuators. When a piece of DE film is sandwiched between two compliant electrodes with a high electric field,due to the electros...Dielectric elastomer (DE) is the most promising electroactive polymer material for smart actuators. When a piece of DE film is sandwiched between two compliant electrodes with a high electric field,due to the electrostatic force between the two electrodes,the film expands in-plane and contracts out-of-plane so that its thickness becomes thinner. The thinner thickness results in a higher electric field which inversely squeezes the film again. When the electric field exceeds the critical value,the dielectric field breaks down and the actuator becomes invalid. An elastic strain energy function with two material constants is used to analyze the stability of the dielectric elastomer actuator based on the nonlinear electromechanical field theory. The result shows that the actuator improves its stability as the ratio k of the material constants increases,which can be applied to design of actuators. Finally,this method is extended to study the stability of dielectric elastomers with elastic strain energy functions containing three and more material constants.展开更多
In this paper, the strain energy function proposed by Shang and Cheng was generalized by introducing a nonlinear term. Void formation and growth in the interior of a sphere composed of compressible hyper-elastic mater...In this paper, the strain energy function proposed by Shang and Cheng was generalized by introducing a nonlinear term. Void formation and growth in the interior of a sphere composed of compressible hyper-elastic material, subjected to a prescribed uniform displacement, was examined. A parametric cavitated bifurcation solution for the radial deformed function was obtained. Stability of the solution of the cavitated bifurcation equation was discussed. With the appearance of a cavity, an interesting feature of the radial deformation near the deformed cavity wall is the transition from extension to compression.展开更多
Mechanical properties, such as the deformation and stress distributions for venous walls under the combined load of transmural pressure and axial stretch, are examined within the framework of nonlinear elasticity with...Mechanical properties, such as the deformation and stress distributions for venous walls under the combined load of transmural pressure and axial stretch, are examined within the framework of nonlinear elasticity with one kind of hyper-elastic strain energy functions. The negative pressure instability problem of the venous wall is explained through energy comparison. First, the deformation equation of the venous wall under the combined loads is obtained with a thin-walled circular cylindrical tube. The deformation curves and the stress distributions for the venous wall are given under the normal transmural pressure, and the regulations are discussed. Then, the deformation curves of the venous wall under the negative transmural pressure or the internal pressure less than the external pressure are given. Finally, the negative pressure instability problem is discussed through energy comparison.展开更多
文摘Dielectric elastomer (DE) is the most promising electroactive polymer material for smart actuators. When a piece of DE film is sandwiched between two compliant electrodes with a high electric field,due to the electrostatic force between the two electrodes,the film expands in-plane and contracts out-of-plane so that its thickness becomes thinner. The thinner thickness results in a higher electric field which inversely squeezes the film again. When the electric field exceeds the critical value,the dielectric field breaks down and the actuator becomes invalid. An elastic strain energy function with two material constants is used to analyze the stability of the dielectric elastomer actuator based on the nonlinear electromechanical field theory. The result shows that the actuator improves its stability as the ratio k of the material constants increases,which can be applied to design of actuators. Finally,this method is extended to study the stability of dielectric elastomers with elastic strain energy functions containing three and more material constants.
文摘In this paper, the strain energy function proposed by Shang and Cheng was generalized by introducing a nonlinear term. Void formation and growth in the interior of a sphere composed of compressible hyper-elastic material, subjected to a prescribed uniform displacement, was examined. A parametric cavitated bifurcation solution for the radial deformed function was obtained. Stability of the solution of the cavitated bifurcation equation was discussed. With the appearance of a cavity, an interesting feature of the radial deformation near the deformed cavity wall is the transition from extension to compression.
基金Project supported by the National Natural Science Foundation of China (Nos. 10772104 and 10872045)the Innovation Project of Shanghai Municipal Education Commission (No. 09YZ12)the Shanghai Leading Academic Discipline Project (No. S30106)
文摘Mechanical properties, such as the deformation and stress distributions for venous walls under the combined load of transmural pressure and axial stretch, are examined within the framework of nonlinear elasticity with one kind of hyper-elastic strain energy functions. The negative pressure instability problem of the venous wall is explained through energy comparison. First, the deformation equation of the venous wall under the combined loads is obtained with a thin-walled circular cylindrical tube. The deformation curves and the stress distributions for the venous wall are given under the normal transmural pressure, and the regulations are discussed. Then, the deformation curves of the venous wall under the negative transmural pressure or the internal pressure less than the external pressure are given. Finally, the negative pressure instability problem is discussed through energy comparison.
基金Project supported by the National Natural Science Foundation of China (Nos. 10772104 and 10872045)the Innovation Project of Shanghai Municipal Education Commission (No. 09YZ12)the Shanghai Leading Academic Discipline Project (No. S30106)
