Under an applied voltage, dielectric elastomers （DEs） produce an actuation strain that is nonlinear, partly because of the material properties. In this study, an experimental characterization is conducted to evaluat...Under an applied voltage, dielectric elastomers （DEs） produce an actuation strain that is nonlinear, partly because of the material properties. In this study, an experimental characterization is conducted to evaluate how the ambient temperature and pre-stretch affected the actuation performance. For DEs with a pre-stretch of 2 × 2, an increase of temperature from -10° to 80° results in a variation in the actuation strain of more than 1700%. Low pre-stretched DEs are more susceptible to temperature change; while highly pre-stretched DEs are relatively insensitive to temperature, because in this case the energy conversion was dominated by mechanical stretching, rather than thermal conduction, during the actuation.展开更多
We propose a multi-field implicit finite element method for analyzing the electromechanical behavior of dielectric elastomers. This method is based on a four-field variational principle, which includes displacement an...We propose a multi-field implicit finite element method for analyzing the electromechanical behavior of dielectric elastomers. This method is based on a four-field variational principle, which includes displacement and electric potential for the electromechanical coupling analysis, and additional independent fields to address the incompressible constraint of the hyperelastic material. Linearization of the variational form and finite element discretization are adopted for the numerical implementation. A general FEM program framework is devel- oped using C＋＋ based on the open-source finite element library deal.II to implement this proposed algorithm. Numerical examples demonstrate the accuracy, convergence properties, mesh-independence properties, and scalability of this method. We also use the method for eigenvalue analysis of a dielectric elastomer actuator subject to electromechanical loadings. Our finite element implementation is available as an online supplementary material.展开更多
The electromechanical phase transition for a dielectric elastomer （DE） tube has been demonstrated in recent experiments, where it is found that the unbulged phase gradually changed into bulged phase. Previous theore...The electromechanical phase transition for a dielectric elastomer （DE） tube has been demonstrated in recent experiments, where it is found that the unbulged phase gradually changed into bulged phase. Previous theoretical works only studied the transition process under pressure control condition, which is not consistent with the real experimental condition. This paper focuses on more complex features of the electromechanical phase transition under internal pressure of constant mass. We derive the equilibrium equations and the condition for coexistent states for a DE tube under an internal pressure, a voltage through the thickness and an axial force. We find that under mass control condition the voltage needed to maintain the phase transition increases as the process proceeds. We analyze the entire process of electromechanical phase transition and find that the evolution of configurations is also different from that for pressure control condition.展开更多
The considerable electric-induced shape change,together with the attributes of lightweight,high efficiency,and inexpensive cost,makes dielectric elastomer,a promising soft active material for the realization of actuat...The considerable electric-induced shape change,together with the attributes of lightweight,high efficiency,and inexpensive cost,makes dielectric elastomer,a promising soft active material for the realization of actuators in broad applications.Although,a number of prototype devices have been demonstrated in the past few years,the further development of this technology necessitates adequate analytical and numerical tools.Especially,previous the-oretical studies always neglect the influence of surrounding med-ium.Due to the large deformation and nonlinear equations of states involved in dielectric elastomer,finite element method(FEM)is anticipated;however,the few available formulations employ homemade codes,which are inconvenient to implement.The aim of this work is to present a numerical approach with the commercial FEM package COMSOL to investigate the nonlinear response of dielectric elastomer under electric stimulation.The influence of surrounding free space on the electric field is analyzed and the corresponding electric force is taken into account through an electric surface traction on the circumstances edge.By employ-ing Maxwell stress tensor as actuation pressure,the mechanical and electric governing equations for dielectric elastomer are coupled,and then solved simultaneously with the Gent model of stain energy to derive the electric induced large deformation as well as the electromechanical instability.The finite element imple-mentation presented here may provide a powerful computational tool to help design and optimize the engineering applications of dielectric elastomer.展开更多
The performance of dielectric elastomer （DE） transducers is significantly affected by viscoelastic relaxation-induced electromechanical dissipations. This paper presents an experi- mental study to obtain the rate de...The performance of dielectric elastomer （DE） transducers is significantly affected by viscoelastic relaxation-induced electromechanical dissipations. This paper presents an experi- mental study to obtain the rate dependent stress-stretch relation of DE membranes （VHBTM9473） subjected to pure shear like loading and electric loading simultaneously. Stretching rate depen- dent behavior is observed. The results also show that the tensile force decreases as the voltage increases. The observations are compared with predictions by a viscoelastic model of DE. This experiment may be used for further studies of dynamic electromechanical coupling properties of DEs.展开更多
We present a finite element method for dielectric elastomer （DE） transducers based on the nonlinear field theory of DE. The method is implemented in the commercial finite element software ABAQUS, which provides a la...We present a finite element method for dielectric elastomer （DE） transducers based on the nonlinear field theory of DE. The method is implemented in the commercial finite element software ABAQUS, which provides a large library functions to describe finite elasticity. This method can be used to solve electromechanical coupling problems of DE transducers with complex configurations and under inhomogeneous deformation.展开更多
为探究介电弹性体发电机在等双轴预拉伸和锥形拉伸相结合下的发电特性,采用Neo-Hookean模型建立了介电弹性体在等双轴预拉伸和锥形拉伸情况下的机电不稳定性模型.运用Matlab/Simulink建立了介电弹性体发电机在此混合拉伸下的机电耦合模...为探究介电弹性体发电机在等双轴预拉伸和锥形拉伸相结合下的发电特性,采用Neo-Hookean模型建立了介电弹性体在等双轴预拉伸和锥形拉伸情况下的机电不稳定性模型.运用Matlab/Simulink建立了介电弹性体发电机在此混合拉伸下的机电耦合模型,对介电弹性体发电机在不同预拉伸、输入偏置电压和锥形拉伸位移下的能量收集性能进行研究.实验及仿真结果表明:该混合拉伸模式不仅可以有效地改善机电不稳定性的影响,还可以提升介电弹性体发电机的能量收集性能.在预拉伸比为4、施加电压为2.5 k V、锥形拉伸位移为60 mm时,介电弹性体发电机产生的能量为114.49 m J,是相同条件下预拉伸比为2时的4倍.展开更多
Experimental analysis of ferroelectric composites with a viscoelastic and dieiectric relax-ation matrix is carried out, and the electromechanical coupling behavior of the ferroelectric composites is calculated by mean...Experimental analysis of ferroelectric composites with a viscoelastic and dieiectric relax-ation matrix is carried out, and the electromechanical coupling behavior of the ferroelectric composites is calculated by means of the constitutive model proposed in this paper. Comparisons between the ex-perimental results and the calculations show that the constitutive model can reflect the electromechanical coupling behavior of the ferroelectric composites. The analysis indicates that the effect of viscoelas-ticity and dieiectric relaxation of the matrix on the electromechanical coupling behavior of ferroelectric composites cannot be neglected.展开更多
基金supported by the Major Program of National Natural Science Foundation of China(51290294)the Doctoral Fund of Ministry of Education of China(20120201110030)
文摘Under an applied voltage, dielectric elastomers （DEs） produce an actuation strain that is nonlinear, partly because of the material properties. In this study, an experimental characterization is conducted to evaluate how the ambient temperature and pre-stretch affected the actuation performance. For DEs with a pre-stretch of 2 × 2, an increase of temperature from -10° to 80° results in a variation in the actuation strain of more than 1700%. Low pre-stretched DEs are more susceptible to temperature change; while highly pre-stretched DEs are relatively insensitive to temperature, because in this case the energy conversion was dominated by mechanical stretching, rather than thermal conduction, during the actuation.
基金the support under A*STAR SERC grant (132-183-0025)
文摘We propose a multi-field implicit finite element method for analyzing the electromechanical behavior of dielectric elastomers. This method is based on a four-field variational principle, which includes displacement and electric potential for the electromechanical coupling analysis, and additional independent fields to address the incompressible constraint of the hyperelastic material. Linearization of the variational form and finite element discretization are adopted for the numerical implementation. A general FEM program framework is devel- oped using C＋＋ based on the open-source finite element library deal.II to implement this proposed algorithm. Numerical examples demonstrate the accuracy, convergence properties, mesh-independence properties, and scalability of this method. We also use the method for eigenvalue analysis of a dielectric elastomer actuator subject to electromechanical loadings. Our finite element implementation is available as an online supplementary material.
基金supported by the National Natural Science Foundation of China(11402185)
文摘The electromechanical phase transition for a dielectric elastomer （DE） tube has been demonstrated in recent experiments, where it is found that the unbulged phase gradually changed into bulged phase. Previous theoretical works only studied the transition process under pressure control condition, which is not consistent with the real experimental condition. This paper focuses on more complex features of the electromechanical phase transition under internal pressure of constant mass. We derive the equilibrium equations and the condition for coexistent states for a DE tube under an internal pressure, a voltage through the thickness and an axial force. We find that under mass control condition the voltage needed to maintain the phase transition increases as the process proceeds. We analyze the entire process of electromechanical phase transition and find that the evolution of configurations is also different from that for pressure control condition.
基金This work was supported by NSFC under Grant(11321062 and 11402186,11402185)China Postdoctoral Science Foundation under Grant(2015M572548).
文摘The considerable electric-induced shape change,together with the attributes of lightweight,high efficiency,and inexpensive cost,makes dielectric elastomer,a promising soft active material for the realization of actuators in broad applications.Although,a number of prototype devices have been demonstrated in the past few years,the further development of this technology necessitates adequate analytical and numerical tools.Especially,previous the-oretical studies always neglect the influence of surrounding med-ium.Due to the large deformation and nonlinear equations of states involved in dielectric elastomer,finite element method(FEM)is anticipated;however,the few available formulations employ homemade codes,which are inconvenient to implement.The aim of this work is to present a numerical approach with the commercial FEM package COMSOL to investigate the nonlinear response of dielectric elastomer under electric stimulation.The influence of surrounding free space on the electric field is analyzed and the corresponding electric force is taken into account through an electric surface traction on the circumstances edge.By employ-ing Maxwell stress tensor as actuation pressure,the mechanical and electric governing equations for dielectric elastomer are coupled,and then solved simultaneously with the Gent model of stain energy to derive the electric induced large deformation as well as the electromechanical instability.The finite element imple-mentation presented here may provide a powerful computational tool to help design and optimize the engineering applications of dielectric elastomer.
基金supported by the National Natural Science Foundation of China (No. 10832009)the Program for New Century Excellent Talents in University (NCET-08-0480)+1 种基金Zhejiang Provincial Natural Science Foundation of China (No. Z1110057)the Fundamental Research Funds for the Central Universities
文摘The performance of dielectric elastomer （DE） transducers is significantly affected by viscoelastic relaxation-induced electromechanical dissipations. This paper presents an experi- mental study to obtain the rate dependent stress-stretch relation of DE membranes （VHBTM9473） subjected to pure shear like loading and electric loading simultaneously. Stretching rate depen- dent behavior is observed. The results also show that the tensile force decreases as the voltage increases. The observations are compared with predictions by a viscoelastic model of DE. This experiment may be used for further studies of dynamic electromechanical coupling properties of DEs.
基金supported by the National Natural Science Foundation of China (No. 10832009)the Program for New Century Excellent Talents in University (NCET-08-0480)+1 种基金the Fundamental Research Funds for the Central Universities,and MRSEC at Harvard Universitysupport by the China Scholarship Council Foundation and Harvard University through the sponsoring of a nine-month visit at Harvard University
文摘We present a finite element method for dielectric elastomer （DE） transducers based on the nonlinear field theory of DE. The method is implemented in the commercial finite element software ABAQUS, which provides a large library functions to describe finite elasticity. This method can be used to solve electromechanical coupling problems of DE transducers with complex configurations and under inhomogeneous deformation.
文摘为探究介电弹性体发电机在等双轴预拉伸和锥形拉伸相结合下的发电特性,采用Neo-Hookean模型建立了介电弹性体在等双轴预拉伸和锥形拉伸情况下的机电不稳定性模型.运用Matlab/Simulink建立了介电弹性体发电机在此混合拉伸下的机电耦合模型,对介电弹性体发电机在不同预拉伸、输入偏置电压和锥形拉伸位移下的能量收集性能进行研究.实验及仿真结果表明:该混合拉伸模式不仅可以有效地改善机电不稳定性的影响,还可以提升介电弹性体发电机的能量收集性能.在预拉伸比为4、施加电压为2.5 k V、锥形拉伸位移为60 mm时,介电弹性体发电机产生的能量为114.49 m J,是相同条件下预拉伸比为2时的4倍.
文摘Experimental analysis of ferroelectric composites with a viscoelastic and dieiectric relax-ation matrix is carried out, and the electromechanical coupling behavior of the ferroelectric composites is calculated by means of the constitutive model proposed in this paper. Comparisons between the ex-perimental results and the calculations show that the constitutive model can reflect the electromechanical coupling behavior of the ferroelectric composites. The analysis indicates that the effect of viscoelas-ticity and dieiectric relaxation of the matrix on the electromechanical coupling behavior of ferroelectric composites cannot be neglected.
基金supported by the National Natural Science Foundation of China(No.11321202)the Zhejiang Provincial Natural Science Foundation of China(No.LR16A020001)
