Electro-elasticity And Stability Analysis Of Soft Dielectrics

Various animal and plant structures in nature are usually soft materials,such as natural rubber,liquid crystals,hydrogels,and biological skins.Compared with traditional hard materials(such as metals,ceramics,etc.),soft materials have the advantages of large deformation,low noise,light weight and low price.Dielectric elastomer is a typical soft electroactive polymer material.Because of its light weight,low price,high elastic energy density,and strong electromechanical conversion efficiency,it is widely used in robots,actuator,energy harvester,sensing devices and other smart device applications.Dielectric elastomers are often accompanied by instability under the action of mechanical and electrical coupling,leading to material failure and structural instability,which greatly affects the normal operation of the material and its application devices.Therefore,it is urgent to study the mechano-electric coupling theory and stability analysis of dielectric elastomers,which has important engineering application value and academic significance.This paper takes soft dielectric materials as the research object to discuss the mechanical behavior of dielectric elastomers under the coupling of force and electricity.The specific research contents include:First of all,dielectric elastomer materials have the characteristics of low elastic modulus and fast electrical response.Under the action of force-electric coupling,they can produce large deformation and are often accompanied by the occurrence of multiple failure modes.This makes the application of dielectric elastomer materials Has been greatly restricted.Previous studies have shown that harder dielectric materials can withstand higher force and charge load,but have less deformation;while softer dielectric materials have greater deformation,but can only carry lower voltages.In this paper,gradient dielectric elastomer materials are used to study the large deformation and electrical traction instability of circular gradient soft dielectric films.The study found that only by changing the modulus of the outer edge of the film,the mechanical-electric coupling behavior can be achieved with the same effect as the homogeneous soft dielectric film,that is,the gradient soft dielectric film has the ability to resist high electric fields and large driving.Furthermore,in order to regulate the electric drive deformation and energy capture ability of dielectric elastomers,seek general evaluation methods and quantitative optimization principles for the application of multifunctional devices,and improve the performance of dielectric elastomer electric drives and high energy capture devices.Performance,research on the electrical drive and energy capture of functionally graded dielectric elastomers.The study revealed that the material inhomogeneity has a significant impact on the nonlinear behavior of dielectric elastomer materials,and provides a new optimal design scheme for the existing actuators and energy traps.Finally,through the study of the mechanical-electrical coupling nonlinear behavior and stability of the soft dielectric material,a new bifurcation phenomenon of the dielectric elastomer film is found,and the linear analysis of the asymmetric deformation of the dielectric elastomer under symmetric loading is established.Bifurcation theory and stability criteria,master the law of mechanical and electrical coupling in the process of large deformation and instability,further optimize and design the nonlinear mechanical behavior of soft dielectric devices,realize the drive with large driving strain,and help promote the nonlinearity.The large deformation and stability theory of field coupling is applied to the drive design of soft dielectric devices.In short,the topic of this thesis is based on the research background of soft material multifunctional devices,Stability analysis is introduced under the framework of the continuum theory of mechanical and electrical coupling,and a nonlinear theory of mechanical and electrical coupling that simultaneously considers large deformation and stability is proposed.The force-electric coupling theory model of gradient dielectric film,and taking gradient Neo-Hookean dielectric film as an example,its large deformation and stability are studied;the failure mode and energy capture area of gradient dielectric film are discussed,and its force is studied.The electrical coupling response provides a theoretical basis for the performance improvement of the electrical drive and energy capture of the functionally graded dielectric elastomer;further improve the existing force-electric coupling theory,bifurcation theory and stability theory,and realize the cross integration of the three.It provides a more complete theoretical basis for the application of soft dielectric material functional devices in more practical problems,and has important theoretical guiding significance and engineering application value.