Modeling and Characteristic Analysis of Visco-Hyperelastic Film Based on Biaxial Tensile Experiment

Dielectric elastomers(DEs)show complex mechanical behaviors with different boundary conditions,geometry sizes,and prestress.In this study,a three-component linear visco-hyperelastic model of DE film is developed based on equibiaxial tension.By applying hereditary integrals to analyze multiple-segment loading processesof film stretching,the model parameters are extracted by fitting the visco-hyperelastic film model to the experimental data.To demonstrate the performance of proposed model,the obtained predictive results are compared with the experimental results under different equibiaxial loading conditions.The good agreement between them shows that the linear visco-hyperelastic model is a promising tool for analytically investigating the property of pre-stretched DE actuators.Finally,the Prony series coefficients are calculated according to the relaxation function.This is helpful for simulation analysis using commercial finite element software.

A Visco-hyperelastic Constitutive Model for Temperature-Dependent Cyclic Deformation of Dielectric Elastomer

Since dielectric elastomers(DEs)exhibit obvious nonlinear visco-hyperelasticity,and remarkable temperature dependence,it is difficult to accurately predict the cyclic deformation of DEs at various temperatures.To address this issue,an improved visco-hyperelastic constitutive model is proposed here to reproduce the complex temperature-dependent cyclic deformation of DEs.In the improved model,the Ogden model is chosen to provide the strain energy density representing the hyper-elastic response,a nonlinear viscosity evolution equation is used to depict the strong viscosity of DEs,and specific temperature-dependent parameters are incorporated to describe the cyclic deformation of DEs at various temperatures.Finally,the prediction capability of the proposed visco-hyperelastic model is validated by reproducing the cyclic deformation of VHB 4910 DE observed in experiments at different temperatures.This study provides a theoretical basis for the rational design of DE devices.

A Visco-hyperelastic Constitutive Model for Rubber Considering the Strain Level and One Case Study in the Sealing Packer

The rubber cylinder is a key component for maintaining the sealing pressure of the packer,particularly in deep underground wells.The stress relaxation of materials,as a typical feature of viscoelasticity,has become one of the main factors causing the failure of rubber cylinders in service.In the present study,a visco-hyperelastic model for the sealing rubber considering different strain levels is proposed based on the Prony series.Subsequently,the uniaxial compression stress relaxation experiments are conducted on the sealing rubber under different temperatures and strain levels,and the model parameters are thereby identified.As a case study,the proposed model is incorporated into the ABAQUS software via the UM AT subroutine,and the finite element simulation of the sealing packer is carried out.The results show that the sealing performance of the packer improves with a decrease in temperature or an increase in strain level.It is also noted that a large strain level can lead to the protrusion of the shoulder of the rubber cylinder.

Dynamic mechanical behavior and nonlinear hyper-viscoelastic constitutive model of SiO_(2) particle-reinforced silicone rubber composite:experimental and numerical investigation

SiO_(2)-particle reinforced silicon rubber composite(SP-RSRC)is a widely utilized material that offers shock absorption protection to various engineering structures in impact environments.This paper presents a comprehensive investigation of the mechanical behavior of SP-RSRC under various strain rates,employing a combination of experimental,theoretical,and numerical analyses.Firstly,quasi-static and dynamic compression tests were performed on SP-RSRC utilizing a universal testing machine and split Hopkinson pressure bar(SHPB)apparatus.Nonlinear stress-strain relationships of SP-RSRC were obtained for strain rates ranging from 1×10^(−3) to 3065 s^(−1).The results indicated that the composite showed evident strain rate sensitivity,along with nonlinearity.Then,a nonlinear visco-hyperelastic constitutive model was developed,consisting of a hyperelastic component utilizing the 3rd-order Ogden energy function and a viscous component employing a rate-dependent relaxation time scheme.The model accurately characterized the dynamic mechanical response of SP-RSRC,effectively mitigating the challenge of calibrating an excessive number of material parameters inherent in conventional viscoelastic models.Furthermore,the simplified rubber material(SRM)model,integrated within the LS-DYNA software,was chosen to depict the mechanical properties of SP-RSRC in numerical simulations.The parameters of the SRM model were further calibrated based on the strain-stress relationships of SP-RSRC,as predicted by the developed nonlinear visco-hyperelastic constitutive model.Finally,an inverse ballistic experiment using a single-stage air gun was conducted for SP-RSRC.Numerical simulations of SHPB experiments and the inverse ballistic experiment were then performed,and the reliability of the calibrated SRM model was verified by comparing the results of experiments and numerical simulations.This study offers a valuable reference for the utilization of SP-RSRC in the realm of impact protection.