Study On Impact Damping Characteristics And Damage Mechanism Of Viscoelastic Materials

Viscoelastic materials have unique mechanical properties and are widely used in aerospace rocket,electronics and automobile industry,especially in construction machinery,often used as a shock absorber.The mechanical behavior of viscoelastic materials is very complex.The stress is not only non-linear with temperature,loading rate and strain,but also related to the deformation process.Therefore,it is necessary to analyze the mechanical behavior of materials under different working conditions.Accurate description of the mechanical behavior of materials is the key to design and optimize related products.In order to better promote and use viscoelastic materials in the field of impact,the following studies are carried out in this paper:(1)The dynamic mechanical properties of viscoelastic silicone rubber materials under different strain rates were tested by using separate Hopkinson pressure bar(SHPB)impact test device.The experimental results show that the silicone rubber material is sensitive to strain rate.With the increase of strain rate,the influence of strain rate on the mechanical behavior of silicone rubber is more and more significant,that is,at the same strain,the greater the strain rate,the greater the stress value.(2)In order to better describe the dynamic mechanical behavior of silicone rubber at high strain rates,the traditional ZWT model was modified based on the power function law and logarithmic law.The results show that the fitted curves of the modified ZWT-rate-dependent constitutive model are in good agreement with the experimental curves,and the R-square values of the fitted results are all above 0.95,which improves the application efficiency of the model and provides data for the following finite element analysis.(3)A numerical model was established for THE SHPB experiment.Combined with the modified ZWT-rate-dependent constitutive model,a numerical simulation study was carried out on silicone rubber materials.The experimental and simulation results were compared and analyzed by setting the influence of different bullet velocity control strain rates.The results show that the numerical model established is accurate and can reflect the dynamic process of silicone rubber sample under impact load,which lays a foundation for the damage analysis of silicone rubber sample.(4)On the basis of the established numerical model,the damage of the silicon rubber sample caused by the friction coefficient of the end face of the silicon rubber sample at different strain rates was studied,and the damage microscopic morphology of the silicon rubber sample was analyzed by electron microscopy.The results show that the stress at different positions on the end face of the silicon rubber sample is not uniform,that is,the deformation at the end face of the sample is not uniform.The area with serious stress is the damage line area,and a lot of residual stress is accumulated.The larger the strain rate is,the more obvious the damage line area is,and the larger the end friction coefficient is,the more obvious the damage line area is.In addition,the damage line area is at the edge of the sample,and the larger the strain rate and the friction coefficient of the end face are,the closer the damage line area is to the center of the sample.