基于 Johnson-Cook 模型的硅橡胶 高应变率力学特性

The sealing ring is subjected to high-speed impact load of gas in the ignition and pressurization of solid rocket motor, and its mechanical response is quite different from that of quasi-static state. Therefore, the uniaxial compression experiment of silicone rubber was carried out by using the split Hopkinson pressure bar (SHPB) device, and the compression experimental data in the strain rate range of 2 100~5 000 s⁻¹ were obtained. The two-parameter Mooney-Rivlin (M-R) hyperelastic model and ZhuWang-Tang (Z-W-T) high strain rate relaxation response term were used to modify the nonlinear equilibrium term and viscoelastic response term of the Johnson-Cook (JC) model, respectively. The visco-hyperelastic modified JC model of silicone rubber under high strain rate was established. The results show that the dynamic compressive mechanical properties of silicone rubber show obvious rate dependence and are much higher than quasi-static ones. At high strain rates, the initial elastic modulus and dynamic yield strength of silicone rubber increase with the increase of strain rate, the peak strain increases linearly with the strain rate, and the peak stress increases exponentially with the strain rate. The fitting results of the modified JC model are in good agreement with the experimental results. However, because the constitutive model does not consider the thermal softening effect, the prediction results of large deformation are higher than the experimental results at the strain rate of 6 000 s⁻¹.