Research on numerical simulation of coal dynamic RHT constitutive model

Using ANSYS/LS-DYNA finite element software, a rock RHT damage constitutive model is used to conduct numerical simulation experiments on the dynamic compression of coal SHPB under different strain rates for the Furong Baijiao coal in Yibin, Sichuan. Firstly, based on the determination method of RHT constitutive model parameters for relevant rocks and the RHT parameter values for Riedel concrete, the optimal parameters of the coal RHT dynamic compression constitutive model are determined through 3 levels of 27 sets of orthogonal experiments under different dynamic strain rates and sensitivity analysis of 13 uncertainty parameters. Secondly, based on the comparison and analysis of numerical simulation experiments and indoor experiments, it is found that the stress-strain curves obtained from the two types of experiments were in good agreement. The numerical simulation test results meet the two assumptions of one-dimensional stress and stress uniformity in SHPB compression test, and the numerical simulation test has a certain degree of reliability. Finally, the RHT damage constitutive model is used to explore the dynamic mechanical properties of coal energy evolution law during the asymptotic deformation and failure process: The research results indicate that the RHT damage constitutive model can better simulate the dynamic deformation and failure process of, and the corresponding mechanical properties and energy evolution process are consistent with the laboratory tests; The RHT model parameters of coal show an increasing trend with the increase of strain rate, and the sensitivity is greatly different. As the strain rate increases from 29.12 s⁻¹ to 95.69 s⁻¹, RHT parameters g_c^*、N、f_t^*、n and p_co are most sensitive to the final simulation effect of coal, while the parameters p_co、ξ、f_s^*、p_co and Q₀ are the least sensitive; With the increase of strain rate, the resistance to deformation of coal is obviously enhanced, the degree of fragmentation is more intense, and the peak compressive strength and dynamic strength factor DIF value increase exponentially; The dynamic energy evolution process of coal has obvious stages. Dynamic characteristic stress division based on the obvious stages of dynamic energy evolution process of coal. It is found that the corresponding characteristic energy increases first, then decreases, and then tends to be stable. The dynamic elastic energy storage capacity and limit energy storage capacity of coal should also be enhanced with the increase of strain rate.