Experiment and simulation on high-pressure equation of state for concrete

Abstract

To study the dynamic compression characteristics of concrete under high hydrostatic pressure and to determine the equation of state parameters of the HJC constitutive model, inverse flyer-impact tests and numerical simulation analysis were conducted with two kinds of concrete flyers of which the compressive strengths were 26.5 MPa and 42.1 MPa, respectively. The concrete flyers were launched by \begin{document}$\varnothing $\end{document} 58 mm gun against TU1 copper targets. The particle velocity histories of the TU1 copper target free surface were measured by DPS (Doppler probe system). Based on the one-dimensional strain shock wave theory, the impact pressure was calculated. The relationships of shock velocity vs. particle velocity and pressure vs. volume strain in the pressure range of 2−11 GPa were fitted. The results show that the relationship between shock velocity and particle velocity of concrete is linear. The relationships of shock velocity vs. particle velocity and pressure vs. volume strain for concretes with similar initial density and porosity but different compressive strengths are obviously different. Under the same pressure, the higher the compressive strength of concrete, the smaller the volume strain is. According to the test results, the equation of state parameters of the HJC constitutive model were determined and the plate-impact tests were simulated by LS-DYNA. The simulated particle velocity histories of the TU1 target free surface were in good agreement with the experimental results. The simulation results show that the phenomenon of chasing and unloading of shock waves in concrete only exists under low velocity impact conditions.