The numerical simulation of large diameter split Hopkinson pressure bar and Hopkinson bundle bar of concrete based on mesoscopic model

Abstract

In the comparison of Hopkinson bundle bar (HBB) system and the large diameter split Hopkinson pressure bar (SHPB) system, the influence of bar diameter on the dispersion effect of the one-dimensional longitudinal wave is analyzed theoretically firstly. Three trapezoidal loads with different peak values are applied to the elastic bars with two types of sections to investigate the stress wave propagation. Then, based on the fractal characteristics of concrete aggregate, the 3D realistic mesoscopic model is constructed as numerical models. And the dynamic responses of concrete under two kinds of test systems have been compared and analyzed. The results show that, the HBB system can more effectively reduce the lateral dispersion in the stress wave propagation and is beneficial to maintain the waveform than the large diameter SHPB system. The large diameter SHPB simulated results based on the 3D realistic mesoscopic model are consistent with the experimental results, which verify the feasibility of the mesoscopic model. The HBB system can obtain the similar simulated results as the large diameter SHPB system, such as the similar waveform with the double peak phenomenon of the reflection wave. However, there is a significant difference in the failure pattern of the specimens under two test systems, which is caused by the boundary effect of the hexahedron specimen in the HBB system. In conclusion, the HBB system can also carry out the dynamic mechanical properties of concrete-like materials. Moreover, HBB system can obtain more detailed information, reflecting the difference of local mechanical properties of concrete. Although there are still some deficiencies, it can still provide additional ideas for related researchers.