ISSUES OF SHPB TEST ON CONCRETE-LIKE MATERIAL

The split Hopkinson pressure bar test is the major method in studying the dynamic properties of concrete-like materials. Firstly, we briefly reviewed the progresses of some issues of the SHPB test of concrete-like materials, i.e. the end friction effect, the aggregate effect, the temperature effect and the inertia effect. Secondly, some mechanism analyses of the inertial effects were performed based on the detailed FE simulation of numerical SHPB tests. It was found that the lateral acceleration caused by the plastic flow of the material model determines the lateral inertia and the parabolic distribution of the confining pressure is caused by the wave propagation in the specimen. And based on the mechanism analysis of the inertial effect, we explained the size effect and actively confining pressure effect in the SHPB test well. Thirdly, in order to explore the dynamic properties of salt rock under confining pressure and temperature, a new SHPB instrument (TSCPT- SHPB) was designed. And the salt rock specimens with the confining pressure ranging from 5 to 25MPa and the condition of temperature ranging from 40℃ to 80℃ were tested on the TSCPT-SHPB. It was observed that the strain-rate effect is not obvious under a higher confining pressure condition. Finally, the effects of the mesoscopic components on the dynamic properties of concrete were discussed based on a 3-D mesoscale concrete model. The simulation results indicated that the dynamic strength of concrete increases with the static strength of the mesoscopic components and the volume fraction of aggregate, but decreases with aggregate size.