Direct dynamic tensile study of concrete materials based on mesoscale model

5 Dynamic tensile tests of concrete materials at high strain rates are primarily splitting experiments and spalling experiments at present, however, certain limitations exist in these methods to indirectly study dynamic tensile mechanical behaviour of concrete materials. Thus it is necessary to perform direct dynamic tensile study of concrete materials with a large-diameter split Hopkinson tensile bar (SHTB). Concrete is considered as a two-phase composite material which composed of coarse aggregates and cement matrix in this paper, then cylindrical and dumbbell-shaped three-dimensional mesoscale concrete models are established and applied to SHTB simulation research. Three contact modes between concrete specimen and member bars are discussed based on existing experiments and our numerical simulation analysis. The results show that established finite element models can effectively simulate SHTB tests and mesoscale concrete models also reflect proper tensile behaviour at high strain rates, which also provides convenience to mesoscopic numerical simulation research of many other heterogeneous materials. At last, a proper contact mode is chosen to perform mesomechanics analysis of concrete materials subjected to four types of tensile impact wave, then five mesoscale concrete models with different aggregates content are established and corresponding numerical simulation analysis are conducted.