Experimental and numerical simulation study of fiber-reinforced high strength concrete at high strain rates

With the widespread use of fiber-reinforced high strength concrete (FRHSC) in military and civil fields, it is necessary to have an accurate understanding of the mechanical properties and failure modes of FRHSC under impact. The dynamic compression experiments were performed on FRHSC using the large-size split Hopkinson pressure bar (SHPB) apparatus. The experimental results were analyzed to determine the reasonable strain rate range of FRHSC under large-size SHPB loading conditions. The strain rate effect, critical strain, and failure mode of FRHSC under dynamic impact were studied. The strain rate and strength parameters in the Holmquist-Johnson-Cook (HJC) model were determined based on the experimental results, and the numerical simulation of SHPB was completed by LS-DYNA. The results revealed that the reasonable strain rate of FRHSC under large-size SHPB loading did not exceed 100 s⁻¹. The material presented an obvious strain rate effect, and the critical strain was almost unchanged with the increased strain rate. Steel fiber improves the toughness of FRHSC. Under quasi-static loading, the tensile-compression ratio of the material was 0.13, and there was no apparent damage under impact. The rationality of the strain rate and strength parameters in the HJC model was verified by comparing the stress wave curve of the pressure bar, the stress-strain curve, and the failure mode of the specimen obtained by experiment and simulation.