Numerical study of fractal analysis of crack propagation in concrete under different strain rates by meso-scale particle element modeling

In order to explore the influence of concrete multiple cracks development on dynamic improvement mechanism under higher strain rates, a method to quantitatively describe the relationship between stress and multiple cracks development in the procesds of higher strain rates is proposed. By meso-scale particle element modeling, SHPB stamping tests of concretes under different strain rates (30s-1 <= epsilon <= 140s-1) are simulated. The simulation results show that the stress-strain relationship and the law of dynamic strength improvement of concrete are consistent with the experimental results. The crack propagation in concrete under different strain rates is recorded and quantitatively described by the fractal box dimension. The crack propagation in concrete under different higher strain rates is divided into three stages, including micro crack initiation and stability stage, connectivity, extension and widening stage and fragmentation stage. This paper establishes and analyzes the relationships between stress, crack fractal dimension and strain rates under different strain rates. The research shows that at low strain rate the development of multiple cracks and failure of aggregates in concrete have a great impact on the dynamic improvement of concrete. As the strain rate increases, the inertia effect has a greater impact on the dynamic improvement of concrete.