Numerical Simulation On SHPB Experiment For Rock

The development and present state of the study on the dynamic compression mechanics properties of rock by SHPB are reviewed and described in the paper. With the help of software ANSYS/LS-DYNA, the three dimensional numerical simulation of the feasibility of measure of rock dynamic properties by SHPB is presented. The finite element theory, the element selection, the hourglass control, the mesh divide, the contact control, and initial loading are discussed in detail. On this basis, numerical modeling for several key problems about the SHPB test on rocks are given as follows:1) Wave dispersion of different diameters input bar, different loading rates, and the different propagation distances in SHPB with rectangle and half-sine wave-loading are analyzed by using the 3D non-linear dynamic finite element code. The results show that the dispersion effect on the diameter of input bar, loading rate, and propagation distance is very small for half-sine waveform loading Compared with the rectangle wave loading. It is validated further that the half-sine wave should be a relatively perfect loading waveform in the test for rock-like materials.2) The stress uniformity process under rectangle and half-sine input wave loading were compared in SHPB tests and the time required for stress uniformity is calculated for the above different loadings. It is confirmed that the half-sine pulse loading method can realized the stress uniformity more easily than the rectangle pulse loading and has significant advantages in the dynamic test of rock-like materials.3) The effect of pulse amplitude and duration, SHPB diameter, specimens'aspect ratio on the average strain rate was analyzed under half-sine input waves loading.4) The stress-strain curves well fitted with the experimental results are obtained under the half-sine input wave loading by using the software. The mechanics properties are analysis under different loading conditions. The HOLMQUIST-JOHNSON-CONCRETE constitutive model is introduced to simulate the failure mechanism in this numerical, and failure and fragmentation characteristics of rock under different strain rates.5) It is demonstrated the axial pre-compression stress has no impact on the wave propagation in the bars and the stress equilibrium in early stage specimen, and it is also found that 1-D stress wave theory is valid for coupled static and dynamic loads on SHPB.