Fracturing characteristics and waveform effect of anthracite under equal‒energy high‒speed impact based on a controlled waveform SHPB platform: laboratory and numerical analysis

This study investigates the dynamic behavior and failure characteristics of anthracite under three various shapes but equal‒energy stress waveforms excited by a controlled waveform split Hopkinson pressure bar (SHPB) system. Uniaxial dynamic compression tests with various waveforms are conducted at three impact pressures ranging from 0.2 to 0.4 MPa to further distinguish how various waveforms affect the dynamic fracturing of anthracite. The morphological and mechanical properties of anthracite residuals are analyzed and the above waveforms are accurately reproduced via the finite discrete element method (FDEM). The key findings include the following: (1) There are significant differences in the dynamic failure of anthracite under different equal‒energy waveforms. Waveform A causes the most severe fragmentation, waveform C the least, and waveform B is intermediate. (2) The energy concentration ( C e ) is positively correlated with the average fractal dimension ( D̄ ), consistent across all equal‒energy waveforms under identical impact energies. (3) The dynamic secant modulus and peak strength of anthracite increase under equal‒energy waveforms with increasing energy concentration toward the wavefront, demonstrating that the time‒domain impact energy distribution significantly influences the dynamic bearing and failure properties of anthracite materials. (4) The waveform with a high strain rate in the early stage significantly crushes the anthracite and results in a higher energy dissipation density, indicating that the energy consumption efficiency of fragmentation is greater in the early stage of the impact process. This study elucidates a pronounced waveform effect in the dynamic failure of anthracite, offering theoretical insights for understanding the dynamic failure under complex stress waveforms.