Study on the Fracture Characteristics and Mechanisms of Iron Ore Under Dynamic Loading

The dynamic fracture process of iron ore under blast loading is an important manifestation of ore fragmentation. To investigate the dynamic fracturing process of iron ore, Hopkinson bar experiments were conducted under different impact loads. The results indicate that under low strain rates, the dynamic stress–strain curve of iron ore exhibits compaction, elastic, and failure stages. However, as the strain rate increases, the compaction stage becomes less distinct, while the elastic modulus decreases and the failure strength increases, indicating the material toughness was enhanced at high strain rate. Moreover, under high strain rates, a significant increase in shear strain promotes the formation of tensile–shear cracks in the ore. In addition, based on the fragmentation of iron ore at different impact pressure, there exists a certain impact pressure, at which the proportion of large fragments decreases only slightly, while the amount of small fragments increases markedly. These findings provide important insights for optimizing fragmentation and improving blasting effectiveness.