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<p>This study investigates the dynamic mechanical behavior, fracture mechanisms, and fragmentation characteristics of magnetite iron ore specimens containing non-persistent edge notches under high strain-loading rate. Dynamic tests carried out with the Split Hopkinson Pressure Bar (SHPB) to analyze the effects of notch geometry (length and inclination angle) and moisture conditions (dry and water-saturated frozen). The effects were further investigated through high-speed imaging, scanning electron microscopy (SEM), and fractal analysis to characterize crack initiation, propagation, and fragmentation patterns. Notch angle and notch length were varied during the test. loading rate was 772&#xa0;s<sup>−1</sup>. Results reveal that ice presence in the notches acts as a temporary stiffener, increasing initial stiffness and delaying crack initiation, thereby enhancing dynamic strength and elastic modulus in saturated frozen specimens. Notch angle significantly affects mechanical response, with minimum strength and stiffness at 30° due to maximum stress concentration, and peak values at 90° where the notch aligns with the loading direction. Increasing notch length reduces strength and stiffness by facilitating crack propagation. Two fracture modes, tensile (smooth surfaces) and shear (rough, pulverized surfaces), were identified via SEM and imaging, supporting mechanical findings. Fragmentation intensity increases with fractal dimension and energy dissipation, both influenced by notch geometry and moisture state. These findings provide valuable guidance that can help to refine blasting design, improve comminution efficiency, and model rock mass behavior in both dry and cold-region mining.</p>

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Dynamic fracture and fragmentation of edge-notched iron ore specimens under high strain rate loading

  • 期刊论文

  • 发表日期：

    2026年4月7日

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  • Shadman Mohammadi Bolbanabad,
  • Masoud Monjezi,
  • Vahab Sarfarazi

摘要

This study investigates the dynamic mechanical behavior, fracture mechanisms, and fragmentation characteristics of magnetite iron ore specimens containing non-persistent edge notches under high strain-loading rate. Dynamic tests carried out with the Split Hopkinson Pressure Bar (SHPB) to analyze the effects of notch geometry (length and inclination angle) and moisture conditions (dry and water-saturated frozen). The effects were further investigated through high-speed imaging, scanning electron microscopy (SEM), and fractal analysis to characterize crack initiation, propagation, and fragmentation patterns. Notch angle and notch length were varied during the test. loading rate was 772 s−1. Results reveal that ice presence in the notches acts as a temporary stiffener, increasing initial stiffness and delaying crack initiation, thereby enhancing dynamic strength and elastic modulus in saturated frozen specimens. Notch angle significantly affects mechanical response, with minimum strength and stiffness at 30° due to maximum stress concentration, and peak values at 90° where the notch aligns with the loading direction. Increasing notch length reduces strength and stiffness by facilitating crack propagation. Two fracture modes, tensile (smooth surfaces) and shear (rough, pulverized surfaces), were identified via SEM and imaging, supporting mechanical findings. Fragmentation intensity increases with fractal dimension and energy dissipation, both influenced by notch geometry and moisture state. These findings provide valuable guidance that can help to refine blasting design, improve comminution efficiency, and model rock mass behavior in both dry and cold-region mining.