Fracture Evaluation and Dynamic Stress Concentration of Granite Specimens Containing Elliptic Cavity under Dynamic Loading

• Main Authors: Ming Tao, Ao Ma, Kang Peng, Yiqing Wang, Kun Du
• Format: Article
• Language: English
• Published: MDPI AG 2019-09-01
• Series: Energies
• Subjects: impact incidence; elliptic cavity; dynamic stress concentration; LS-DYNA
• Online Access: https://www.mdpi.com/1996-1073/12/18/3441

The Split-Hopkinson pressure bar (SHPB) was used to determine the fracture characteristics of a long bar rock specimen with an elliptical cavity under different axial ratios and dip angles. A high speed camera was applied to record the fracturing process of the granite specimen around the cavity. The experimental results showed that the fracture characteristics around the elliptical cavity were closely related to the axial ratio and dip angle. A three-dimensional numerical model was established using LS-DYNA to quantitatively analyze the dynamic stress state around the cavity. The numerical results indicate that the dip angle and axial ratio of the elliptical cavity significantly affected the dynamic stress concentration factor (DSCF), then affected the rock failure. The location of higher DSCF led to a higher possibility of spalling failure. The maximum DSCF remarkably decreased with a decreasing dip angle and increased the axial ratio. In the dynamic loading propagate process, the stress concentration distribution around the cavity formed by a compression stress wave had a certain damaging effect on the destruction of rock around the cavity, and the stress concentration generated by the tensile stress wave was the main factor of the rock fracture, which was most notable in the peak area of the stress concentration.