Stress Evolution in Linear Cutting Tests: Laboratory and Numerical Methods
Jie Liu; Zhaofeng Liu; Gangyuan Jiang
Small-scaled linear cutting tests were first performed to study the influence of penetration on fracture characteristics by a CCS (constant cross-section) cutter. The results indicate that the increase in penetration (ranging from 2.5 mm to 5.5 mm) effectively increases chip masses between cuts and further promotes cutting efficiency. To further understand the fracture mechanism for various penetrations, 3D numerical simulations were performed using PFC 3D. The numerical fracture characteristics agree well with laboratory tests. In addition, the dynamic stress evolution analysis clearly shows that the increase in rolling force frequently results in stress concentrations in rock specimens. When stresses concentrate into critical values, fractures occur. Subsequently, these fracture propagations frequently result in stress dissipations and decreases in rolling force. Thus, the relation between the fluctuations of rolling force and the rock fractures is revealed. In addition, the increase in penetration results in the promoted stress concentrations. This phenomenon can explain why the increased penetration can result in severer fractures.
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