Effect of point heat source on growth of subsurface crack induced in brittle material machining

Based on the indentation fracture mechanics, a thermal-assisted grinding model is established to investigate the effect of heat source on subsurface crack propagation. Combining the complex function method with the continuous distribution technique of dislocations, the stress intensity factors (SIFs) near the crack tip under various thermal and mechanical loads are calculated numerically. Results show that whether the median crack propagation is inhibited or promoted by the heat source mainly depends on the relative positions between thermal loading and mechanical loading. The stronger heat source in front of the abrasive grain can inhibit the growth of subsurface crack. When the heat source is located behind the abrasive grain, a minimum value of SIF can be obtained if the grinding parameters are well controlled. Especially, with the increase in heat source intensity, the maximum and minimum SIFs occur when the heat source is located at 1.5 times the distance of half crack length behind and in front of the abrasive grain, respectively.