SPH/FEM modeling for laser-assisted machining of fused silica

Abstract

Laser-assisted machining (LAM) is a promising technology for the machining of difficult-to-cut materials with reduced cutting forces, improved surface finishing, and enhanced tool life. Smoothed particle hydrodynamics (SPH) method is used to study the cutting mechanism during the laser-assisted machining of fused silica. In the present study, a 3-D transient thermal model is initially proposed to predict the temperature field distribution in the cutting zone of the fused silica. A Fortran subroutine is developed to simulate the moving laser with the Gaussian distribution. Both simulation and experiment results indicate that the thermal model produces an accurate prediction of the temperature in the workpiece. Then, temperature distributions are taken as the initial condition to establish the thermo-mechanical coupled cutting model. The dynamic cutting process is visualized in the cutting model. Moreover, discontinuous and continuous chips are found in both simulation and experiment. It implies that the cutting mechanism works under a hybrid mode of brittle fracture and plastic deformation in the LAM process. The variation of effective stress and plastic strain with temperature is analyzed in the cutting process. It is found that the application of the laser heating remarkably reduces fluctuations of the cutting force. Then, simulated cutting forces are evaluated experimentally. Comparisons show that simulated forces have excellent agreement with those from the experiment. It is concluded that localized high temperature originating from the laser significantly improves the machined surface quality.