Numerical Analysis of Laser-controlled Thermal Stress Cutting of an Alumina Ceramic
J. Hu, Q-Q. Cao and J-W. Luo
This paper establishes a three-dimensional symmetrical finite element (FE) model of the distribution of the temperature field and the thermal stress field during the laser cutting of an alumina ceramic. The study achieved dynamic simulation of the crack speed, elaborated on the role of the cutting point thermal stress change and analysed the impact of processing parameters, such as laser power, ceramic thickness, cutting speed, on the maximum temperature and stress value on the surface of the alumina ceramic. It is found that normal stress on the laser cutting path undergoes a process of no stress → tensile stress → compressive stress → tensile stress → no stress during the cutting process until the crack grows. The maximum temperature was proportional to the laser power and approximately inverse to the cutting speed. The critical normal stress was found to increase with increasing laser power, a thinner workpiece or slower cutting speed; all of which made microcracks on the fracture surface more evident and thus the surface roughness increased. The FE analysis outcome was verified by experiments leading to a model that could be used to instruct optimization of the laser processing parameters.
Keywords: Laser cutting, finite element (FE) model, thermal stress cutting, temperature field, thermal stress, processing parameters, cutting quality