Based on the fracture behavior during laser irradiating brittle materials, a controlling fracture technique was used for cutting brittle materials. In order to investigate the mechanism of fracture behavior during pulsed laser irradiating single silicon, a three-dimensional finite element thermoelastic calculational model which contains a pre-existing crack was established based on the heat transfer theory. The development of the temperature field and thermal stress field were investigated during the pulse duration and the changes of stress intensity factor around a crack tip were analyzed. The simulation results show that there are two tensile stress zones induced by the laser heating zone. When the laser spot is near the edge of the silicon wafer, the larger tensile stress is induced at the edge of the silicon wafer, and when the pulsed laser scans the silicon wafer, the pre-existing crack can induce the fracture to propagate along the moving direction of the laser beam. Obtained results are well coincident with the crack expanding process reported by the literature.%基于脆性材料在激光辐照下的断裂行为,将可控断裂激光切割技术应用于脆性材料的加工.为了分析脉冲激光辐照脆性材料过程及脉冲激光扫描过程中产生的断裂行为机理,采用数值计算方法建立了含有裂纹的三维有限元热弹计算模型.分析了脉冲激光辐照单晶硅片过程中温度场和热应力场的变化情况,并模拟计算了硅片边缘含有裂纹时裂纹尖端应力强度因子的变化.计算结果表明,在激光加热区域前后位置存在两个拉应力区,且激光加热区域靠近硅片边缘位置时,硅片边缘会产生较大拉应力;脉冲激光扫描硅片过程中,裂纹尖端的应力集中现象诱发材料持续开裂并引导裂纹沿激光扫描方向扩展.得到的结果与文献报道的裂纹扩展过程相符.
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