飞秒激光切割CFRP质量实验及模拟研究

为了探究飞秒激光切割碳纤维增强树脂基复合材料(CFRP)的主要影响因素,采用控制变量法探究了不同能量密度和光斑重叠率对热影响区宽度、表面粗糙度及切缝锥度的影响规律,基于双温方程,采用时间差分法模拟了飞秒激光与碳纤维相互作用时电子-晶格的温度场演变过程。实验结果显示:在脉冲频率不变条件下,提高激光功率可使切缝热影响区宽度增加,粗糙度及切缝锥度加大,切割质量下降;在固定激光功率并单一提升脉冲频率条件下,切割质量随脉冲频率增加而降低并趋于饱和。模拟结果显示:能量密度越大,电子和晶格的平衡温度越高,达到热平衡所用的时间越长,热效应越明显。分析指出光斑重叠率和脉冲能量密度是影响加工质量的两个重要因素,激光功率及脉冲频率的改变可改变脉冲能量密度和光斑重叠率,间接影响加工质量。

Experimental and Simulation Study on the Quality of Femtosecond Laser Cutting CFRP

In order to explore the main influencing factors of femtosecond laser cutting of carbon fiber reinforced resin matrix composites (CFRP), the influence of different energy densities and spot overlap rates on the width of the heat affected zone, surface roughness, and slit taper was investigated using the controlled variable method. Based on the dual temperature equation, the temperature field evolution process of the electron lattice during the interaction between femtosecond laser and carbon fiber was si-mulated using the time difference method. The experimental results show that under the condition of constant pulse frequency, increasing laser power can increase the width of the heat affected zone of the cutting seam, increase the roughness and taper of the cutting seam, and decrease the cutting quality; Under the condition of fixed laser power and a single increase in pulse frequency, the cutting quality decreases but tends to saturate as the pulse frequency increases. The simulation results show that the higher the energy density, the higher the equilibrium temperature of electrons and lattice, the longer it takes to reach thermal equilibrium, and the more obvious the thermal effect. The analysis points out that the overlap rate of light spots and the pulse energy density are two important factors affecting the processing quality. Variations in laser power and pulse frequency can change the pulse energy density and overlap rate of light spots, indirectly affecting the processing quality.