脉冲激光烧蚀凹腔的实验分析及数值模拟

Experiment Study and Numerical Simulation of Pulsed Laser Ablation Crater

为分析脉冲个数对烧蚀凹腔形貌的影响,利用纳秒脉冲激光在灰铸铁表面加工微凹腔造型,分析了凹腔相貌与脉冲个数的关系。在低于10个脉冲的作用下,凹腔深度随脉冲数的增加近似呈线性增长,之后,凹腔深度随脉冲数增加的增长趋势逐渐变缓,凹腔直径随着脉冲个数的增加会有所增大,但增大幅度很小。当脉冲个数大于15以后,由于凹腔较深,熔融的金属难以喷溅出凹腔,导致加工质量较差。凹腔直径随着脉冲个数的增加会有所增大,但增大幅度很小。对加工过程的温度场进行数值模拟,得到了烧蚀过程中温度的变化曲线和凹腔相貌的变化规律。将模拟得到的凹腔深度与实验结果相比较,两者基本吻合,验证了模型的合理性。

In order to study the influence of the pulse number on the topography of ablation craters. Craters were processed on the surface of the cast iron by nanosecond pulse laser. The relationship between the depth of the crater and the number of the pulses was analyzed. The crater depth almost linearly increases when the pulse number is under 10. Then the depth growth rate becomes slower and slower. When the pulse count is above 15, the quality of the crater is poor, because of the crater is deeper, and the molten metal cannot splash out of the crater. The increase of crater diameter will be slower with the pulse number. In order to get the temperature distribution and the topography of craters, the temperature field of the ablation was simulated. The simulation results are consistent with the measurement results, which demonstrate the rationality of the model.