纳秒激光脉冲宽度对2024铝合金损伤特性的影响

Influence of Nanosecond Laser Pulse Width on Damage Characteristics of 2024 Aluminum Alloy

飞机激光除漆对2024铝合金蒙皮可能造成潜在的损伤,需探究激光参数变化对基体材料表面的作用规律,其中脉冲宽度对激光-材料作用与材料损伤特性具有重要影响。本文采用COMSOL Multiphysics软件模拟分析了不同脉冲宽度时激光作用铝合金表面的温升特性,并借鉴ISO 11254 1-on-1激光损伤阈值测试方法研究了脉冲宽度对铝合金损伤阈值的影响,进一步分析了不同脉冲宽度下的烧蚀凹坑微观形貌、直径与深度变化规律。结果表明:铝合金表面峰值温度随脉冲宽度增加而降低;脉冲宽度从150 ns增加到240和330 ns时,铝合金损伤阈值从9.96 J/cm^(2)分别增加到11.24和12.66 J/cm^(2),当激光能量密度达到损伤阈值时,3μm厚氧化膜被完全损伤,破坏了铝合金表面完整性;烧蚀凹坑直径和深度随脉冲宽度增加而增加,深度受影响程度更大。该研究可为激光与材料作用的脉冲宽度选择提供一定的参考。

Aircraft laser paint removal might cause potential damage to the 2024 aluminum alloy skin.It was necessary to explore the effect of laser parameter changes on the surface of the matrix material,in which the pulse width had an important impact on the laser-material interaction and material damage characteristics.In this paper,the temperature rise characteristics of the aluminum alloy surface exposed to laser with different pulse width were simulated and analyzed by COMSOL Multiphysics software,and the ISO 112541-on-1 laser damage threshold test method was used to reveal the influence of pulse width on aluminum alloy damage threshold.Furthermore,the micro-morphology,diameter and depth of ablation pits were further analyzed under different pulse widths.The results show that the peak temperature of aluminum alloy surface decreases with the increase of pulse width.When the pulse width increases from 150 ns to 240 and 330 ns,the damage threshold of aluminum alloy increases from 9.96 J/cm^(2) to 11.24 and 12.66 J/cm^(2),respectively.The laser energy density reaches the damage threshold,the 3μm thick oxide film is completely damaged,which destroys the surface integrity of the aluminum alloy.The diameter and depth of the ablation pits increase with the increase of the pulse width,and the depth is more affected.This research can provide a reference for the selection of pulse width for the interaction between laser and materials.