Determination of energy coupling to material in laser welding by a novel “sandwich” method

来源期刊:中国有色金属学报(英文版)2012年第7期

论文作者:张屹 史如坤 李力钧

文章页码:1701 - 1710

关键词:激光焊接;能量耦合模型;“三明治”方法;小孔

Key words:laser welding; mathematical energy coupling model; “sandwich” method; keyhole

摘    要:建立激光与能量耦合模型以研究激光在小孔内的传输和孔壁能量的分布。该模型的主要特点包括:1)小孔和孔内等离子体的逆韧致吸收系数均为实验测量所得;2) 入射激光为高斯分布的聚焦光束而非平行光束;3) 同时考虑了激光光束在孔内多次反射的菲涅尔吸收和逆韧致吸收。计算结果表明:孔壁所吸收的激光能量并不一致;尽管激光未能直接照射孔底,但是小孔孔底所吸收的激光能量最多。基于聚焦光束的特征分析,焦平面的位置对小孔前沿所吸收的激光能量较后沿更重要。

Abstract: A mathematical energy coupling model was developed to analyze the light transmission in the keyhole and energy distribution on the keyhole wall. The main characteristics of the model include: 1) a prototype of the keyhole and the inverse Bremsstrahlung absorption coefficient in the keyhole plasma are obtained from the experiments; 2) instead of using a parallel incident beam, a focused laser beam with real Gaussian intensity distribution is implemented; 3) both Fresnel absorption and inverse Bremsstrahlung absorption during multiple reflections are considered. The calculation results show that the distribution of absorbed laser intensity by the keyhole wall is not uniform. The maximum laser energy is absorbed by the bottom of the keyhole, although no rays irradiate directly onto the bottom. According to analysis of beam focusing characteristics, the location of the focal plane plays a more important role in the laser energy absorption by the front wall than by the rear wall.

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