电子束焊接过程温度应力场三维有限元仿真

Three-dimensional calculation of temperature and stress field in Al-Li alloy during electron beam welding by finite element analysis

利用MSC.MARC有限元分析软件,在考虑电子束焊接匙孔效应基础上,采用双椭圆热模型,通过增大热传导系数、降低弹性模量和屈服强度的方法来模拟焊接过程中流体的流动效应,并采用自编子程序模拟了热源移动的过程,给出了铝锂合金电子束焊接过程中的温度应力场分布。计算结果表明:铝锂合金电子束焊接时,电子束热源对焊缝热冲击较大,焊缝附近处最高温度可达1300℃左右,三维方向上存在巨大温度梯度,成为热应力集中产生的根源。同时分析了焊缝不同位置处的等效应力演化过程,发现焊缝初始端应力剧烈振荡,处于复杂的三维应力状态,且自始至终高于焊缝的其他位置处的应力分布,成为接头区域薄弱环节。

In the paper, three-dimensional temperature and stress fields formed in electron beam welding Al-Li alloy were analyzed on the basis of considering the affects of keyhole. Adopting bielliptical thermal model, the fusion pool fluxion effect during the welding process was simulated by enlarging the conduction coefficient and lowering the elastic modulus and yield strength of the materials. The calculated results show that there exists obvious temperature gradient along the three-demission and the maximal temperature was up to 1 300 ℃ near the weld. The electron beam thermal source had a great heat impact on the weld then resulted in residual stress. The equivalent stress evolving process of different positions was also studied. The results indicated the stress was intensively vibrated at the begin of the weld in complex three-demission pattern and the value was higher than other locations during the whole welding procedure, which was then the weakness zone of the weld.