中文摘要：

依据传热学及有限元理论，采用高斯＋双椭球组合热源模型对铝合金穿孔等离子弧焊接温度场进行了数值模拟，并用APDL编程语言通过循环嵌套方式完成了焊接过程中正反极性期间不同形态的热源载荷的加载。计算出了5mm厚的铝合金在规定焊接参数条件下穿孔熔池的形成时间和合适的焊接速度。通过数值计算证实了等离子弧由于压缩效应，能量集中，焊接效率高的特点，为实际焊接过程中合理选择焊接参数提供了理论指导。

英文摘要：

Based on the heat transfer mechanism and the finite element theory, a combined heat source （ Gaussian planar heat source ＋ double - ellipsoidal heat source） has been used to calculate temperature fields in keyhole plasma arc welding of aluminum alloy. The loading of heat source with different features during EN/ EP stage is done by way of loop nesting and with use of ANSYS Parametric Design Language. Meanwhile, the formation time of keyhole is calculated. Time and appropriate speed of welding are calculated under conditions of set welding parameters, for aluminum alloy with the welding depth being 5mm. Through numerical calcula- tion, it is confirmed that plasma arc is characteristic of high efficiency of welding, energy concentration and compression effect, which provides valuable theoretical guidance in the selection of rational welding parame- ters.