AZ31B镁合金双弧焊接熔滴行为的FLUENT模拟

发布时间：2018-03-06 22:23

本文选题：AZ31B镁合金　切入点：双弧焊　出处：《南昌大学》2017年硕士论文　论文类型：学位论文

【摘要】：本文根据AZ31B镁合金的特性和物性参数,结合熔滴过渡理论和自由表面跟踪算法VOF法,并利用ANSYS Workbench集成下的FLUENT软件,结合UDF函数开展AZ31B镁合金双弧焊和单弧焊熔滴过渡行为的数值模拟,同时借助图像采集系统和图像处理技术进行了实验验证,以期为AZ31B镁合金双弧焊焊接工艺参数的优化提供一定的理论参考。本文首先借助软件Workbench14.5建立了一个新颖的二维非对称的AZ31B镁合金双弧焊数学模型,并用FLUENT14.5软件借助UDF函数同时优选VOF模型来追踪镁合金双弧焊熔滴的自由表面,模拟了旁路电流为100A不变的情况下,总电流分别为170A,220A和280A时对熔滴过渡整个过程的影响。为了具体的了解总电流对熔滴偏移距离的影响,以10A的间隔模拟了总电流从170A增加到280A的熔滴的偏移距离并进行了规律分析。为了优化焊接参数,研究了镁合金双弧焊接熔滴过渡的临界电流,得到的结果大致为195A,并探讨了不同的总电流条件下获得射滴过渡(包括射流过渡)的旁路电流的范围大小。然后,搭建了AZ31B镁合金双弧焊焊接实验系统,拍摄得到了旁路电流为100A,总电流为170A,220A和280A时的熔滴图像,借助Matlab软件编写的一系列算法,分别选取熔滴图像的一个典型时刻进行了处理,最终得到了熔滴的边缘轮廓尺寸,结果显示实验得到的镁合金双弧焊熔滴的尺寸与模拟结果之间的误差很小,最大误差只有6.78%。最后,在保证焊接平台主要参数相同的情况下,对比了镁合金双弧焊和单弧焊的临界电流和熔滴内部速度场的不同,结果显示镁合金单弧焊的临界电流为224A,与镁合金双弧焊相差29A;在同样的焊接电流下镁合金单弧焊熔滴的最大速度是1.71m/s,而添加100A旁路电流的镁合金双弧焊熔滴的最大速度是2.58m/s,最大速度变大。
[Abstract]:According to the properties and physical properties of AZ31B magnesium alloys, the theory of droplet transfer and the free surface tracking algorithm (VOF) are combined, and the FLUENT software integrated with ANSYS Workbench is used in this paper. The droplet transfer behavior of double arc welding and single arc welding of AZ31B magnesium alloy is simulated with UDF function, and the experimental results are verified by image acquisition system and image processing technology. In order to provide some theoretical reference for optimization of welding process parameters of AZ31B magnesium alloy double arc welding, a novel two-dimension asymmetric mathematical model of double arc welding for AZ31B magnesium alloy is established with the help of software Workbench14.5. The free surface of droplet in double arc welding of magnesium alloy is tracked by FLUENT14.5 software with the help of UDF function and the VOF model is selected at the same time, and the bypass current is 100 A invariant. The effect of total current of 170An 220A and 280A on the whole process of droplet transfer. The offset distance of droplet increasing from 170A to 280A was simulated at 10A intervals and the regularity was analyzed. In order to optimize welding parameters, the critical current of droplet transfer in magnesium alloy double-arc welding was studied. The results obtained are approximately 195A, and the range of bypass current of droplet transfer (including jet transfer) obtained under different total current conditions is discussed. Then, a double-arc welding experiment system for AZ31B magnesium alloy is built. The droplet images with 100A bypass current, 170A 220A and 280A total current were recorded. A typical time of the droplet image was selected and processed by a series of algorithms written by Matlab software. Finally, the size of the edge profile of the droplet was obtained. The results show that the error between the size of droplet and the simulation results is very small, and the maximum error is only 6.78. Finally, when the main parameters of the welding platform are the same, The difference of critical current and droplet velocity field between double arc welding and single arc welding of magnesium alloy is compared. The results show that the critical current of single arc welding of magnesium alloy is 224A, which is 29 A different from that of double arc welding of magnesium alloy, and the maximum velocity of droplet of single arc welding of magnesium alloy is 1.71 m / s under the same welding current, while that of double-arc welding droplet of magnesium alloy with 100A bypass current is the highest. The big speed is 2.58 m / s, and the maximum speed gets bigger.
【学位授予单位】：南昌大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG457.19

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