铝合金激光深熔焊温度场数值模拟及改善方案研究

发布时间：2018-09-11 21:23

【摘要】：激光焊接技术具有速率高、精度高和可靠性高等优点,在工业生产中有广泛应用。铝合金激光焊接是一个复杂的物理化学过程,铝合金反射率高和导热系数大,铝合金激光焊接容易产生表面塌陷和内部气孔等缺陷,采用工艺试验进行激光焊接过程研究,需要时间长和材料成本高,国内外研究人员采用试验和数值分析相结合的方法对铝合金激光焊接进行了有效的研究。数值模拟中热源的选取是仿真计算的关键,本文选取双高斯圆柱体热源对铝合金作了三维温度场的仿真模拟,研究了激光焊接薄板铝合金的工艺参数对焊缝成形的影响规律,并通过实验验证,具有重要的学术理论价值和实用意义。焊接材料为1mm厚6061铝合金,激光器型号为YLS-2000。首先,针对国内外激光焊接数值模拟的研究现状进行深入分析,再结合薄板铝合金的材料属性的特点,提出采用双高斯圆柱体热源模型的技术方案,并借助FLUENT软件自定义的UDF程序加载了这种模型,建立了1mm厚6061铝合金激光焊接的三维数值模拟模型,完成激光深熔焊焊铝合金的温度场数值模拟。其次,通过数值模拟的结果分析,确定了工艺试验的研究方案,并通过多次试验结果,调整数值模拟中的网格和求解参数,直到模拟与试验结果吻合良好。最后,总结了模拟与试验结果分析,得出工艺参数对焊缝成形的影响规律,为激光焊接薄板铝合金提供了定量的数据参考与数值模拟的理论基础。本文介绍了两种改善焊缝质量的方案。一种是改变工件倾斜角度,采用数值模拟与工艺试验相结合的研究方法,证实了这种焊接方式确实具有改善塌陷和气孔缺陷的作用;另一种是激光重复焊接工件,只采用了工艺试验的研究方法,得出了在未熔透的情况下,这种焊接方式具有改善焊缝产生气孔缺陷的作用,但不适用工件熔透的情况。
[Abstract]:Laser welding technology has been widely used in industrial production because of its high rate, high precision and high reliability. Laser welding of aluminum alloy is a complicated physical and chemical process. The laser welding of aluminum alloy is easy to produce defects such as surface collapse and internal porosity. It takes a long time and high cost of materials. Researchers at home and abroad have carried out effective research on laser welding of aluminum alloy by means of combination of experiment and numerical analysis. The selection of heat source in numerical simulation is the key to the simulation calculation. In this paper, the three-dimensional temperature field of aluminum alloy is simulated with double Gao Si cylinder heat source, and the influence of laser welding process parameters on weld forming is studied. And through the experimental verification, it has important academic value and practical significance. Welding material is 1mm thick 6061 aluminum alloy, laser type is YLS-2000. Firstly, according to the research status of numerical simulation of laser welding at home and abroad, combined with the characteristics of material properties of thin plate aluminum alloy, the technical scheme of adopting double Gao Si cylindrical heat source model is put forward. The 3D numerical simulation model of laser welding of 6061 aluminum alloy with 1mm thickness was established by loading the model with the UDF program defined by FLUENT software, and the numerical simulation of temperature field of laser deep fusion welding aluminum alloy was completed. Secondly, through the analysis of the results of numerical simulation, the research scheme of process test is determined, and the mesh and solution parameters in numerical simulation are adjusted through the results of many experiments, until the simulation results are in good agreement with the experimental results. Finally, the simulation and test results are summarized, and the influence of process parameters on weld forming is obtained, which provides a theoretical basis for quantitative data and numerical simulation for laser welded aluminum alloy sheet. In this paper, two schemes to improve weld quality are introduced. One is to change the tilting angle of the workpiece, and the other is to combine the numerical simulation with the process test, which proves that the welding method has the effect of improving the collapse and the porosity of the workpiece, and the other is the laser repeated welding of the workpiece. Only the research method of process test is adopted. It is concluded that this welding method can improve the porosity of weld without penetration, but it is not suitable for the penetration of workpiece.
【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】：TG457.14

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