薄壁铝合金T形结构MIG焊接热源复合模型的构建与模拟

Construction and Simulation of Heat Source Composite Model for MIG Welding of T-shaped Thin Wall Aluminum Alloy

针对薄壁铝合金材料焊接变形有限元模拟精度低的问题,以2 mm厚6082-T6铝合金型材T形接头为研究对象,通过有限元模拟和实际样件校核结合的方法,开展了铝合金MIG焊专属热源模型的研究。计算了2D高斯、3D高斯、双椭球三种典型焊接热源模型的熔池形貌和变形量。校核对比发现,三种典型热源模型计算的熔池尺寸和变形量与实际样件均存在差距:2D高斯热源热流过小,焊缝区熔池宽度和深度明显小于实际熔池尺寸;3D高斯热源可体现热流在厚度方向上的作用,但熔池深度和宽度略大;双椭球热源在熔池上半部的形状及宽度与实际接近,但熔池较浅。综合三种模型特点,通过反求法获得基于典型热源模型基础上的“双椭球+3D高斯”的优化复合热源模型,熔池尺寸及偏移量与实际工件吻合度达90%,模型可靠,可用于薄壁6082铝合金T形接头MIG焊接的精准模拟。

Aiming at the problem of low accuracy of finite element simulation of welding deformation of thin-wall aluminum alloy,taking 2 mm profile T-joint of 6082-T6 aluminum alloy as the research object,the special heat source model of aluminum alloy MIG welding was studied by combining finite element simulation and actual sample checking.The morphology and deformation of weld pool of 2D Gaussian,double ellipsoid and 3D Gaussian are calculated.It is found that there is a gap between the size and deformation of molten pool calculated by the three typical heat source models and the actual sample.The heat flow of 2D Gaussian heat source is too small,and the width and depth of molten pool in the weld zone are significantly smaller than the actual molten pool size.The 3D Gauss heat source can reflect the effect of heat flow in the thickness direction,but the depth and width of the molten pool are slightly larger.The shape and width of the double ellipsoid heat source in the upper part of the pool are close to the actual ones,but the pool is shallow.Based on the characteristics of the three models,the optimized composite heat source model of"double ellipsoid+3D Gaussian"based on the typical heat source model is obtained by inverse calculation method.The weld pool size and offset are 90%consistent with the actual workpiece.The model is reliable and can be used for accurate simulation of MIG welding of thin-wall 6082 aluminum alloy T-joint.