激光焊线强度模型的建立以及失效预测

ESTABLISHMENT OF INTENSITY MODEL FOR LASER WELDING LINE AND PREDICTION OF FAILURE

针对冷成型热轧汽车结构钢S420MC和S520MC的激光焊接接头横截面进行压痕测试,建立焊线熔融区、热影响区和母材的材料本构方程。在韧性断裂和剪切失效的基础上,考虑到焊线破坏的时率相关性以及损伤累积性,采用Kolmogorov积分方程判断材料的失效,提出一种新的焊线失效模型(微观失效模型)。利用该模型模拟激光焊线在冲击载荷下的力学行为,并与现行的两种焊线数值模型(宏观一维模型和宏观三维模型)仿真结果对比。仿真对比结果表明,基于微观失效模型不仅获得了一致的强度评价,而且能够预测焊线撕裂发生时间以及撕裂开始发生的区域,更加真实地反映激光焊线在冲击载荷下的力学行为。

According to the welded joints of cold formed hot-rolled automobile structural steel S420 MC and S500 MC, indentation tests on the cross-section were carried out to establish the constitutive relation for melting zone、heat affected zone and base metal. Based on ductile rupture and shear failure, a new failure model(micro failure model) for welding line was proposed, in which Kolmogorov integral equation was used to be a failure criterion taking account into the time correlation and damage accumulation. On the basis of the model, mechanical behaviors of welding line under the condition of impact load were simulated, then compared the results with two other numerical models(macro one-dimensional model and macro three-dimensional model). The comparison results indicate that the simulation with micro failure model not only gives the uniform strength evaluation, but also can predict the time and area for initial ductile. Micro failure model could reflect the mechanical behaviors of laser welding line under impact load.