地铁铝合金型材焊接及焊后热处理的数值模拟仿真分析

Analysis of Numerical Simulation of Welding and Post-Weld Heat Treatment of Aluminum Alloy Extrusion for Metro Vehicles

根据某工厂焊接生产实际工艺流程,对某地铁车底架型材MIG焊及焊后热处理过程进行数值模拟研究.首先对该结构进行非线性有限元建模,运用Fortran语言建立焊接热源模型,采用顺序耦合法来模拟焊接过程及焊后热处理过程中残余应力的变化.计算结果表明,焊接过后焊缝的纵向残余应力可以达到接近材料的屈服强度,横向残余应力较小.经过适当的焊后热处理之后,残余应力明显下降,降低幅度可达70%左右.该仿真分析结果对实际焊接过程中残余应力的释放效果提供了足够的数值依据,并且对焊后热处理的数值模拟也提供了相应的技术支持.

The numerical simulation of welding and post-weld heat treatment of an underframe for metro vehicles was carried out according to the engineering technology of the factory.The underframe structure was modeled by nonlinear finite element,the welding heat source model was established by Fortran language,and the welding and post-weld heat treatment process was simulated by sequence coupling.The calculation results show that the longitudinal residual stress of the weld nearly reachs the yield stress of the material,and the transverse residual stress is small.After post-weld heat treatment,the residual stress is obviously decreased by 70%.The results provide a basis of reducing residual stress in practical production,and provide technological support for further research on residual stress.