网格尺寸对别克轿车副车架总成焊接变形预测精度的影响

焊接时焊缝及其附近因热膨胀受到周围温度较低金属的拘束，产生大量的压缩塑性应变（简称残余塑变），残余塑变的大小和分布决定了最终的残余应力和变形。副车架的焊接变形对汽车底盘的制造精度和质量有重要的影响。本文用残余塑变法对别克轿车副车架焊接总成时，连接前梁、后梁、左梁和右梁的21条焊缝焊接以后的变形规律进行了有限元建模与分析。计算采用了两种大小的有限元网格尺寸，结果表明，对副车架焊接变形分析，焊缝附近大小为15mm的网格尺寸是合理的。所得焊接变形的有关数据可供焊接工艺设计时的预留变形量、工艺参数以及夹具设计等参考，从而保证底盘件的焊接精度和质量。

Effect of Mesh Sizes on Welding Deformation Prediction Precision of Buicks Underframe Assembly

In welding process the stmcture undergoes a locally high temperature cycle.The thermal expansion of the welds and nearby areas is restricted by the constraint of surrounding metals where the temperature is rather low.The compressive plastic strains in the welds and nearby area will be caused and remained at mom temperature after welding.The residual plastic strain, also named inherent strain, is considered as a source causing the welding stresses and deformations.Welding deformation of underframe is one of main factors determining the car''s quality.Residual plastic strain method is applied to the welding deformation prediction of the large structure-GM''s Buick''s chassis underframe beam assembly which is made of four bridges with 21 welds.Two kinds of mesh sizes are used in welding deformation analysis of the underframe.The results show that 15mm is pennitted for meshes near the welds in the analysis.The analysis method and results can be used for the instruction of practical production of others cars.