焊接工艺对客车骨架T形接头强度的影响

为了给客车骨架T形接头焊接工艺方案的选择提供参考依据和技术指导，以某全承载式客车为载体，研究焊接顺序和焊接电流对客车骨架T形接头强度的影响。选取底架上3处危险T形接头作为研究对象，采用与所选取接头截面尺寸相同的方钢进行焊接试验，对其在不同焊接顺序和焊接电流方案下的焊接变形进行测量与统计。根据试验数据建立变形后的T形接头有限元模型，在其端部施加反向位移，从而获得T形接头在各个方案下的焊接变形应力。通过建立车身整体梁壳混合模型，对所研究T形接头在整车危险工况下的工作应力进行统计，并将焊接变形应力引入整车分析，基于应力叠加的方法，获得T形接头处的实际应力值，以此为依据研究不同焊接工艺参数对客车骨架T形接头强度的影响。研究结果表明：焊接工艺对T形接头强度存在较大影响，针对选取的3处T形接头，当采用不同的焊接顺序时，应力最高值与最低值相差可达40%以上；当采用不同的焊接电流时，应力最高值与最低值相差达到了30%左右；合理选择焊接工艺参数可以避免焊接变形应力与工作应力的叠加，从而有效降低接头处的应力水平，进一步提高车身骨架整体的承载性能。

Effect of Welding Process on Local Strength of T-joints in Bus Body Frame

In order to provide the reference and technical guidance for selecting the welding process scheme of T-joints in bus body frame, the influence of welding sequence and welding current on T-joint strength was investigated based on a certain integral bus. Three dangerous T-joints on chassis were selected as the research objects, and the welding deformations of T-joint under different welding sequence and welding current were measured through the welding experiment of square steel with the same section size of selected T-joints. According to the experimental data of different welding sequence and welding current schemes, the deformed T-joints finite element model was established, whilst the welding deformation stress was obtained by applying reverse displacement. The beam-shell element mixed model of bus body was established and the working stress of T-joints under the dangerous working condition of the vehicle was analyzed and counted. The welding deformation stress of the T-joints was introduced into the complete vehicle analysis, the method of superimposed stresses was employed to obtain the actual stress at the local of T-joints. Based on the calculated values, the influence of different welding parameters on the strength of T-joint in bus body frame was investigated. The results show that welding process has an obvious effect on T-joint strength. For three selected T-joints, the difference between maximum and minimum stress value is more than 40% when taking different welding sequences. The difference between maximum and minimum stress value is about 30%, when taking different welding current into account. Therefore, the reasonable selection of welding parameters can avoid the superposition of welding deformation stress and working stress, effectively reduce the stress of joints, and can improve the bearing capacity of whole body frame.