商用车SCR箱吊架焊缝失效分析与改进

Analysis of Failure Reasons and Improvement of the SCR Box Bracket on Commercial Vehicle

某商用车在强化路试行驶里程达10000Km至40000Km时,SCR箱吊架支座焊缝处出现裂纹、断裂现象,严重影响车辆质量与安全;为查明故障的根本原因并提高结构的使用寿命,基于Hyperworks软件建立吊架的有限元模型,分别对不同结构形式的吊架在不同路况下进行CAE模拟分析。分析结果表明,在支座与钢管的焊接部位,存在应力集中,并在变载荷的交替作用下产生疲劳断裂;对支架设计进行优化,通过改变材料、改善接方式、控制零部件质量等措施加强支架强度,分析与试验结果表明措施有效。合理的焊接形式以及材料选择能够改善结构强度及应力分布,在结构设计时具有较大的参考意义。

When a commercial vehicle was running in a road test about 10000 km to 40000 km for reliability, a bracket which was mounted on SCR box appeared crack and breakage, This seriously affects the safety and quality of vehicles. In order to find out the root cause of failure and improve the service life of part, a finite element model was building with Hyperworks, and carried out CAE analysis of components with different structures under different road conditions. The result has shown that the stress concentration exists in the welding position between the support and the pipe, and fatigue cracks occur under the action of variable load. The bracket was redesigned that material, welding and quality were optimized, The analysis and test results show that strength had great improvement. Reasonable welding method and material selection can improve the structural strength and stress distribution, which has great reference significance in structural design.