基于热点应力法的扭梁焊缝可靠性分析及优化

Reliability Analysis and Aptimization of Torsion Beam Weld Based on Hot Spot Stress Method

基于热点应力外推法对扭梁关键焊缝进行疲劳分析并验证了优化方案。介绍了热点应力的基本概念、类型及计算方法,建立某量产车型扭梁的有限元模型,并对关键焊缝周边区域进行网格细化,综合考虑环境因素修正了用于疲劳分析的焊缝S-N曲线,在两个典型整车工况下(制动、转向),根据线性累积损伤理论计算了各热点位置的疲劳寿命,结果表明,该焊缝的最小疲劳寿命不足10万次,通过在搭接边内侧增加一条副焊缝的方法优化此处的焊接结构,分析结果表明,优化后焊缝的疲劳寿命显著提升,以优化的结构进行样件试制及台架耐久试验,试验结果表明,优化后的结构能显著提高该区域在纵向力及侧向力台架下的疲劳寿命,提高了扭梁焊缝的可靠性。

Based on the hot spot stress extrapolation method,the fatigue analysis of the key welds of torsional beams is carried out and the optimization scheme is verified in this paper.The basic concept,type and calculation method of the hot spot stress are introduced;the finite element model of a torsion beam is then established;and grid refinement for the surrounding area of the key weld is completed.The weld S-N curve for fatigue analysis is modified by considering the environmental factors;under the two typical vehicle operating conditions(braking,steering),the fatigue life of each hot spot location is calculated according to the linear cumulative damage theory.The results show that the minimum fatigue life of the weld is less than 100,000 times.By adding a secondary weld inside the lap edge to optimize the welding structure;the analysis results show that the fatigue life of the optimized weld is significantly improved.Then the sample production and bench endurance test are carried out with the optimized structure;the results show that the optimized structure can significantly improve the fatigue life of the region under longitudinal and lateral forces and improve the reliability of torsional beam weld.