基于模态瞬态法的发动机罩焊点疲劳优化

针对某车型整车耐久路试过程中发动机罩铰链加强板焊点出现开裂的问题，采用模态瞬态法对发动机罩焊点进行疲劳分析。根据发动机罩模态应变能分布情况优化铰链加强板结构和焊点分布，试验车整改后在整车耐久路试中发动机罩焊点未再出现开裂现象。发动机罩铰链加强板焊点开裂是振动疲劳问题，采用基于惯性释放的准静态法计算疲劳损伤不能预测焊点开裂问题,采用模态瞬态法疲劳计算方法才能更好地预测发动机罩焊点疲劳损伤。从模态应变能角度对结构振动疲劳开裂问题进行优化能明显提高优化效率。

Fatigue optimization on welding spot of engine hood based on modal transient method

As to the cracking problem that the welding spots of the hinge reinforcing plate of the engine hood during the endurance road test of whole vehicle, the fatigue analysis of welding spots of the engine hood is carried out by modal transient method. According to the distribution of modal strain energy of engine hood, the structure of hinge reinforcing plate and the distribution of welding spots are optimized. The test vehicle is rectified, and the engine hood welding spots do not crack again in the vehicle durability road test. The cracking of the welding spots of the hinge reinforcing plate of the engine hood is a vibration fatigue problem, and the quasi static method based on inertia release is used to calculate the fatigue damage, which can not predict the welding spot cracking, and the fatigue damage of engine hood welding spots can be better predicted using the fatigue calculation method of modal transient method. The optimization of structural vibration fatigue cracking based on the perspective of modal strain energy can significantly improve the optimization efficiency.