大功率柴油机连杆疲劳试验和数值模拟

Fatigue test and numerical simulation on connecting rod in high power diesel engine

对某型大功率柴油机连杆进行疲劳强度试验,观察连杆断口的微观形貌,分析连杆断裂的主要影响因素.试验结果表明:连杆杆身的残余压应力通常会使疲劳裂纹萌生在构件次表层,具有高平均应力水平的连杆小头对表层夹杂缺陷更加敏感.运用三维有限元数值计算方法和疲劳寿命预测理论,对连杆疲劳耐久性试验进行数值模拟.连杆疲劳试验与虚拟疲劳寿命预估结果的比较表明,基于材料S-N曲线的疲劳寿命预估方法在一定程度上能对疲劳试验中连杆破坏的薄弱部位和疲劳寿命进行模拟与预测.

The fatigue strength testes are done on the connecting rods of a high power diesel engine to observe the microscopic topography of the fractures, and the main influencing factors that lead to the fracture of connecting rod are analyzed. The test results show that the fatigue cracks that caused by the residual compressive stress of connecting rod are usually conceived at the subsurface, and the small end of connecting rod is more sensitive to the mixed defect of the surface because of its high level of average stress. The numerical simulation of fatigue durability test on connecting rod is done using 3D finite element numerical calculation method and fatigue life prediction theory. The comparison between fatigue test and virtual fatigue life prediction results for connecting rod shows that, to a certain extent, the fatigue life prediction method based on the S-N curve of the material can simulate and predict the weak part and fatigue life, where the connecting rod is destroyed in the fatigue test.