某柴油机水泵轴疲劳断裂的分析及改进设计

Fatigue Fracture Analysis and Design Improvement of the Water Pump Shaft in One Diesel Engine

轴类零件在机械行业设备中是一个重要的、核心的零部件。我们结合某柴油机用水泵轴出现的断裂问题,利用对断轴化学成分、显微组织和裂纹、断口特征的分析,初步判断泵轴在承受循环应力扭转载荷作用下,过渡圆角附近产生了疲劳源,并导致了疲劳断裂。采用有限元分析模拟分析水泵轴工作情况,得到水泵轴的应力分布状况,计算其疲劳强度,并以降低最大应力为目标,通过有限元软件开展参数化研究,掌握结构圆角几何尺寸、材料与其应力分布和疲劳强度之间的关系,通过加大圆角和改变水泵轴的材料提高水泵轴的疲劳可靠性,对增强高应力区域的抗疲劳性能有着重要的现实意义。

Shafts are important and core spare parts for the equipment of machinery industry. In view of the fracture problem appearing in the water pump shaft of a diesel, after analysis is made to the shaft’s chemical components, microscopic structure and cracks, and also the fracture features, it is primarily determined that the fatigue source is produced around the transition fillet and then fatigue fracture is caused as the torsion load of cyclic stress is imposed to the pump shaft. Afterwards, finite element analysis is adopted to simulate the work conditions of water pump shaft, to learn its stress distribution and calculate the fatigue strength; then, with maximum stress reduction as the goal, parametric study is conducted with ANSYS software, so as to acquire the relationship between the fillet’s geometric dimension, material and its stress distribution and fatigue strength. Hereby, the paper aims to improve the fatigue reliability of water pump shaft through enlarging fillet and changing the shaft’s material, which may be of important practical significance to enhancing the anti-fatigue performance of high stress area.