汽车发动机曲轴扭转疲劳失效形式与原因分析

摘要

通过对典型曲轴扭转疲劳试验失效案例的分析，介绍了汽车发动机曲轴常见的扭转疲劳失效形式，分析了导致各种失效形式的原因。结果表明：曲轴的扭转疲劳失效的主要形式是连杆颈斜油孔失效，异常失效形式有曲柄臂失效和连杆颈下止点失效；异常失效原因涉及曲轴毛坯结构设计、原材料缺陷、机加工不良、受力过大等的多个环节；曲轴曲柄臂凹陷和凸起的标识、原材料夹杂、斜油孔内部加工刀痕和受载过大都会导致曲轴异常的扭转失效。最后结合失效原因提出了相应的预防措施。%The modes and causes of torsional fatigue failure of automobile engine crankshafts were analyzed by studying typical failure cases in torsional fatigue tests. The results show that the main torsional fatigue failure mode of crankshafts is rod journal oil hole failure, and abnormal failure modes are crank web failure and rod journal bottom center failure. The abnormal failure causes include the structure design, material defect, improper machining, excessive stress, and so on. Concave and convex of crank arm, raw material inclusions, internal machining marks of oil hole and excessive loading will lead to abnormal torsional failure of crankshafts. Finally, some improvement measures were put forward according to the failure causes.