某柴油机曲轴失效分析

Failure Analysis of a Diesel Engine Crankshaft

针对某型号单缸柴油机曲轴断轴率较高的问题,首先运用有限元计算的方法,找出最大应力及其位置并分析结构设计是否合理,其次通过对断裂曲轴进行理化分析,考察失效曲轴金相、硬度等指标是否符合图纸及国家标准,并根据国家标准对其进行检验及评定,找出曲轴加工热处理方面的薄弱环节,分析结果表明:曲轴结构设计符合要求,但材质疏松,且表面加工质量达不到设计要求,提出了改进方案及措施,使曲轴的断轴率下降,发动机可靠性得到改善。

A certain kind of crankshafts of diesel engine fractured frequently.Several methods were used to find out the major cause of the crankshafts' failure.Firstly,Finite Element Method(FEM)was used to determine whether the design is feasible by calculating stress distribution.Then physical-chemical analysis such as metallographic examination,hardness analysis and Scanning Electrom Microscope(SEM) observation,were performed to verify the material quality.Results show that the structure design of crankshaft is reasonable,but the material quality and the mechanical machining quality fall short of requirements.Quality control is suggested and the reliability of crankshafts has been improved remarkably.