应用有限元法研究柴油机活塞的断裂破坏

本文应用有限元法和光弹性试验对活塞顶的裂纹进行断裂力学分析。针对活塞结构复杂的特点,推荐一种能对实际零件进行断裂分析的有限元计算法,计算程序简单,计算精度较高,可给出实际零件裂纹尖端附近的应力场和应力强度因子。另外,应用光弹性试验对活塞模型进行了断裂分析,叙述了试验中应注意的事项。对一台柴油机的活塞顶断裂破坏进行了分析,给出了裂纹存在对活塞顶应力场和温度场的影响,以及裂纹尖端附近的应力强度因子。有限元计算值和光弹性试验值吻合良好,并且同实际破坏相符合。

Research on the Piston Failure of Diesel Engine by Finite Element Method

This paper studies the fracture mechanics of piston crown crack by means of finite element method and photoelastic method. In view of the complication of piston construction, a finite element method is proposed to analyse the cause of failure, and to determine the stress field and stress intensity factor at the tip of crack. Based on this method, the programing is rather simple and the calculation result is quite accurate. This paper analysed also the failure of piston model by means of photoelastic method, and gives some points worthy of attention in carrying out this test. As an example, a piston crown failure of a diesel engine is analysed. The effects of crack on the stress field and temperature field, and the stress intensity factor at the tip of the crack are described. It could be seen that the calculated values by finite element method are in good agreement with the test values by photoelastie method. Then the actual broken phenomena can be readily explained by these two methods.