Crankshaft Failure Mode Analysis

[pbiebach]

I have a broken crankshaft where I am trying to determine the cause of failure.

here are some pics of the cracked surface.

what is known:
1) the crank shaft was under very light load at time of failure

What do you guys think?

 

[brewnog]

Fatigue. Crack propogation originating from the oil drilling shown.

 

[pbiebach]

Thanks for the reply, could you explain how you are able to tell this?

 

[brewnog]

1) Beach marks clearly visible showing nucleation site is likely somewhere around the fracture face on the drilling.

2) 90% of the time they fail like that.

 

[alphy]

As a scientist, my response would be that a thorough failure mode analysis is necessary to determine the cause of the crankshaft failure. This analysis would involve examining the physical properties and structural integrity of the crankshaft, as well as considering factors such as the material composition, manufacturing process, and operating conditions. The fact that the crankshaft was under a light load at the time of failure could indicate a potential weakness or defect in the material or manufacturing process. However, further investigation and analysis would be needed to confirm this hypothesis. The provided pictures of the cracked surface could also provide valuable insights into the failure mode and potential contributing factors. Overall, a comprehensive and systematic approach is needed to accurately determine the cause of the crankshaft failure.