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.

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pbiebach	Crankshaft Failure Mode Analysis Tweet 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 Recognitions: Gold Member Science Advisor	Fatigue. Crack propogation originating from the oil drilling shown.

brewnog Recognitions: Gold Member Science Advisor	Crankshaft Failure Mode Analysis 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.