Crankshaft Failure Mode Analysis


by pbiebach
Tags: failure analysis
pbiebach
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#1
Dec21-10, 06:45 PM
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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?
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brewnog
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#2
Dec22-10, 01:55 PM
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Fatigue. Crack propogation originating from the oil drilling shown.
pbiebach
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#3
Dec22-10, 02:07 PM
P: 5
Thanks for the reply, could you explain how you are able to tell this?

brewnog
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#4
Dec22-10, 02:12 PM
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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.


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