Crankshaft Failure Mode Analysis

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

    here are some pics of the cracked surface.
    [​IMG]
    [​IMG]
    what is known:
    1) the crank shaft was under very light load at time of failure

    What do you guys think?
     
  2. jcsd
  3. brewnog

    brewnog 2,793
    Science Advisor
    Gold Member

    Fatigue. Crack propogation originating from the oil drilling shown.
     
  4. Thanks for the reply, could you explain how you are able to tell this?
     
  5. brewnog

    brewnog 2,793
    Science Advisor
    Gold Member

    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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