assigments

Failure of a straddle carrier wheel

The submitted wheel had a crack on the HAZ of the filled weld that connected the rim to the bolt circle of the wheel. Sixteen more wheels presented the same type of failure.

The examination identified the crack as a fatigue crack which was created in a stress concentration area i.e. in an existing geometric anomaly associated with the closing of the weld bead.Elimination of the anomaly by grinding it after the welding or by performing the welding with better parameters and engineering practice should be adequate for improving the wheel fatigue life to much higher level.

 

 
 

Failure of connecting bolts from a Diesel Generator

Majority of bolts failures is usually attributed to one of the following causes:
   • Insufficient design
   • Product faults
   • Operational errors
   • Installation Errors
 

In this case failure mechanism was attributed to excessive operational tensile stresses which led to overloading and fracture of the components.

 

 

 
 

Failure of slewing crane bearings

Evidence of failure was identified when loading operations at an open water anchorage unusual sounds were heard from the damaged crane.

The investigation showed spalling of the bearings contact surfaces as a result of a rolling contact fatigue mechanism. The bearings had already consumed about 45% of their predicted fatigue life duration but excessive loads have caused premature fatigue failure of the contact surfaces due to repeated heavy loadings of the rolling elements on the raceway.

 

 

 
 

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