Mechanical analysis is used during the course of a failure investigation to assist in the identification of design problems or ascertain the source of unintentional loading.  Mechanical analysis can include computer analysis by finite element modeling or actual physical measurement using strain gauges or accelerometers.  Frequently it is found that the materials and fabrication processes used in the manufacturing process are acceptable, but other factors including cyclic loads or vibrations experienced during service result in the failure of a component.

The failure analysis of a small step stool included the mechanical analysis of the structure.  The prepared computer model presented here was created to confirm the component’s suitability to the CSA CAN3-Z11 performance code for portable ladders.

The replacement of two squirrel cage-type draft fans in a 70-foot tall reformer furnace resulted in unanticipated vibrations of the supporting structure.  In-field vibration measurements taken during operation, and subsequent structural modifications, eliminated the problem and resulted in satisfactory operation of the fans.

Large-scale mining trucks were experiencing fatigue cracking of some of the 1 ½” diameter front suspension bolts.  To measure the loads during operation of the trucks, several bolts were internally strain gauged, installed in the operating trucks and the output dynamically recorded.  As a result of the analysis, a source of unexpected and inadvertent loading was discovered and operator procedures were modified to eliminate it.

Zeus Engineering Ltd.
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