Why: The naïve expectation is that individually the impact of a single insult will not destroy reliability of the component. However, you frequently have multiple insults occurring which results in failures that are not predicted up front but which can be perfectly explained after the components have failed.

When: The multiple destructive events are more predominate in complex devices and highly stressed devices which too often have small safety factors which cannot cope with the overload conditions and thus failures occur.

Where: The foolishness of humans adds further insults to the interactions of many different failure mechanism which demands high maintenance interventions and frequent inspections. Of course the solution to many of these cases where failures occur is to increase safety factors by adding extra material (when possible) but this adds extra weight and extra costs.

These definitions are written by H. Paul Barringer and are also posted on his web site at www.barringer1.com

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