Define Failure

What is meant by "failure" must be defined early since avoiding failure is the objective both of design and prediction. "Failure," even for the same material, means different things to different industries and even for the same industry depending on the component:

Once failure is defined, it is possible, then, to define what information is necessary to develop a predictive model and to define what elements of feedback are necessary during operation in order to prevent failure. Defining failure at the outset also provides a basis for the margin necessary to avoid failures in the future.

Lifetime Prediction, Roger W. Staehle, Adjunct Professor, Department of Chemical Engineering and Materials Science, University of Minnesota, Staehle Consulting Co.