Evaluation of S–N curves with more than one failure mode

In very high cycle fatigue, researchers and engineers are often confronted with S–N curves which exhibit more than one type of failure. Generally, it is assumed that every specific crack-initiation type has its own S–N curve, so that in this case two or more S–N curves can be drawn in the S–N diagrams. This paper will show an S–N diagram with two failure types and will provide a generalised method of drawing correct S–N curves for every single type of failure.