Volume 1, Issue 8 (September 2004)
High Cycle Variable Amplitude Fatigue of a Nodular Cast Iron
This paper provides a brief summary of life prediction methods for variable amplitude fatigue. Special attention is given to cracks propagating from nominally defect free components in the high cycle regime where a significant portion of the fatigue damage can be attributed to cycles with amplitude less than the fatigue limit observed under constant amplitude loading. Constant and variable amplitude fatigue data for a nodular cast iron are presented. An effective stress method for variable amplitude loaded similar to the Topper model is developed. Most model parameters are derived from constant amplitude S-N curves and the Haigh diagram, but two sets of long life variable amplitude tests are needed to derive the variable amplitude interaction parameters.