Published Online: 30 August 2004
Page Count: 17
Professor, Lappeenranta University of Technology, Lappeenranta,
Section Manager, Wärtsilä Technology, Vaasa,
Senior Research Scientist, VTT Industrial Systems, Espoo,
(Received 3 May 2002; accepted 19 June 2003)
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.
Paper ID: JAI19021