Volume 41, Issue 2 (March 2013)
Assessment of the Mean-Stress Sensitivity Factor Method in Stress-Life Fatigue Predictions
The mean-stress sensitivity factor model developed by Schütz in 1967 is considered the most comprehensive method to account for the mean-stress effect on high-cycle fatigue life and strength, which is applicable to various materials (such as steels, steel castings, ductile irons, malleable cast irons, grey cast iron, wrought aluminum alloys, and cast aluminum alloys) and to a broad mean-stress or stress-ratio range. Even though the mean-stress sensitivity factor method has been frequently used in European-based fatigue commercial software and engineering design codes, such as the Rechnerischer Festigkeitsnachweis für Maschinenbauteile (FKM) Guideline, it has not received a great deal of attention worldwide. Although the FKM Guideline provides extensive experimental test validation, very little evidence from independent sources have illustrated the validity of this method. Thus, it is the objective of this paper to examine the Schütz mean-stress sensitivity factor model by comparing the Walker mean-stress correction equation to the best fitting parameters published for steels, aluminum alloys, and titanium alloy. It was concluded that the Schütz mean-stress sensitivity factor model exhibits a reasonable degree of agreement with the Walker equation over a wide variety of materials.