The Effects of Mean Strain on the Fatigue Life of the SAE 1541 Carbon Steel Based on the Strain-Life Approach

Abstract

AbstractThis study aims to determine the effects of the mean strain on the SAE 1541 carbon steel fatigue life based on the strain-life approach. The strain data were developed with negative, zero, and positive mean values consisting of constant and variable amplitude loadings in the range of 200–2000 με. The strain data has two variations: tensile-compress and compress-tensile modes. For variable amplitude loadings, the strain data also has two types: of low–high and high-low cycles. The results show that the Coffin–Manson model did not provide a different fatigue life for negative, zero, or positive mean strains. This was because the model assumes that strain data has a zero mean value. Based on the Morrow and SWT models, however, strain data with a negative mean value provided a longer fatigue life than strain data with zero and positive mean values. The results also show that constant and variable amplitude loadings gave a different fatigue life, but tensile-compress and compress-tensile modes gave a similar result. A small difference only happened between low–high and high-low cycles. It concluded that the mean value does not affect the fatigue life of strain data significantly based on the strain-life approach. It can be concluded that the strain-life approach does not consider the cycle sequence effect in its analysis.KeywordsFailureStressAmplitude