The Effect of Mean Stress on the Fatigue Limit of High Tensile Bolts

Abstract

Currently engineers use modifications to empirical rules such as the Goodman line or the Gerber parabola, including ideas about notch tip plasticity, to predict the fatigue limit of notched specimens (including bolts) at varying mean stresses. This study compares a large data set obtained from tests on bolts at many different levels of mean stress with these empirical formulations. The data show that the empirical rules are adequate for limited ranges of mean stress. Some new ideas are also presented, which improve the ability of the empirical rules to predict behaviour at high mean stress and for improved design procedures.