Local strain assessment and fatigue life prediction of surface notched specimens

DING Mingchao; BIAN Shuguang; CAI Long; HUANG Jiaxing; YANG Lipo; WANG Liming

doi:10.16579/j.issn.1001.9669.2026.05.003

Abstract：[Objective]The Neuber criterion and the equivalent strain energy density(ESED)criterion serve as fundamental theories for evaluating notch strain and predicting fatigue life.However,few studies have been reported the influence of the remaining thickness at the notch root on the fatigue life prediction results of specimens with surface notches.Optimizing the accuracy of fatigue life prediction for notched components is crucial for assessing the fatigue life of TC4 titanium alloy specimens with surface notches.[Methods]Firstly,TC4 titanium alloy specimens with surface notches on the substrate were designed,and fatigue tests were carried out to obtain tested fatigue life values.Secondly,the strains at the notch were calculated using the Neuber criterion and the ESED criterion respectively.Fatigue life prediction was performed in combination with the Manson-Coffin formula,and the fatigue life prediction accuracy based on the two criteria was verified.Finally,the ESED criterion was modified,and the accuracy of fatigue life prediction results based on the revised ESED criterion was analyzed.[Results]Fatigue life prediction results based on the Neuber criterion generally fall within the 2 times scatter band,without excessive conservatism.Moreover,as the notch width increases,the predictions shift from conservative to nonconservative.Fatigue life prediction results using the unmodified ESED criterion all lie outside the 8 times scatter band and exhibit significant overprediction.A strong correlation exists between the remaining thickness to radius of curvature at the notch root,and the tested fatigue life.The modified ESED criterion proposed based on this correlation yields fatigue life prediction results that mainly lie within the 2 times scatter band,with overall conservative estimates,and the prediction accuracy and reliability are significantly improved.