Estimation of Fatigue Crack Initiation Life of Notched Plates

Influence of Transverse Stress at Notch Root

Abstract

The influence of transverse stress at the notch root on the fatigue crack initiation life of side notched plates was discussed. Axial, transverse and equivalent stresses at the notch root of the side notched large plates were calculated using the strains measured with strain gauges. Further the same plates were fatigue-tested to relate the fatigue crack initiation life with stress amplitudes at the notch root.
The results obtained are as follows:
(1) Equivalent stress at the edge was slightly smaller than that at the notch root. This corresponded to the test result that fatigue crack did not initiate at the edge.
(2) The fatigue crack initiation life coincided with that calculated by using σ-ε relation, S-N relation of the material and the relation among shape factor, plastic stress concentration factor and strain concentration factor.