Technique for direct measurement of effective fatigue threshold of materials

Abstract

A new method for studying crack growth behaviour in the fatigue threshold regime is reported here. The method uses a simple rotating bending test set-up, instead of servohydraulic or electromagnetic resonance test systems, to determine the fatigue threshold of structural materials. The reliability of the new technique is demonstrated by determining fatigue threshold of a 0.62%C steel by this technique and comparing the results with those obtained from conventional tests following the procedure of ASTM standard E647. The suggested technique provides higher sensitivity of measurement for crack growth rate and directly gives the fatigue threshold value for the steel that is in good agreement with the effective fatigue threshold determined by conventional tests.