On the failure condition in strain-controlled low cycle fatigue

Abstract

Axial-strain controlled low cycle fatigue tests were performed on several materials in different metallurgical conditions using various test-piece geometries, strain ranges, temperatures and frequencies in order to arrive at a proper choice for the definition of failure. Several alternative failure criteria proposed in the literature were examined in terms of load response measurements and the shape of the hysteresis loop in the compressive portion of the cycle. A 20% fall in the saturation stress in tension and cusp formation in the compressive portion of the cycle have been identified as the two best criteria for defining the failure life of laboratory specimens in strain-controlled low cycle fatigue testing.