Volume 20, Issue 3 (May 1992)
Fatigue Threshold Regime of a Low Alloy Ferritic Steel under Closure-Free Testing Conditions: Part I—Compliance Variations in the Threshold Regime
Compliance variations in the threshold regime of a high strength ferritic steel tested under closure-free conditions at room temperature and in air are reported. In contrast to the Paris regime, and irrespective of whether the data during load shedding, at threshold, or after post-threshold load increase are considered. it is found that compliance varies inconsistently in the threshold regime. Therefore a 1:1 correlation between the averaged optical crack length and that inferred from compliance was not observed. Possible reasons of this discrepancy are discussed, and the crack front lag inferred is explained in terms of the constraint.