A Relation between the Critical Alternating Propagation Stress and Crack Length for Mild Steel

Fatigue tests have been carried out on mild steel specimens containing edge cracks of various lengths and the alternating stress just insufficient to cause the cracks to grow obtained. It was found that the relation between this critical alternating stress σ and the crack length l was given by σ3l = constant. By means of this relation it was possible to correlate a wide variety of hitherto unrelated notch fatigue data.