Cyclic Stress Required to Propagate Edge Cracks in Eight Materials

Abstract
Fatigue tests have been carried out at zero mean load on plate specimens, of eight materials, containing two opposite small co-planar edge cracks. The results confirmed that whether or not a crack would grow was governed by the parameter ρ3*** l where ρ is the semi-range of the nominal alternating stress and l is the edge-crack length. If ρ3 l > C a crack would grow; if ρ3 l < C a crack would remain dormant. The value of C was determined for each material.