A modified Miner rule to predict crack initiation

We propose a damage cumulation rule and an upper bound of cumulated damage before propagation using: linear damage function, linear cumulation in proportional or non proportional loading in presence of overloading or ratchetting. We take into account effect of prehardening on Cyclic Stress Strain Curve (C.S.S.C), and define a non proportional state cyclically equivalent to an uniaxial one. We show an important difference between a load controlled and a strain controlled experiment for difficult cross-slip materials as 316 stainless steel described by a non stable C.S.S.C. (author). 17 refs., 10 figs