Mode I fatigue crack-propagation mechanism based on the renewal stochastic damage-accumulation model

A mechanism of mode I fatigue-crack propagation, which involves the initiation and opening of the cleavage-mode crack, is proposed. This approach uses a renewal stochastic damage-accumulation model for crack propagation, in which the parameters are defined based on the dislocation density and the elastic energy of dislocation. The calculated results of ΔKeff for da/dn agree with the experimental data. ΔKeff th is calculated under the condition that the energy of cleavage-crack initiation is equal to that given from the outside of material. The plastic-zone size is calculated based on the number of dislocations on each slip line contained within it.