The influenced zones of stress intensity factor and plasticity at multi-crack tips

The influence range of crack interaction is studied using the distribution dislocation technique, and is defined as the influenced zone. For elastic materials with cracks, the equivalent stress intensity factor influenced zone is obtained, while for plastic materials with cracks, the plasticity influenced zone is determined. The interaction between multiple cracks can be analyzed by introducing the concept of the influenced zone, which simplifies the analysis. The results indicate that if a crack is located outside the influenced zone of another crack, the effect of the former on the latter can be ignored within an acceptable range of error. The influenced zone for elastic materials depends on the length and inclined angle of a crack, whereas for plastic materials, the plastic influenced zone is affected by the crack length, inclined angle, and material yield limit simultaneously. In the case of plastic materials with multiple cracks, fusion of plastic zones between two cracks may occur at certain positions under the influence of other cracks. These theoretical findings can simplify the analysis of the fatigue fracture behavior of materials with multiple cracks, whether they are elastic or plastic.