PRISE EN COMPTE DES CONTRAINTES RESIDUELLES ET DES DEFORMATIONS PLASTIQUES DANS UN CRITERE DE FATIGUE

Abstract

In this study we propose a method for prediction of the fatigue-life for different materials subjected to constant amplitude multiaxial proportional loading. We have planned a new fatigue criterion based on Crossland’s one, but it takes into account both residual stresses and plastic strains. The fatigue life can be evaluated from knowledge of both the equivalent stress and the SN curves in reversed torsion and alternating bending. We test the model on a carbon steel type S 45 C. To demonstrate the use of algorithm developed in this work, one case study problems was solved. This case consists of a specimen which is subjected to uniaxial tensile stress combined with alternating bending moment. The model can determine the safe domains in the frame with axis load forces, in order to choose the adequate force loads. The computing program can be used by many industries to decide the adequate loading for a given fatigue life. We have also compared the fatigue life in both cases of material state: shot peened and no shot peened . The results of this comparison leads to show the beneficial effects of shoot peening process on fatigue behavior of materials.