Fatigue Limits Prediction of Shot Peened Materials

Author:  H. Guechichi*, L. Castex**
Source:  Conf Proc: ICSP-9 (pg 221-228)
Doc ID:  2005089
Year of Publication:  2005
*Department of Mechanics, Mostaganem University, B.P. 188 Mostaganem, Algeria. **INSA Toulouse, 135 Avenue de Rangueil, 31077 Toulouse Cedex 4, France ABSTRACT Shot peening is an effective method of improving the fatigue strength of components and structure. The change in surface layer properties caused by shot peening was evaluated by residual stress and cold work. The X-ray diffraction non-destructive method of measuring is used. In order to predict fatigue strength of metal components, it is necessary to apply a fatigue limit criterion that takes into consideration compressive residual stress and cold work. The theoretical model, gives a better approach of shot peening material fatigue behaviour. The model takes into account two essential beneficial effects that are: compressive residual stresses and the increase of cold work. It was demonstrated that the effect of cold work on fatigue strength is more important than that of residual stress. The fatigue limit criterion predicts that the crack origin is located into the region under the surface hardened layer. Comparison of predictions of this criterion against experimental fatigue limit data showed good agreement. The methodology followed to build this model could be adequately modified to derive models for other surface treatments.

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