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Experimental investigations into shot peened ductile steel have been carried out, applying three surface nishing conditions: as machined, standard shot peening using 100% coverage and severe shot peening with 1000% coverage (high exposure time). The properties of the shot peened surfaces were examined and characterised, and specimens were then submitted to three point bending tests. The fatigue limit was determined for each case. In this way, the dependence of fatigue behaviour on initial surface nishing properties was determined, and a relationship is suggested to describe and correlate fatigue limits with initial surface properties. A phenomenological approach is proposed to characterise and to correlate qualitatively and quantitatively the in uence of local shot peened surface properties on fatigue limit of treated specimens. The Crossland multiaxial failure high cycle fatigue criterion is used in this approach to model the in uence of each surface property.MST/4921

This work proposes an engineering approach to investigate the fatigue lifetime of styrene–butadiene rubber under uniaxial loadings. Two specimen geometries are considered: axisymmetric sample AE2 and diablo sample AE42. Specimens are cycled with a sinusoidal waveform at 5 Hz for different maximum displacement values and a zero load ratio. The various damage parameters, commonly used for fatigue life calculation, are reviewed and discussed. Then fatigue models with diverse damage parameters are generated from the fatigue lives experimentally observed for specimen AE2. The efficiency of each predictive model is evaluated in terms of coefficient of determination R2. It is shown that all the studied damage parameters allow excellent fatigue-life estimations with R2 greater than 0.9. A nonlinear finite element analysis model using ABAQUS software for specimen AE42 is then set up. It is found that the model developed for specimen AE2 is appropriate to estimate the fatigue life time of AE42. Indeed, the obtained fatigue live predictions are in excellent agreement with the experimental fatigue results.

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