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Modélisation de l'influence des défauts de surface sur le comportement en fatigue de nuances d'acier innovantes

Abstract : The steel manufacturers develop nowadays high strength steels as CP800 grade for automotive applications for the purpose of lightening vehicles. Such steels are strongly sensitive from the fatigue behaviour point of view to the surface defects generated by metal forming or cutting of steel sheets. Surface defects of different types and sizes were machined by electroerosion on CP800 specimens so that they are similar to the surface defects observed on steel sheets after stamping or cutting. The present study deals with the numerical and the experimental fatigue behaviour simulation of these specimens.The defect influence modelisation about the steel fatigue behaviour uses either the critical plane approach or the integral approach in multiaxial fatigue.The stress gradient influence contributes also to the fatigue life prediction of the defective simples.The numerical simulation aims to assess stress states and stress gradient fields within the tested specimens in the vicinity of their own surface defects. Accounting for stress gradients strongly improves the ability of multiaxial fatigue criteria to accurately predict the actual fatigue resistance of defective specimens. It shows also that multiaxial criteria have to be calibrated over fatigue test results with high stress gradients to properly predict the fatigue behaviour of high strength steel with surface small defect.
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Submitted on : Tuesday, January 5, 2021 - 2:19:55 PM
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2019CLFAC086_NIAMCHAONA.pdf
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  • HAL Id : tel-03097660, version 1

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Wichian Niamchaona. Modélisation de l'influence des défauts de surface sur le comportement en fatigue de nuances d'acier innovantes. Génie mécanique [physics.class-ph]. Université Clermont Auvergne, 2019. Français. ⟨NNT : 2019CLFAC086⟩. ⟨tel-03097660⟩

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