Damage tolerance issues peculiar to supersonic civil transport aircraft

International audienceThis paper presents results of experimental investigations on creep, fatigue and creep-fatigue crack growth behaviour of the 2650-T6 aluminium alloy in temperature, along with numerical simulation of stress distribution around the tip. The results will provide a preliminary database on the fatigue properties of the 2650 T6 alloy under loading representative of service conditions and predict the damage tolerance assessment of the future civil transport aircraft fuselage. Testing were carried out to evaluate the effect of creep-fatigue interaction and get insight into the damage processes. Numerical simulation of stress field around the crack tip were performed to account for the observed behaviour. The crack growth rates measured on CT specimens were correlated with the stress intensity factor K. In creep tests, an influence of the initial value of K on the low crack growth rates is shown. The behaviour is not deeply affected by temperature in the range 100-130°C. However, at 160°C, crack growth rates are faster than at 130°C due to an increase of creep contribution in local stress-strain response, that might be enhanced by ageing. In fatigue (triangular wave loading), no difference is noticed in crack growth rates at 20 and 130°C. In creep-fatigue, the crack growth rates (trapezoidal wave loading) at 130°C are faster than during creep or fatigue crack growth in a given domain of K. The fracture surfaces indicate that creepfatigue interaction is characterised by a higher portion of intergranular fracture. Thus, a detrimental creep-fatigue interaction at 130°C has to be taken into account in crack propagation law used in damage tolerance analysis. The constitutive law used in the calculations for numerical simulation was identified on the basis of cyclic relaxation tests. The computation results indicate that the von Mises stress at the beginning of dwell during creep-fatigue is higher than in the case of creep and fatigue

Fatigue properties of rail steels

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1983.MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE.Includes bibliographical references.by Bertrand Journet.M.S

Prévision de la fissuration par fatigue en présence de contraintes résiduelles

La démonstration de la sécurité des structures aéronautiques repose sur des calculs de scénarii de fissuration en fatigue. Les calculs de propagation doivent prendre en compte la présence éventuelle de contraintes résiduelles qui sont induites par les procédés d'assemblage des pièces. Les alésages des jonctions de fuselage sont concernés par cet aspect. Une approche prévisionnelle de la fissuration en fatigue des alésages expansés et montés en interférence est présentée. L'approche est validée sur des essais représentatifs des cas de service. Une application de l'approche à des calculs d'aide à la conception est présentée

Modelling the mineralogical composition and solubility of mineral dust in the Mediterranean area with CHIMERE 2017r4

International audienceModelling of mineral dust is often done using one single mean species. But for biogeochemical studies, it could be useful to access to a more detailed information on differentiated mineral species and the associated chemical composition. Differentiating between mineral species would also induce different optical properties and densities and then different radiative impact, transport and deposition. In this study, the mineralogical differentiation is implemented in the CHIMERE regional chemistry-transport model, by using global databases. The results show that this implementation does not change the results much in terms of aerosol optical depth, surface concentrations and deposition fluxes. But the information on mineralogy, with a high spatial (a few kilometres) and temporal (1 h) resolution, is now available and is ready to be used for future biogeochemical studies

Chaînages de code amont et aval à la simulation numérique du soudage pour optimiser les structures soudées

International audienc

Problèmes d'adaptation du traitement antivitamine K dans les troubles du rythme supraventriculaires avant choc électrique externe (suivi sur un an dans le Service de cardiologie du Groupe hospitalier Sud Réunion)

BESANCON-BU Médecine pharmacie (250562102) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF

Couplage entre essais et simulation en soudage

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