No abstract

It is proposed to develop and identify a probabilistic two-scale model for HCF that accounts for the failure of samples but also for the thermal effects during cyclic loadings in a unified framework.The probabilistic model is based on a Poisson point process. Within the weakest link theory, the model corresponds to a Weibull law for the fatigue limits. The thermal effects can be described if one considers the same hypotheses apart from the weakest link assumption. A method of identification is proposed and uses temperature measurements to identify the scatter in an S/N curve. The validation of the model is obtained by predicting S/N curves for different effective volumes of a dual-phase steel.

Identification of the scatter in high cycle fatigue from temperature measurements. Comptes Rendus Mécanique, Elsevier Masson, 2004, 332, pp.

The influenceofp lasticinstabilitieson the mechanicalp ropertiesof ahigh-manganese austeniticF eMnCsteelThe serrationsobserved on the stress-strain curvesof a Fe-22Mn-0.6Cwt.% steel presentall the phenomenological featuresassociated withd ynamicstrain ageing,including negativestrain ratesensitivity and thermalactivation. We showt hatt he activation energyis,however,inexplicably lowand thatt he dynamicstrain ageing contribution to work-hardening islimited,i. e. mechanicaltwinning ist he dominants train hardening mechanism. Finally,novel insitu experiments areused tostudyt he dynamicb ehaviour of intensestrain localisation bandsw hichf ormo ntensile samples.Inspiteo fthe localisation behaviour seen in tensile tests,stamped parts do notpresentanysurfacedefects.

No abstract