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INTEGRATION DES PHENOMENES DYNAMIQUES DANS L'ANALYSE EN FATIGUE DES GARNITURES DE FORAGES

Abstract : Failures of drillstrings are costly events for oil and gas industry. In our researches, we focus on threaded connections submitted to cyclic loadings occurring during the drilling process.
The objective of this work is therefore to elaborate a fatigue design methodology based on a multiscale approach:
• the drillstring's scale dedicated to the determination of the loading history (tension, torsion and flexion),
• the threaded connection's scale devoted to the computation of the macroscopic stress field,
• the grain of metal's scale dedicated to the problem of fatigue.
Because of the time computation, the use of finites elements method is not suitable for estimating instantaneously the damage of the different components during the drilling process. Thereby we developed a semi-analytical elastic stress field solution.
Finally fatigue tests have been performed on small scale threaded connection and the results are compared with the fatigue life predictions obtained with an extension of the Dang Van criterion in the finite life domain. The results show that fatigue phenomenon are induced by stress concentrations and that the application of a local fatigue criterion leads to conservative fatigue life estimations. Therefore a numerical study at the crystal scale has been performed to explain these observations and correction are made to improve the fatigue life predictions.
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Contributor : Mohamed Ferjani <>
Submitted on : Thursday, March 1, 2007 - 4:30:34 PM
Last modification on : Thursday, September 24, 2020 - 4:00:22 PM
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  • HAL Id : tel-00134358, version 1

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Mohamed Ferjani. INTEGRATION DES PHENOMENES DYNAMIQUES DANS L'ANALYSE EN FATIGUE DES GARNITURES DE FORAGES. Matériaux. Ecole Polytechnique X, 2006. Français. ⟨tel-00134358⟩

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