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Etude expérimentale et modélisation de l'endommagement du contact aube-disque de soufflante soumis à des chargements de fretting fatigue

Abstract : Optimization of structures design requires a better understanding of their damage process. This study focuses on the characterisation of the blade/disk contact damaging process on aircraft engines. That mechanical structure is subjected to a normal load (centrifugal forces) combined with a tangential force (blade dynamic). Thus the Ti-6Al-4V disk seat sees a complex fretting fatigue loading. This type of solicitation can generate a series of degradations like cracking. Experimental and numerical simulation of this damaging is very difficult considering the present state of arts. The first aim of this work is to develop a new experimental set-up with the appropriate instrumentation in order to conduct a qualitative and a quantitative analysis of the cracking in a Ti-6Al-4V/Ti6-Al-4V contact. The second goal is to build a life prediction numerical model that would be able to use the data obtain with the new experimental tests. The new dual-actuator fretting-fatigue set-up is now operational. It allows to run single contact test under different loading combinations: fretting and fatigue loads can be applied in phase or in a way to simulate the real 'in flight' conditions. New instrumentations have been added in order to follow the crack initiation and propagation: potential-drop technique and acoustic emission. Thanks to this new test procedure, the first fretting Wöhler curve to crack nucleation have been described (fretting load vs number of cycles to crack nucleation) for two contact geometries (cylinder on flat and flat on flat). The separate influences of fatigue and fretting parameters have been determined. The mains parameters are: the contact characteristics, the stress level and the force combination modes ('in phase' cycles or 'in-flight' cycles). Moreover, the very first crack propagation kinetics have been drowned. Also, a major influence of the fretting on the crack propagation has been exposed. The qualitative analysis conducted with the acoustic emission has revealed a three steps crack propagation process. The crack propagation process evolves with the decrease of the contact influence. A model has been developed in order to predict crack initiation and propagation lives. Even if the model suffers from a major limitation due to the difficult considerations of the stress gradient effects, it has shown very good results through its ability to directly include experimental data. This work has led to major breakthroughs in the understanding of the cracking mechanisms and their simulation. This forms solid foundations for future predictions of the blade/disk interface durability.
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https://tel.archives-ouvertes.fr/tel-00730679
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Submitted on : Thursday, November 8, 2012 - 6:37:16 PM
Last modification on : Wednesday, November 20, 2019 - 2:27:33 AM
Long-term archiving on: : Saturday, February 9, 2013 - 3:51:24 AM

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TH_T2268_jmeriaux.pdf
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  • HAL Id : tel-00730679, version 2

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Jean Meriaux. Etude expérimentale et modélisation de l'endommagement du contact aube-disque de soufflante soumis à des chargements de fretting fatigue. Mécanique des matériaux [physics.class-ph]. Ecole Centrale de Lyon, 2010. Français. ⟨NNT : 2010ECDL0014⟩. ⟨tel-00730679v2⟩

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