r ECOLE DOCTORALE SI-MMEA (http://simmea.ed.univ-poitiers.fr/) 2014 Doctoral research projects for PhD recruitment I- General information : VILLE, LABORATOIRE Town, Laboratory Etablissement Institution TITRE en français French title TITRE en anglais English title Directeur(s) de thèse (HDR) Supervisor(s) Taux d’encadrement prévu (%) Supervising rates (%) Co-encadrant(s) Co-supervisor(s) Taux d’encadrement prévu (%) Supervising rates (%) Contact pour informations Contact for information Compétences requises Pre requisite Poitiers (FR) : x P’D1* P’D2* P’D3* Limoges (FR) : SPCTS* GEMH* La Rochelle (FR) : LaSIE* UP* ENSMA* UL* ENSCI* ULR* INFLUENCE DU VIEILLISSEMENT SUR LA RESISTANCE A LA FISSURATION PAR FATIGUE A HAUTE TEMPERATURE D’ALLIAGES DE TITANE POUR MATS-REACTEURS INFLUENCE OF AGEING ON FATIGUE CRACK GROWTH RESISTANCE OF TITANIUM ALLOYS FOR ENGINE PYLONS Nom 1 : Villechaise Nom 2 : Hénaff Nom 1 : Arzaghi Prénom 1 : Patrick % : 33 Prénom 2 : Gilbert % : 33 Prénom 1 : Mandana HDR ? oui x non %: Nom 2 : Prénom 2 : HDR ? oui non %: Nom : Hénaff Tel : 33 5 49 49 82 33 Prénom : Gilbert Email : [email protected] Metallurgy – Mechanics of Materials – Fracture Mechanics *Sigle : P’D1, P’D2 et P’D3 : Départements D1, D2 et D3 de l’institut P’ : http://www.pprime.fr/; SPCTS : http://www.unilim.fr/spcts/; GEMH : http://www.avrul.fr/spip.php?rubrique39; LaSIE : http://www.univ-larochelle.fr/LaSIE, UP http://www.univ-poitiers.fr/, ENSMA http://www.ensma.fr/, UL : http://www.unilim.fr/, ENSCI : http://www.ensci.fr/, ULR : http://www.univ-larochelle.fr/. II- Description of the 3 year doctoral research project (please make a complete description of the doctoral research project. Do not forget to mention when the contrat will start and to give an estimation of the net salary per month) In order to meet with the requirements of fuel saving and environmental performance of airlines, and more generally from the civil society, engine manufacturers develop more efficient engines with higher bypass ratio. This trend induces direct consequences on the design of the pylon. Indeed, increasing the bypass ratio implies that the outer diameter of the platform increases, thus reducing the space between the engine and the wing. Therefore the design of pylons moves towards greater compactness and therefore potentially to higher service temperatures. This raises the question of the durability of the metals used in such aerostructures which are designed according to a damage tolerance philosophy. Indeed, due to elevated temperature, these materials have to withstand, in addition to mechanical loading, surface oxydation and metallurgical ageing mechanical. The objectives of the DUSTI research program sponsored by the National Research Agency (ANR) is r thus to get insights into metallurgical processes induced by long term thermal exposure and to evaluate the impact of this ageing on mechanical properties of a selection of three titanium alloys. More precisely, the PhD thesis proposed here aims in characterising the Fatigue Crack Growth resistance of these materials at room and at elevate temperatures, in the as-received as in different ageing conditions. The guidelines of this work are based on one hand in approaching as close the actual conditions of service, on the other hand in uncoupling the various processes governing damage at the crack tip. The objective is to predict the damage tolerance capability of the structure for a given ageing condition. This implies in particular to determine the effect of ageing on the Cyclic-StressStrain behaviour of the material as the interaction between cyclic deformation and oxydation. The research program will be organised as follows: - Microstructural analyses of the alloys in the as-received and in the aged conditions; - Contribution to the determination of the kinetics of the metallurgical processes involved in ageing - Characterisation of the FCG behaviour of the 3 alloys in the as-received at room and at maximum service temperature, which depends on the alloy under consideration; - Evaluation of the impact of selected ageing conditions on FCG; - Characterisation of the CSS behaviour of the alloys, in the as-received and in selected ageing conditions; - Evaluation of the respective effect of environment and temperature on FCG, in particular by conducting specific tests under vacuum; The research work is basically experimental. However modelling and FEA will be implemented in the program, for instance to compute the stress-strain field at the crack tip in order to propose a fatigue crack growth model that can account for the governing processes that will have been identified. With this respect, a close connexion with a parallel study conducted in the framework of DUSTI in CIRIMAT (Toulouse) on the characterisation on local mechanical properties in a zone affected by oxydation at the crack tip will have to be established. Lab facilities to be used: electro-mechanical and servo –hydraulic load frames for fatigue test at elevated temperature, light microscope, SEM, EBSD, ATG, computation facilities. Partners: Airbus, Airbus Group Innovations, Liebherr Aerospace, Aubert&Duval, Institut Jean Lamour, CIRIMAT The contract is expected to start on October 1st, 2014. Salary : ~ 1300 € net/month