PSI - Issue 2_B

ScienceDirect Available online at www.sciencedirect.com Av ilable o line at ww.sciencedire t.com ScienceDirect Structural Integrity Procedia 00 (2016) 000 – 000 Procedia Structu al Integrity 2 (2016) 95 –957 Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia 00 (2016) 000–000 Available online at www.sciencedirect.com ScienceDir ct Structural Integrity Procedia 00 (2016) 000–000

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XV Portuguese Conference on Fracture, PCF 2016, 10-12 February 2016, Paço de Arcos, Portugal Thermo-mechanical modeling of a high pressure turbine blade of an airplane gas turbine engine P. Brandão a , V. Infante b , A.M. Deus c * a Department of Mechanical Engineering, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1, 1049-001 Lisboa, Portugal b IDMEC, Department of Mechanical Engineering, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1, 1049-001 Lisboa, Portugal c CeFEMA, Department of Mechanical Engineering, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1, 1049-001 Lisboa, Portugal Abstract During their operation, modern aircraft engine components are subjected to increasingly demanding operating conditions, especially the high pressure turbine (HPT) blades. Such conditions cause these parts to undergo different types of time-dependent degradation, one of which is creep. A model using the finite element method (FEM) was developed, in order to be able to predict the creep behaviour of HPT blades. Flight data records (FDR) for a specific aircraft, provided by a commercial aviation company, were used to obtain thermal and mechanical data for three different flight cycles. In order to create the 3D model needed for the FEM analysis, a HPT blade scrap was scanned, and its chemical composition and material properties were obtained. The data that was gathered was fed into the FEM model and different simulations were run, first with a simplified 3D rectangular block shape, in order to better establish the model, and then with the real 3D mesh obtained from the blade scrap. The overall expected behaviour in terms of displacement was observed, in particular at the trailing edge of the blade. Therefore such a model can be useful in the goal of predicting turbine blade life, given a set of FDR data. 21st European Conference on Fracture, ECF21, 20-24 June 2016, Catania, Italy Near-threshold fatigue propagation of physically short and long cracks in Titanium alloy Chretien Gaëlle a,b , Sarrazin-Baudoux Christine a , Leost Laurie b , Hervier Zeline b a Institut Pprime, UPR CNRS 3346, CNRS – Université de Poitiers – ENSMA, Physics and Mechanics of Materials Department, ISAE-ENSMA, 1 avenue Clément Ader, BP 40109, 86961 Futuroscope – Chasseneuil, France b Turbomeca – SAFRAN Group, Materials, Processes and Investigations Department, 64511 Bordes Cedex, France Abstract Damage tolerance is today imposed by the regulations to dimension aeronautical turbine critical parts. Thus resistance of these parts to potential anomalies is assessed. It requires to study, besides standard long cracks, the propagation of cracks of little dimension (some tenth of mm for initial length) which can have an atypical behavior consisting in crack propagation at lower stress intensity factor range than the threshold for long crack. In this context, this study is focused on a bimodal Titanium alloy (TA6V) tested at different temperatures: room temperature and 400°C at a low load ratio R of 0.1, which corresponds to loading of manufactured compressor impellers in these materials. Tests are run on compact tension specimens initially pre-cracked at constant applied stress intensity factor range (  ) and then cracked to threshold in view of obtaining a long crack of a/W~0,5. Physically 2D through-thickness short fatigue cracks are created by gradually removing the plastic wake of this long crack in order to obtain a crack length as short as possible (0.1 mm). Next the short crack obtained is propagated in view of getting different thresholds for different crack lengths according to a procedure of load decrease. Crack closure contribution is systematically measured using the compliance variation technique with umerical data acquisition and filtering for accurate detection of the stress intensity factor (SIF) at the crack opening. 2D short crack propagation behavior is compared to long crack behavior with a special attention given to crack closure. The threshold evolution in function of the crack length is investigated using a Kitagaw diagra approach for deter ini g a non-propaga ion criterion of short cracks. © 2016 The Authors. Published by Els vier B.V. Peer-review under responsibil ty f the Scien ific Committee of ECF21. Keywords: near threshold fatigue crack propagation, short cracks, crack opening, Kitagawa diagram 1. Introduction Damage tolerance calculations are more and more required by European Aviation Safety Agency (EASA) in order to better know life of aeronautical turbine critical parts. The presence in these parts of preexisting anomalies, which are non-detectable by actual inspection means, or anomalies due to functioning requires defining the conditions under which cracks or defects are efficiently non-propagating. The existence of threshold stress intensity factor range dependent on environmental and solicitation conditions is not sufficient to determine if it will propagate. Elber (1970) defined the concept of effective stress intensity factor range, which leads to an effective threshold stress intensity factor more representative of the intrinsic material properties (Elber (1970), Newman and Elber (1988)). The importance to characterize near-threshold fatigue crack growth has been emphasized by the specificities of short fatigue cracks (Pearson (1975), Miller (1982), Suresh and Ritchie (1984), Zeghloul and Petit (1985), Lankford and Ritchie (1986), Pineau (1986), Ritchie and Yu (1986), McClung and Sehitoglu (1988)). 21st European Conference on Fracture, ECF21, 20-24 June 2016, Catania, Italy Near-threshold fatigue propagation of physically short and long cracks in Titanium alloy Chretien Gaëlle a,b , Sarrazin-Baudoux Christine a , Leost Laurie b , Hervier Zeline b a Institut Pprime, UPR CNRS 3346, CNRS – Université de Poitiers – ENSMA, Physics and Mechanics of Materials Department, ISAE-ENSMA, 1 avenue Clément Ader, BP 40109, 86961 Futuroscope – Chasseneuil, France b Turbomeca – SAFRAN Group, Materials, Processes and Investigations Department, 64511 Bordes Cedex, France Abstract Damage tolerance is today imposed by the regulations to dimension aeronautical turbine critical parts. Thus resistance of these parts to potential anomalies is assessed. It requires to study, besides standard long cracks, the propagation of cracks of little dimension (some tenth of mm for initial length) which can have an atypical behavior consisting in crack propagation at lower stress intensity factor range than the threshold for long crack. In this context, this study is focused on a bimodal Titanium alloy (TA6V) tested at different temperatures: room temperature and 400°C at a low load ratio R of 0.1, which corresponds to loading of manufactured compressor impellers in these materials. Tests are run on compact tension specimens initially pre-cracked at constant applied stress intensity factor range (  ) and then cracked to threshold in view of obtaining a long crack of a/W~0,5. Physically 2D through-thickness short fatigue cracks are created by gradually removing the plastic wake of this long crack in order to obtain a crack length as short as possible (0.1 mm). Next the short crack obtained is propagated in view of getting different thresholds for different crack lengths according to a procedure of load decrease. Crack closure contribution is systematically measured using the compliance variation technique with numerical data acquisition and filtering for accurate detection of the stress intensity factor (SIF) at the crack opening. 2D short crack propagation behavior is compared to long crack behavior with a special attention given to crack closure. The threshold evolution in function of the crack length is investigated using a Kitagawa diagram approach for determining a non-propagation criterion of short cracks. © 2016 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of ECF21. Keywords: near threshold fatigue crack propagation, short racks, crack opening, Kitagawa diagram 1. Introduction Damage tolerance calculations are more and more required by European Aviation Safety Agency (EASA) in order to better know life of aeronautical t ine critical parts. Th pres nce in these parts of preexisting anomalies, which are non-detectable by actual inspection means, or anomalies due to functioning requires defining the conditions under which cracks or defects are efficiently non-propagating. The existence of threshold stress intensity factor range dependent on environmental and solicitation conditions is not sufficient to determine if it will propagate. Elber (1970) defined the concept of effective stress intensity factor range, which leads to an effective threshold stress intensity factor more representative of the intrinsic material properties (Elber (1970), Newman and Elber (1988)). The importance to characterize near-threshold fatigue crack growth has been emphasized by the specificities of short fatigue cracks (Pearson (1975), Miller (1982), Suresh and Ritchie (1984), Zeghloul and Petit (1985), Lankford and Ritchie (1986), Pineau (1986), Ritchie and Yu (1986), McClung and Sehitoglu (1988)). Copyright © 2016 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://cr ativecomm s.org/licens s/by-nc-nd/4.0/). r-r ie un r r i ilit f t i ifi itt f . © 2016 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of PCF 2016. Keywords: High Pressure Turbine Blade; Creep; Finite Element Method; 3D Model; Simulation.

* Corresponding author. Tel.: +351 218419991. E-mail address: amd@tecnico.ulisboa.pt * Corresponding author. Tel.: +33 5 49 49 82 16; fax: +33 5 49 49 82 38. E-mail address: gaelle.chretien@ensma.fr * Corresponding author. Tel.: +33 5 49 49 82 16; fax: +33 5 49 49 82 38. E-mail address: gaelle.chr tien@ensm .fr

2452-3216 © 2016 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of PCF 2016. Copyright © 2016 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license ( http://creativecommons.org/licenses/by-nc-nd/4.0/ ). Peer review under responsibility of the Scientific Committee of ECF21. 10.1016/j.prostr.2016.06.122 2452-3216 © 2016 The Authors. Published by Elsevier B.V. Peer- eview under responsibility of the Scientific Committee of ECF21. 2452-3216 © 2016 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of ECF21.