PSI - Issue 2_A

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 Struc ural Integrity 2 (2016) 166 –1667 Available online at www.sciencedirect.com ScienceDirect 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 Application of local approach to fracture of an RPV steel: effect of the crystal plasticity on the critical carbide size. Pierre Forget* a , Bernard Marini a , Ludovic Vincent a a CEA, DEN-Service de Recherches Métallurgiques Appliquées, Université Paris-Saclay, Gif-sur-Yvette, F-91191, France Abstract Avoidance of brittle fracture is a key issue of the integrity assessment of the nuclear reactor pressure vessels (RPV). The microstructural heterogeneities of these heavy components are in direct relation with the scatter of brittle fracture toughness. A microstructure informed brittle fracture (MIBF) model is used here to capture the effect of some microstructural features. This local approach type model is based on the Griffith criterion for brittle fracture applied to micro cracks nucleated on carbides. The size distribution of the cleavage initiators introduces a source of scatter for the fracture stress. The originality of the MIBF model is to introduce a second source of scatter: the stress distribution inside a representative aggregate of the bainitic microstructure. These stresses are the average for each bainitic packet of the maximum principal stresses. Their non-uniform distribution is due to the incompatibilities of plastic deformation introduced by crystallographic misorientations between packets. Finite elements simulations on aggregates repres ntative of the steel bainitic microstructure ar performed to identify the stress distributions. The size distribution of cleavage initiators is the carbide size distribution as the carbides cracking induced by plastic deformation is considered to be the main damage leading to cleavage propagation in RPV steel. The only free parameter of the model is the effective surface energy  f . Applied to the Euro fracture toughness dataset, the MIBF model predicts the specimen size effect on fracture toughness as well as the temperature dependence of the fracture toughness up to 200 MPa√m. The analysis of the numerical results shows that taking into account the incompatibility stresses widens the size range of carbides potentially implied in the fracture process. However, approximatively half of these carbides have still a size larger than the largest observed sizes underlining the importance to perform the determination of size distributions on a very large number of precipitates. 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. © 2016 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of PCF 2016. © 2016 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of ECF21. Keywords: fracture toughness ; brittle fracture; RPV steel ; microstructure ; carbides ; local approach ; MIBF model

Keywords: High Pressure Turbine Blade; Creep; Finite Element Method; 3D Model; Simulation.

* Corresponding author. Tel.: +33-1-69087896; fax: +33-169087167. E-mail address: pierre.forget@cea.fr

* Corresponding author. Tel.: +351 218419991. E-mail address: amd@tecnico.ulisboa.pt 2452-3216 © 2016 The Authors. Published by Elsevier B.V. Peer-review 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 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.2016.06.210