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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. Dynamic fracture in rubber toughened polymers: the influence of the fracture surface roughness Jean-Benoˆıt Kopp a, ∗ , Christophe Fond b , Jean Schmittbuhl c , Olivier Noel d a I2M, Universite´ de Bordeaux, Esplanade des Arts et Me´tiers, F33400 Talence b ICUBE, Universite´ de Strasbourg, 2 rue Boussingault, F67000 Strasbourg c EOST, Universite´ de Strasbourg, 5 rue Re e´ Descartes, F67000 Strasbourg d IMMM, Universite´ du Maine, Avenue Olivier Messiaen, F72085 Le Mans Abstract Dynamic fracture tests have been performed with rubber toughened polymethylmethacrylate (RT-PMMA) samples. For these kinds of materials the macroscopic crack tip velocity ˙ a ≈ 0.6 c r is observed to not change during propagation whatever the available dy namic energy release rate. Therefore dynamic fracture energy values G Idc , according to the crack velocity in a classical formalism, are not unique at the branching velocity (approximately 0.6 c r ). Otherwise the classical formalism considers the amount of created surface during propagation as a flat rectangle (the sample thickness multiplied by the crack length). Nevertheless the RT-PMMA fracture surface roughness are observed to fluctuate as a function of the dynamic energy release rate. The more (respectively less) the dynamic critical energy release rate the rough (respectively smooth) the fracture surface. The real 3D topography of the created surface has to be included in the energy balance to quantify an intrinsic material fracture energy. If not, fracture energy can be significantly underestimated. Using di ff erent types of profilometer, the precise amounts of created surfaces for di ff erent locations along the fracture were measured both before and after branching at di ff erent scales. Since the fracture surface roughness depends on the analysis scale some precautions are requested in the fracture surface analysis. A self-a ffi ne geometrical model is introduced using two parameters: the Hurst exponent and the topothesy. The multi-scale description of the fracture surface roughness by a self-a ffi ne model is shown to provide a significantly better approximation of the created surface. A new and original geometrical method is introduced to estimate self-a ffi ne parameters: the 3D surface scaling method. It is based on the estimate of the amount of created fracture surface using a routine which makes a surface triangulation. Hurst exponents are shown to be unique, χ = 0 . 6 ± 0 . 1 for the di ff erent fracture zones and measurement scales. It is shown that topothesy ratios indicate a significant di ff erence of fracture surface roughness amplitude depending on the observation resolution when the detrending technique is not correctly introduced. Indeed, the lower the topothesy, the smoother the fracture surface. c � 2016 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of ECF21. Dynamic fracture in rubber toughened polymers: the influence of the fracture surface roughness Jean-Benoˆıt Kopp a, ∗ , Christophe Fond b , Jean Schmittbuhl c , Olivier Noel d a I2M, Universite´ de Bordeaux, Esplana e des Arts et Me´tiers, F33400 Talence b ICUBE, Universite´ de Strasbourg, 2 rue Boussingault, F67000 Strasbourg c EOST, Universite´ de Strasbourg, 5 rue Rene´ Descartes, F67000 Strasbourg d IMMM, Universite´ du Maine, Avenue Olivier Messiaen, F72085 Le Mans Abstract Dynamic fracture tests have been performed with rubber toughened polymethylmethacrylate (RT-PMMA) samples. For these kinds of materials the macroscopic crack tip velocity ˙ a ≈ 0.6 c r is observed to not change during propagation whatever the available dy namic energy release rate. Therefore dynamic fracture energy values G Idc , according to the crack velocity in a classical formalism, are not unique at the branching velocity (approximately 0.6 c r ). Otherwise the classical formalism considers the amount of created surface during propagation as a flat rectangle (the sample thickness multiplied by the crack length). Nevertheless the RT-PMMA fracture surface roughness are observed to fluctuate as a function of the dynamic energy release rate. The more (respectively less) the dynamic critical energy release rate the rough (r spectively smooth) the fracture surface. The real 3D topography of the created surfac has to be nclud d in the e rgy balance to quantify an ntrinsic mat rial fracture en y. If not, fracture energy can be signific ntly underestimated. Using di ff erent types of profilometer, the precise amounts of cr at d surfaces for di ff erent ocations along the fracture were measured oth before and fter branching at di ff e ent cales. Since the fracture surface roughn ss depends on the anal sis scale some prec utions are request d in the frac ure surfac analysis. A self-a ffi n geometrical model is introduced usi g two pa am ters: the Hur t exponent an the to othe y. The multi-scale descr ption of the fracture surface roughn ss by a self-a ffi mod l is shown to provide a significantly better approximation of the created surface. A new and orig nal geometrical method is int odu ed to estimate self-a ffi ne parameters: the 3D surface scaling method. It is based n the estimate of the amount of created fracture surface using a routine which makes a surface triangulation. Hurst exponents are shown to be unique, χ = 0 . 6 ± 0 . 1 for the di ff erent fracture zones and measurement scales. It is shown that topothesy ratios indicate a significant di ff erence of fracture surface roughness amplitude depending on the observation resolution when the detrending technique is not correctly introduced. Indeed, the lower the topothesy, the smoother the fracture surface. c � 2016 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of ECF21. Keywords: Dynamic fracture ; polymers ; surface roughness and self-a ffi nity. 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/). r-review under responsibility f the Scienti Committee of ECF21. © 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. 21st European Conference on Fracture, ECF21, 20-24 June 2016, Catania, Italy 21st European Conference on Fracture, ECF21, 20-24 June 2016, Catania, Italy

Keywords: Dynamic fracture ; polymers ; surface roughness and self-a ffi nity.

* Corresponding author. Tel.: +351 218419991. E-mail address: amd@tecnico.ulisboa.pt ∗ Corresponding author. Tel.: + 33 556845392. E-mail address: jean-benoit.kopp@ensam.eu ∗ Corresponding author. Tel.: + 33 556845392. E-mail address: jean-benoit.kopp@ensam.eu

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.2016.06.061 2452-3216 c � 2016 The Authors. Published by Elsevier B.V. e r-review under responsibility of the Scientific Committee of ECF21. 2452-3216 c � 2016 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of ECF21.