PSI- Issue 9

ScienceDirect Available online at www.sciencedirect.com Av ilable o line at www.sciencedire t.com Sci ceDirect Structural Integrity Procedia 00 (2016) 000 – 000 Procedia Structu al Integrity 9 (2018) 25 –256 Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia 00 (2018) 000–000 Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia 00 (2018) 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. IGF Workshop “Fracture and Structural Integrity” Engineering thoughts on Hydrogen Embrittlement G.Gabetta a , P.Cioffi a , R.Bruschi b a Eni DOT, Via Emilia 1, 20097 San Donato Milanese, Italy b Saipem SpA, Via Toniolo, Fano, Italy Abstract Hydrogen Embrittlement (HE) is a topical issue for pipelines transporting sour products. Engineers need a simple and effective approach in materials selection at design stage. In other words, they must know if a material is susceptible to cracking, to be able of:  selecting the right material  and apply correct operational measures during the service life. Following ASTM F2078, HE is “a permanent loss of ductility in a metal or alloy caused by hydrogen in combination with stress, either externally applied or internal residual stress”. In many cases, hydrogen can play a role in crack propagation, as for instance in Stress Corrosion Cracking (SCC) and Corrosion Fatigue (CF). Three parameters are required to cause failure: presence of hydrogen, tensile stress, and material susceptibility. The two previous ones are triggering the failure, while the root cause is usually material susceptibility. This is why material selection is the important step to safely manage engineering structural materials. As an example, material selection for sour service pipeline is the object of well-known standards, e.g. by Nace International and EFC: they pose some limits in the sour service of steels, with reference to surface hardness. These standards have shown some weak points, namely: • In the definition of sour service; • In defining the role of crack initiation and propagation, considering that in Hydrogen embrittlement, stress state and stress variations are very important. As for the second point, in hydrogen generation anodic processes shall be taken into account too. For instance, there is a relationship between corrosion resistance and crack susceptibility. In carbon and low alloy steels, cracking will not normally occur when there is a significant corrosion rate. If a brittle layer (or a brittle spot) is present on the metal surface, this one can initiate a crack. IGF Workshop “Fracture and Structural Integrity” Engineering thoughts on Hydrogen Embrittlement G.Gabetta a , P.Cioffi a , R.Bruschi b a Eni DOT, Via E ilia 1, 20097 San Donato Mi anese, Italy b Saipem SpA, Via Toniolo, Fano, Italy Abstract Hydrogen E brittlement (HE) is a topical issue f r pipeline transporting s ur products. Engineers need a simple and eff ctiv approach in materials selection at design stage. In other words, they must know if a material is susceptible to cracking, to be able of: selecting the right mater al  and apply correct operational measure during he service life. Following ASTM F2078, HE is “ p rmanent loss of ductility in a metal or alloy caused by hydrogen in combination with tress, eithe externally applied or internal residual stres ”. In many cases, hydrogen can play rol in crack propagation, as for instance in Stress Corrosion Cracking (SCC) and Corrosion Fa igue (CF). Thr e paramet s are required to caus failure: pre ence of hydrogen, tensile stress, and mat rial susceptibility. The tw previous on s are triggeri g th failur , while the r ot caus is usually material susceptibility. This is why material sele tion is th important step to safely manage engine ring structural materials. As an example, material selection for sour service pipeline is th object of well-known standards, .g. by Nace Int rnatio al and EFC: they pose some limits in the sour service of steels, with reference to surface hardness. These standards have shown some weak points, namely: the definition of sou service; • In defining the role of crack initiation and propagation, considering that in Hydrogen embrittlement, stress state and stress variations are very important. As for the second point, in hydrogen generation anodic processes shall be t ken into ac ount too. For instance, there is a relationship betwee corrosi n resistanc and crack susc ptibility. In carbon and low alloy steels, cracking will not normally occur when there is a significant corrosion rate. If a brittle layer (or a brittle spot) is present on the metal surface, this one can initiate a crack. © 2016 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of PCF 2016. © 2018 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Gruppo Italiano Frattura (IGF) ExCo. © 2018 The Authors. Published b Elsevier B.V. Peer-review under responsibility of the Gruppo Italiano Frattura (IGF) ExCo. © 2018 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Gruppo Italiano Frattura (IGF) ExCo. Keywords: High Pressure Turbine Blade; Creep; Finite Element Method; 3D Model; Simulation. Keywords: Hydrogen Embrittlement; Environmentally Assisted Cracking; Stress Corrosion Cracking; Sour Service; Pipeline Steel Keywords: Hydrogen Embrittlement; Environmentally Assisted Cracking; Stress Corrosion Cracking; Sour Service; Pipeline Steel

* Corresponding author. E-mail address: Giovanna.Gabetta@eni.com * Corresponding author. E-mail address: Giovanna.Gabetta@eni.com

2452-3216 © 2016 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of PCF 2016. 2452-3216  2018 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Gruppo Italiano Frattura (IGF) ExCo. 10.1016/j.prostr.2018.06.038 * Corresponding author. Tel.: +351 218419991. E-mail address: amd@tecnico.ulisboa.pt 2452 3216 © 2018 Th Authors. Published by Elsevier B.V. Peer-review under responsibility of the Gruppo Italiano Frattura (IGF) ExCo. 2452-3216 © 2018 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Gruppo Italiano Frattura (IGF) ExCo.