PSI - Issue 13

ScienceDirect Available online at www.sciencedirect.com Av ilable o line at ww.sciencedirect.com ScienceDirect Structural Integrity Procedia 00 (2016) 000 – 000 Procedia Structu al Integrity 13 (2018) 21 –217 Available online at www.sciencedirect.com ScienceDirect StructuralIntegrity Procedia 00 (2018) 000–000 Available online at www.sciencedirect.com ScienceDirect StructuralInt grity 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. ECF22 - Loading and Environmental effects on Structural Integrity Hydrogen embrittlement of steel pipelines during transients Zahreddine Hafsi a,b,* , Manoranjan Mishra b , Sami Elaoud a a Laboratory of Applied Fluids Mechanics Process and Environment Engineering, National Engineering School of Sfax, Sfax, 3038, Tunisia b Department of Mathematics, Indian Institute of Technology Ropar, 140001 Rupnagar, Punjab, India b Department of Chemical Engineering, Indian Institute of Technology Ropar, 140001 Rupnagar, Punjab, India Abstract Blending hydrogen into natural gas pipelines is a recent alternative adopted for hydrogen transportation as a mixture with natural gas. In this paper, hydrogen embrittlement of steel pipelines originally designed for natural gas transportation is investigated. Solubility, permeation and diffusion phenomena of hydrogen molecules into the crystalline lattice structure of the pipeline material are followed up based on transient evolution of internal pressure applied on the pipeline wall. The transient regime is created through changes of gas demand depending on daily consumptions. As a result, the pressure may reach excessive values that lead to the acceleration of hydrogen solubility and its diffusion through the pipeline wall. Furthermore, permeation is an important parameter to determine the diffusion amount of hydrogen inside the pipeline wall resulting in the embrittlement of the material. The numerical obtained results have shown that using pipeli s designed for natural gas conduction to transport hydrogen is a r sky choic . Actually, added to overpressure and great fluctuations during transients th t may cause fatigu a d damage the structure, also the latter pressure evolution is likely to induce the diffusion phenomena of hydrogen molecules into the lattice of the structure leading to brittle the pipe material. The numerical simulation reposes on solving partial differential equations describing transient gas flow in pipelines coupled with the diffusion equation for mass transfer. The model is built using the finite elements based software COMSOL Multiphysics considering different cases of pipe material; API X52 (base metal and nutrided) and API X80 steels. Obtained results allowed tracking the evolution with time of hydrogen concentration through the pipeline internal wall based on the pressure variation due to transient gas flow. Such observation permits to estimate the amount of hydrogen diffused in the metal to avoid leakage of this flammable gas. Thus, precautions may be taken to prevent explosive risks due to hydrogen embrittlement of steel pipelines, among other effects, that can lead to alter safe conditions of gas conduction. ECF22 - Loading and Environmental effects on Structural Integrity Hydrogen embrittlement of steel pipelines during transients Zahreddine Hafsi a,b,* , Manoranjan Mishra b , Sami Elaoud a a Laboratory of Applied Fluids Mechanics Process and Environment Engineering, National Engineering School of Sfax, Sfax, 3038, Tunisia b Department of Mathemati s, Indian I stitute of Technology Rop r, 140001 Rupnagar, Punjab, India b Department of Chemic l Engineeri g, I dian Institute of Technology Ropar, 140001 Rupnagar, Punjab, India Abstract Blending hydrogen into natural gas pipelines is a recent alternative adopted for hydrogen transportation as a mixture with natural gas. In this paper, hydrogen embrittlement of steel pipelines originally designed f r natural gas transportation is investigated. Solubility, perm ation and diffusion phenomena of hydroge m lecules into the crystalline lattice structure of the pipeline material are followed up based on transient evolution of internal pressure applied on the pipeline wall. The transient regime is created through changes of gas dema d depending daily consumptions. As a result, the pressure may reach excessive values that lea to the acceleration of hydrogen solubility and its diffusion through the pipeline wall. Furthermore, perm ation is an important parameter to determine the diffu ion amount of hy rogen inside the pipelin wall resulting in the mbrittl ment of the aterial. The numerical obtained results have shown that using pipeli es designed for natural gas co duction to transport hydrogen is risky choice. Actu lly, add d to overpressure a d great fluctuations during transients that may ca se fatigue and damage the structure, also the latter pressur ev lution is likely to induce the diffusion phenomena of hydrogen molecules into the lattice of the structure leading to brittle the pipe material. The numerical simulation repos s on solving partial differential equations describing transient gas flow in pipelin s coupled with t diffusion equation for mass tran fer. The model is built using the finite elements based software COMSOL Multiphysics considering diff rent cases of pipe material; API X52 (base metal and nutrid d) and API X80 steels. Obtained results allowed tracking the evolution with time of hydrog n concentration through the pipeline internal wall based on the pressure variation due to transient gas flow. Such observation permits to estimate the amount of hydrogen diffused in the metal to avoid leakage of this fl mmable gas. Thus, precautions may be tak n to prev nt explosive risks due to hydrogen embrittlement of steel pipelines, among other effects, that can lead to alter safe co ditions of gas conduction.

© 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 ECF22 organizers. © 2018 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ECF22 organizers. © 2018 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ECF22 organizers. Keywords: hydrogen flow; transient behaviour, Ficks’law; embrittlement; diffusion, steel pipeline Keywords: High Pressure Turbine Blade; Creep; Finite Element Method; 3D Model; Simulation. Keywords: hydrogen flow; transient behaviour, Ficks’law; embrittlement; diffusion, steel pipeline

* Corresponding author. E-mail address: zahreddine.hafsi@enis.tn * Corresponding author. E-mail ad ress: za reddine.hafsi@enis.tn

* Corresponding author. Tel.: +351 218419991. E-mail address: amd@tecnico.ulisboa.pt 2452-3216© 2018 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ECF22 organizers. 2452-3216© 2018 The Authors. Published by Elsevier B.V. Peer review under responsibility of the ECF22 organizers.

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 ECF22 organizers. 10.1016/j.prostr.2018.12.035