PSI - Issue 13

ScienceDirect Available online at www.sciencedirect.com Av ilable o line at www.sciencedirect.com ienceDirect Structural Integrity Procedia 00 (2016) 000 – 000 Procedia Structural Integrity 13 (2018) 1215–122 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. ECF22 - Loading and Environmental effects on Structural Integrity Electrochemical fracture analysis of in-service natural gas pipeline steels Hryhoriy Nykyforchyn a *, Oleksandr Tsyrulnyk a , Olha Zvirko a a Karpenko Physico-Mechanical Institute of the National Academy of Sciences of Ukraine, 5, Naukova St., Lviv 79060, Ukraine Long-term operation of natural gas transit pipelines implies aging, hydrogen-induced and stress corrosion cracking and it causes hydrogen embrittlement of steels, degradation of mechanical properties associated to a safe serviceability of pipelines, and failure risk increase. The implementation of effective diagnostic measures of pipelines steels degradation would allow planning actions in order to reduce a risk of fracture. In this paper, a new scientific and methodical approach based on the electrochemical analysis of fracture surface for evaluation of in-service degradation of operated pipeline steels was developed. It was suggested that carbon diffusion to grain boundaries and to defects inside grains, intensified by hydrogen, under long-term operation led to formation of nanoparticles of carbides, which resulted in intergranular cracking of operated pipeline steels under service and their transgranular cracking under impact toughness testing. Therefore, fracture surface was enriched by carbon compounds, and electrochemical characteristics were sensitive to this. In-service degradation of ferrite-pearlite pipeline steels was accompanied by a sharp shift in open-circuit potential of the fracture surface (brittle fracture) of specimens after impact toughness tests compared with that of polished steel surfaces. A significant difference between potentials of the fracture surface and the polished steel surface (over 60 mV in 0.3% NaCl solution) of specimens made of ferrite-pearlite pipeline steels observed after their long term operation was evidently due to the increased content of carbon compounds on the fracture surface. Mechanism of ferrite pearlite pipeline steels embrittlement under operation consisted in carbides enrichment not only grain boundaries, but also intragranular defects, has been revealed, as it is indicated by an increase of carbon content on transgranular fracture surfaces determined electrochemically. ECF22 - Loading and Environmental effects on Structural Integrity Electrochemical fracture analysis of in-service natural gas pipeline steels Hryhoriy Nykyforchyn a *, Oleksandr Tsyrulnyk a , Olha Zvirko a a Karpenko Physico-Mechanical Institute of the National Academy of Sciences of Ukraine, 5, Naukova St., Lviv 79060, Ukraine Abstract Long-term operation of natural gas transit pipelines implies aging, hydrogen-induced and stress corrosion cracking and it causes hydrog n embrittlement of steels, degradation of mechanical properties associated to a safe serviceability of pipelines, and failure risk increase. The implementation of effective diagnostic measures of pipelines steels degradation would allow planning actions in order to reduc a risk fra ture. In this paper a new scientific and methodical approach ased on the electrochemical analysis of fracture surface for evaluation of in-service degradatio of operated pipeline steels was develop d. It was suggested that carbon diffusion to grain boundaries and to defects inside grains, intensified by hydrogen, und r long-term operation led to formation of na oparticles of carbides, which resulted i inter r nular cracking of operated pipeline steels under service and their transgranular cracking under impact toughness testing. Therefore, fracture surface was enriched by carbon compounds, and electrochemical characteristics were sensitive to this. In-service degradation of ferrite-pearlite pipeline steels was accompanie by a sharp shift in open-circuit potential of the fracture surface (brittle fracture) of specimens after impact toughness tests compared with that of polished steel surf ces. A significant difference between potentials of the fracture surface and t e polished steel surface (over 60 mV in 0.3% NaCl solution) of specimens mad of ferrite-pearlite pipeline steels observed after their long term operation was evidently due to the increased cont nt of carbon compounds on the fracture surface. Mechanism of ferrite pearlite pipeline ste ls mbrittlement under operation consisted in arbides enrichm nt not only grain boundaries, but also intragranular defects, has been rev aled, as it is indicated by an i crease of carbon co te t on transgranular fracture s rfaces determi ed electrochemically. © 2018 The Authors. Published by Els vier B.V. Peer-review under responsibility of the ECF22 organizers. © 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. Keywords: Pipeline steel; hydrogen assisted degradation; electrochemical analysis; fracture surface; brittle fracture resistance Abstract Keywords: Pipeline steel; hydrogen assisted degradation; electrochemical analysis; fracture surface; brittle fracture resistance

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

* 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 r sponsibility of the ECF22 organizers. * Corresponding author. Tel.: +380-32-263-2133; fax: +380-32-264-9427. E-mail address: nykyfor@ipm.lviv.ua (H. Nykyforchyn) * Corresponding author. Tel.: +380-32-263-2133; fax: +380-32-264-9427. E-mail ad ress: nykyfor@ipm.lviv.ua (H. Nyky orchyn)

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.2018.12.250