PSI - Issue 13

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 Structural Integrity 13 (2018) 217 –2173 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 Analysis of causes of a locomotive draw hook brittle fracture Nový F. a , Jambor M. a , Trško L. b , Palček P. a , Bokůvka O. a a University of Zilina, Department of Materials Engineering, Zilina, Slovakia b University of Zilina, Research Center, Zilina, Slovakia The traction force of locomotives is constantly increasing due to the pulling of heavier trains, while the material of the draw hooks remained the same as 50 years ago. The use of the current UIC standards and the relevant national standards defining the methodology for testing the mechanical properties of the hooks is very problematic. Despite the fact that all material properties of the draw hooks, tested according to UIC 825 and other related standards (I Czech an Slovak republic TN Ž 28 2612 standard) fully comply with the minimum values set by the standards, in ope ation the unexpected failure occurs frequently. This article deals with causes of brittle fractures of locomotive draw hooks operated by Slovak Railways. An exemplary study uses a traction hook of a locomotive that broke when a freight train accelerated after the stop at signal between the two stations in the winter period at ambient air temperature of -2 °C. The performed analysis showed that the brittle fracture of the draw hook was caused by usage of the low-toughness steel with the coarsened microstructure. All experimentally measured material properties of a broken hook met the limits specified in UIC 825 and TN Ž 28 2612 standards as the material testing at temperatures below +20 °C is not required in those standards. This study shows that the only technical solution to the long-term persistent problem of brittle fractures of locomotive draw hooks is to redefine their acceptance conditions and change the prescription for testing of the impact strength of the steels, from which the draw hooks are made. © 2018 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ECF22 organizers. Keywords: draw hook failure, brittle fracture, cause analysis © 2018 The Authors. Published by Elsevier B.V. Peer-review und r responsibility of the ECF22 organizers. ECF22 - Loading and Environmental effects on Structural Integrity Analysis of causes of a locomotive draw hook brittle fracture Nový F. a , Jambor M. a , Trško L. b , Palček P. a , Bokůvka O. a a University of Zilina, Department of Materials Engineering, Zilina, Slovakia b University of Zilina, Research Center, Zilina, Slovakia Abstract The traction force of locomotives is constantly increasing due to the pulling of heavier trains, while the material of the draw hooks remained the same as 50 years ago. The use of the current UIC standards and the relevant national standards defining the methodology for testing the mech nical properties of the hooks is very problematic. D spite the fact that all material properties of th draw hooks, tested according to UIC 825 and ther related standards (In Cze h and Slovak republic TN Ž 28 2612 standard) fully comply with th minimum values set by the standards, in operatio the unexpected failure occurs frequently. This article eals with auses of brittle fractures of locomotive draw hooks operat d by Slovak Railways. An exemplary st dy uses a tr ction hook of a locomotive that broke when a freight train accelerated after the stop at sign l between the two stations in the winter period at ambient air temperature of -2 °C. Th performed analysis showed that the brittle fractur of t e draw ho k was caused by usage of the low-toughness steel with the coarsened icrostructure. All xperimentally measured material properties of a broken hook met t limits specified in UIC 825 and TN Ž 28 2612 standards as the material testing at temperatures below +20 °C is not required in t ose standards. This study shows that the only technical solution to the long-term persistent problem of brittle fractures of locomotive draw hooks is to redefine their acceptance conditi ns and change the prescription for testing of the impact strength of the steels, from which the draw hooks are made. © 2018 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ECF22 organizers. Keywords: draw hook failure, brittle fracture, cause analysis Abstract

© 2016 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of PCF 2016. 1. Introductio 1. Introduction

Keywords: High Pressure Turbine Blade; Creep; Finite Element Method; 3D Model; Simulation. Increasing amount of the railway transport, using the existing infrastructure, is accommodated introducing the heavier trains, which travel faster, Sirong (2018). As a consequence, the requirements on the mechanical properties of the draw hook assembly substantially increase. Despite the aforementioned facts, the properties of the draw hook used in Slovakia are prescribed by the national TN Ž 28 2612 standard, which was introduced in 1979! The question of the tensile mechanical properties is not so problematic, much more important is the impact toughness and the way how these values are prescribed in the standard. The minimum value of the impact toughness at +20 °C, prescribed in the Increasing amount of the railway transport, using the existing infrastructure, is accommodated introducing the heavier trains, which travel faster, Sirong (2018). As a consequence, the requirements on the mechanical properties of the draw hook assembly substantially increase. Despite the aforementioned facts, the properties of the draw hook used in Slovakia are prescribed by the national TN Ž 28 2612 standard, which was introduced in 1979! The question of the tensile mechanical properties is not so problematic, much more important is the impact toughness and the way how these values are prescribed in the standard. The minimum value of the impact toughness at +20 °C, prescribed in the

* 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.

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.2018.12.146