PSI - Issue 4

ScienceDirect Available online at www.sciencedirect.com Av ilable o line at ww.sciencedire t.com ienceDirect Structural Integrity Procedia 00 (2016) 000 – 000 P o edi Structural Integr ty 4 (2017) 87–94 Available online at www.sciencedirect.co Structural Integrity Procedia 00 (2017) 000–000 Available online at www.sciencedirect.com Structural Integrity Procedia 00 (2017) 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. ESIS TC24 Workshop ”Integrity of Railway Structures”, 24-25 October 2016, Leoben, Austria Determination of inspection intervals for welded rail joints on a regional network S. Romano a , S. Beretta* a , G.S. Galli b , R. Riccardo b a POLItecnico di MIlano, Dept. Mechanical Engineering, Milan, Italy b FERROVIENORD, Saronno, Italy Abstract One of the most frequent and dangerous failu e modes in continuous welded rails s fatigue crack propagation terminated by brittle fracture. Due to the brittleness of the weld material and the scatter in its mechanical properties, a probabilistic approach is necessary. The paper deals with surface cracks at the foot base of aluminothermic welded rails, developing a probabilistic methodology for determining the day by day prospective failure probability. The model used is based on weld material characterization, simulation of fatigue crack growth and day-by-day failure probability calculation using the Monte Carlo method. The model is then adopted to assess the time dependent safety margin during fatigue crack propagation and to understand which variables are really influencing the failure probability. Finally, the results are compared to the standard rail classification method, considering the real tra ffi c condition in several railway lines. c 2017 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of ESIS TC24. Keywords: Rails; Fatigue crack in welds; Failure probability; Residual lifetime; Thermite welds; Defects The introduction of continuously welded rails has considerably improved the problems of wear and dynamic over loads that were the main causes of failure with mechanically joined rails. However, the several benefits introduced by this technology are partially bal nced by frequent bri tle fatigue failures originating and propagating in the welds (see Welding Technology Institute of Australia (2006); Mutton and Alvarez (2003); Salehi et al. (2011)). One of the most common failure modes is the vertical failure caused by cracks originating from the heat a ff ected zone at the weld foot. This failure mode is not critical for safety but rather for network availability. The aim of the research project is to model said failure mode, in order to evaluate the e ff ect of the variables involved and to improve the track maintenance. This was achieved in three main steps: ESIS TC24 orkshop ”Integrity of Railway Structures”, 24-25 October 2016, Leoben, Austria eter ination of inspection intervals for elded rail joints on a regional network S. Romano a , S. Beretta* a , G.S. Galli b , R. Riccardo b a POLItecnico di MIlano, Dept. Mechanical Engineering, Milan, Italy b FERROVIENORD, Saronno, Italy Abstract One of the most frequent and dangerous failure modes in continuous welded rails is fatigue crack propagation terminated by brittle fracture. Due to the brittleness of the weld material and the scatter in its mechanical properties, a probabilistic approach is necessary. The paper deals with surface cr cks at the foot base of aluminothermic welded rails, developing a pr babilistic methodology for determining the day by day prospective failure probability. The model used is based on weld material characterization, simulation of fatigue crack growth and day-by-day failure probability calculation using the Monte Carlo method. The model is then adopted to assess the time dependent safety margin during fatigue crack propagation and to understand which variables are really influencing the failure probability. Finally, the results are compared to the standard rail classification method, considering the real tra ffi c condition in several railway lines. c 2017 The Authors. Publishe by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of ESIS TC24. Keywords: Rails; Fatigue crack in welds; Failure probability; Residual lifetime; Thermite welds; Defects 1. Introduction The introduction of continuously welded rails has considerably improved the problems of wear and dynamic over loads that were the main causes of failure with mechanically joined rails. However, the several benefits introduced by this technology are partially balanced by frequent brittle fatigue failures originating and propagating in the welds (see Welding Technology Institute of Australia (2006); Mutton and Alvarez (2003); Salehi et al. (2011)). One of the most common failure modes is the vertical failure caused by cracks originating from the heat a ff ected zone at the weld foot. This failure mode is not critical for safety but rather for network availability. The aim of the research project is to model said failure mode, in order to evaluate the e ff ect of the variables involved and to improve the track maintenance. This was achieved in three main steps: Copyright © 2017. The Authors. Publish d by Elsevier B.V. P r-review under responsibility of the Scientific Committee of ESIS TC24. © 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. 1. Introduction

* Corresponding author. Tel.: +351 218419991. E-mail address: amd@tecnico.ulisboa.pt ∗ Corresponding author. Tel.: + 39-0223998246. E-mail address: stefano.beretta@polimi.it ∗ Corresponding author. Tel.: + 39-0223998246. E-mail address: stefano.beretta@polimi.it

2452-3216 © 2016 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of PCF 2016. 2452-3216 Copyright  2017. The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of ESIS TC24 10.1016/j.prostr.2017.07.004 2452-3216 c 2017 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of ESIS TC24. 2452-3216 c 2017 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of ESIS TC24.