PSI - Issue 8

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2452-3216 © 2016 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of PCF 2016. ∗ Corresponding author. Tel.: + 39-02-23998246 ; fax: + 0-000-000-0000. E-mail address: stefano.beretta@polimi.it 2210-7843 c 2017 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of AIAS 2017 International Conference on Stress Analysis. ∗ Corresponding author. Tel.: + 39-02-23998246 ; fax: + 0-000-000-0000. E-mail address: stefano.beretta@polimi.it 2210-7843 c 2017 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of AIAS 2017 International Conference on Stress Analysis. * Corresponding author. Tel.: +351 218419991. E-mail address: amd@tecnico.ulisboa.pt 2452-3216 Copyright  2018 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of AIAS 2017 International Conference on Stress Analysis 10.1016/j.prostr.2017.12.060 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. Copyright © 2018 The Aut ors. Published by Elsevier B.V. Peer-revi w under responsibility of the Scientific Committee of AIAS 2017 International Conferen e on St ess Analysis AIAS 2017 International Conference on Stress Analysis, AIAS 2017, 6–9 September 2017, Pisa, Italy Comparison of SIF solutions for cracks under rotating bending and their impact upon propagation lifetime of railway axles Amir Pourheidar a,b , Stefano Beretta b, ∗ , Daniele Ragazzi c , Cemal Baykara a a Istanbul Technical University, Mechanical Engineering Department, Maslak, 34467 Istanbul, Turkey b Politecnico di Milano, Mechanical Engineering Department, Via La Masa 1, 20156 Milan, Italy c Lucchini RS, Via G. Paglia 45, 24065 Lovere, Italy Abstract The stress intensity factor (SIF) is a crucial input parameter for the definition of the inspection intervals based on the damage tolerance approach. In the present work the applicability and precision of existing analytical stress intensity factor solutions for the cracks in railway axle geometries,subjected to rotary bending and residual stresses is discussed, by comparison with a reference set of solutions obtained from finite element (FE) analyses. Both the SIFs and the crack shape evolution are considered, comparing the predicted crack shape growth, from FE and analytical solutions, with a series of experimental data from the literature. Finally, the e ff ect of the di ff erent approximations for the propagation lifetime and non-destructive tests (NDT) reliability of railway axles is discussed. c 2017 The Authors. Published by Elsevier B.V. P r-review under responsibility of the Scientific Committee of AIAS 2017 International Conference on Stress Analysis. Keywords: railway axles; stress intensity factor comparison; residual stresses; residual lifetime Railway axles are designed to have an infinite life-time. Even if this is accepted as adequate, the fact remains that occasional failures have been and are observed in service. Hillmansen and Smith [1] recently cited 37 failures during a period of 27 years (1975 - 2002) for a total number of 170 000 axles circulating in UK. Similar figures have been observed all around Europe in other references [2]. The typical failure positions are the press- fits for wheels, gears, and brakes or the axle body close to notches and transitions[2]. Such failures always occur as fatigue crack propagation whose nucleation can be due to di ff erent causes. In the case of railway axles, the presence of widespread corrosion or the possible damage due to the ballast impacts [3] may constitute such causes. This kind of failures is usually tackled by employing the ’damage tolerance’ methodology, whose philosophy consists in determining the most opportune inspection interval given the ’probability of detection’ (POD) of the AIAS 2017 International Conference on Stress Analysis, AIAS 2017, 6–9 September 2017, Pisa, Italy Co parison of SIF solutions for cracks under rotating bending and their impact upon propagation lifetime of railway axles Amir Pourheidar a,b , Stefano Beretta b, ∗ , Daniele Ragazzi c , Cemal Baykara a a Istanbul Technical University, Mechanical Engineering Department, Maslak, 34467 Istanbul, Turkey b Politecnico di Milano, Mechanical Engineering Department, Via La Masa 1, 20156 Milan, Italy c Lucchini RS, Via G. Paglia 45, 24065 Lovere, Italy Abstract The stress intensity fac or (SIF) is a crucial input parameter for the definition of th inspection inter als b sed on the damage tolerance approach. In the present work the applicability and precision of existing analytical stress intensity factor solutions for the cracks in railway axle geometries,subjected to rotary bending and residual stresses is discussed, by comparison with a reference set of solutions obtained from finite element (FE) analyses. Both the SIFs and the crack shape evolution are considered, comparing the predicted crack shape growth, from FE and analytical solutions, with a series of experimental data from the literature. Finally, the e ff ect of the di ff erent approximations for the propagation lifetime and non-destructive tests (NDT) reliability of railway axles is discussed. c 2017 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of AIAS 2017 International Conference on Stress Analysis. Keywords: railway axles; stress intensity factor comparison; residual stresses; residual lifetime 1. Introduction Railway axles are designed to have a infinite life-time. Even if this is accepted as adequate, the fact remains that occasional failures have been and are observed in service. Hillmansen and Smith [1] recently cited 37 failures during a period of 27 years (1975 - 2002) for a total number of 170 000 axles circulating in UK. Similar figures have been observed all around Europe in other references [2]. The typical failure positions are the press- fits for wheels, gears, and brakes or the axle body close to notches and transitions[2]. Such failures always occur as fatigue crack propagation whose nucleation can be due to di ff erent causes. In the case of railway axles, the presence of widespread corrosion or the possible damage due to the ballast impacts [3] may constitute such causes. This kind of failures is usually tackled by employing the ’damage tolerance’ methodology, whose philosophy consists in determining the most opportune inspection interval given the ’probability of detection’ (POD) of the © 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