PSI - Issue 7

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 Structu al Integrity 7 (2017) 214–221 Structural Integrity Procedia 00 (2017) 000–000 Available online at www.sciencedirect.com Structural Integrity Procedia 00 (2017) 000–000 Available online at www.sciencedirect.com

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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.: + 39-0223998246 ; fax: + 39-0223998202. 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 the 3rd International Symposium on Fatigue Design and Material Defects. Compressor blades can be subjected to Combined Cycle Fatigue (CCF) conditions, where the service cycles are characterized by a low cycle fatigue cycle (LCF) controlled by the centrifugal, pressure and thermal loads, onto which the loadings at load ratio R > 0 . 5 induced by blade vibrations are then superimposed. This peculiar kind of load cycle can seen as major load cycles at R = 0, with a target number of repetitions up to 6000 (depending on the type of turbine and the operating profile), and vibration cycles at R > 0 . 5. The blade vibrations can take place during startups, baseload and engine shut down operations. A simple engineering assessment can be based only on the LCF ∗ Corresponding author. Tel.: + 39-0223998246 ; fax: + 39-0223998202. 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 the 3rd International Symposium on Fatigue Design and Material Defects. 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 © 2017 The Auth rs. Publis ed by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of the 3rd International Symposium on Fatigue Design and Material Defects. 3rd International Symposium on Fatigue Design and Material Defects, FDMD 2017, 19-22 September 2017, Lecco, Italy Crack propagation under combined cycle fatigue for a precipitation hardened steel L. Patriarca a , S. Foletti a , S. Beretta a, ∗ , S. Parodi b , A. Riva b a Politecnico di Milano, Dept. Mechanical Engineering, Via La Masa 1, Milano 20156, Italy b Ansaldo Energia, Via A. Lorenzi, Genova , Italy Abstract Compressor blades are generally subjected to Combined Cycle Fatigue (CCF) conditions, where the service cycles are characterized by a low cycle fatigue (LCF) cycle controlled by the centrifugal, pressure and thermal loads superimposed to high frequency loadings at positive load ratios R > 0 . 5 as generated, for example, by the blade vibrations. The recent increasing adoption of renewable energy sources leads to the request to higher level of flexibility for the energy production supplied by gas turbines. The required number of cycles under LCF conditions is increasing leading to lower allowable design stresses. It is thus foundamental to reduce the convervatism adopted with the classical design philosophies. According to a damage tolerance approach, in this activity we have analysed the propagation of small cracks under CCF conditions on a precipitation hardened martensitic steel. The experimental results have mainly shown that the small cracks under CCF are able to propagate at growth rates comparable to the the absence of crack closure. This result, tog ther with the Kitagawa diagram, all wed to determin less conservative criteria f r the acceptability of surface damages on components subjected to CCF. c 2017 The Authors. Published by Elsevier B.V. Peer-review under r sponsibility of the Scie tific Committee of the 3rd Internatio al Symposium o Fatigue Design and Material D fects. Keywords: combined cycle fatigue; acceptable defects; damage 3rd International Symposium on Fatigue Design and Material Defects, FDMD 2017, 19-22 September 2017, Lecco, Italy Crack propagation under combined cycle fatigue for a precipitation hardened steel L. Patriarca a , S. Foletti a , S. Ber tta a, ∗ , S. P rodi b , A. Riva b a Politecnico di Milano, Dept. Mechanical Engineering, Via La Masa 1, Milano 20156, Italy b Ansaldo Energia, Via A. Lorenzi, Genova , Italy Abstract Compressor blades are generally subjected to Combined Cycle Fatigue (CCF) conditions, where the service cycles are characterized by a low cycle f tigue (LCF) cycle co trolled by the centrifugal, pressure and thermal loads superimp sed to high frequency loadings at positive load ratios R > 0 . 5 as generated, for example, by the blade vibrations. The recent increasing adoption of renewable energy sources leads to the request to higher level of flexibility for the energy production supplied by gas turbines. The required number of cycles under LCF conditions is increasing leading to lower allowable design stresses. It is thus foundamental to reduce the convervatism adopted with the classical design philosophies. According to a damage tolerance approach, in this activity we have analysed the propagation of small cracks under CCF conditions on a precipitation hardened martensitic steel. The experimental results have mainly shown that the small cracks under CCF are able to propagate at growth rates comparable to the the absence of crack closure. This result, together with the Kitagawa diagram, allowed to determine less conservative criteria for the acceptability of surface damages on components subjected to CCF. c 2017 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of the 3rd International Symposium on Fatigue Design and Material D fects. Keywords: combined cycle fatigue; acceptable defects; damage © 2016 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of PCF 2016. 1. Introduction Keywords: High Pressure Turbine Blade; Creep; Finite Element Method; 3D Model; Simulation. Compressor blades can b subject d to Combined Cycle Fatigu (CCF) conditions, where the service cycles are characterized by a low cycle fatigue cycle (LCF) controlled by the centrifugal, pressure and thermal loads, onto which the loadings at load ratio R > 0 . 5 induced by blade vibrations are then superimposed. This peculiar kind of load cycle can seen as major load cycles at R = 0, with a target number of repetitions up to 6000 (depending on the type of turbine and the operating profile), and vibration cycles at R > 0 . 5. The blade vibrations can take place during startups, baseload and engine shut down operations. A simple engineering assessment can be based only on the LCF * Corresponding author. Tel.: +351 218419991. E-mail address: amd@tecnico.ulisboa.pt 2452-3216 Copyright  2017 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of the 3rd International Symposium on Fatigue Design and Material Defects. 10.1016/j.prostr.2017.11.080 1. Introduction