PSI - Issue 8

ScienceDirect Available online at www.sciencedirect.com Av ilable o line at ww.sciencedire t.com cienceDirect Structural Integrity Procedia 00 (2016) 000 – 000 Procedia Structural Integrity 8 (2018) 501–508 Available online at www.sciencedirect.com Structural Integrity Procedia 00 (2017) 000–000 Available online at www.sciencedirect.com Structural Integrity Procedia 00 (2017) 000–000

www.elsevier.com/locate/procedia www.elsevier.com / locate / procedia www.elsevier.com / locate / procedia

2452-3216 © 2016 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of PCF 2016. ∗ R. Valentini Tel.: + 39-50-221-7859 ; fax: + 39-50-221-8065. E-mail address: renzo.valentini@unipi.it 2210-7843 c 2017 The Authors. Published by Elsevi r B.V. Peer-r view under responsibility of the Scientific Committee f AIAS 2017 International Conference on Stress Analysis. ∗ R. Valentini Tel.: + 39-50-221-7859 ; fax: + 39-50-221-8065. E-mail address: renzo.valentini@unipi.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.2017.12.049 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 Authors. Published by Elsevier B.V. Peer-review u der r sponsibility of th Scientific Committee of AIAS 2017 I erna ional Conference on Stress Analysis Experimental study of hydrogen embrittlement in Maraging steels M. Barsanti a,b , M. Beghini a , F. Frasconi b , R. Ishak a , B. D. Monelli a , R. Valentini a,b, ∗ a Universita` di Pisa, Dipartimento di Ingegneria Civile e Industriale, 56122 Pisa, Italy b INFN Sezione di Pisa, Largo Pontecorvo 2, 56125 Pisa, Italy Abstract This research activity aims t investigating the hydr gen embrittlement of Maraging steels in conne tion to real sudden failures of some of the suspension blades of the Virgo Project experimental pparatus. Some of them failed after 15 years of service in working conditions. Typically, in the Virgo detector, blades are loaded up to 50-60% of the material yield strength. For a deeper understanding of the failure, the relationship between hydrogen concentration and mechanical properties of the material,have been investigated with specimens prepared in order to simulate blade working conditions. A mechanical characterization of the material has been carried out by standard tensile testing in order to establish the e ff ect of hydrogen content on the material strength. Further experimental activity was executed in order to characterize the fracture surface and to measure the hydrogen content. Finally, some of the failed blades have been analyzed in DICI-UNIPI laboratory. The experimental results show that the blades failure can be related with the hydrogen embrittlement phenomenon. c 2017 The Authors. Publish d y Elsevier B.V. e - ie unde respons bil ty of the Sc entific Committee of AIAS 2017 International Conf r nce o Stress Analysis. Keywords: Hydrogen embrittlement; Maraging; fracture analysis. AIAS 2017 International Conference on Stress Analysis, AIAS 2017, 6–9 September 2017, Pisa, Italy Experimental study of hydrogen embrittlement in Maraging steels M. Barsanti a,b , M. Beghini a , F. Frasconi b , R. Ishak a , B. D. Monelli a , R. Valentini a,b, ∗ a Universita` di Pisa, Dipartimento di Ingegneria Civile e Industriale, 56122 Pisa, Italy b INFN Sezione di Pisa, Largo Pontecorvo 2, 56125 Pisa, Italy Abstract This research activity aims at investigating the hydrogen embrittlement of Maraging steels in connection to real sudden failures of some of the suspensi n blades of the Virgo Project experimental apparatus. Some of them failed after 15 years of service in working conditions. Typically, in the Virgo detector, blades are l aded up to 50-60% of the material yield strength. For a deeper understanding of the failure, the relationship between hydrogen conce tratio and mechanical properties of the material,have been investigated with specimens prepared in order to simulate blade working conditions. A mechanical characterization of the material has been carried out by standard tensile testing in order to establish the e ff ect of hydrogen content on the material strength. Further experimental activity was executed in order to characterize the fracture surface and to measure the hydrogen content. Finally, some of the failed blades have been analyzed in DICI-UNIPI laboratory. The experimental results show that the blades failure can be related with the hydrogen embrittlement phenomenon. 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: Hydrogen embrittlement; Maraging; fracture analysis. Keywords: High Pressure Turbine Blade; Creep; Finite Element Method; 3D Model; Simulation. Purpose of this work is the study of Hydrogen embrittlement of Maraging steel. Maraging is a class of Ultra High Strength Steels (UHSS) with a yield strength that can reach 2400 MPa, h rdened by precipitation of intermetallic compounds during an aging process [Sha and Guo (2009)]. These steels are highly susceptible to hydrogen damage, as is common for high-strength alloys. Maraging steel is the material used for the construction of some crucial components of the Virgo experiment [Beccaria et al. (1998)], like the blades of the suspension system of the interferometer mirrors (super-attenuators) shown in Fig. 1. The loads acting on the blades are very strong, because each filter must carry the weight of the underlying ones. Therefore these high loads can cause microcreep [Gurewitz et al. (1977)], that is present also in the Purpose of this work is the study of Hydrogen embrittlement of Maraging steel. Maraging is a class of Ultra High Strength Steels (UHSS) with a yield strength that can reach 2400 MPa, hardened by precipitation of intermetallic compounds during an aging process [Sha and Guo (2009)]. These steels are highly susceptible to hydrogen damage, as is common for high-strength alloys. Maraging steel is the material used for the construction of some crucial components of the Virgo experiment [Beccaria et al. (1998)], like the blades of the suspension system of the interferometer mirrors (super-attenuators) shown in Fig. 1. The loads acting on the blades are very strong, because each filter must carry the weight of the underlying ones. Therefore these high loads can cause microcreep [Gurewitz et al. (1977)], that is present also in the AIAS 2017 International Conference on Stress Analysis, AIAS 2017, 6–9 September 2017, Pisa, Italy 1. Introduction © 2016 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of PCF 2016. 1. Introduction