PSI - Issue 2_B

ScienceDirect Available online at www.sciencedirect.com Av ilable o line at ww.sciencedire t.com ienceDirect Structural Integrity Procedia 00 (2016) 000 – 000 Procedia Struc ural Integrity 2 (2016) 1101–11 8 Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia 00 (2016) 000–000 il l li t . i i t. tr t r l I t rit r i ( )

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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. 21st European Conference on Fracture, ECF21, 20-24 June 2016, Catania, Italy Very high cycle fatigue of high-strength steels: Crack initiation by FGA formation investigated at artificial defects D. Spriestersbach a , A. Brodyanski b , J. Lösch b , M. Kopnarski b , E. Kerscher a * a Materials testing, University of Kaiserslautern, Gottlieb-Daimler-Straße, 67663 Kaiserslautern, Germany b Institute for surface and thin film analysis GmbH, Trippstadter Straße 120, 67663 Kaiserslautern, Germany Abstract It is well known, that high-strength steels do not show a classical fatigue limit and failure occurs still after 10 7 cycles. The reason for this late failure is that the fatigue properties in the long life region are strongly affected by non-metallic inclusions inside the material (Murakami et al. (1989)). After VHCF a characteristic fine granular area, or short FGA, can be observed at the fracture surface. The FGA formation is responsible for the late initiation of a propagable long crack (Grad et al. (2012); Sakai et al. (2002)). In recent years a lot of research was carried out to reveal the mechanism responsible for the crack initiation by FGA formation (Grad et al. (2012); Murakami et al. (1999); Sakai, Kokubu, et al. (2015); Shiozawa et al. (2008)). Multiple different theories exist in literature trying to explain VHCF failure. Because of its occurrence solely below the surface by now only the fracture surface could be observed after the failure occurred. This makes it impossible to gain a full understanding of the mechanisms leading to failure. Consequently all proposed mechanisms remain unprovable theories, up to now. In order to further investigate FGA formation we have simulated the VHCF-failure at artificial surface defects. According to literature the absence of any environment seems to be crucial for VHCF subsurface failure by FGA formation in high-strength steels (Billaudeau et al. (2004)). Thus, fatigue tests were performed in ultra-high vacuum to simulate subsurface condition at surface defects. Thereby the FGA formation can be reproduced at the surface and gets observable quasi in situ. Microstructural investigations were carried out with transmission electron microscopy inside the FGA at artificial defects. These measurements show the comparability of the resulting microstructure at artificial defects with the FGA microstructure after failure at subsurface inclusions. Therefore, it is possible to gain new insights into FGA formation gained with the use of artificial defects. Thereby fatigue test with artificial defect can be interrupted and enable the in situ investigation of pre-stages of FGA formation by microstructural analyses with transmission electron microscopy. With this testing procedure it should be possible to enhance the knowledge of the very high cycle fatigue in high-strength steels and the associated failure mechanisms. © 2016 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of ECF21. b b a a t i l t ti , i it f i l t , ttli - i l - t , i l t , b I tit t f f t i fil l i , i t t t , i l t , t i ll , t t i t t t l t l i l ti li it il till t l . reason for thi l t il i t t t ti ti i t l li i t l t t lli i l i i i t material (Murakami et al. (1989)). After VHCF a characteristic fine l , t , t t t . ti i i l t l t i iti ti l l t l. ; i t l. . t l t i t t l t i i l t i iti ti ti t l. ; i t l. ; i, , t l. ; i t l. . lti l i t t i i t i lit t t i t l i il . it l l l t l t fractur could b t t il . i it i i l t i ll t i t i l i t il . tl ll i i l t i , t . In ord t t i ti t ti i l t t il t ti i i l t . i t literature the absence of any environment seems t i l il ti i i t t t l ill t l. . Thus, ti t t i lt i t i l t iti t t . t ti t t t l i i it . i t t l i ti ti i t it t i i l t i i i t t ti i i l t . t t ilit t lti i t t t ti i i l t it t i t t t il t i l i . , it i i l t i i i t i t ti i it t ti i i l t . fatigue test with artificial defect can be int t l t i it i ti ti t ti i t t l l it t i i l t i . it t i t ti it l i l t t wl dg t i h cycle fatigue in high-strength t ls and the associ t il i . 2 Aut . li l i . . r-revi i ilit t ientific Committee of ECF21. Copyright © 2016 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer-review under responsibility of the Scientific Committee of ECF21. © 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.

* D. Spriestersbach. Tel.: +49-631-205-5536; fax: +49-631-205-5261. E-mail address: Spriestersbach@mv.uni.kl.de . ri t r . l.: - - - ; f : - - - . - il : ri t r . i. l.

* Corresponding author. Tel.: +351 218419991. E-mail address: amd@tecnico.ulisboa.pt 2452-3216 © 2016 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of ECF21. l i r . . i i ilit t i ti i itt . - t r . li

2452-3216 © 2016 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of PCF 2016. Copyright © 2016 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license ( http://creativecommons.org/licenses/by-nc-nd/4.0/ ). Peer review under responsibility of the Scientific Committee of ECF21. 10.1016/j.prostr.2016.06.141