PSI - Issue 2_A

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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 Assessment of Cleavage Fracture in Specimens with a Curved Crack Front for High-Strength Steels in Offshore Applications Xudong Qian*, Shuang Chen, Aziz Ahmed Department of Civil and Environmental Engineering, Centre for Offshore Research and Engineering, National University of Singapore, Singapore 117576 Abstract The significant petroleum reserve in the Arctic drives the need for offshore facilities in the Arctic made of ferritic structural steels. Such steel materials often exhibit a brittle fracture mode without noticeable prior plastic deformations. This paper presents a com ined experimental and numerical investigation to assess the cleavage fracture failure for high-strength steels used in offshore applications. The experimental program includes a set of non-conventional, special single-edge notched bend, SSE(B) specimens, tested under a lower mbient temper ture of -90 o C. In contrast to the conventional through-thickn ss fracture specimens, which experience an approximately uniform crack driving for e along the entir crack front, the specimens with a curved crack front indicates str g variations in both the crack driving forces and constraints along the crack front. This study therefore utilizes an average toughness value calculated from the η -approach to describe the scatter observed in the fracture toughness. This study also presents a numerical investigation using the local Weibull stress approach to estimate the probability of cleavage fracture in the fracture tests. A combination of the fracture initiation zone defined by the J -integral values with a local Weibull stress driving force predicts reasonably well the probability of fracture of the experimental specimens. © 2016 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of ECF21. 21st European Conference on Fracture, ECF21, 20-24 June 2016, Catania, Italy Assessment of Cleavage Fracture in Specimens with a Curved Crack Front for High-Strength Steels in Offshore Applications Xudong Qian*, Shuang Chen, Aziz Ahmed Department of Civil and Environmental Engineering, Centre for Offshore Research and Engineering, National University of Singapore, Singapore 117576 Abstract The significant petroleum reserve in the Arctic drives the need for offshore facilities in the Arctic made of ferritic structural steels. Such steel materials often exhibit a brittle fractur mode with ut notic able prior plastic defor ations. This paper presents a combin d experimental a d numerical investigation to ass ss the cleavag fracture failure for high-strength steels used in offshore applications. The experimental progr m includes a set of non-conv ntional, special singl -edge notch d bend, SSE(B) specimens, tested under a lower ambi tempe ture of -90 o C. In contrast to the conventional through-thickness fracture specimens, which exp rie ce an approxi at ly uniform ck drivi g for e alo g the entire rack fro t, the spe im n with a curved crack front indicates strong variation in both th n f s and co traints along the crack front. Thi study th refore utilizes an averag toughness v lue calculated from the η -approac to describe the scatter observed in th fracture to ghness. This s udy also pr sents a num rical investigation using e local Weibull stress approa h o estimat the probability of cle vage fracture in the fracture tests. A comb nation of the fracture i itiation zone defined by the J -integral values with a local Weibull str ss driving forc predicts r a onably well he probability of fracture of the experimental specimens. © 2016 The Authors. Published by Elsevier B.V. Peer-review under espons bility of the Scientific Committee of ECF21. Keywords: Cleavage fracture; global approach; local approach; Weibull stress; Probability of fracture. Copyright © 2016 The Authors. Published y Elsevier B.V. T is is an ope access article und r the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer-review und r responsibility of the Scientific Committe of ECF21.

© 2016 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of PCF 2016. Keywords: Cleavage fracture; global approach; local approach; Weibull stress; Probability of fracture.

Keywords: High Pressure Turbine Blade; Creep; Finite Element Method; 3D Model; Simulation.

* 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. 2452-3216 © 2016 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of ECF21. * Corresponding author. Tel.: +65-6516-6827; fax: +65-6779-1635. E-mail address: qianxudong@nus.edu.sg * Corresponding author. Tel.: +65-6516-6827; fax: +65-6779-1635. E-mail address: qianxudong@nus.edu.sg

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.2016.06.257