PSI - Issue 3

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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. Copyright © 2017 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 r sponsibility of the Scientific Committee of IGF Ex-Co. XXIV Italian Group of Fracture Conference, 1-3 March 2017, Urbino, Italy Correlation f pressure stimulated currents and acoustic emissions during 3PB of cement-mortar beams and the role of loading rate D. Triantis a , E. D. Pasiou b , I. Stavrakas a , I. Dakanali b , S. K. Kourkoulis b, * a Laboratory of Electronic Devices and Materials, Technological Educational Institution of Athens, Athens 122 10, Greece b Laboratory for Testing and Materials, National Technical University of Athens, Zografou Campus 157 73, Greece Abstract An experimental p otocol was implemented to vestigate possible correlations b tween th data pro ided by the Acoustic Emiss ons and the Pressure Stimulated Currents techniques and the role of the loading rate induced. Prismatic cement-mortar specimens were subjected to three-point bending (3PB) under various loading rates. It was concluded that optimum correlation is achieved in terms of the energy released. The specific relation was found to obey a power law independently of the loading rate, in spite of the fact that the characteristic quantities of each technique do depend in one way or another on the loading rate. In addition, it was concluded that the total electric charge released appears insensitive to changes of the loading rate at least in the range tested. © 2017 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of IGF Ex-Co. Keywords: Pressure Stimulated Currents; Acoustic Emissions; cement mortar; three point bending; pre-failure indicators 1. Introducti n The onset and propagation of cracks in quasi- rittle and h terogeneous m erials, like for example cement-based ones, is a complicated process, and the mechanisms activated during this process are not as yet clearly understood. The Acoustic Emission (AE) technique is one of the non-invasive methods widely used to monitor such processes in structures made of cement-based materials in order to detect and assess the damage accumulated during mechanical loading. Acoustic emissions are elastic stress waves produced in the material under loading due to the internal stress redistribution (Grosse & Ohtsu 2008). Indeed, during loading and fracture processes of quasi-brittle materials acoustic events of various amplitudes are detected, which are attributed to the formation and growth of micro-cracks (Ohtsu XXIV Italian Group of Fracture Conference, 1-3 March 2017, Urbino, Italy Correlation of pressure stimulated currents and acoustic emissions during 3PB of cement-mortar beams and the role of loading rate D. Triantis a , E. D. Pasiou b , I. Stavrakas a , I. Dakanali b , S. K. Kourkoulis b, * a Laboratory of Electronic Devices nd Materials, Technological Educational Institutio of Athens, Athens 122 10, Greece b Laboratory for Testing and Materials, National Technical University of Athens, Zografou Campus 157 73, Greece Abstract An experimental protocol was implemented to investigate possible correlations between the data provided by the Acoustic Emissions and the Pressure S imulated Curr nts techniques and the role of th l adi g at i duced. Prismatic cement-mortar specime were subjected to three-point bendi g (3PB) under various loading r tes. It was concl d that optimum correlation i achieved in terms of the energy released. The specific relation was found to obey a power law independently of the loading rate, in spite of the fact tha th characteristic quantiti s of each technique do depend in one way or another on the loading rate. In addition, it was concluded that the otal electric charge r leased appears insensitive to changes of the loading rat at least in the range tested. © 2017 The Authors. Published by Elsevier B.V. Peer-review under espons bility of the Scientific Committee of IGF Ex-Co. Keywords: Pressure Stimulated Currents; Acoustic Emissions; cement mortar; three point bending; pre-failure indicators 1. Introduction The onset and propagation of cracks in quasi-brittle and heterogeneous materials, like for example cement-based ones, is a complicated process, and the mech isms activated during this proc ss are not as yet clearly understood. Th Acoustic Emission (AE) techniqu is one of the non-invasive methods wid ly us d to moni or such proc s es in structures made of cement-based materials in rder to detect and ass ss the damage accumulated during me hanical loading. Acoustic emissions r elastic stress wav s produ ed in the material under loading du to the internal stress redistribution (Grosse & Ohtsu 2008). Ind ed, during loa ing and fracture processes of quasi-brittle materials coustic even s of various amplitudes are detecte , which are attr buted to the formation and growth of micro-c cks (Ohtsu © 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.

* Corresponding author. Tel.: +351 218419991. E-mail address: amd@tecnico.ulisboa.pt 2452-3216 © 2017 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of IGF Ex-Co. 2452-3216 © 2017 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of IGF Ex-Co. * Corresponding author. Tel.: +30-210-7721263; fax: +30-210-7721302. E-mail address: stakkour@central.ntua.gr * Corresponding author. Tel.: +30-210-7721263; fax: +30-210-7721302. E-mail address: stakkour@central.ntua.gr

2452-3216 © 2016 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of PCF 2016. Copyright © 2017 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 IGF Ex-Co. 10.1016/j.prostr.2017.04.027