PSI - Issue 2_B

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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 Mixed-Mode I/II fracture behavior of asymmetric composite joints Moslem Shahverdi a,b, *, Anastasios P. Vassilopoulos b , Thomas Keller b a Swiss Federal Laboratories for Materials Science and Technology, Empa, 8600 Dübendorf, Switzerland b Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland Abstract The partitioning of the total strain energy release rate, G tot , into the Mode I, G I , and Mode II, G II , components is challenging, especially in asymmetric cracks. Althou h many researchers have studied th fracture behavior of composite materials under mixed-mode loading using symmetric and/or asymmetric mixed-mode bending (MMB) specimens, few studies exist in the literature regarding the experimental investigation and analysis of the fracture behavior of asymmetric MMB specimens comprised of orthotropic layered adherends. In this study, a new approach, designated as the “extended global method”, was established the fracture mode partitioning. The “extended global method” was applied for the analysis of the experimental data. The mixed-mode fracture behavior of adhesively-bonded composite joints was experimentally investigated using asymmetric mixed-mode bending specimens. Finite element models were developed in order to validate the approach. The virtual crack closure technique was used for the calculation of the fracture components at the crack tip and an exponential traction-separation cohesive law was used to simulate the fiber bridging zone. The crack propagated along paths outside the symmetry plane and, therefore, mode partition could not be performed in commonly accepted ways followed for symmetric specimens. In addition, the experimental compliance method was used for calculating the fracture energy of the examined asymmetric mixed-mode bending specimens. Results obtained using the “extended global method” and the experimental compliance method were in good agreement with the results from FE models. The outcome of this study combined with the results obtained from pure Mode I and Mode II xperiments can be us d to establish f ilur criteria for the examined join s, that can be ventually be used for designing structural joints with the same adherends and adhesives. © 2016 The Authors. Published by Elsevi r B.V. Peer-revi w under responsibility of the Scientific Committee of ECF21. 21st European Conference on Fracture, ECF21, 20-24 June 2016, Catania, Italy Mixed-Mode I/II fracture behavior of asymmetric composite joints Moslem Shahverdi a,b, *, Anastasios P. Vassilopoulos b , Thomas Keller b a Swiss Federal Laboratories for Materials Science and Technology, Empa, 8600 Dübendorf, Switzerland b Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland Abstract The partitioning of the total strain energy release rate, G tot , into the Mode I, G I , and Mode II, G II , components is challenging, especi lly i asymmetric cracks. Although many es archers have studied the fr cture behavior of co posite materials under mixed-mode loading using symmetric and/or asymmetric mixed-mode bending (MMB) specimens, few studies xist in the literature r garding the experimen al investig tion and analysis of the fracture behavior of asymmetric MMB spec mens comprised of orthotropic layered adherends. In this study, a new approach, designated as the “extended global method”, was established the fracture mode partitioning. The “extended global method” was applie for the analysis of the experimental data. The mixed-mode fracture behavior of adhesiv ly-bonded composite joints was experimental nvestigated using asymme ric mixed-mo e bending specim ns. Finite element models were developed in ord r to valid te the approach. The virtual crack closure t chnique was us d for th calculation of the fractur compone ts at the crack tip and an exp nential traction-sep ration cohesive law was u ed to simulat the fiber bridging zone. The crack prop gated along paths outside the symmetry plan and, therefore, mode partition could not be performed in commonly accepted ways followed for symmetric specimens. In addition, the experimental compliance method was used for calculating the fracture energy of the examined asymmetri ixed-mo e be ding specimens. Results obtained using the “extended global method” and the experimental compliance thod were in good agreement with the results from FE models. The outcome of this study combined w th the results obtained from pure M de I and Mode II experiments can be use to establish failure criteria for the examined joints, tha can be ventually b use for designing structural joints with the same adherends and adhesives. © 2016 The Author . Published by Elsevier B.V. Peer-review under espons bility of the Scientific Committee of ECF21. Keywords: fracture mechanics; mode partition; asymmetric crack propagation; finite element; composites; cohesive element 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. Keywords: fracture mechanics; mod partition; asymme ric crack propagation; finite ement; composites; cohesive element

* 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. * Corresponding author. Tel.: +41 58 765 42 83; fax: +41 58 765 69 55. E-mail address: moslem.shahverdi@empa.ch 2452-3216 © 2016 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of ECF21. * Corresponding author. Tel.: +41 58 765 42 83; fax: +41 58 765 69 55. E-mail address: moslem.shahverdi@empa.ch

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.2016.06.237