PSI - Issue 12

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2452-3216 © 2016 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of PCF 2016. 2452-3216  2018 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/3.0/) Peer-review under responsibility of the Scientific Committee of AIAS 2018 International Conference on Stress Analysis. 10.1016/j.prostr.2018.11.086 ∗ Corresponding author. Tel.: + 39 3407793659. E-mail address: riccardo.panciroli@unicusano.it 2210-7843 c 2018 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 / 3.0 / ) Peer-review under responsibility of the Scientific Committee of AIAS 2018 International Conference on Stress Analysis. ∗ Corresponding author. Tel.: + 39 3407793659. E-mail address: riccardo.panciroli@unicusano.it 2210-7843 c 2018 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 / 3.0 / ) Peer-review u der re ponsibility of he Scientific ommitt e of AIAS 2018 International Conference on Stress Analysis. 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. © 2018 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/3.0/) Peer-review under responsibility of the Scientific Committee of AIAS 2018 International Conference on Stress Analysis. AIAS 2018 International Conference on Stress Analysis Viscoelastic experimental characterization of flax / epoxy composites P.M. Giuliani a , O. Giannini a , R. Panciroli a, ∗ a Niccol Cusano University, via don Carlo Gnocchi 3, 00166, Rome, Italy Abstract This work presents an experimental characterization of the mechanical behavior of unidirectional composites based on flax fibers and (bio-)epoxy resins. The study focuses on the viscoelastic and the pseudo-plastic response on the composites. Specimens have been produced through a LRTM process and tested in pure monotonic tension, and cyclic tension. The e ff ect of the strain rate has been also investigated. This is found to have a strong influence due to the very high creep sensitivity of the material. Finally, intra-laminate variability of the mechanical properties has been also investigated. Results show that the mechanical properties of flax-based composites might show either good repeatability or high dispersio , based on the supplier quality of the rough materials. However, results show a defined transition point between E 1 and E 2 , nd a strain-based failure criterion. c 2018 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 / 3.0 / ) Peer-review under responsibility of the Scientific Committee of AIAS 2018 International Conference on Stress Analysis. K ywords: Viscoelasticity; Flax; Natural composites 1. Introduction The urging need to reduce the footprint of materials utilized in industrial design is boosting the interest on natural composites. Nowadays, when referring to composites, despite the numerous e ff orts, the development of structural fully recyclable components is still in a arly stage, while bio-based composites with reduced footprint are already on their way. Hemp and flax-based composites are particularly fascinating designers (Pil et al. (2016)). There have been many authors reporting the results from mechanical characterizations of flax-based composites, as reported in the reviews by Yan et al. (2014) and Mahboob and Bougherara (2018). Mahboob et al. (2017) performed tensile and compressive tests on flax composites. They reported that it is necessary to evaluate both modulus and inelastic strain to fully describe the composite damaged response at any stage of loading. Shah (2016) studied the sti ff ness degradation in natural-fiber based composites, which is related to the loss of performance over life. Therein, the author proposes that the initial elastic modulus should not be considered due to its rapid drop. He rather suggests to use the stabilized elastic modulus after 0.4% of applied strain. A remarkable di ff erence between natural fibers and glass fiber based composites stands on the evolution of sti ff ness in the vicinity of AIAS 2018 International Conference on Stress Analysis Viscoelastic experi ental characterization of flax / epoxy co posites P.M. Giuliani a , O. Giannini a , R. Panciroli a, ∗ a Niccol Cusano University, via don Carlo Gnocchi 3, 00166, Rome, Italy Abstract This work presents an experimental characterization of the mechanical behavior of unidirectional composites based on flax fibers and (bio-)epoxy resins. The study focuses on the viscoelastic and the pseudo-plastic response on the composites. Specimens have been produced through a LRTM process and tested in pure monotonic tension, and cyclic tension. The e ff ect of the strain rate has been also investigated. This is found to have a strong influence due to the very high creep sensitivity of the material. Finally, intra-laminate variabili y of the mecha ical properties has b en also investigated. Results h w that the mechanical propertie f flax-based composites might show either good repeatability or high dispersion, based on the supplier quality of the rough materials. However, results show a defined transition point between E 1 and E 2 , and a strain-based failure criterion. c 2018 The Authors. Published by Elsevier B.V. is is an open access article under the CC BY-NC-ND license (http: // creativecommons.org / licenses / by-nc-nd / 3.0 / ) r-review under responsibility of the Scientific Committee of AIAS 2018 I ternational C ference on Stress Analysis. Keywords: Viscoelasticity; Flax; Natural composites 1. Intro uction The urging need to reduce the footprint of materials utilized in industrial design is boosting the interest on natural composites. Nowadays, when referring to composites, despite the numerous e ff orts, the development of structural fully recyclable components is still in a early stage, while bio-based composites with reduced footprint are already on their way. Hemp and flax-based composites are particularly fascinating designers (Pil et al. (2016)). There have been many authors reporting the results from mechanical characterizations of flax-based composites, as reported in the reviews by Yan et al. (2014) and Mahboob and Bougherara (2018). Mahboob et al. (2017) performed tensile and compressive tests on flax composites. They reported that it is necessary to evaluate both modulus and inelastic strain to fully describe the composite damaged response at any stage of loading. Shah (2016) studied the sti ff ness degradation in natural-fiber based composites, which is related to the loss of performance over life. Therein, the author proposes that the initial elastic modulus should not be considered due to its rapid drop. He rather suggests to use the stabilized elastic modulus after 0.4% of applied strain. A remarkable di ff erence between natural fibers and glass fiber based composites stands on the evolution of sti ff ness in the vicinity of © 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