PSI - Issue 13

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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. © 2018 The Authors. Published by Elsevier B.V. Peer-review under r sponsibility of the ECF22 organizers. ECF22 - Loading and Environmental e ff ects on Structural Integrity Large plastic zones and extensive influence of notch under near-threshold mode II and mode III loading of fatigue cracks Hrstka, M. a, ∗ , Zˇ a´k, S. a , Vojtek, T. a,b a Central European Institute of Technology (CEITEC), Brno University of Technology; Purkynˇova 123, 612 00, Brno, Czech Republic b CEITEC IPM, Institute of Physics of Materials, Ac demy of Sciences of the Czech R public; Zˇ izˇkova 22, 616 62, Brno, Czech Republic Abstract Plastic zone shapes and sizes were determined for a cylindrical specimen for mode II and mode III crack testing made of ARMCO iron. Three methods of calculation were applied: Irwins approximate solution, HRR field and finite element method. The plastic zones were found to be very large under mode II and mode III loadi g eve at the loading level corresp nding to fatigue crack growth threshold. The di ff erence between sizes of plastic zones under tensile-mode and shear-mode loading was explained by di ff erent stress gradients and corresponding stress concentration factors of notches under shear and tensile type loading. This is also the reason for a much further influence of notch on stress intensity factors for mode II and mode III cracks emanating from the notch than the influence under mode I loading. Preliminary results for reversed plastic zone size indicated that it is smaller than the theoretical size of 1 / 4 of the monotonic zone which explained the presence of large monotonic zone at threshold loading. c 2018 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ECF22 organizers. Keywords: plastic zone; mode II; mode III; fatigue; notc 1. Introduction Plastic zone size is a significant input parameter for many engineering applications that deal with a crack stability assessment. There are several analytical methods that provide a conservative estimation of a process zone. Within the presented work, two common fracture mechanics approaches were investigated - linear-elastic Irwin’s solution and elastic-plastic HRR theory. Resulting plastic zone shapes will be compared with a numerical analysis by using FEM computations of the real specimen with consideration of multi-linear elastic-plastic material behaviour. The knowledge of the plastic zone sizes is also used for assessment of the small-scale yielding (SSY) conditions. It was found that plastic zone sizes are very large under mode II and mode III loading even at the loading level corresponding to e ff ective threshold. It should be emphasized that under mode II and mode III loading the e ff ective threshold is several times lower than the applied threshold. Therefore, at threshold loading, the plastic zones are even much larger. The di ff erence between sizes of plastic zones under tensile-mode and shear-mode loading can be ECF22 - Loading and Environmental e ff ects on Structural Integrity Large plastic zones and extensive influence of notch under near-threshold mode II and mode III loading of fatigue cracks Hrstka, M. a, ∗ , Zˇ a´k, S. a , Vojtek, T. a,b a Central European Institute of Technology (CEITEC), Brno University of Technology; Purkynˇova 123, 612 00, Brno, Czech Republic b CEITEC IPM, Institute of Physics of Materials, Academy of Sciences of the Czech Republic; Zˇ izˇkova 22, 616 62, Brno, Czech Republic Abstract Plastic zone shapes and sizes were determined for a cylindrical specimen for mode II and mode III crack testing made of ARMCO iron. Three methods of calculation were appl ed: Irwins ap roximate solution, HRR field and finite element method. The plastic zones were found to be very large under mode II and mode III loading even at the loading level corresponding to fatigue crack growth threshold. The di ff erence between sizes of plastic zones under tensile-mode and shear-mode loading was explained by di ff erent stress gradients and corresponding stress concentration factors of notches under shear and tensile type loading. This is also the reason for a much further influence of notch on stress intensity factors for mode II and mode III cracks emanating from the notch than the influence under mode I loading. Preliminary results for reversed plastic zone size indicated that it is smaller than the theoretical size of 1 / 4 of the monotonic zone which explained the presence of large monotonic zone at threshold loading. c 2018 The Authors. Published by Elsevier B.V. r-review under responsibility of the ECF22 organizers. Keywords: plastic zone; mode II; mode III; fatigue; notch 1. Introduction Plastic zone size is a significant input parameter for many engineering applications that deal with a crack stability assessment. There are several analytical methods that provide a conservative estimation of a process zone. Within the presented work, two common fracture mechanics approaches were investigated - linear-elastic Irwin’s solution and elastic-plastic HRR theory. Resulting plastic zone shapes will be compared with a numerical analysis by using FEM computations of the real specimen with consideration of multi-linear elastic-plastic material behaviour. The knowledge of the plastic zone sizes is also used for assessment of the small-scale yielding (SSY) conditions. It was found that plastic zone sizes are very large under mode II and mode III loading even at the loading level corresponding to e ff ective threshold. It should be emphasized that under mode II and mode III loading the e ff ective threshold is several times lower than the applied threshold. Therefore, at threshold loading, the plastic zones are even much larger. The di ff erence between sizes of plastic zones under tensile-mode and shear-mode loading can be © 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 ∗ Corresponding author. Tel.: + 420 726 81 2871 E-mail address: Miroslav.Hrstka@ceitec.vutbr.cz ∗ Corresponding author. Tel.: + 420 726 81 2871 E-mail address: Miroslav.Hrstka@ceitec.vutbr.cz

2452-3216 © 2016 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of PCF 2016. 2210-7843 c 2018 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ECF22 organizers. 2210-7843 c 2018 The Authors. Published by Elsevier B.V. Peer-revi w under responsibility of the ECF22 orga izers. 2452-3216  2018 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ECF22 organizers. 10.1016/j.prostr.2018.12.235