PSI - Issue 7

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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. Peer-review under responsibility of the Scientific Committee of the 3rd International Symposium on Fatigue Design and Material Defects. 3rd International Symposium on Fatigue Design and Material Defects, FDMD 2017, 19-22 September 2017, Lecco, Italy Analysis of Crack Extension Mechanism in the Near-Threshold Regime in an Aluminum Alloy M.Wicke a *, A. Brueckner-Foit a , T. Kirsten b , M. Zimmermann b , F. BuelBuel c , H.-J. Christ c a Institue for Materials Engineering, University of Kassel, D-34125 Kassel, Germany b Institue for Materials Engineering, Technical University of Dresden, D-01069 Dresden, Germany c Institue for Materials Engineering, University of Siegen, D-57068 Siegen, Germany Abstract Short cracks initiated from pre-existing flaws are known to propagate in an intermittent way below threshold as the crack tip field interacts with the microstructure. If the stress amplitude is very low, similar effects as observed for short cracks may happen to long cracks leading to unexpected crack extension. This phenomenon is studied in this paper using flat dogbone specimens of a commercial aluminum alloy in two heat treatment states. Compression pre-cracked specimens were used to determine the threshold by continuous load increase according to a procedure proposed by Pippan et al. [Pippan et al. (1994)]. On this basis, crack growth experiments with an approximately constant ΔK -value propagation rate were performed at a stress ratio of R = 0.1. Results indicate that primary precipitates act as microstructural barriers causing crack deflection and crack branching. If the stress amplitude is low enough, shear-dominated crack extension has been found to be possible even for long cracks in the near-threshold regime. Both mechanisms keep the crack from extending continuously. © 2017 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of the 3rd I ternational Symposium on Fatigue Design and Material Defects. 3rd International Symposium on Fatigue Design and Material Defects, FDMD 2017, 19-22 September 2017, Lecco, Italy Analysis of Crack Extension Mechanis in the Near-Threshold Regime in an Aluminum Alloy M.Wicke a *, A. Brueckner-Foit a , T. Kirsten b , M. Zimmermann b , F. BuelBuel c , H.-J. Christ c a s Kassel 34125 Kassel b Institue for Materials Engineering, Technical University of Dresden, D-01069 Dresden, Germany c Institue for Materials Engineering, University of Siegen, D-57068 Siegen, Germany Abstract Short cracks initiated from pr -existing flaws are known to propagate in an int rmittent w y below threshold as the crack tip field interacts with the microstructure. If the stress amplitude is very low, similar effects as observ d for short cracks may happen to long cracks leading to unexpected crack extension. This henomenon is studied in this paper using flat dogbone pecimens of a commercial aluminum all y in two heat treatment states. Compression pre-cracked specimens were used to determine the threshold by continuous load increase ccording to a procedure proposed by Pippan et al. [Pippan et al. (1994)]. On this basis, crack growth xperiments with an approximat ly constant ΔK -value propagation rate were performed at stress ratio of R = 0.1. Results indicate that primary precipitates act as icrostructural barriers causing crack deflection and crack branching. If the stress amplitude is low enough, shear-dominated crack extension has been found to be possible even for long cracks in the near-threshold regime. Both mechanisms keep the crack from extending continuously. © 2017 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of the 3rd International Symposium on Fatigue Design and Material D fects. © 2016 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of PCF 2016. Keywords: Aluminum alloys; compression pre-cracking; threshold; fatigue crack growth Keywords: Aluminum alloys; compression pre-cracking; threshold; fatigue crack growth

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

* Corresponding author. Tel.: +49 561-804-3656 E-mail address: marcel.wicke@uni-kassel.de * Corresponding author. Tel.: +49 561-804-3656 E-mail address: marcel.wicke@uni-kassel.de

2452-3216 © 2017 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of the 3rd International Symposium on Fatigue Design and Material Defects. 2452-3216 © 2017 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of the 3rd International Symposium on Fatigue Design and Material Defects.

* 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 PCF 2016.

2452-3216 Copyright  2017 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of the 3rd International Symposium on Fatigue Design and Material Defects. 10.1016/j.prostr.2017.11.083