PSI - Issue 2_A

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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 Computational modelling of transversely isotropic high-cycle fatigue using a continuum based model Sami Holopainen a , Reijo Kouhia a, ∗ , Juho Ko¨nno¨ b , Timo Saksala a a Tampere University of Technology, Department of Mechanical Engineering and Industrial Systems, P.O. Box 589, FI-33101 Tampere, Finland b Research & Development, Wa¨rtsila¨ Finland Oy, Abstract In this paper a computational implementation of a continuum based transversely isotropic high-cycle fatigue model is described. The k y idea of that model is the movi endurance s rface where the movement is descri ed by a back stress type tensor, the evolution of which is described by a rate type equation. Furthermore, damage accumulation is also governed by a rate type evolution equation. The endurance surface is given in terms of invariants from the integrity basis of the transversely isotropic symmetry group. The key point of the formulation is the additive split of the stress tensor in two components; one in the transverse isotropic plane and another in the longitudinal direction. The material parameters are calibrated for the forged 34CrMo6 steel and for the isotropic AISI-SAE 4340 steel. The model is implemented in the Abaqus FE-program using the user material subroutine. c 2016 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of ECF21. Keywords: high-cycle fatigue; transverse isotropy; endurance surcafe; Abaqus UMAT 1. Introduction Fatigue of materials under variable loads is a complicated physical process which can result in catastrophic failure of engineering components. It is characterized by nucleation, coalescence and stable growth of cracks. Nucleation of cracks starts from stress concentrations near persistent slip bands, grain interfaces and inclusions, see e.g. Suresh (1998); Bolotin (1999); Socie and Marquis (2000). In high-cycle fatigue, the macroscopic behavior of the material is primarily elastic, while in the low-cycle fatigue regime considerable macroscopic plastic deformations take place. Transition between low- and high-cycle fatigue occurs between 10 3 − 10 4 cycles. In recent years, it has been observed that fatigue failures can also occur at very high fatigue lives 10 9 − 10 10 , below the previously assumed fatigue limits. In this paper only high-cycle fatigue modelling is considered. Many di ff erent approaches have been proposed to model the high-cycle fatigue behaviour which can roughly be classified into stress invariant, or average stress based and critical plane approaches. In those approaches damage accumulation is usually based on cycle-counting, which makes their use questionable under complex load histories, see Ottosen et al. (2008); Lemaitre and Desmorat (2005). 21st European Conference on Fracture, ECF21, 20-24 June 2016, Catania, Italy Computational modelling of transversely isotropic high-cycle fatigue using a continuum based model Sami Holopainen a , Reijo Kouhia a, ∗ , Juho Ko¨nno¨ b , Timo Saksala a a Tampere University of Technology, Department of M chanical Engineering and Industrial Systems, P.O. B x 589, FI-33101 Tampere, Finland b Research & Development, Wa¨rtsila¨ Finland Oy, Abstract In this paper a computational implementation of a continuum based transversely isotropic high-cycle fatigue model is described. The key idea of that model is the moving endurance surface where the movement is described by a back stress type tensor, the evolution of which is described by a rate type equation. Furthermore, damage accumulation is also governed by a rate type evolution equation. The endurance surface is given in terms of invariants from the integrity basis of the transversely isotropic symmetry group. The key point of the formulation is the additive split of the stress tensor in two components; one in the transverse isotropic plane and another in the longitudinal direction. The material parameters are calibrated for the forged 34CrMo6 steel and for the isotropic AISI-SAE 4340 steel. The model is implemented in the Abaqus FE-program using the user material subroutine. c 2016 The Authors. Published by Elsevier B.V. Peer- eview under r sponsibility of the Scientific Committee of ECF21. Keywords: high-cycle fatigue; transverse isotropy; endurance surcafe; Abaqus UMAT 1. Introduction Fatigue of materials under variable loads is a complicated physical process which can result in catastrophic failure of engineering components. It is characterized by nucleation, coalescence and stable growth of cracks. Nucleation of cracks starts from stress concentrations near persistent slip bands, grain interfaces and inclusions, see e.g. Suresh (1998); Bolotin (1999); Soc e and Marquis (2000). In high-cycle fatigue, the macroscopic behavior of the material is primarily elastic, while in the low-cycle fatigue regime considerable macroscopic plastic deformations take place. Transition between low- and high-cycle fatigue occurs between 10 3 − 10 4 cycles. In recent years, it has been observed that fatigue failures can also occur at very high fatigue lives 10 9 − 10 10 , below the previously assumed fatigue limits. In this paper only high-cycle fatigue modelling is considered. Many di ff erent approaches have been proposed to model the high-cycle fatigue behaviour which can roughly be classified into stress invariant, or average stress based and critical plane approaches. In those approaches damage accumulation is usually based on cycle-counting, which makes their use questionable under complex load histories, see Ottosen et al. (2008); Lemaitre and Desmorat (2005). 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.

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.2016.06.339 ∗ Corresponding author. Tel.: + 358-40-849-0561; fax: + 0-000-000-0000. E-mail address: reijo.kouhia@tut.fi 2452-3216 c 2016 The Authors. Published by Elsevier B.V. e r-review under responsibility of the Scientific Committee of ECF21. ∗ Corresponding author. Tel.: + 358-40-849-0561; fax: + 0-000-000-0000. E-mail address: reijo.kouhia@tut.fi 2452-3216 c 2016 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of ECF21. * Corresponding author. Tel.: +351 218419991. E-mail address: amd@tecnico.ulisboa.pt