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 On constitutive assumptions in phase field approaches to brittle fracture Michael Strobl a , Thomas Seelig a a Institute of Mechanics, Karlsruhe Institute of Technology, Otto-Ammann-Platz 9, 76131 Karlsruhe, Germany Abstract Constitutive assumptions involved in phase field models of fracture in order to capture the behavior of cracks on the (smeared) continuum level are critically reviewed and several improvements are suggested. While some of the deficiencies of existing models are connected to the variational structure of respective phas field approaches, non-variation l approaches are shown to allow for greater flexibility towards constitutive assumptions needed f r a realistic representation of cracks. Benefits of the latter are illustrated by numerical examples. c 2016 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of ECF21. Keywords: Br ttle fracture; Phase field appro ch; Finite lements; Crack nucleation; Damage me hanics 1. Introduction Phase field approaches to brittle fracture have recently proven their excellent ability to reproduce situations with complex crack patterns including initiation of crack and d termination of unknow crack pat s, e.g. Karma et al. (2001), Henry and Levin (2004), Miehe e al. (2010a) and Kuhn and Mu¨ ller (2010). These features follow directly from variational global energy minimization principles extending the classical Gri ffi th theory of fracture as suggested by Francfort and Marigo (1998) and cast into a regularized (phase field) approximation by Bourdin et al. (2000), which is more suitable for a numerical (e.g. finite element) solution. In certain cases, however, additional constitutive assumptions have to be included in the phase field model in order to obtain physically reasonable solutions. For instance, these assumptions aim to prevent damage in compressed regions by introducing a tension-compression asymmetric material response (e.g. Amor et al. (2009)) or prevent the onset of damage before a critical state is reached (e.g. Miehe et al. (2015)). To some extent, this can only be achieved at the cost of giving up the underlying variational concept of brittle fracture. 21st European Conference on Fracture, ECF21, 20-24 June 2016, Catania, Italy On constitutive assumptions in phase field approaches to brittle fracture Michael Strobl a , Thomas Seelig a a Institute of Mechanics, Karlsruhe Institute of Technology, Otto-Ammann-P atz 9, 76131 Karlsruhe, Germany Abstract Constitutiv ssumptions involved in phase field m dels of fracture in order to capture the behavior of cracks on the (sme red) continuum level are critically reviewed and several improvements are suggested. While some of the deficiencies of existing models are connected to the variational structure of respective phase field approaches, non-variational approaches are shown to allow for greater flexibility towards constitutive assumptions needed for a realistic representation of cracks. Benefits of the latter are illustrated by numerical examples. c 2016 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of ECF21. Keywords: Brittle fracture; Phase field approach; Finite elements; Crack nucleation; Damage mechanics 1. Introduction Phase field approaches to brittle fracture have recently proven their excellent ability to reproduce situations with complex crack patterns including initiation of cracks and determination of u known crack aths, e.g. Karma et al. (2001), Henry and Levine (2004), Miehe et al. (2010a) and Kuhn and Mu¨ ller (2010). These features follow directly fro vari tional global energy minim zation pr ciples extending th classical Gri ffi th theory of fracture as suggested by Francfort and Marigo (1998) and cast into a regularized (phase field) approximation by Bourdin et al. (2000), which is more suitable f r a numerical ( .g. finite element) solution. In certain cases, however, additio al constitutive assumptions have to be included in the phase field model in order to obtain physically reasonable solutions. For instance, these assumptions aim to prevent damage in compressed regions by introducing a tension-compression asymmetric material response (e.g. Amor et al. (2009)) or prevent the onset of damage before a critical state is reached (e.g. Miehe et al. (2015)). To some extent, this can only be ac ieved at the cost of giving up the underlying variational concept of brittle fracture. The present work focuses on the choice of constitutive assumptions and analyzes their impact on the perfor- 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/). er-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. The present work focuses on the choice of constitutive assumptions and analyzes their impact on the perfor-

* Corresponding author. Tel.: +351 218419991. E-mail address: amd@tecnico.ulisboa.pt ∗ Corresponding author. Tel.: + 49 721 608 47794 ; fax: + 49 721 608 47990. E-mail ddress: michael.strobl@kit.edu ∗ Corresponding author. Tel.: + 49 721 608 47794 ; fax: + 49 721 608 47990. E-mail address: michael.strobl@kit.edu

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.2016.06.460 2452-3216 c 2016 The Authors. Published by Elsevier B.V. e r-review under responsibility of the Scientific Committee of ECF21. 2452-3216 c 2016 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of ECF21.