PSI - Issue 2_A

ScienceDirect Available online at www.sciencedirect.com Av ilable o line at ww.sciencedire t.com Scie ceDirect Structural Integrity Procedia 00 (2016) 000 – 000 Procedia Struc ural Integrity 2 (2016) 203 –2037 Available online at www.sciencedirect.com Structural Integrity Procedia 00 (2016) 000–000 Available online at www.sciencedirect.com Structural Integrity Procedia 00 (2016) 000–000

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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. 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.2016.06.255 ∗ Corresponding author. Tel.: + 7-495-433-6257; fax: + 7-499-739-9531. E-mail address: perelm@ipmnet.ru 2452-3216 c ⃝ 2016 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of ECF21. Models of a crack with interaction of its faces make it possible to combine approaches of mechanics and physics of fracture while analyzing a crack growth. Zones of crack faces interaction adjoin crack tips and these zones are commonly in lude the crack part where cohesion forces are applied to the crack faces and suppress the complete crack opening. Di ff erent versions of such models (cohesive or bridged) for an lyzing brittle, elastic-plastic and vis coelastic fracture were proposed. In this paper to model fracture toughness of interfacial junctions the multilevel crack bridging concept is proposed and used. It is assumed within the concept: there are bonds of the di ff erent levels (in termolecular forces, molecular bundles, fibers, particles) between joined materials (the interfacial adhesion layer); a zone of weakened bonds in this layer is considered as the interfacial crack with distributed nonlinear spring-like bonds between the crack faces (bridged zone). The bonds properties on the di ff erent material levels define the stress state in the crack bridged zone and, hence, the fracture toughness of the interface junction. In the general case, the size of the interface crack bridged zone is comparable to the whole crack length. In the case of the crack bridged zone of large scale the conditions of the limit equilibrium and quasi-static growth of cracks must be reconsidered for modelling quantitatively the bridging e ff ects. The quantitative evaluation of the interfacial fracture toughness accounting for the bridging e ff ects consists of the following main steps: 1) development of the bond deformation law; 2) evaluation of stresses along the crack bridged zone; 3) application of the non-local crack growth criterion to analyze the fracture parameters of the interface junction taking into account fracture toughness of interface itself. ∗ Corresponding author. Tel.: + 7-495-433-6257; fax: + 7-499-739-9531. E-mail address: perelm@ipmnet.ru 2452-3216 c ⃝ 2016 The Authors. Published by Elsevier B.V. e r-review under responsibility of the Scientific Committee of ECF21. te n o ru ⃝ 0 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 Bridged crack model of interfacial toughness Mikhail Perelmuter ∗ A. Ishlinsky Institute for Problems in Mechanics RAS, prosp. Vernadskogo 101-1, Moscow, 119526 Russia Abstract The multilevel model of bridged cracks for analysis of the interfacial fracture toughness and cracks growth process is proposed and used. It is assumed: there are bonds of the di ff erent levels between jointed materials (the interface layer); a zone of weakened bonds in this layer is considered as an interfacial crack with distributed nonlinear spring-like bonds between the faces of a crack (the bridged zone); the size of the interface c ack bridged zone is comparable to the whole crack size. The qu ntitative analys f the bridging e ff ect on interfacial toughness is performed accounting for the influence of the boundary conditions of structures. c ⃝ 2016 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of ECF21. Keywords: interface fracture toughness; bridged crack model; nonlocal criterion 1. Introducti Models of a crack with interaction of its fa es m ke it p ssible to combine approaches of mechanics and physics of fracture while analyzing a crack growth. Zones of crack faces interaction adjoin crack tips and these zones are commonly include the crack parts where cohesion forces are applied to the crack faces and suppress the complete crack opening. Di ff erent versions of such models (cohesive or bridged) for analyzing brittle, elastic-plastic and vis coelastic fracture were proposed. In this paper to model fracture toughness of interfacial junctions the multilevel crack bridging concept is proposed and used. It is assumed within the concept: there are bonds of the di ff erent levels (in termolecular forces, molecular undl s, fibers, particles) between joined materials (the interfacial adhesion layer); a zon of weakened bonds in th s layer is o sidered as th interfacial crack with distributed nonlinear spring-like bonds between the crack faces (bridged zone). The bonds properties on the di ff erent material levels define the stress state in the crack bridged zone and, hence, the fracture toughness of the interface junction. In the general case, the size of the interface crack bridged zone is comparable to the whole crack length. In the case of the crack bridged zone of large scale the conditions of the limit equilibrium and quasi-static growth of cracks must be reconsidered for modelling quantitatively the bridging e ff ects. The quantitative evaluation of the interfacial fracture toughness accounting for the bridging e ff ects consists of the following main steps: 1) development of the bond deformation law; 2) evaluation of stresses along the crack bridged zone; 3) application of the non-local crack growth criterion to analyze the fracture parameters of the interface junction taking into account fracture toughness of interface itself. 21st European Conference on Fracture, ECF21, 20-24 June 2016, Catania, Italy Bridg d crack model of interfacial toughness Mikhail Perelmut r ∗ A. Ishlinsky Institute for Problems in Mechanics RAS, prosp. Vernadskogo 101-1, Moscow, 119526 Russia Abstract The multil vel odel of bridged cracks for analysis of the interfa ial fracture toughness nd crack growth process is proposed and used. It is assumed: there are bonds of the di ff erent levels between jointed materials (the interface layer); a zone of weakened bonds in this layer is considered as an interfacial crack with distributed nonlinear spring-like bonds between the faces of a crack (the bridged zone); the size of the interface crack bridged zone is comparable to the whole crack size. The quantitative analysis of the bridging e ff ect on interfacial toughness is performed accounting for the influence of the boundary conditions of structures. c ⃝ 2016 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of ECF21. Keywords: interface fracture toughness; bridged crack model; nonlocal criterion 1. Introduction e T a ff b n ( 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/). P r-review u der 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. * Corresponding author. Tel.: +351 218419991. E-mail address: amd@tecnico.ulisboa.pt