PSI - Issue 2_B

ScienceDirect Available online at www.sciencedirect.com Av ilable o line at ww.sciencedire t.com Sci ceDirect Structural Integrity Procedia 00 (2016) 000 – 000 Procedia Struc ural Integrity 2 (2016) 1156–1163 Available online at www.sciencedirect.com ScienceDire t Structural Integrity Procedia 00 (2016) 000–000 Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia 00 (2016) 000–000

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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 Modeling and simulation of temperature-dependent cyclic plastic deformation of austenitic stainless steels at the VHCF limit P.-M. Hilgendorff a, *, A. Grigorescu b , M. Zimmermann c,d , C.-P. Fritzen a , H.-J. Christ b a Institut für Mechanik und Regelungstechnik - Mechatronik, Universität Siegen, D-57068 Siegen, Germany b Institut für Werkstofftechnik, Universität Siegen, D-57068 Siegen, Germany c Institut für Werkstoffwissenschaft, TU Dresden, D-01069 Dresden, Germany d Fr unhofer Institut für Werkstoff- und Strahltechnik, D-01277 Dresden, Germany Abstract The exploration of fatigue mechanisms in the VHCF regime is gaining importance since many components have to withstand a very high number of loading cycles due to high frequency or long product life. In this regime, the period of fatigue crack initiation and thus the localization of plastic deformation play an important role. The material that was investigated in this study is the metastable austenitic stainless steel AISI 304 in the initially purely austenitic condition. The experimental investigations during quasi-isothermal fatigue tests revealed that a moderate increase of temperature from room temperature up to 150°C led to a reduced VHCF strength. At both temperatures the 304 grade still undergoes a pronounced localization of plastic deformation in shear bands accompanied by a deformation-induced martensitic phase transformation from the γ-austenite to the α’-martensite during VHCF loading. In the present study, the experimental study is extended by modeling and simulation of the relevant temperature-dependent VHCF deformation mechanisms in order to provide a more profound understanding of the observed cyclic deformation. For this purpose, two-dimensional (2-D) morphologies of microstructures are modeled in the mesoscopic scale by the use of the boundary element method (BEM), and cyclic plastic deformation is considered by certain mechanisms defined in a simulation model. It describes the localization of plastic deformation in shear bands taking into account the formation, plastic sliding deformation and cyclic slip irreversibility of each shear band. The deformation-induced martensitic phase transformation is represented by introducing martensitic nuclei into the modeled microstructure depending on the plastic deformation in shear bands. The influence of temperature is incorporated into the simulation model by the use of empirical data and a kinetic model, each related to the tensile test. The simulated cyclic deformation and phase transformation is compared to experimental observations and allows for assessing the individual influence of deformation mechanisms on the temperature dependent fatigue behavior. Finally, a temperature-independent ‘limit curve’ for the accumulated irreversible plastic sliding deformation regarding failure in the VHCF regime is proposed. © 2016 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of ECF21. 21st European Conference on Fracture, ECF21, 20-24 June 2016, Catania, Italy Modeling and simulation of temperature-dependent cyclic plastic deformation of austenitic stainless steels at the VHCF limit P.-M. Hilgendorff a, *, A. Grigorescu b , M. Zimmermann c,d , C.-P. Fritzen a , H.-J. Christ b a Institut für Mechanik und Regelungstechnik - Mechatronik, Universität Siegen, D-57068 Siegen, Germany b Institut für Werkstofftechnik, Universität Siege , D-57068 Si gen, Germany c Institut für Werkstoffwissenschaft, TU Dresden, D-01069 Dresden, Ger any d Fraunhofer Institut für Werkstoff- und Strahltechnik, D- 1277 Dresden, Germany Abstract The exploration of fatigue mechanisms in the VHCF regime is gaining importance since many components have to withstand a very high number of loading cycles due to high frequency or lo g product life. I this regime, the period of fatigue crack initiation a d thus the calization of plastic deformation play an important role. The material that was investigated in this study s he metastable austenitic sta nless steel AISI 304 in the initially u ely austenitic condition. The experimental investigations during quasi-isothermal fatigue test rev aled that a moderate increase of temperature from r om temperature up to 150°C led to a reduced VHCF st ength. At both temp ratures the 304 g de still undergoes a pronounced l calization of plastic deformation in shear bands accompa ied by a defor ation-induc d martensitic phase transformati n from the γ-austenite to the α’-mar ensite during VHCF l ading. In the present study, the xperimental study is extended by m deling and simulation of the rel vant temperature-depen ent VHCF deformation mechanisms in order to provid a more pr fou d u erstanding of the obs rved cyclic deformatio . For this purpose, two-dimensional (2-D) morphologies of mic ostructures are modeled in the meso copic scale by the use of the boundary el ment method (BEM), and cyclic plastic deformation is considered by certain mechanisms defined in a imulation mo el. It describes the localizatio of plastic deformation in shear bands taking into account the formation, plastic slidi g deformation and cyclic slip irreversibility of each she r band. The deformation-induced martensitic phase transformation is represented by introduc ng martensitic nuclei into t e modeled microstructure depending on the plas deformation in shear bands. The influence f temperatur i incorporated into the simulation model by the use of empirical data and a kinetic model, e ch relat d to the t nsil test. The s mulated cyclic deformation nd phase transformation is comp re to experimental observations and allows for assessing t individual influence of deformation mechanisms on the te perature de ndent fatigu behavior. Finally, a temperature-independent ‘ imit curv ’ or the accumulated irreversible plastic sliding deformation regarding failure in the VHCF regime is propose . © 2016 The Authors. Pub ished by Elsevier B.V. Peer-review under espons bility of the Scientific Committee of ECF21. Copyright © 2016 The A thors. 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. Keywords: simulation; austenitic stainless steel; very high cycle fatigue; cyclic deformation mechanisms Keywords: simulation; austenitic stainless steel; very high cycle fatigue; cyclic deformation mechanisms

* Corresponding author. Tel.:+49 (0)271 740 4633; E-mail address: philipp.hilgendorff @uni-siegen.de * Corresponding author. Tel.:+49 (0)271 740 4633; E-mail address: philipp.hilgendorff @uni-siegen.de

* 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 ECF21. 2452-3216 © 2016 The Authors. Published by Elsevier B.V. Peer review under r sponsibility of the Scientific Committee of ECF21.

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.2016.06.148