PSI - Issue 13

ScienceDirect Available online at www.sciencedirect.com Av ilable o line at ww.sciencedire t.com ScienceDirect Structural Integrity Procedia 00 (2016) 000 – 000 Procedia Structu al Integrity 13 (2018) 932–938 Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia 00 (2018) 000 – 000 Available online at www.sciencedirect.com ScienceDirect Structural Int grity Procedia 00 (2018) 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. ECF22 - Loading and Environmental effects on Structural Integrity Development of a damage mechanics based limit strain concept using an enhanced Rousselier model Florian Fehringer a *, Xaver Schuler a , Michael Seidenfuß b a Materials Testing Institute (MPA) – University of Stuttgart, Pfaffenwaldring 32, 70569 Stuttgart, Germany b Institute for Materials Testing, Materials Science and Strength of Materials – University of Stuttgart, Pfaffenwaldring 32, 70569 Stuttgart, Germany Abstract Several incidents in the past showed the risks of environmental caused accidents, which exceed the design limits of power plant components. According to technical standards, for the evaluation of safety margins usually stress based criteria are used. These criteria are unable to fully utilize the high deformation capabilities of most materials used for power plant components. To overcome this disadvantage, a proposal for a strain based structural integrity assessment (SIA) concept will be made. The proposed SIA concept is based on damage mechanics simulations using an enhanced Rousselier model. Therefore, three extensions were made to the standard Rousselier model. First, the integration of an additional term allowing the prediction of failure under shear stress conditions developed by Nahshon and Hutchinson is presented. Second, the extension with a kinematic term using a back-stress tensor to the Rousselier model to properly describe very low cyclic loading behavior will be described. For the description of the back stress tensor, models developed by Drucker/ Prager, Armstrong/ Frederick and Chaboche are used. Third, the plasticity behavior at low stress triaxialities was improved by replacing the von Mises plasticity law by a Hosford like yield criterion. The extensions were evaluated with a large experimental program using a ferritic and an austenitic steel. For the derivation of the limit strain concept, differe t influences of stress triaxiality, compon nt size, non pr portional loa ing and multiple l a ing on the limit strains are investigated experimentally and numerically. ECF22 - Loading and Environmental effects on Structural Integrity Development of a damage mechanics based limit strain concept using an enhanced Rousseli r model Florian Fehringer a *, Xaver Schuler a , Michael Seidenfuß b a Materials Testing Institute (MPA) – University of Stuttgart, Pfaffenwaldring 32, 70569 Stuttgart, Germany b Institute for Materials Te ting, Materials Science and Str ngth Ma erials – University of Stuttgart, Pfaffenwaldring 32, 70569 Stuttgart, Germany Abstract Several incidents in the past showed the risks of environmental caused accidents, which exceed the design limits of power plant components. According to technical standards, for the evaluation of safety margins usually stress based criteria are used. These criteria are unabl to fully utilize the high deform ti capabilities of most m terials used for power plant components. To overcome this disadvantag , a proposal for a strain based structural integrity asse sment (SIA) concept will b made. The pr posed SIA concept is based n damage mechanics imulations using an enhanced Rousselier model. Therefore, three extensions were made to the standard Rousselier model. First, the integration of an additional term allowing t e prediction of failure under she r stress conditions developed by Nahshon and Hutchins is presented. Second, the extensi n with a kinematic term using a back-stress tensor to the Rousselier model to properly describe very low cyclic loading behavior will be described. For the description of the back stress tensor, models developed by Drucker/ Prager, Armstrong/ Frederick and Chab che are used. Third, the plasticity behavior at low str ss triaxialities was improved by replacing th von Mises plasti ity law by a Hosford like yield crit rion. The extensions were evaluated with a large experimental progra using a ferritic a an austenitic ste l. For the erivation of the limit strain concept, t e different i fluenc s of stress triaxiality, compon t ize, non proportional loading and multiple loading on the limit strains are investigated experimentall and numerically. © 2016 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of PCF 2016. © 2018 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ECF22 organizers. © 2018 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ECF22 organizers. © 2018 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ECF22 organizers. Keywords: damage mechanics; Rousselier model; limit strain concept; stress triaxiality; non-proportional loading, size effect Keywords: High Pressure Turbine Blade; Creep; Finite Element Method; 3D Model; Simulation. Keywords: damage mechanics; Rousselier model; limit strain concept; stress triaxiality; non-proportional loading, size effect

* Corresponding author. Tel.: +49-711-685-69695; fax: +49-711-685-62635. E-mail address: Florian.Fehringer@mpa.uni-stuttgart.de * Corresponding author. Tel.: +49-711-685-69695; fax: +49-711-685-62635. E-mail ad ress: Florian.Fehringer@mpa.uni-stuttg rt.de

* Corresponding author. Tel.: +351 218419991. E-mail address: amd@tecnico.ulisboa.pt 2452-3216 © 2018 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ECF22 organizers. 2452-3216 © 2018 The Authors. Published by Elsevier B.V. Peer review under r sponsibility of the ECF22 o ganizers.

2452-3216 © 2016 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of PCF 2016.

2452-3216  2018 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ECF22 organizers. 10.1016/j.prostr.2018.12.175