PSI - Issue 2_A

ScienceDirect Available online at www.sciencedirect.com Av ilable o line at www.sciencedire t.com cienceDirect Structural Integrity Procedia 00 (2016) 000 – 000 Procedia Struc ural Integrity 2 (2016) 2463–247 Available online at www.sciencedirect.com ScienceD rect 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 Developme t of New Formulation and Likelihood Function on Probabilistic Fracture Initiation Model Itsuki Kawata a *, Shuhei Yoshizu b , Hiroaki Nakai c , Kazuki Shibanuma a , Shuji Aihara a a The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo, Japan b The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo, Japan (Presently Mitsubishi Heavy Industries, Ltd.) c The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo, Japan (Presently IHI Corporation, Ltd.) Abstract The authors propose a new model on cleavage fracture toughness of steels. Fracture toughness of steels is controlled by the weakest link mechanism, so it has intrinsic scatter. Beremin proposed Weibull stress through probabilistic fracture initiation model b sed on the weakest link theory, and it has been widely used for describing fracture toughness scatter. In his model, only propagation of micro crack is considered. However, micro crack nucleation should also be incorporated in order to estimate fracture toughness distributi n more accurately. Bordet i troduc d micro crack initiation to the Beremin model, in wh ch probability of micro crack nucleation is assume proportional to plastic train. Some previous stu ies have shown, howev r, that micro crack ucleation probability increases non-linearly with plastic strain. Then, we developed a new probabilistic model by introducing micro crack nucleation probability as a non-linear function of plastic strain. Furthermore, the authors developed a new method for obtaining Weibull parameters, in which not only distribution of fracture toughness values but also location of fracture initiation sites are considered through a newly developed likelihood function. We conducted fracture toughness tests with different specimen configurations and carried out convergence calculation for determining Weibull parameters by applying the likelihood function mentioned above. As a result of the calculation, the authors confirmed that the present model can obtain the Weibull parameters less sensitive to the specimen configurations and simulate distribution of fracture toughness more accurately than the previous models. © 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 Development of New Formulation and Likelihood Function on Probabilistic Fracture Initiation Model Itsuki Kawata a *, Shuhei Yoshizu b , Hiroaki Nakai c , Kazuki Shibanuma a , Shuji Aihara a a The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo, Japan b The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo, Japan (Presently Mitsubishi Heavy Industries, Ltd.) c The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo, Japan (Presently IHI Corporation, Ltd.) Abstract The authors propose a new model on cleavage fracture toughness of steels. Fracture toughness of steels is controlled by the weakes link mechanism, so it has i trinsic scatter. B remin proposed Weibull s ress through probabili tic frac ure initiation model based on the weakest link theory, and it has been widely used for describing fracture toughness scatter. In his model, only pr pagation f micro crack is considered. However, micro crack nucleation should also be incorporated in order t estimate fracture t ughness dist ibution more accurately. Bordet introduced micr crack initiation to the Ber m model, in which probabili y of micro crack nucleati n is assum d proportional to plastic strain. Some p vious stu ies have sh wn, however, that micro rack nucleation probability increases non-linearly with plasti strain. Then, we develope a new probabilistic model by introducing micro crack nucleation robability as a on- inear function of plastic strain. Fu thermore, the authors developed a new method f r obtaining Weibull p rameters, in which not only distribution of fr cture to g ness values b als location of fr cture initiati n sites are considered through a ne ly develope likelihood function. W c nducted fracture toughness tests with different specimen f gu ations and carried out converg nce calculati n for determining Weibull parameters by applying th likelihood functi mentioned above. As a res lt of the calculation, the authors confirmed that the present model can obtain the Weibull parameters less sensitive to the specimen configurations and simulate distr bution of fractu toughness more accura ely than the previous models. © 2016 The Authors. Published by Elsevier B.V. Peer-review under espons bility of the Scientific Committee of ECF21. Keywords: Fracture toughness; Cleavage fracture; Maximum likelihood estimation; Scatter; Fracture initiation site Copyright © 2016 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativ commons.org/lic nses/by-nc-nd/4.0/). Peer-revi w under respon ibility of the Scientifi 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: Fracture toughness; Cleavage fracture; Maximum likelihood estimation; Scatter; Fracture initiation site

* Corresponding author. Tel.: +81-3-5841-6503. E-mail address: kawata@fract.t.u-tokyo.ac.jp * Corresponding author. Tel.: +81-3-5841-6503. E-mail address: kawata@fract.t.u-tokyo.ac.jp

* 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 responsibility 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.2016.06.308