PSI - Issue 13

ScienceDirect Available online at www.sciencedirect.com Available online at ww.sciencedire t.com ienceDirect Structural Integrity Procedia 00 (2016) 000 – 000 Procedia Structural Integrity 13 (2018) 1261–1266 Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia 00 (2018) 000–000 Available online at www.sciencedirect.com ScienceDirect Structural I t gri y 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 Multi-parameter average strain energy density factor criterion applied on the bi-material notch problem Jan K usák a *, Ondřej Krepl a a CEITEC IPM, Institute of Physics of Material s AS CR, Žižkova 22, Brno 616 62, Czech Republic Abstract The stress field near a bi-material notch tip has the singular character. The power of singularity is lower in comparison to the case of a crack. The stress field can be described by the asymptotic stress series, in which each term contains generalized stress intensity factor and stress term exponent. The terms can be either s ngular o non-singular depending on the value f stress term exponent. The exponents are determined as solution of eigenvalue problem and depend on material properties and local geometry. The factors are calculated by analytical-numerical approaches and depend on global geometry and applied loading. The singular terms become unbounded when approaching the bi-material notch tip while the non-singular terms vanish. The non-singular terms increase precision in stress description on larger distances from the notch tip. The crack initiation conditions from the notch tip can be assessed by the average strain energy density factor (SEDF) criterion. In the case of bi-material notch problem, the crack can initiate in the direction of global minimum, the local minimum or the interface. The actual crack initiation load is calculated for each of abovementioned directions considering the individual fracture tou hnesses. C trary to the case of a crack, the direction of minimum of SEDF changes in dependence on the distanc from the tip, therefore the average value over sp cific distance is use . The multi-parameter crit rion considers s ngular and non-singular stress terms. Therefore in cas s, when th specific distance is large, the on-singular terms provi e means to improve precisi n of prediction of crack initiation parameters. © 2018 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ECF22 organizers. Keywords: Generalized fracture mechanics, Crack initiation, Bi-material notch, Stability criterion, Strain energy density factor; 1. Introduction – Stress distribution near sharp or bi-material notches In modern engineering constructions or devices notches or bi-material interfaces often occur. They can be responsible for a crack initiation and propagation and then for damage of whole structure. Sharp notches in homogeneous material © 2018 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ECF22 organizers. ECF22 - Loading and Environmental effects on Structural Integrity Multi-parameter average strain energy density factor criterion applied on the bi-material notch problem Jan Klusák a *, Ondřej Krepl a a CEITEC IPM, Institute of Physics of Material s AS CR, Žižkova 22, Brno 616 62, Czech Republic Abstract The stress field near a bi-material notch tip has the singular character. The power of singularity is lower in comparison to the case of a crack. The stress field can be described by the asymptotic stress series, in which each term contains g neralized stress intensity factor and stress term exponent. The terms can be either singular or n n-singular depending on the value of str ss term exponent. The exponents are deter ined as solution of eig nvalue problem and depe d on material properties and local geometry. The factors ar calculated by analytical-numerical approaches and depend o global ge metry and ap lied loading. The singular terms becom unbounded whe approaching the bi-material notch tip while the non-sin ular terms vanish. The non-singular terms increase precision in stress description on larger distances from the notch tip. T e crack initiation conditions from the notch tip can be assessed by the average strain energy density factor (SEDF) criteri n. In the case of bi-material n tch problem, the crack can initiate in the direction of global mi imum, th local minimum or the interface. The actual crack initiation load is calculated for each of abovementioned directions co sidering the individual fracture toughnesses. Contrary to the case of a crack, the direction of minimum of SEDF changes in depe dence on the dista ce from the tip, th refor the average value over sp cific distance is use . The multi- a meter criteri n con id rs singular and non-singular stress terms. Therefore in cas s, when th sp cifi di tance is large, th non-singul r rms provi means to improve precision of prediction of crack initiation param ters. © 2018 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ECF22 organizers. Keywords: Generalized fracture mechanics, Crack initiation, Bi-material notch, Stability criterion, Strain energy density factor; 1. Introduction – Stress distribution near sharp or bi-material notches In modern engineering constructions or devices notches or bi-material interfaces often occur. They can be responsible for a crack initiation and propagation and then for damage of whole structure. Sharp notches in homogeneous material © 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.: +420532290348. E-mail address: klusak@ipm.cz * Corresponding author. Tel.: +420532290348. E-mail ad ress: klusak@ipm.cz

* 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 organizers.

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.2018.12.258