PSI - Issue 7

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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 7 (2017) 383–39 Structural Integrity Procedia 00 (2017) 000–000 Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia 00 (2017) 000–000 ScienceDirect

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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. Copyright © 2017 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of the 3rd International Symposium on Fatigue Design and Material Defects. 3rd International Symposium on Fatigue Design and Material Defects, FDMD 2017, 19-22 September 2017, Lecco, Italy An analytical approach to quantify the effect of the R-ratio on da/dN in the Paris regime Hans-Jakob Schindler* Mat-Tec AG, Unterer Graben 27, 8400 Winthethur, Switzerland Abstract The R-ratio is known to play an important role in fatigue crack growth. However, a controversy still exists concerning its effect on the growth rate da/dN in the so-called Paris-regime for R > 0. There are two contradictory concepts to capture this effect: Crack closure and “K max -sensitivity”. In the present paper, the influence of R on da/dN is considered from a theoretical point of view, based on fundamental relations of linear-elastic fracture mechanics. “Paris’ law” is derived mainly on analytical grounds, with the exponent n as the only open parameter. In the resulting equation, R appears as another parameter, quantifying its effect on da/dN. The analytical curves agree well with experimental data. On this ground, the above mentioned existing empirical approaches are discussed. It is shown that the main reason for the R-dependence and K max -sensitivity is the nonlinear relation between ∆ K and the range of CTOD, and that crack closure is not necessarily required for R-effects, but may contribute to them. © 2017 The Authors. Publishe by Elsevier B.V. Pe r-review under res on ibili y of the Scientific Committee of he 3rd Int rnation l Symposium on Fatigue D ign and Mat rial Def cts. Keywords: R-ratio; analytical approach; fatige crack growth; Paris regime, R-dependenc ; crack clusure 1. Introduction The rate da/dN of fatigue crack growth (FCG) is well known to depend first of all on the load range in terms of stress intensity factor (SIF), ∆ K, and on the R-ratio, defined as 3rd International Symposium on Fatigue Design and Material Defects, FDMD 2017, 19-22 September 2017, Lecco, Italy An analytical approach to quantify the effect of the R-r tio on da/dN in the Paris regime Hans-Jakob Schindler* Mat-Tec AG, Unterer Graben 27, 8400 Winthethur, Switzerland Abstract The R-r tio is known to play an important role in fatigu crack growth. H wever, a controversy still exis s c ncerning ts ef ect on the gr wth rate da/dN in the so-ca led Paris-regime for R > 0. There are two contradictory concepts to capture this effect: Crack closur and “K max -sensitivity”. In th present paper, the influe ce of R on da/dN is consider d from a theoretical point of view, based on fundamental relations of l near-elastic fr cture mechanics. “Paris’ law” is derived mainly on analytical grounds, with th exponent n as the nly open paramet r. In the resulting equation, R appears as another parameter, quantifying its effect on da/dN. The analytical curves agree well with experim ntal data. On this ground, the above mentioned existing e pirical approaches are discussed. It is shown that the main reason for the R-dependence and K max -sensitivity is the nonlinear relation between ∆ K and the range of CTOD, and that crack closure is not necessarily required for R-eff ts, but may contribute to them. © 2017 The Authors. Published by Elsevier B.V. Peer-revi w under responsibility of the Scientific Committee of the 3rd International Symposium on Fatigue Design and Material D fects. Keywords: R-ratio; an lytical appro c ; fatige crack growth; Paris regi e, R-depen ence; crack cl sure 1. Introduction The rate da/dN of fatigue crack growth (FCG) is well known to depend first of all on the load range in terms of stress intensity factor (SIF), ∆ K, and on the R-ratio, defined as © 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.: +41 522025444 E-mail address: schindler@mat-tec.ch * Corresponding author. Tel.: +41 522025444 E-mail address: schindler@mat-tec.ch

2452-3216 © 2017 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of the 3rd International Symposium on Fatigue Design and Material Defects. 2452-3216 © 2017 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of the 3rd International Symposium on Fatigue Design and Material Defects.

* Corresponding author. Tel.: +351 218419991. E-mail address: amd@tecnico.ulisboa.pt

2452-3216 Copyright  2017 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of the 3rd International Symposium on Fatigue Design and Material Defects. 10.1016/j.prostr.2017.11.103

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