PSI - Issue 13

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 Structural Integrity 13 (2018) 19 8–1914 Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia 00 (2018) 000–000 Available online at www.sciencedirect.com ScienceDirect Structural Integrity 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 Effects of crack tunneling and plasticity on the elastic unloading compliance technique for SE(B) – current limitations and proposals Leonardo Giangiulio Ferreira de Andrade a , Gustavo Henrique Bolognesi Donato a * a Centro Universitário FEI, Humberto de A. Castelo Branco Av., 3972, São Bernardo do Campo, 09850-901, Brazil Abstract Understanding how cracks behave in high toughness structural materials is critical for high responsibility applications. Design and fitness-for-service activities in this scenario are highly dependent on accurate resistance curves ( J-R curves) and fatigue crack growth data ( da/dN- Δ K ). Such mechanical properties correlate crack driving forces with instantaneous crack size a , determined using real time techniques such as the Elastic Unloading Compliance ( EUC ). In this method, load P and displacement V ( CMOD ) allow real-time compliance ( V/P ) computation, whose increase can be used to predict increasing crack size a . Despite usually accurate, EUC predictions sometimes deviate from post-mortem analyses (errors above 10% were found by the research group) or present spurious effects such as apparent negative crack growth. Several phenomena may affect EUC accuracy, including: stress triaxiality, side-grooves, specimen rotation, closure, crack tip plasticity and crack tip tunneling. This paper investigates the effects of tunneling and plasticity on the EUC technique applied to SE(B) specimens of varying thicknesses and geometrical features. Very refined numerical simulations were conducted considering varying thicknesses, levels of crack depths and five levels of crack curvatures. Regarding tunneling, results show that for the same equivalent ASTM-E1820 straight crack, elastic compliance decreases with the increase of crack front curvature, leading to a predicted crack smaller than ASTM equivalent. No significant deviations were detected within ASTM limits, however, when such limits are violated, significant deviations occur. As a step to improve size predictions for tunneled cracks, a new proposal for determining the equivalent straight crack was developed and expands the applicability of current methods. In terms of plasticity, results revealed that near-tip plasticity causes a decrease followed by an increase in specimen’s compliance, whose deviation varies depending on its geometry and material properties. The effects of varying plasticity levels on crack size estimation could be identified and discussed. © 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. ECF22 - Loading and Environmental effects on Structural Integrity Effects of crack tunneling and plasticity on the elastic unloading complianc technique for SE(B) – current limitations and proposals Leonardo Giangiulio Ferreira de Andrade a , Gustavo Henrique Bolognesi Donato a * a Centro Universitário FEI, Humberto de A. Castelo Branco Av., 3972, São Bernardo do Campo, 09850-901, Brazil Abstract Understanding how cracks behave in high toughness structural materials is critical for high responsibility applications. Design and fit ess-for-service a tivities in this scenari are highly dependent on accu ate resistance curves ( J-R curves) and fatigue cr ck growth data ( da/dN- Δ K ). Such mechanical properties correlate crack driving fo ces with instantaneous c ack size a , determined using real time techniques s c as the Elastic Unloading Complian e ( EUC ). In this me od, load P and displacement V ( CMOD ) allow r l-ti e compliance ( V/P ) computation, whose increase can be used to predict increasing crack ize a . Despite usually ccurat , EUC predictio s sometimes devi e from post-mo tem analys s (errors above 10% were found by the research group) or presen spurious ffects such as apparent negative crack growth. Several phenomena may affect EUC accuracy, including: stress triaxiality, side-groove , specimen rotatio , closure, crack tip plasticity nd crack tip tunneling. This paper investigates the effect of tunneling and plasticity on the EUC technique applied to SE(B) specimens of varying thick esses and g ometrical f atur s. Very refined numerical simulati s were conducted considering varying thicknesses, levels of crack depths and five levels of crack curvatures. Reg rding tunneling, results show that for the same equivalent ASTM-E1820 straigh cr ck, elastic compliance decreases with the i crease of crack front curvature, leading to a predicted crack smaller than ASTM equival nt. No significant viations were detected within ASTM limits, how ver, when such limits are violated, significant deviations occur. A a step to improve ize pre ictions for tunneled crack , a new proposal for determining the quivalent straight crack was developed and ex ands the a plicability f c rrent methods. In terms of plasticity, results revealed th t ear-tip plasti ity caus s a decre se followed by an increase in specime ’s compliance, who e devi tion vari depending on its geometry and material properti s. Th effects of varying pl ticity l vels on crack size estimation could be identified a discussed. © 2018 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ECF22 organizers. Keywords: Fracture testing; Fatigue crack growth testing; Elastic unloading compliance; SE(B); Effects of crack tunneling; Effects of plasticity. © 2016 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of PCF 2016. Keywords: Fracture testing; Fatigue crack growth testing; Elastic unloading compliance; SE(B); Effects of crack tunneling; Effects of plasticity.

Keywords: High Pressure Turbine Blade; Creep; Finite Element Method; 3D Model; Simulation.

* Corresponding author. Tel.: +55-11-43532900. E-mail address: gdonato@fei.edu.br * Corresponding author. Tel.: +55-11-43532900. E-mail ad ress: gdonato@fei.edu.br

* Corresponding author. Tel.: +351 218419991. E-mail address: amd@tecnico.ulisboa.pt 2452-3216 © 2018 The Authors. Published by Elsevier B.V. Peer-review und r responsibil ty 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.2018.12.271