PSI - Issue 13

ScienceDirect Available online at www.sciencedirect.com Av ilable o line at ww.sciencedire t.com cienceDirect Structural Integrity Procedia 00 (2016) 000 – 000 Procedia Structu al Integrity 13 (2018) 279–284 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 Influence of crack initiation on short crack propagation and cyclic lifetime of AA 7475-T761 Meike Funk*, Jürgen Bär University of the Bundeswehr, Institute for Material Science, 85577 Neubiberg, Germany The propagation of short cracks covers the main part of the lifetime of cyclic loaded components. Thus, investigations in this field are necessary to enable reliable lifetime predictions. To investigate the influence of different crack initiation scenarios on the cy lic lifetime, SEN-specimens were fatigue under constant stress amplitude. For additional support of the crack initiation in some specimens single overload was introduced after 200 cycles, in others the crack initiation was forced by laser cuts in the notch root. In all experiments, the crack length was measured with a high-resolution DC-potential drop method. This investigation approves and explains the relationship between the cyclic lifetime and the presence of steps on the fracture surface, as a reason of a retarded crack coagulation. The results clearly indicate that the scatter of the cyclic lifetime is determined by the differences in the crack initiation scenarios. Further on, a significant influence of a single overload on the cyclic lifetime can be verified. © 2018 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ECF22 organizers. Keywords: fatigue; crack propagation; short crack; crack initiation 1. Introduction A precise prediction of the lifetime of cyclic loaded components is the main goal of the research in the field of fatigue. A great problem is the scatter of the experimental data especially in the period of crack initiation and short crack propagation. These two periods are often combined to a period ending with a so-called technical incipient crack © 2018 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ECF22 organizers. ECF22 - Loading and Environmental effects on Structural Integrity Influence of crack initiation on short crack propagation and cyclic lifetime of AA 7475-T761 Meike Funk*, Jürgen Bär University of the Bundeswehr, Institute for Material Science, 85577 Neubiberg, Germany Abstract The propagation of short cracks covers the main part of the lifetime of cyclic loaded components. Thus, investigations in this field are necessary to enable reliable lifetime predictions. To investigate the influence of different crack i itiation scenarios on the cyclic lifetime, SEN-specimens were fatigued under constant stress amplitude. For additional support of the crack initiation in some s eci ens a single overload was introduced after 200 cycles, in others the crack initiation was forced by laser cuts in the notch root. In all experiments, the crack length was measured with a high-resolution DC-potential drop method. This investigation approves and explains the relationship between the cyclic lifetime and the presence of steps on the fracture surface, as a reason of a retarded crack c agulation. The results clearly indicate that the scatter of the cyclic lifetime is determined by the differences in the crack initiation scenarios. Further on, a significant influence of a single overload on the cyclic lifetime ca be verified. © 2018 The Authors. Published by Elsevier B.V. Peer-review under responsibility of th ECF22 organiz rs. Keywords: atigue; crack prop gation; short crack; crack initiation 1. Introduction A precise prediction of the lifetime of cyclic loaded components is the main goal of the research in the field of fatigue. A great problem is the scatter of the experimental data especially in the period of crack initiation and short crack propagation. These two periods are often combined to a period ending with a so-called technical incipient crack © 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. Abstract

* 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. * Corresponding author. Tel.: +49-89-6004-2552; fax: +49-89-6004-3055. E-mail address: meike.funk@unibw.de * Corresponding author. Tel.: +49-89-6004-2552; fax: +49-89-6004-3055. E-mail ad ress: meike.funk@unibw.de

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.2018.12.047