PSI - Issue 8

ScienceDirect Available online at www.sciencedirect.com Av ilable o line at www.sciencedire t.com ienceDirect Structural Integrity Procedia 00 (2016) 000 – 000 P o edi Structural Integr ty 8 (2018) 67–74 Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia 00 (2017) 000 – 000 Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia 00 (2017) 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. Copyright © 2018 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of AIAS 2017 International Conference on Stress Analysis AIAS 2017 International Conference on Stress Analysis, AIAS 2017, 6-9 September 2017, Pisa, Italy Sensibility analysis of the fatigue critical distance values assessed by combining plain and notched cylindrical specimens C. Santus a, *, D. Taylor b , M. Benedetti c a Department of Civil and Industrial Engineering, University of Pisa, Pisa, Italy b Department of Mechanical & Manufacturing Engineering, Trinity College Dublin, Dublin, Ireland c Department of Industrial Engineering, University of Trento, Trento, Italy Abstract The material critical distance is often deduced from plain and notched specimens, instead of experimentally measuring the (long) crack threshold, which is a challenging task and not adequate in some cases. A dedicated V-notched specimen was proposed along with a dimensionless numerical procedure to derive the critical distance from the fatigue stress concentration factor, by implementing both the line and the point methods. An experimental validation activity is provided here on 42CrMo4+QT steel, focusing on how the critical distance result is sensitive to the actual local radius, the specimen sharpness, and the choice between the line or the point method. The determination of the critical distance with the point method systematically provides higher values than the line method. However, these length discrepancies do not produc large effects in terms of the component strength assessment if the same met od for the fatigu limit evaluation is us d. By alternatively considering the specimen not involved in the critical distance determination, a a potenti l design component, the rediction accuracy was evaluated. This an lysis confirmed that a small n tch radius is recommended for the fatigue str ngth assessment of larger ra ius notches or ven of a crack, whereas by deduci g the critical distanc from a blunt notch, a oticeabl inaccuracy can be found on smaller radius and crack threshold. © 2017 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of AIAS 2017 International Conference on Stress Analysis. AIAS 2017 International Conference on Stress Analysis, AIAS 2017, 6-9 September 2017, Pisa, Italy Sensibility analysis of the fatigue critical distance values assessed by combining plain and notched cylindrical specimens C. Santus a, *, D. Taylor b , M. Benedetti c a Department of Civil and Industrial University of Pisa, P sa, Italy b Department of Mechanical & Manufacturi g Engineer ng, Trinity College Dublin, Dublin, Ireland c Department of Industrial Engineering, University of Trento, Trento, Italy Abstract The material critical distance is often deduced from plain and notched specimens, instead of experimentally measuring the (l ng) crack threshold, which is a challenging task and not adequate in some cases. A dedicated V-notched specimen was proposed along with a dimensionless numerical proc dure to derive the critical distance from the fatigue stress concentrati n factor, by implementing bot the line and the point methods. An experimental valid tion activity is provided here o 42CrM 4+QT st l, focusing on ow the critical distance result is se sitive to the actual local radius, the speci en sharpness, and the choice between the line or t point method. Th determination of the criti al distance with the point method systematically provides higher values than the line thod. However, these length discrepancies do not produce large effects in terms of the comp ne t strength assessment if the same method for the fatigue limit evaluation is used. By alternatively considering the specimen not involved in the critical distance determination, as a potential esign compon nt, the pr diction a curacy was evaluated. This analysis o firmed th t a small notch radius is recommended for the fatigue strength assessment of larger radius notches or even of a r , whereas by deducing the critical distance fr m a blunt notch, oticeable inacc r cy can b found on smaller radius and crack threshold. © 2017 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of AIAS 2017 International Conference on Stress Analysis. © 2016 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of PCF 2016. Keywords: Critical distance determination; Line and point methods; 42CrMo4+QT steel; Rounded V-notched specimen; Sharp and blunt notches Keywo ds: Critical istance determinati n; Line and point methods; 42CrMo4+QT steel; Rounded V-notched specimen; Sharp and blunt notches

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

* Corresponding author. Tel.: +39-050-2218007; fax: +39-050-2210604. E-mail address: ciro.santus@ing.unipi.it * Correspon ing auth r. Tel.: +39-050-2218007; fax: +39-050-2210604. E-mail address: ciro.santus@ing.unipi.it

2452-3216 © 2017 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of AIAS 2017 International Conference on Stress Analysis. 2452 3216 © 2017 Th Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of AIAS 2017 International Conference on Stress Analysis.

* 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 PCF 2016.

2452-3216 Copyright  2018 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of AIAS 2017 International Conference on Stress Analysis 10.1016/j.prostr.2017.12.008