PSI - Issue 2_A

ScienceDirect Available online at www.sciencedirect.com Av ilable o line at ww.sciencedire t.com ienceDirect Structural Integrity Procedia 00 (2016) 000 – 000 Procedia Struc ural Integrity 2 (2016) 3073–308 Available online at www.sciencedirect.com Structural Integrity Procedia 00 (2016) 000–000 Available online at www.sciencedirect.com Structural Integrity Procedia 00 (2016) 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. 21st European Conference on Fracture, ECF21, 20-24 June 2016, Catania, Italy Fatigue Crack G owth Under Variable Amplit de Loading Thr ugh XFEM Haydar Dirik a,b , Tuncay Yalçinkaya a, ∗ a Middle East Technical University, Department of Aerospace Engineering, Ankara 06800, Turkey b Turkish Aerospace Industries (TAI), 06980 Ankara, Turkey Abstract Predicting fatigue crack growth (FCG) rate and path under variable amplitude loading (VAL) is a crucial issue in damage tolerant design commonly used in aerospace industry. The aim of the current study is to predict FCG life under VAL through Extended Finite Element Method (XFEM) and to explicitly illustrate both FCG life and crack propagation. For this purpose an algorithm is developed and integrated in ABAQUS software to analyze 3D crack propagation under VAL using Modified Generalized Willen borg (MGW) retardation model. The results are compared with NASGRO crack propagation software and experimental FCG test data on 7075-T6 aluminum alloy under various over load (OL) and over load-under load (OL-UL) conditions which exhibit a good agreement. c 2016 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of ECF21. Keywords: Fatigue crack growth; variable amplitude loading; XFEM; 1. Introduction The FCG life of structural components in aerospace industry under constant amplitude loading (CAL) can be determined with good accuracy by using various methods existing in literature. The early pioneering work of Paris and Erdogan (1963) introduced a stress intensity factor (SIF) based empirical relation (Paris equation) for FCG analysis which was modified by considering the e ff ect of the mean stress (see Walker (1970)). Forman et al. (1967) introduced the parameter of critical SIF for predicting the final fracture regime. Hartman and Schijve (1970) suggested a modified form of Paris law by adding a parameter of threshold SIF range and Elber (1971) modified the Paris equation by considering crack closure concept. The NASGRO equation is used in this study for FCG rate determination, which is based on the crack growth equation according to Forman (1992) considering plasticity-induced crack closure using the crack opening function introduced by Newman (1984). Through these enhancements of Paris equation, crack propagation under CAL can be predicted with great accuracy. However, structural components especially in aircrafts are commonly subjected to variable amplitude loading (VAL) during their service life. The problem of predicting FCG life under VAL is still challenging due to load sequence e ff ect. Neglecting the e ff ect of load cycle in FCG 21st European Conference on Fracture, ECF21, 20-24 June 2016, Catania, Italy Fatigue Crack Growth Under Variable Amplitude Loading Through XFEM Haydar Dirik a,b , Tuncay Yalçinkaya a, ∗ a Middle East Technical University, Department of Aerospace Engi eering, Ankara 06800, Turkey b Turkish Aerospac Industries (TAI), 06980 Ankara, Turkey Abstract Predicting fatigue crack growth (FCG) rate and path under variable amplitude loading (VAL) is a crucial issue in damage tolerant design commonly used in aerospace industry. The aim of the current study is to predict FCG life under VAL through Extended Finite Element Method (XFEM) and to explicitly illustrate both FCG life and crack propagati n. For this purpose an algorithm is developed and integrated in ABAQUS software to analyze 3D crack propagation under VAL using Modified Generalized Willen borg (MGW) retardation model. The results are compared with NASGRO crack propagation software and experimental FCG test data on 7075-T6 aluminum alloy under various over load (OL) and over load-under load (OL-UL) conditions which exhibit a good agreement. c 2016 The Authors. Published by Elsevier B.V. Peer-review under r sponsibility of the Scientific Committee of ECF21. Keywords: Fatigue crack growth; variable amplitude loading; XFEM; 1. Introduction The FCG life of structural compone ts in aerospace industry under constant amplitude loading (CAL) can be determined with good accuracy by using various methods existing in literature. The early pioneering work of Paris and Erdogan (1963) introduced a stress intensity factor (SIF) based empirical relation (Paris equation) for FCG analysis which was modified by considering the e ff ect of the mean stress (see Walker (1970)). Forman et al. (1967) introduced the parameter of critical SIF for predicting the final fracture regime. Hartman and Schijve (1970) suggested a modified form of Paris law by adding a parameter of threshold SIF range and Elber (1971) modified the Paris equation by considering crack closure concept. The NASGRO equation is used in this study for FCG rate determination, which is based on the crack growth equation according to Forman (1992) considering plasticity-induced crack closure using the crack opening function introduced by Newman (1984). Through these enhancements of Paris equation, crack propagation under CAL can be predicted with great accuracy. However, structural components especially in aircrafts are commonly subjected to variable amplitude loading (VAL) during their service life. The problem of predicting FCG life under VAL is still challenging due to load sequence e ff ect. Neglecting the e ff ect of load cycle in FCG ity, D P e b 1. Introduction t e n a Copyright © 2016 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). P r view under esponsibility of the Scientific Committee of ECF21. © 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.: +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. Copyright © 2016 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license ( http://creativecommons.org/licenses/by-nc-nd/4.0/ ). Peer review under responsibility of the Scientific Committee of ECF21. 10.1016/j.prostr.2016.06.384 ∗ Corresponding author. Tel.: + 90-312-210-4258 ; fax: + 90-312-210-4250. E-mail address: yalcinka@metu.edu.tr 2452-3216 c 2016 The Authors. Publi hed by Elsevier B.V. Pe r-review under responsibility of the Scientific Committee of ECF21. ∗ Corresponding author. Tel.: + 90-312-210-4258 ; fax: + 90-312-210-4250. E-mail address: yalcinka@metu.edu.tr 2452-3216 c 2016 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of ECF21.