PSI - Issue 13

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 Structural Integrity 13 (2018) 1695–17 1 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 Theoretical Prediction of Fracture of Initially Crack-Free Brittle Materials Fuzuli Ağrı Akçay İstanbul Teknik Üniversitesi Gemi İnşaatı ve Deniz Bilimleri Fakültesi, Maslak, İstanbul 34469, Turkey Milli Savunma Üniversitesi Deniz Harp Okulu, Deniz Harp Okulu Dekanlığı, Tuzla, İstanbul 34942, Turkey Accurate determination f failure is crucial for designing engineering structures as their failure may cause not only economic loss but also loss of human life. Brittle fracture is a type of material failure, and literature on brittle fracture mainly focuses on fracture of bodies with pre-existing crack. In this study, however, a new brittle fracture criterion (of tensile mode) that is applicable at quasi static loading conditions is proposed for initially crack-free bodies. The fracture criterion is based on the continuum modeling of energy release rates and it is developed using Karr-Akçay energy balance concept. The criterion can be implemented to determine (Mode I) fracture toughness of a material as well as (fracture) strength of a material if its characteristic length is known, whereas the characteristic length of a material can be obtained (using the proposed criterion) if its (fracture) strength is known. Tensile strength of a gray cast iron is determined using the proposed criterion and compared to the results in the literature. Theoretical result is in good agreement with the experimental result published in the open literature. © 2018 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ECF22 organizers. Keywords: Brittle fracture; Strength; Characteristic length; Energy release rates 1. Introduction Brittle fracture is a type of material failure and results in abrupt loss of carrying capability of the structure. Major development on brittle fracture has been progressed in the last century. Although Griffith (1921) made a considerable contribution to the field (of linear elastic fracture mechanics, LEFM), particular attention has been paid after catastrophic failure of large structures, such as Liberty ships, during World War II. Researchers have endeavored great deal of effort to advance the field since then (Cotterell, 2002; Anderson, 2005). Nevertheless, literature on brittle fracture mainly focuses on fracture of bodies with pre-existing crack. In this study, however, a new brittle fracture criterion (of tensile mode) that is applicable at quasi-static loading conditions is proposed for initially crack-free © 2018 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ECF22 organizers. ECF22 - Loading and Environmental effects on Structural Integrity Theoretical Prediction of Fracture of Initially Crack-Free Brittle Materials Fuzuli Ağrı Akçay İstanbul Teknik Üniversitesi Gemi İnşaatı ve Deniz Bilimleri Fakültesi, Maslak, İstanbul 34469, Turkey Milli Savunma Üniversitesi Deniz Harp Okulu, i Harp Okulu Dekanlığı, Tuzla, İstanbul 34 42, Turkey Abstract Accurate determination of failure is crucial for designing engineerin structures as their failure may cause not only economic loss but also loss of human life. Brittle fracture is a type of material failure, and lit rature on brittle fracture mainly focuses on fracture of bodies with pre-existing crack. In this study, however, new brittle fr cture criterion (of tensile mode) that is applicable at quasi static loading conditions is proposed for initially crack-free bodies. The fracture criterion is based on the continuum modeling of energy release rates and it is developed using Karr-Akçay energy balance concept. The criterion can be implemented to determine (Mode I) fracture toughness of a material as well as (fr cture) strength of a material if its characteristic length is known, whereas the characteristic len th of a material can be obtained (using the prop sed criterion) if its (fracture) stre t is kno n. Tensile strength of a gray cast ir n is determined using the proposed criteri n an ompared to the results in the literature. Theoretical result is in good agreement with the exp rime tal result ublished in the open liter ture. © 2018 The Authors. Published by Elsevier B.V. Peer-review under responsibility of th ECF22 organiz rs. Keywords: Brittle fracture; Strength; Characteristic l ngth; Energy rele se rates 1. Introduction Brittle fracture is a type of material failure and results in abrupt loss of carrying capability of the structure. Major development on brittle fracture has been progressed in the last century. Although Griffith (1921) made a considerable contribution to the field (of linear elastic fracture mechanics, LEFM), particular attention has been paid after catastr phic failure of large structures, such as Liberty ships, during World War II. Researchers have endeavored great deal of effort to advance the field since then (Cotterell, 2002; Anderson, 2005). Nevertheless, literature on brittle fracture mainly focuses on fracture of bodies with pre-existing crack. In this study, however, a new brittle fracture criterion (of tensile mode) that is applicable at quasi-static loading conditions is proposed for initially crack-free © 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.

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.2018.12.353