PSI - Issue 13

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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. © 2018 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ECF22 organizers. ECF22 - Loading and Environmental e ff ects on Structural Integrity An improved K I expression for a semi-elliptical surface crack in a finite plate subjected to uniform tension Yinghao Dong a , Xiaofan He a, ∗ , Yuhai Li a a School of Aeronautic Science and Engineering, Beihang University, Beijing 100191, China Abstract Newman-Raju solution for a surface cracked plate under uniform tension has been widely used in surface crack-related problems. However, comparisons of Newman-Raju solution with numerical stress intensity factor ( K I ) solutions indicated the accuracy of Newman-Raju solution at the depth point inferior to that at the surface point. Therefore, we feel there is a need to improve the accuracy of Newman-Raju solution. With the domain integral method provided by Abaqus, numerical K I solutions with high accuracy were obtained for a wide range of surface crack configurations. By fitting assumed functions to the numerical results, a K I expression was developed for a surface cracked finite plate subjected to uniform tension. The proposed expression can be used to determine K I at an arbitrary point on the crack front. A detailed analysis was conducted on the accuracy of the K I expression, with two appli ation ranges respectively allowing for accuracy better than 3% and 5% provided. The K I expression yields better accuracy than Newman-Raju solution within the application ranges that cover most surface crack configurations occurring in practice, and the accuracy of Newman-Raju solution at the crack depth int has b en subs antially improved. © 2018 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ECF22 organizers. Keywords: surface crack, str ss intensity factor, uniform ten ion, fi i e element meth , curve fitting me hod ECF22 - Loading and Environmental e ff ects on Structural Integrity An improved K I expression for a semi-elliptical surface crack in a finite plate subjected to unifor tension Yinghao Dong a , Xiaofan He a, ∗ , Yuhai Li a a School of Aeronautic Science and En ineering, Beihang University, Beijing 100191, China Abstract Newman-Raju solution for a surface cracked plate under uniform tension has been widely used in surface crack-related problems. However, comparisons of Newman-Raju solution with numerical stress intensity factor ( K I ) solutions indicated the accuracy of Newman-Raju solutio at the depth point inferior to that at the surface point. Therefore, we feel there is a need to improve the accuracy of Newman-Raju solution. With the domain integral method provided by Abaqus, numerical K I solutions with high accuracy were obtained f r a wide range of surface crack configurations. By fitting assumed functions t the numerical results, a K I expression was developed for a surface cracked finite plate subjected to uniform tension. The proposed expression can be used to determine K I at an arbitrary point on the crack front. A detailed analysis was conducted on the accuracy of the K I expression, with two application ranges respectively allowing for accuracy better than 3% and 5% provided. The K I expression yields better accuracy than Newman-Raju solution within the application ranges that cover most surface crack configurations occurring in practice, and the accuracy of Newman-Raju solution at the crack depth point has been substantially improved. © 2018 The Authors. Published by Elsevier B.V. - iew unde responsibility of the ECF22 organizers. Keywords: surface crack, stress intensity factor, uniform tension, finite element method, curve fitting method Keywords: High Pressure Turbine Blade; Creep; Finite Element Method; 3D Model; Simulation. Semi-elliptical surface cracks are among the most common flaws in aircraft structures. The growth of surface cracks accounts for a significant portion of fatigue life, requiring fatigue crack growth (FCG) analyses pertinent to surface cracks. Because the accuracy of stress intensity factor (SIF) solutions determines the accuracy of FCG analyses as a main factor, an accurate SIF solution for a surface crack is desired. A surface cracked plate-like component is often reduced to a surface cracked finite plate. Remote uniform tension is a simple but essential loading case. However, there is no exact K I (i.e. mode I SIF) solution for a surface cracked finite plate subjected to remote uniform tension. To address this issue, over the last four decades, a range of methods Semi-elliptical surface cracks are among the most common flaws in aircraft structures. The growth of surface cracks accounts for a significant portion of fatigue life, requiring fatigue crack growth (FCG) analyses pertinent to surface cracks. Because the accuracy of stress intensity factor (SIF) solutions determines the accuracy of FCG analyses as a main factor, an accurate SIF solution for a surface crack is desired. A surface cracked plate-like component is often reduced to a surface cracked finite plate. Remote uniform tension is a simple but essential loading case. However, there is no exact K I (i.e. mode I SIF) solution for a surface cracked finite plate subjected to remote uniform tension. To address this issue, over the last four decades, a range of methods 1. Introduction © 2016 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of PCF 2016. 1. Introduction

* Corresponding author. Tel.: +351 218419991. E-mail address: amd@tecnico.ulisboa.pt ∗ Corresponding author. Tel.: + 86 01082315738. E-mail address: xfhe@buaa.edu.cn ∗ Corresponding author. Tel.: + 86 01082315738. E-mail address: xfhe@buaa.edu.cn

2452-3216 © 2016 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of PCF 2016. 2210-7843 © 2018 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ECF22 organizers. 2210-7843 © 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 responsibility of the ECF22 organizers. 10.1016/j.prostr.2018.12.360