PSI - Issue 2_B

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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 Prediction of fracture toughness for carbon nanotubes Chyanbin Hwu a * and Yu-Kuei Yeh a a Department of Aeronautics and Astronautics, National Cheng Kung University, Tainan, Taiwan, R.O.C. Abstract A modified molecular-continuum model is employed to predict fracture toughness of carbon nanotubes. In this model, the modified Morse potential function is used to evaluate the potential energy, and the near tip solution of linear elastic fracture mechanics is used to locate the atoms of the cracked specimen under tensile or shear loads. The representative volume is selected to be a circular region with center at the crack tip and radius determined from the equivalence of strain energy and virtual work for crack advancement. Using the relation between strain energy release rate and stress intensity factor, a nonlinear generalized stress-strain diagram is generated and the fracture toughness is then estimated to be the maximum point of this diagram. Through proper choice of representative volume and crack simulation, a vast of computational time can be saved and the results predicted by this model are shown to be consistent with those predicted by the other experimental or numerical methods. © 2016 The Authors. Published by Elsevier B.V. Peer-review under resp nsibility of the Scientific Committee of ECF21. Keywo ds: stre gth, fracture toughness, nanomateria , carbon nanotub , molecular-continuum model 1. Introduction Due to the superior physical properties, carbon nanotubes continue to attract considerable attention in scientific co munities (Stankovich et al., 2006; Lee et al., 2008; Castro Neto et al., 2009). Although some experimental works such as (Treacy et al., 1996; Wong et al., 1997; Krishnan et al., 1998; Yu et al., 2000) have been done to get their mechanical properties, to have a proper guidance on their further advancement, a lot of efforts have been put on the prediction of their mechanical properties through theoretical and numerical simulation (Liew et al., 2004; Faccio et al., 2009). Unlike stiffness, relative fewer studies can be found for the prediction of strength and toughness of nan materials (Belytschko et al., 2002; Liew t al., 2004; Xu, 2009; Wang et al., 2012; Zhang et al., 2012). Recently, by combining the concept of molecular dynamics and continuum mechanics, a molecular-continuum a a a t t f ti t ti , ti l i it , i , i , . . . i i l l ti l i l t i t t t t . t i l, t i i t ti l ti i t l t t t ti l , t ti l ti li l ti t i i t l t t t t i nder tensile or shear loads. The representative volume is selected t i l i it t t t ti i te i t i l t i i t l t. i t l ti t t i l t t i t it t , li li t t i i i t t t t i t ti t t t i i t t i i . i t ti l i l ti , t t ti l ti t lt i t t i l t i t t it t i t t t i t l i l t . © 2 t . li l i . . Peer-review under responsibility of the Scie ti i itt . t t , t t , t i l, t e, l l ti l . Du , ., ., ., . ., ., ., ., , , ., ., . , ., ., , ., ., . , , 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. © 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.: +886-6-2757575; fax: +886-6-2389940. E-mail address: chwu@mail.ncku.edu.tw i t . l.: ; : . il il. . .t

* 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 ECF21. l i . . i i ilit t i ti i itt . t . li

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.2016.06.169