PSI - Issue 3

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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. XXIV Italian Group of Fracture Conference, 1-3 March 2017, Urbino, Italy Analysis of ailure in q asi-brittle materials by 3D multiplane cohesive zone models combining damage, friction and interlocking Roberto Serpieri a , Marco Albarella a , Giulio Alfano b, * Elio Sacco c a Dipartimento di Ingegneria, Università degli Studi del Sannio, Piazza Roma, 21, Benevento, 82100, Italy b School of Engineering and Design, Brunel University, Uxbridge, UB8 3PH, UK c Dipartimento di Ingegneria Civile e Meccanica, Università di Cassino e del Lazio Meridionale,Via di Biasio n. 43, Cassino (FR), 03043, Italy This paper presents the latest advances in the development of multiplane cohesive-zone models that are able to account for damage, friction and interlocking, including in particular their extension to a general three-dimensional (3D) case. Starting from the work proposed in a recent article by some of the authors, a simplified micromechanical formulation is used, whose main idea is to represent the asperities of the developing fracture surface in the form of a periodic arrangement of distinct inclined elementary planes, denominated Representative Multiplane Element (RME). The interaction between the two faces of each of these elementary planes is governed by the interface formulation propos d by Alfano nd Sacco, which couples frictio with damage but do s not specifically account for the a perities of the fract re surface nd the associated interlocking. A k y feature of the model is that, or each elementary plane, it is possible to use a ‘base-line’ cohesive-zone model characterized by the same critical energy release rate in (local) modes I and II, becau e such value repr sents the ‘ruptu e’ energy needed to a hieve de cohesion, in absence of any frictional dissipation. Numerical results and the r correlation with experimental data re pr sented to show how the model is able to capture the increase in total (measured) fracture energy n the RME with incre sing mode I-to mode II ratio thanks to the geometry of the elementary planes and their influence on the frictional dissipation. The model has then been further refined to account for the finite depth of the asperities of the fracture surface and for their wear as a result of frictional slip. The enhanced model has been validated against experimental results for problems involving monotonic and cyclic loading. Finally, the main strategy used to extend the model to a general 3D case is presented, and some of the key issues are discussed. © 2017 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of IGF Ex-Co. XXIV Italian Group of Fracture Conference, 1-3 March 2017, Urbino, Italy Analysis of failure in quasi-brittle materials by 3D multiplane cohesive zone models combining damage, friction and interlocking Roberto Serpieri a , Marco Albarella a , Giulio Alfano b, * Elio Sacco c a Dipartimento di Ingegneri , Università d gli Studi del Sannio, Piazza Roma, 21, Benevento, 82100, Italy b School of Engineering and Design, Brunel University, Uxbridge, UB8 3PH, UK c Dipartimento di Ingegneria Civile e Meccanica, Università di Cassino e del Lazio Meridionale,Via di Biasio n. 43, Cassino (FR), 03043, Italy Abstract This paper presents the latest advances in the development of multiplane cohesive-zone models that are able to account for damage, f iction and interlocking, including in particular their extension to a general thre -dimensional (3D) case. St rting from the work prop sed in a r cent article by some of the authors, a simplified microm chanical formulation is used, whose main idea is to represent the asperities of the developing fracture urface in the form of a periodic arr ngement of distinct incl n d elementa y planes, denominated Representative Multiplane Element (RME). The interaction between the two faces of each of th se element ry planes is govern d by the nterface formulation proposed by Alfano and Sacco, which couples friction with damage but does not specifically account for th asp rities of he fracture surface and the associated interlo king. A key feature of the model is t at, for each elementary plane, it is possible to use ‘base-line’ cohesiv -zone model chara terized by the sam critical energy rel ase ate in (local) modes I and II, b caus s ch value repr sents the ‘rupture’ nergy ne ded to achieve de ohesion, in abs nce of ny frictional dissipatio . Num rical res lts and their correlation with experimental data are present d to show how the mod l is able o captu e the increase i total (measured) fractur energy on RME with increasing mode I-t - m d II ratio anks to the geometry of the elementary planes an their infl ence on the frict onal dissip tion. The m l has then been furt er refined to account for the inite depth of th asp riti s of the fracture surfa e a d for their ear s a result of frictional slip. The nhanced model has be n validat d against ex rim ntal results for probl ms i volving monotonic nd cyclic loading. Finally, th m in strategy used to exten the model to a general 3D case is presented, a d some of the key issues are discussed. © 2017 The Authors. Published by Elsevier B.V. Peer-review under espons bility of the Scientific Committee of IGF Ex-Co. © 2016 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of PCF 2016. Copyright © 2017 The Authors. Published by Els vier 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 IGF Ex-Co. Keywords: Interface Friction; Cohesive zone models; Interlocking; Fracture Energy. Keywords: High Pressure Turbine Blade; Creep; Finite Element Method; 3D Model; Simulation. Keywords: Interface Friction; Cohesive zone models; Interlocking; Fracture Energy. Abstract

* Corresponding author. Tel.: +351 218419991. E-mail address: amd@tecnico.ulisboa.pt 2452-3216 © 2017 The Authors. Published by Elsevier B.V. Peer-review und r responsibility of the Scientific Committee of IGF Ex-Co. 2452-3216 © 2017 The Authors. Published by Elsevier B.V. Peer-review under r sponsibility of the Scientific Committee of IGF Ex-Co. * Corresponding author. Tel.: +44(0)1895 267062; fax: +44(0)1895 256392. E-mail address: giulio.alfano@brunel.ac.uk * Corresponding author. Tel.: +44(0)1895 267062; fax: +44(0)1895 256392. E-mail address: giulio.alfano@brunel.ac.uk

2452-3216 © 2016 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of PCF 2016. Copyright © 2017 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 IGF Ex-Co. 10.1016/j.prostr.2017.04.066