PSI - Issue 2_B

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ScienceDirect Available online at www.sciencedirect.com Av ilable o line at ww.sciencedire t.com Sci ceDirect Structural Integrity Procedia 00 (2016) 000 – 000 Procedia Struc ural Integrity 2 (2016) 3676–3683 Available online at www.sciencedirect.com Structural Integrity Procedia 00 (2016) 000–000 Available online at www.sciencedirect.com Structural Integrity Procedia (201 ) 0–000 tr t r l I t rit r i 0 ( 6)

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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 Tra sition from smeared to localized cracking in macro-defect-free quasibrittle structures Jaime Planas a, ∗ , Beatriz Sanz a , Jose´ M. Sancho b a Universidad Polite´cnica de Madrid, ETS de Ingenieros de Caminos, Canales y puertos, Profesor Aranguren 3, Madrid 28040, Spain b Universidad Polite´cnica de Madrid, ETS de Arquitectura, Avda. Juan de Herrera 4 , Madrid 28040, Spain Abstract The present paper addresses the transition from distributed crackin to localized cracks in structures of quasibrittle materials. Numerical simulations are carried out for an unnotched beam subjected to three-point bending, and for a slab subjected to a simplified shrinkage field. The simulations use a fully local finite element formulation developed in previous works by the authors, in which a cohesive crack is embedded in constant strain elements. The calculations are carried out over a wide range of meshes and loading steps and show that the method is able to consistently follow the transition from di ff use crack patterns to fully localized cracks. The method is also robust since it comes to a solution for any of the step sizes investigated (in a range as large as 1 to 50). As a main conclusion, the overall properties of crack pattern seem to be free from spurious mesh or step sensitivity, but the details (the exact position of each crack, e.g.) do depend on the mesh and on the step size. c 2016 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of ECF21. Keywords: Quasibrittle materials, finite element modeling, cohesive crack, crack pattern, smeared cracking, localization 1. Introduction The present paper addresses the transition from distributed cracking to localized cracks in structures of quasibrittle materials, with concrete, ceramics or rock in mind. A paradigmatic case is that of shrinkage cracks at the surface of a quasibrittle continuum, as studied by Bazˇant and coworkers in the late nineteen seventies (Bazˇant et al., 1979), in which the concept of a crack spacing related to the crack depth, due to mutual crack shielding was elaborated based on linear elastic fracture mechanics. This phenomenon has been studied in various contexts and by various methods, for example, Bisschop and Wittel (2011) studied microcracking of hardened cement paste, Jenkins (2005, 2009) used an energetic semi-analytical approach to study the optimal spacing of elastic cracks in a slab of finite depth, a method that was extended by Jiang et al. (2012) to study thermal shock of ceramics, which included experimental as well as numerical results; Białas et al. (2005) investigated crack spacing in thermal barrier coatings using finite elements with cohesive zone interfaces, while, at a di ff erent scale, Bolander Jr. and Berton (2004) used rigid particle models connected by softening springs to simulate shrinkage cracking of a concrete repair overlay. 21st European Conference on Fracture, ECF21, 20-24 June 2016, Catania, Italy Transition from smeared to localized cracking in macro-defect-free quasibrittle structures Jaime Planas a, ∗ , Beatriz Sanz a , Jose´ M. Sancho b a Universidad Polite´cnica de Madrid, ETS de Ingenieros de Caminos, Canales y puertos, Profesor Aranguren 3, Madrid 28040, Spain b Universidad Polite´cnica de Madrid, ETS de Arquitectura, Avda. Juan de Herrera 4 , Madrid 28040, Spain Abstract The present paper addresses the transition from distributed cracking to localized cracks in structures of quasibrittle materials. Numerical simulations are carried out for an unnotched beam subjected to three-point bending, and for a slab subjected to a simplified shrinkage field. Th simul tions use a fully local finite element formulat on developed in previous works by the authors, in which a cohesive crack is embedded in constant strain elements. The calculations are carried out over a wide range of meshes and loading steps and show that the method is able to consistently follow the transition from di ff use crack patterns to fully localized cracks. The method is also robust since it comes to a solution for any of the step sizes investigated (in a range as large as 1 to 50). As a main conclusion, the overall properties of crack pattern seem to be free from spurious mesh or step sensitivity, but the details (the exact position of each crack, e.g.) do depend on the mesh and on the step size. c 2016 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of ECF21. Keywords: Quasibrittle materials, finite el ment modeling, cohesive crack, crack p ttern, smeared r cking, localization 1. Introduction The present paper addresses the transition from distributed cracking to localized cracks in structures of quasibrittle materials, with concrete, ceramics or rock i mind. A paradigm tic case is that of shrinkage cra ks at the surface of a quasibrittle continuum, as studied by Bazˇant a coworkers in the lat nineteen eventies (B zˇant et al., 1979), in which the con ept of a cr ck spacing related to the rack d pth, du to mutual crack shielding was elaborated based on linear elastic fracture mechanics. This phenom non has been st died in various contexts and by various methods, for example, Bisschop and Wittel (2011) studied microcr cking of hardened cement paste, Jenkins (2005, 2009) used an energetic semi-analytical approach to st y the optimal spacing of elastic racks in a slab of finite depth, a metho that was extended by Jiang et al. (2012) to study ther al shock of ceramics, which included exp rimental as well as numerical results; Bi łas t l. ( 05) investigated crack spacing in thermal barrier coatings using finite elements with cohesive zone interf ces, while, at a di ff erent scale, Bolander Jr. and Berton (2004) used rigid particl model connected by softeni g springs to simulate shrinkage cracking of a concrete r pair overlay. , i i lit´ i i , I i i , l t , f , i , i i i lit´ i i , it t , . , i , i s t t t iti i t i t i t l li i t t i ittl t i l . i l i l ti i t t j t t t i t i , l j t t i li i l . i l ti ll l l it l t l ti l i i t t , i i i i i t t t i l t . l l ti i t i l i t t t t t i l t i t tl ll t t iti i ff tt t ll l li . t i l t i it t l ti o t t i i ti t i l t . i l i , t ll ti tt t i t iti it , t t t il t t iti , . . t t t i . t . li l i . . -r i i ilit t i ti itt . i rittl t ri l , it l t li , i r , r tt r , r r i , l li ti . i t t t iti i t i t i t l li i t t i ittl t i l , it t , i in i . i ati i t t i c t t i ittl ti , t i t nd i t l te i t ti t t l., , i i t c t i l t t t t , t t l i l i l t on li l ti t i . i tu i i i t t i t , l , i itt l t i i i t t , i , ti i l ti l t t t ti l i l ti c i l it t , t d t t t i t l. t t t l i , i i l e i t l ll i l lt ; i ł t l. i ti t i i t l i ti i it l t it i i t , il , t i t l , l . t i i ti l ls t t i i t i l t i i t i l . 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 eview 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.2016.06.457 ∗ Corresponding author. Tel.: + 34-91-336-5374 ; fax: + 34-91-336-6681. E-mail address: jaime.planas@upm.es 2452-3216 c 2016 The Authors. Published by Elsevier B.V. Pe r-review under responsibility of the Scientific Committee of ECF21. ∗ Corresponding author. Tel.: + 34-91-336-5374 ; fax: + 34-91-336-6681. E-mail address: jaime.planas@upm.es 2452-3216 c 2016 The Auth rs. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of ECF21. t r. l.: - - - ; f : - - - . - il ddres : j i . l @ . 52-321 c 2016 Th ut or . li l evier B. . r-r i r r i ilit f t i ti ittee of ECF21. rr i