PSI - Issue 2_A

ScienceDirect Available online at www.sciencedirect.com Av ilable o line at ww.sciencedire t.com cienceDirect Structural Integrity Procedia 00 (2016) 000 – 000 Procedia Struc ural Integrity 2 (2016) 3625–3646 Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia 00 (2016) 000–000 Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia 00 (2016) 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. 21st European Conference on Fracture, ECF21, 20-24 June 2016, Catania, Italy 3-D Stress Intensity Factors due to Full Autofrettage for Inner Radial or Coplanar Crack Arrays and Ring Cracks in a Spherical Pressure Vessel M. Perl a,b,* , and M. Stein r a,c a Aaron Fish Professor of Mechanical Engineering-Fracture Mechanics and Graduate student respectively, Pearlstone Center for Aeronautical Engineering Studies Department of Mechanical Engineering Ben-Gurion University of the Negev Beer-Sheva 84105, Israel b Fellow ASME c Presently PhD student Faculty of Aerospace Engineering, Tech on Isr el Institute of Techn logy, Haifa, Israel. Abstract Three dimensional, Mode I, Stress Intensity Factor (SIF) distributions for radial or coplanar crack arrays as well as ring cracks emanating from the inner surface of an autofrettaged spherical pressure vessel are evaluated. The 3-D analysis is performed via the finite element (FE) method employing singular elements along the crack front. A novel realistic autofrettage residual stress field incorporating the Bauschinger effect is appli d t the v ssel. The residual stress fi ld is simulated in the FE analysis using an equiv ent t mperature field. Numerous radial and coplanar crack rray configu ations ar analyz d as well as ring cracks of various epths. SIFs distributions are evaluated for arrays of radial or coplanar cracks consisting of cracks f depth wall thickness ratios of a/t =0.1-0.6, and llipticities of a/c =0.2-1.0 prevailing in a fully utofrettaged spherical vessels, ε =100%, of different geom tries R 0 /R i =1.1, 1.2, and 1.7. SIFs are evaluated for radial arrays containing n =1-20 cracks, and for arrays f coplanar cracks of δ=0 - 0.95 densities. Furthermore, SIFs for inner ring cracks of various crack depth to wall thickness ratios of a/t =0.025-0.6 are also evaluated. In total, about three hundred different crack configurations are analyzed. A detailed study of the influence of the above parameters on the prevailing SIF is conducted. The results clearly demonstrate the favorable effect of autofrettage which may considerably reduce the prevailing effective stress intensity factor, thus delaying crack initiation and slowing down crack growth rate, and hence, substantially prolonging the total fatigue life of the vessel. Furthermore, the results emphasize the importance of properly accounting for the Bauschinger effect including re-yielding, as well as the significance of the three dimensional analysis herein performed. Furthermore, it is shown that in some cases the commonly accepted approach that the SIF for a ring crack of any given depth is the upper bound to the maximum SIF occurring in an array of coplanar cracks of the same depth is not universal. © 2016 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of ECF21. Keywords: Stress intensity factors; Autofrettage; Spherical pressure vessel; Radial crack arrays; Coplanar crack arrays; Ring cracks; Lunular crack; Crescentic crack 21st European Conference on Fracture, ECF21, 20-24 June 2016, Catania, Italy 3-D Stress Int sity ctors due to Full Autofrettage for Inner Radial or Coplanar Crack Arrays and Ring Cracks in a Spherical Pressure Vessel M. Perl a,b,* , and M. Steiner a,c a Aaron Fish Professor of M chanical Engineering-Fracture Mecha ics a d Graduate student respectively, Pearlstone Center for A ronautical Engineering Studies Department of Mechanical Engineering Ben-Gurion University of the Negev Beer-Sheva 84105, Israel b F llow ASME c Presently PhD student Faculty of Aerospace Engineering, Technion Israel Institute of Technology, Haifa, Israel. Abstract Three dimensional, Mode I, Stress Intensi y Factor (SIF) d stributions for radial or copl nar crack arrays as well as ring cracks emanating from the inner surfac of an autofrettaged sph rical pressure vessel are evaluat d. The 3-D analysis is p rformed via th finite eleme t (FE) method mploying ingu ar ele ents along t crack front. A novel realistic utofrettage residual stress field in orporating t e Bauschinger ffect is pp ied to t e vessel. The esidual stres field is simulat in he FE analysis u ing an eq ivalent temperature field. Numerous r dial and coplanar crack ar ay c nfigurations ar analyzed as well as ring cracks of various d hs. SIFs distributions r eva uat d for arrays of radial r copl nar cr cks consisting of r cks of depth to w ll thi kness ratios of a/t =0.1-0.6, and ellipticities of /c =0.2-1.0 prevailing in a fully autofrettaged spherical vessels, ε =100%, diff rent geometries R 0 /R i =1.1, 1.2, and 1.7. SIFs are evaluated for ra i l arrays containing n =1-20 cracks, and for array coplanar cracks of δ=0 - 0.95 densities. Furthermo e, SIFs for inner ring cracks o va ious cr ck depth to wall th ckness ratios of a/t =0.025-0.6 are also evaluated. In total, about three hundred different crack configurations ar analyzed. A detailed study of the influence of the above paramete s on the prevailing SIF is conduct d. The results clearly demonstr te the f vorable effect of autofrettage which may consid r bly r duce the prevailing effective stress intensity fact r, thus delaying crack initiation and slowing down crack growth rate, and hence, substantially prolonging the to al fatigue life of the ves el. Furthermore, the results emphasize the importance of prop rly acc unting fo t e Bauschinger effec including re-yi lding, as well as the significance of e t r e dimensional an lysis herein performed. Furthermore, it is shown that in some cases the commonl accepted pp oach that the SIF for a ring crack of ny given depth is the upper bound to the maximum SIF occurring in an array of coplanar cracks of the sam dep is not universal. © 2016 The Autho s. Publ shed by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of ECF21. Keywords: Stress intensity factors; Autofrettage; Spherical pressure vessel; Radial crack arrays; Coplanar crack arrays; Ring cracks; Lunular crack; Crescentic crack 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.: +351 218419991. E-mail address: amd@tecnico.ulisboa.pt ____________________ * Corresponding author. Tel.: 972-52-8795841; fax: 972-8-6900501. E-mail address: merpr01@bgu.ac.il 2452-3216 © 2016 The Authors. Published by Elsevier B.V. Peer-review und r responsibility of the Scientific Committee of ECF21. ____________________ * Correspon ing author. Tel.: 972-52-8795841; fax: 972-8-6900501. E mail address: m rpr01@bgu.ac.il 2452 3216 © 2016 Th Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of ECF21.

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.2016.06.452