PSI - Issue 5

ScienceDirect Available online at www.sciencedirect.com Av ilable o line at ww.sciencedire t.com ienceDirect Structural Integrity Procedia 00 (2016) 000 – 000 Procedia Structu al Integrity 5 (2017) 809–816 Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia 00 (2017) 000 – 000 Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia 00 (2017) 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. Synthesis of experimental testing and fatigue behavior of laser stake-welded T-joints on medium-high cycle fatigue range P. Gallo a,b,* , J. Romanoff b , D. Frank c , A. Karttunen b , H. Remes b a Kyoto University, Dep. of Mech. Eng. and Science, Kyoto-daigaku-Katsura, Nishikyo-Ku, Kyoto 615-8540, Japan b Aalto University, Dep. of Mech. Eng., Puumiehenkuja 5A, Espoo 02150, Finland c as2con-Alveus Ltd., Rijeka 51000, Croatia The paper presents a synthesis of experimental fatigue tests and theoretical studies of laser stake-welded T-joints in steel sandwich panels. The experiments indicate that the slope of the fatigue strength curves varies significantly depending on the type of loading the joint experiences, but also on the geometry. Therefore, the focus is on the influence of crack tip plasticity when the joints are loaded under tension and bending. This is investigated by two different approaches based on square root of J-integral. With this parameter, the experimental fatigue curves meet at the fatigue limit for all of the loading modes and geometries. To investigate the change in slope in the medium-high cycle fatigue range, the suitability of stress gradient and plastic zo e size as defi ed by Irwin are studied. It is shown that the gradient of principal stress correlates well with the variation of slope, but it does not give a practical tool for fatigue assessment of the joints. Instead, based on the plastic zone approach, a new method is proposed that permits the estimation of number of cycles to failure under bending directly from the tension fatigue curve. The method is verified with experiments. © 2017 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of ICSI 2017. Keywords: Crack tip plasticity; laser stake-welds; fatigue assessment; slope of fatigue curve; 2nd International Conference on Structural Integrity, ICSI 2017, 4-7 September 2017, Funchal, Madeira, Portugal Synthesis f exp rimental testing and fatig e behavior of laser stake-welded T-joints on medium-high cycle fatigue range P. Gallo a,b,* , J. Romanoff b , D. Frank c , A. Karttunen b , H. Remes b a Kyoto University, Dep. of Mech. Eng. and Science, Kyoto-daigaku-K tsura, Nishikyo-Ku, Kyoto 615-8540, Japan b Aalto University, Dep. f Mech. Eng., Puumiehenkuja 5A, Espoo 02150, Finland c as2con-Alveus Ltd., Rijeka 51000, Croatia Abstract The paper presents a synthesis of experimental fatigue tests and theoretical studies of laser stake-w lde T-joi ts in ste l sandwich panels. The experiments indicate that the slope of the fatigue strength curves varies significantly de ending on the type of loading the joint experiences, but also o the geometry. Ther fore, the focus is on the influence of crack tip plasticity when the joints are loaded under t nsion and bending. This i inv stigat d by two different approaches based on square root of J-integral. With this parameter, the ex erimental fatigue cu ves m et at the fatigue limit for all of he lo ing modes an geometri s. To investigate he chang n slope in the medium-high cycle fatigue rang , the suitability of stress gradient and plastic zon size as defined by Irwin are studied. It is shown t at the g adie t of principal stress correlates well with the variation of slope, but it does n t give a practical tool for fatigu assessment of the joint . Instead, based on the plastic zone approach, new method is proposed that permits the stimatio of number of cycles to failure under bending directly from the tension fatigue curve. The method is verified with experiments. © 2017 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of ICSI 2017. © 2017 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of ICSI 2017 2nd International Conference on Structural Integrity, ICSI 2017, 4-7 September 2017, Funchal, Madeira, Portugal Abstract

© 2016 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of PCF 2016. Keywords: Crack tip plasticity; laser stake-welds; fatigue assessment; slope of fatigue curve;

Keywords: High Pressure Turbine Blade; Creep; Finite Element Method; 3D Model; Simulation.

* Corresponding author. Tel.: +81-70-2803-1673. E-mail address: pasquale.gallo@aalto.fi * Correspon ing author. T l.: +81-70-2803-1673. E-mail address: pasquale.gallo@aalto.fi

2452-3216 © 2016 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of PCF 2016. 2452-3216  2017 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of ICSI 2017 10.1016/j.prostr.2017.07.055 * Corresponding author. Tel.: +351 218419991. E-mail address: amd@tecnico.ulisboa.pt 2452 3216 © 2017 Th Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of ICSI 2017. 2452-3216 © 2017 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of ICSI 2017.