PSI - Issue 2_A

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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.2016.06.114 ∗ Corresponding author. Tel.: + 358-40-849-0561; fax: + 0-000-000-0000. E-mail address: reijo.kouhia@tut.fi 2452-3216 c 2016 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of ECF21. Creep is an important deformation mechanism for metal structures operating at temperatures over 30 % of their absolute melting temperature. Many technical applications require higher operating temperatures. The basic test in studying creep deformation and fracture is the uniaxial creep test where a smooth tensile bar is subjected to a con stant load. As already observed by da Costa Andrade (1910), the experimental creep curve consists of three phases corresponding to decreasing, constant and increasing strain rate. These phases are termed as primary, secondary and tertiary creep stages. Strain hardening and thermally activated recovery of the dislocation structure are the main mech anisms in the primary and secondary phases, while formation of grain boundary cavities and changes in a dislocation microstructure can be ascribed to the tertiary phase. ∗ Corresponding author. Tel.: + 358-40-849-0561; fax: + 0-000-000-0000. E-mail address: reijo.kouhia@t t.fi 2452-3216 c 2016 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of ECF21. Creep is an important deformation mechanism for metal structures operating at temperatures over 30 % of their absolute melting temperature. Many technical applications require higher operating temperatures. The basic test in studying creep deformation and fracture is the uniaxial creep test where a smooth tensile bar is subjected to a con stant load. As already observed by da Costa Andrade (1910), the experimental creep curve consists of three phases corresponding to decreasing, constant and increasing strain rate. These phases are termed as primary, secondary and tertiary creep stages. Strain hardening and thermally activated recovery of the dislocation structure are the main mech anisms in the primary and secondary phases, while formation of grain boundary cavities and changes in a dislocation microstructure can be ascribed to the tertiary phase. ∗ Corresponding author. Tel.: + 358-40-849-0561; fax: + 0-000-000-0000. E-mail address: reijo.kouhia@tut.fi 2452-3216 c 2016 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of ECF21. 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 A continuum damage model for creep fracture and fatigue analyses Pette i Kauppila a , R ijo Kouhia b, ∗ , Juha Ojanpera¨ a , Timo Saksala b , Tim Sorjonen a a Valmet Technologies Oy, P.O. Box 109, FI-33101 Tampere, Finland b Tampere University of Technology, Department of Mechanical Engineering and Industrial Systems, P.O. Box 589, FI-33101 Tampere, Finland Abstract In this paper a thermodynamically consistent formulation for creep and creep-damage modelling is given. The model is developed for isotropic solids by using proper expressio s for the Helmholtz free energy and the complementary form of the dis ipation potential, and can be proven to fullfil the dissipation inequality. Also the coupled energy equation is derived. Continuum damage model with scalar damage variable is used to facilitate simulations with tertiary creep phase. The complementary dissipation potential is written in terms of the thermodynamic forces dual to the dissipative variables of creep strain-rate and damage-rate. The model accounts for the multiaxial stress state and the di ff erence in creep rupture time in shear and axial loading as well as in tensile and compressive axial stress. In addition, the model is simple and only four to eight material model parameters are required in addition to the elasticity parameters. A specific version of the proposed model is obtained when constrained to obey the Monkman Grant relationship between the minimum creep strain-rate and the creep rupture time. The applicability of the Monkman-Grant hypothesis in the model development is discussed. The proposed 3D-model is implemented in the ANSYS finite element software by the USERMAT subroutine. Material parameters have been estimated for the 7CrMoVTiB10-10 steel (T24) for temperatures ranging from 500 to 600 degrees of celcius. Some test cases with cyclic thermal fatigue analysis are presented. c 2016 The Authors. Published by Elsevier B.V. Peer-revi w under responsibility of the Scientific Committee of ECF21. Keywords: creep fatigue; damage mechanics; Ansys USERMAT Creep is an important deformation mechanism for metal structures operating at temperatures over 30 % of their absolute melting t mperature. Many t chn cal applications require higher operating temperatures. The basic test in studying creep deformation and fracture is the uniaxial creep test where a smooth tensile bar is subjected to a con stant load. As already observed by da Costa Andrade (1910), the experimental creep curve consists of three phases corresponding to decreasing, constant and increasing strain rate. These phases are termed as primary, secondary and tertiary creep stages. Strain hardening and thermally activated recovery of the dislocation structure are the main mech anisms in the primary and secondary phases, while formation of grain boundary cavities and changes in a dislocation microstructure can be ascribed to the tertiary phase. 21st European Conference on Fracture, ECF21, 20-24 June 2016, Catania, Italy A continuum damage model for creep fracture and fatigue analyses Petteri Kauppila a , Reijo Kouhia b, ∗ , Juha Ojanpera¨ a , Timo Saksala b , Timo Sorjonen a a Valmet Technologies Oy, P.O. Box 109, FI-33101 Tampere, Finland b Tampere University of Technology, Department of Mechanical Engineering and Industrial Systems, P.O. Box 589, FI-33101 Tampere, Finland Abstract In his paper a thermodynamically consistent formulation for creep and creep-damag modelling is giv n. The model is developed for isotropic so ids by using proper expressio s for the Helmholtz free energy and the complementary form of the , and can be proven to fullfil the issipation inequality. Also the coupled energy equation is de iv d. Continuum damag with scalar damage vari ble i used to facilitat simulations with tertiary creep ph se. The complementary dissipation potential is written in terms of the thermodynamic forces dual to the dissipative var ables of creep strain-rate and damage-rate. The model accounts for the multiaxial stress state and the di ff erence in cr ep rupture time i shear and axial loading as well as in tensile and compressive axial stress. In addition, th model is simple and only fo r to eight mat ri l model paramet rs are required in addition to the elasticity parameters. A specific version of the proposed model is obtain d when constrained to ob y th Monkman Grant relationship between the minimum creep strain-rate and the creep rup ure time. The applicability of the Monk an-Grant hypothesis in the model development is di cussed. The proposed 3D-mod l is implem nted in the ANSYS finite element software by the USERMAT ubroutine. Material pa ameters have been estimated for the 7CrMoVTiB10-10 steel (T24) for temperatures ranging from 500 to 600 degrees f celcius. Some test cases with cyclic thermal fatigue analysis are pr sented. c 2016 The Authors. Published by Elsevier B.V. Peer-review under responsibi ity of the Scientific Committee of ECF21. Keywords: creep fatigue; damage mechanics; Ansys USERMAT 1. Introduction 21st European Conference on Fracture, ECF21, 20-24 June 2016, Catania, Italy A continuum damage model for creep fracture and fatigue analyses Petteri Kauppila a , Reijo Kouhia b, ∗ , Juha Ojanpera¨ a , Timo Saksala b , Timo Sorjonen a a Valmet Technologies Oy, P.O. Box 109, FI-33101 Tampere, Finland b Tamper University of T chnology, Department of Mechan cal Engineering and Industrial Systems, P.O. Box 589, FI-33101 Tamper , Finland Abstract In this paper a thermodynamically consistent formulation for creep and creep-damage modelling is given. The model is developed for isotropic solids by using proper expressions for the Helmholtz free energy and the complementary form of the dissipation potential, and can be proven to fullfil the dissipation inequality. Also the coupled energy equation is derived. Continuum damage model with scalar damage variable is used to facilitate simulations with tertiary creep phase. The complementary dissipation potential is written in terms of the thermodynamic forces dual to the dissipative var abl s of creep strain-rate and damage-rate. The model accounts for the multiaxial stress state and the di ff erence in creep rupture time in shear and axial loading as well as in tensile and compressive axial stress. In addition, the model is simple and only four to eight material model parameters are required in addition to the elasticity parameters. A specific version of the proposed model is obtained when constrained to obey the Monkman Grant relationship between the minimum creep strain-rate and the creep rupture time. The applicability of the Monkman-Grant hypothesis in the model development is discussed. The proposed 3D-model is implemented in the ANSYS finite element software by the USERMAT subroutine. Material parameters have been estimated for the 7CrMoVTiB10-10 steel (T24) for temperatures ranging from 500 to 600 degrees of celcius. Some test cases with cyclic thermal fatigue analysis are presented. c 2016 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of ECF21. Keywords: creep fatigue; damage mechanics; Ansys USERMAT 1. Introduction Copyright © 2016 The Authors. Publishe by Elsevier B.V. This is an open access articl under the CC BY-NC-ND license (http://creativecommons. rg/lice ses/by-nc-n /4.0/). Pe r view 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 1. Introduction