PSI - Issue 13

ScienceDirect Available online at www.sciencedirect.com Av ilable o line at ww.sciencedire t.com ScienceDirect Structural Integrity Procedia 00 (2016) 000 – 000 Procedia Structural Integrity 13 8 91–96 Available online at www.sciencedirect.com Structural Integrity Procedia 0 (2018) 0– 0 Available online at www.sciencedirect.com Structural Integrity Procedia 00 (2018) 000–000

www.elsevier.com/locate/procedia www.elsevier.co / locate / procedia www.elsevier.com / locate / procedia

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. © 2018 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ECF22 organizers. ECF22 - Loading and Environmental e ff ects on Structural Integrity The E ff ect of Negative Stress Triaxialities on Ductile Damage and Fracture Behavior in Metal Sheets Marco Schmidt a, ∗ , Ste ff en Gerke a , Michael Bru¨nig a a Institut fu¨r Mechanik und Statik, Universita¨ t der Bundeswehr Mu¨nchen, Werner-Heisenberg-Weg 39, 85579 Neubiberg, Germany Abstract The paper deals with an anisotropic continuum damage and fracture model and a series of biaxial experiments with focus on negative stress triaxialities. The continuum model is based on the assumption that di ff erent damage mechanisms are present and have to be taken into account depending on stress triaxiality and Lode parameter. Therefore, modeling of onset and evaluation of damage are based on a stress-state-dependent damage condition and a stress-state-dependent damage rule. To identify the corresponding parameters biaxial experiments with specimens taken from aluminum sheets have been performed and results of corresponding numerical simulations are discussed in detail. The experimental behavior has been analyzed with a digital image correlation system to compare the strain fields with those obtained by numerical simulations. In addition, fracture modes are detected by scanning electron microscopy. Based on the experimental and numerical results a stress-state-dependent cut-o ff value for negative stress triaxialities is proposed. c 2018 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ECF22 organizers. Keywords: Continu m amage model; Ducti e metal sheets; Stress-s te-depend nce; Experiments; Num rical simulations 1. Introduction Currently big e ff ort is made to use all capacities of materials in order to save resources and costs. This requires more in-depth knowledge of the material and more sophisticated material models to reflect its behavior su ffi ciently accurate and to ensure safety at the same time. In this context focus is given on the deterioration behavior of ductile metals which are of interest in several engineering disciplines. Thus, corresponding phenomenological material models have to be capable to reflect besides the elastic-plastic behavior also the damage and failure processes. Especially the damage behavior strongly depends on the stress state: Void nucleation, growth and coalescence occur at high positive stress triaxialities whereas micro-shear cracks appear at stress triaxialities around zero and below. The influence of positive stress triaxialities on the damage and fracture behavior could be investigated with uniaxial tension tests of unnotched and notched specimens, see for example Bao and Wierzbicki (2004), Bru¨nig et al. (2008), Gao et al. (2010) and Dunand and Mohr (2011). In addition, further uniaxial test specimens with special geometry ECF22 - Loading and Environmental e ff ects on Structural Integrity The E ff ect of Negative Stress Triaxialities on Ductile Da age and Fracture Behavior in etal Sheets Marco Schmidt a, ∗ , Ste ff en Gerke a , Michael Bru¨nig a a Institut fu¨r Mechanik und Statik, Universita¨ t er Bundeswehr Mu¨nchen, Werner-Heisenberg-Weg 39, 85579 Neubiberg, Germany Abstract The paper deals with an anisotropic continuum damage and fracture model and a series of biaxial experiments with focus on negative stress triaxialities. The continuum model is based on the assumption that di ff erent damage mechanisms are present and have to be taken into account depending on stress triaxiality and Lode parameter. Therefore, modeling of onset and evaluation of damage are based on a stress-state-dependent damage condition and a stress-state-dependent damage rule. To identify the corresponding para ters biaxi l experiments with specimens taken from aluminum sheets have been performed and results of corresponding numerical simulations are discussed in detail. The experimental behavior has been analyzed with a digital image correlation system to compare the strain fields with those obtained by numerical simulations. In addition, fracture modes are detected by scanning electron microscopy. Based on the experimental and numerical results a stress-state-dependent cut-o ff value for negative stress triaxialities is proposed. c 2018 The Authors. Published by Elsevier B.V. -review unde responsibility of the ECF22 organizers. Keywords: Continuum damage model; Ductile metal sheets; Stress-state-dependence; Experiments; Numerical simulations 1. Introduction Currently big e ff ort is made to use all capacities of materials in order to save resources and costs. This requires more in-depth knowledge of the material and more sophisticated material models to reflect its behavior su ffi ciently accurate and to ensure safety at the same time. In this context focus is given on the deterioration behavior of ductile metals which are of interest in several engine ring disciplines. T us, corresponding phenomenological material models have to be capable to reflect besides the elastic-plastic behavior also the damage and failure processes. Especially the damage behavior strongly depends on the stress state: Void nucleation, growth and coalescence occur at high positive stress triaxialities whereas micro-shear cracks appear at stress triaxialities around zero and below. The influence of positive stress triaxialities on the damage and fracture behavior could be investigated with uniaxial tension tests of unnotched and notched specimens, see for example Bao and Wierzbicki (2004), Bru¨nig et al. (2008), Gao et al. (2010) and Dunand and Mohr (2011). In addition, further uniaxial test specimens with special geometry © 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.

2452-3216 © 2016 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of PCF 2016. ∗ Corresponding author. Tel.: + 49-89-60043413 ; fax: + 49-89-60044549. E-mail address: m.schmidt@unibw.de 2210-7843 c 2018 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ECF22 organizers. ∗ Corresponding author. Tel.: + 49-89-60043413 ; fax: + 49-89-60044549. E-mail address: m.schmidt@unibw.de 2210-7843 c 2018 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ECF22 organizers. * Corresponding author. Tel.: +351 218419991. E-mail address: amd@tecnico.ulisboa.pt 2452-3216  2018 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ECF22 organizers. 10.1016/j.prostr.2018.12.016