PSI - Issue 13

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 Structu al Integrity 13 (2018) 607–612 Available online at www.sciencedirect.com Structural Integrity Procedia 00 (2018) 000– 0 Available online at www.sciencedirect.com Structural Integrity Procedia 00 (2018) 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. © 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 A Novel Micromechanics Approach for Understanding of Fatigue in Nodular Cast Iron Mehul Lukhi*, Geralf Hütter, Meinhard Kuna TU Bergakademie Freiberg, Institute of Mechanics and Fluid Dynamics, Lampadiusstr. 4, 09599, Freiberg, Germany Abstract Nodular cast iron (NCI) experiences failure under static loading in manner of nucleation, growth, and coalescence of voids. Under cyclic loading, m terials with el stic-plastic behaviour show an ncrease in porosity with ach cycle which is c lled void ratchetting. A number of finite element studies in literature proved this mechanism by means of a few cyles with unit cell models. In the present study, low cycle fatigue (LCF) in nodular cast iron is investigated using the cell models for void ratchetting till final failure. The cyclic necking due to plastic strain accumulation is observed as mechanism in the final stage. The proposed methodology uses only input parameters defining the elastic-plastic material behavior and geometrical features of the microstructure. The strain-life curves extracted from the simulations are compared with experimental data collected from the literature. From the comparison, it is confirmed that void ratchetting is the relevant mechanism of LCF in NCI. The e ff ects of material strength, temperature and load sequencing on the fatigue behaviour are studied. c 2018 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ECF22 organizers. Keywords: nodular cast iron, void ratchetting; low cycle fatigue; strain-life approach ECF22 - Loading and Environmental e ff ects on Structural Integrity A Novel icro echanics Approach for Understanding of Fatigue in Nodular Cast Iron Mehul Lukhi*, Geralf Hütter, Meinhard Kuna TU Bergakademie Freiberg, Institute of M chanics and Fluid Dynamics, Lampadiusstr. 4, 09599, Freiberg, Germany Abstract Nodular cast iron (NCI) experiences failure under static loading i man er of nucleation, growth, and coalescence of void . Under cyclic loading, materials with elastic-plastic behaviour show an increase in porosity with each cycle which is called void ratchetting. A number of finite element studies in literature proved this mechanism by means of a few cyles with unit cell models. In the present study, low cycle fatigue (LCF) in nodular cast iron is investigated using the cell models for void ratchetting till final failure. The cyclic necking due to plastic strain accumulation is observed as mechanism in the final stage. The proposed methodology uses only input parameters defining the elastic-plastic material behavior and geometrical features of the microstructure. The strain-life curves extracted from the simulations are compared with experimental data collected from the literature. From the comparison, it is confirmed that void ratchetting is the relevant mechanism of LCF in NCI. The e ff ects of material strength, temperature and load sequencing on the fatigue behaviour are studied. c 2018 The Aut ors. Published by Elsevier B.V. P r-review unde responsibility of the ECF22 organizers. Keywords: nodular cast iron, void ratchetting; low cycle fatigue; str in-life approach Keywords: High Pressure Turbine Blade; Creep; Finite Element Method; 3D Model; Simulation. Nodular cast iron (NCI) is ferrous material widely used material in di ff erent applications like gearboxes, crankshafts, wind turbine rotors, nuclear storage and transportation casks etc. It o ff ers similar mechanical strength and ductility as engineering steels but with reduced manufacturing costs. The improved mechanical properties of NCI are related to the nodular shape of graphite particle, cf. e. g. (Hütter et al., 2015). Fatigue tests with ferritic ductile cast iron (FDI) material have been carried out in the (extremely) low-cycle regime by Komotori et al. (1998). They have observed void growth and coalescence in NCI under cyclic strain-controlled loading. The schematic diagram of the damage process is presented in Fig. 1. Generally, fatigue cracks are assumed to initiate at the surface (notches or other surface defects) from where they propagate into the bulk. However, the Nodular cast iron (NCI) is ferrous material widely used material in di ff erent applications like gearboxes, crankshafts, wind turbine rotors, nuclear storage and transportation casks etc. It o ff ers similar mechanical strength and ductility as engineering steels but with reduced manufacturing costs. The improved mechanical properties of NCI are related to the nodular shape of graphite particle, cf. e. g. (Hütter et al., 2015). Fatigue tests with ferritic ductile cast iron (FDI) material have been carried out in the (extremely) low-cycle regime by Komotori et al. (1998). They have observed void growth and coalescence in NCI under cyclic strain-controlled loading. The schematic diagram of the damage process is presented in Fig. 1. Generally, fatigue cracks are assumed to initiate at the surface (notches or other surface defects) from where they propagate into the bulk. However, the 1. Introduction © 2016 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of PCF 2016. 1. Introduction

* Corresponding author. Tel.: +351 218419991. E-mail address: amd@tecnico.ulisboa.pt ∗ Corresponding author. Tel.: + 49-3731393322 E-mail address: mehul.lukhi@imfd.tu-freiberg.de ∗ Corresponding author. Tel.: + 49-3731393322 E-mail address: mehul.lukhi@imfd.tu-freiberg.de

2452-3216 © 2016 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of PCF 2016. 2210-7843 c 2018 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ECF22 organizers. 2210-7843 c 2018 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ECF22 organizers. 2452-3216  2018 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ECF22 organizers. 10.1016/j.prostr.2018.12.100