PSI - Issue 2_B

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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.2016.06.211 ∗ Corresponding author. Tel.: + 44-161-306-4286. E-mail address: christopher.seal@manchester.ac.uk 2452-3216 c 2016 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of ECF21. Fracture, by its nature, is a stochastic proc ss and can be modelled using a probabilistic appro ch. This type of analy is assumes that the probability of fracture occurring follows a continuous distribution which can be represented by a standard statistical model. Typically for fracture f ferritic steels, the best representations of the likelihood of failure follow either a lognormal or a Weibull distribution. ∗ Corresponding author. Tel.: + 44-161-306-4286. E-mail address: christopher.seal@manchester.ac.uk 2452-3216 c 2016 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientifi Committee of ECF21. Fracture, by its nature, is a stochastic process and can be modelled using a probabilistic approach. This type of analysis assumes that the probability of fracture occurring follows a continuous distribution which can be represented by a standard statistical model. Typically for fracture of ferritic steels, the best representations of the likelihood of failure follow either a lognormal or a Weibull distribution. ∗ Corresponding author. Tel.: + 44-161-306-4286. E-mail address: christopher.seal@manchester.ac.uk 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 Weibull distribution of brittle failures in the transition region C.K. Seal a, ∗ , A.H. Sherry a,b a The University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom b National Nuclear Laboratory, Warrington Road, Warrington WA3 6AE, United Kingdom Abstract The Weibull stress is a well-known means of predicting the likelihood of weakest link brittle fracture that has been shown to accurately model the behaviour of ferritic steels in the lower transition region. Weibull stress is based on its use of a two parameter Weibull distribution, a commonly used distribution in probabilistic engineering. The distribution is defined by a shape parameter, the Weibull modulus, and a scaling parameter. In the lower transition region, the Weibull modulus is relatively insensitive to temperature and the likelihood of failure can readily be defined by assuming it is constant and scaling the distribution with a ‘measured’ scaling parameter. This assumption, however, does not hold as the temperature increases into the upper transition zone and becomes less accurate as the upper shelf is approached. This manifests itself as a broadening of the failure distribution that can be attributed to the increased size of the plastic zone ahead of a defect, which in turn ‘samples’ more potential failure sites, while simultaneously increasing the likelihood of blunting these sites and initiating ductile tearing. Thus, while more potential cleavage initiation sites are sampled, the likelihood of an individual defect causing failure is reduced. This paper details the changes in the Weibull modulus and Weibull stress calculated from the ‘Euro’ fracture toughness data. The di ff erences in the Weibull modulus nd the mechanistic reason for these di ff erences are explored to enable greater understanding of the factors that influence fracture toughness in the upper transiti n regime. c 2016 The Authors. Published by Elsevier B.V. Peer-review under re ponsibility of the Sci ntific Committee of ECF21. Keywords: Cleavage; Statistical analysis; Weibull stress; Fracture toughness; Ductile to brittle transition 21st European Conference on Fracture, ECF21, 20-24 June 2016, Catania, Italy Weibull distribution of brittle failures in the transition region C.K. Seal a, ∗ , A.H. Sherry a,b a The University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom b National Nuclear Laboratory, Warrington Road, Warrington WA3 6AE, United Kingdom Abstract The Weibull stress is a well-kn wn means of predicting the likel hood of weakest link brittle fracture that has been shown to accurately model the behaviour of ferritic eels n the lower trans tion region. Weibull stress is based on its use of a two r t r W ibull distribution, a commonly used distribution in probabilistic engineering. The distribution is defined by a shape parameter, the Weibull modulus, and a scaling parameter. In the lower transition region, the Weibull modulus is relat vely insensitive to t mperature and the lik lihood of failure can readily be defined by assuming it is constant and scaling the distribution with a ‘measured’ sca ing parameter. This assumption, however, does not hold as the temperature increases into the upper transition zone and becomes less accurate as the upper shelf is approached. This manifests itself as a broadening f the failure distribut on that can be at ributed to the increased size of the plastic zone ahead of a defect, which in turn ‘s mples’ more potential failure sites, while simul aneously increasing the likelihood of blunting these sites and in tiating ductile tearing. Thus, while more potential cleavage initiation sites are sampled, the likelihood of an individual defect causing failure is reduc d. This paper details the changes in the Weibull modulus and Weibull str ss calculated from the ‘Eur ’ fr cture toughness data. The di ff erences in t e Weibull modul s and t e mechanistic r aso for these di ff er nces are explored to enable great r understanding of the factors that influence fracture toughness in the upper transition regime. c 2016 The Autho s. Publ shed by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of ECF21. Keywords: Cleavage; Statistical analysis; Weibull stress; Fracture toughness; Ductile to brittle transition 21st European Conference on Fracture, ECF21, 20-24 June 2016, Catania, Italy eibull distribution of brittle failures in the transition region C.K. Seal a, ∗ , A.H. Sherry a,b a The University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom b National Nuclear Laboratory, Warringt n Ro d, Warrington WA3 6AE, United Kingdom Abstract The Weibull stress is a well-known means of predicting the likelihood of weakest link brittle fracture that has been shown to accurately model the behaviour of ferritic steels in the lower transition region. Weibull stress is based on its use of a two parameter Weibull distribution, a commonly used distribution in probabilistic engineering. The distribution is defined by a shape parameter, the Weibull modulus, and a scaling parameter. In the lower tr nsition region, the Weibull modulus is relat vely i sensitive to temp rature and the likelihood of failure can readily be defined by assuming it is constant and scaling the distribution with a ‘measured’ scaling parameter. This assumption, however, does not hold as the temperature increases into the upper transition zone and becomes less accurate as the upper shelf is approached. This manifests itself as a broadening of the failure distribution that can be attributed to the increased size of the plastic zone ahead of a defect, which in turn ‘samples’ more potential failure sites, while simultaneously increasing the likelihood of blunting these sites and initiating ductile tearing. Thus, while more potential cleavage initiation sites are sampled, the likelihood of an individual defect causing failure is reduced. This paper details the changes in the Weibull modulus and Weibull stress calculated from the ‘Euro’ fracture toughness data. The di ff erences in the Weibull modulus and the mechanistic reason for these di ff erences are explored to enable greater understanding of the factors that influence fracture toughness in the upper transition regime. c 2016 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of ECF21. Keywords: Cleavage; Statistical analysis; Weibull stress; Fracture toughness; Ductile to brittle transition Copyright © 2016 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://cr ativecommons.org/ icenses/by-nc- d/4.0/). er-review 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. 1. Intro uction * Corresponding author. Tel.: +351 218419991. E-mail address: amd@tecnico.ulisboa.pt Fracture, by its nature, is a stochastic process and can be modelled using a probabilistic approach. This type of analysis assumes that the probability of fracture occurring follows a continuous distribution which can be represented by a standard statistical model. Typically for fracture of ferritic steels, the best representations of the likelihood of failure follow either a lognormal or a Weibull distribution. 1. Introduction 1. Introduction