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 18) 85–90 Available online at www.sciencedirect.com Structural Integrity Procedia 00 (2018) 000–000 Available online at www.sciencedirect.com Structural Integrity Procedia 00 (2018) 000–000

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ECF22 - Loading and Environmental e ff ects on Structural Integrity ECF22 - Loading and Environmental e ff ects on Structural Integrity

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. Identification of crack positions and crack loading quantities from strain gauge data by inverse problem solution Ramdane Boukellif a, ∗ , Andreas Ricoeur a a Institute of Mechanics, Department of Mechanical Engineering, University of Kassel, 34125 Kassel, Germany Abstract A method for the detection of cracks in fi ite and semi-infinite plane structures is pre ented. This allows both the identific tion of crack position parameters such as length, location and inclination angles with respect to a reference coordinate system and the calculation of stress intensity factors (SIFs). The method is based on strains measured at di ff erent locations on the surface of a structure and the application of the dislocation technique. Cracks and boundaries are modelled by continuous distributions of dislocation densities. This approach gives a set of singular integral equations with Cauchy kernels, which can be solved using Gauss-Chebyshev numerical quadrature [Erdogan et al. (1973)]. Once knowing the dislocation densities, the strain at an arbitrary point can be calculated. The crack parameters as well as external loads are parameters which are determined by solving the inverse problem with a genetic algorithm. Once knowing loading and crack parameters, the SIFs can be calculated. c � 2018 The Authors. Publishe by Elsevier B.V. Peer-review under res onsibility of the ECF22 organizers. Keywords: Crack detection; distributed islocations; inverse pr blem; finite plate; strain gauges 1. Introduction Engineering structures are in general exposed to cyclic or stochastic mechanical loading. Exhibiting incipient cracks, particularly light-weight shell and plate structures su ff er from fatigue crack growth, limiting the life time of the structure a sup lying the risk of a fatal failure. Due to the uncertainty of loading boundary conditions and the geometrical complexity of many engineering structures, numerical predictions of fatigue crack growth rates and residual strength are not reliable. Most experimental monitoring techniques, nowadays, are based on the principle of wave scattering at the free surfaces of cracks. Many of them are working well, supplying information about the position of cracks. One disadvantage is that those methods do not provide any information on the loading of the crack tip. In this work, the development of a concept for the detection of cracks in finite and semi-infinite plate structures under mixed mode loading conditions is presented. The concept is based on the measurement of remote strain fields by using strain gauges and the application of the distributed dislocation technique of linear elasticity [Bilby et al. (1968); Weertman (1996)]. As an approach, di ff erent from the FEM, cracks are modelled with a collocation of discrete Identification of crack positions and crack loading quantities from strain gauge data by inverse problem solution Ramdane Boukellif a, ∗ , Andreas Ricoeur a a Institute of Mechanics, Department of Mechanical Engineering, University of Kassel, 34125 Kassel, G rmany Abstract A method for the detection of cracks in finite and semi-infinite plane structures is presented. This allows both the identification of crack position parameters such as length, location and inclination angles with respect to a reference coordinate system and the calculation of stress intensity factors (SIFs). The method is based on strains measured at di ff erent locations on the surface of a structure and the application of the dislocation technique. C acks and boundaries are modelled by continuous distributions of dislocation densities. This approach gives a set of singular integral equations with Cauchy kernels, which can be solved using Gauss-Chebyshev numerical quadrature [Erdogan et al. (1973)]. Once knowing the dislocation densities, the strain at an arbitrary point can be calculated. The crack parameters as well as external loads are parameters which are determined by solving the inverse problem with a genetic algorithm. Once knowing loading and crack parameters, the SIFs can be calculated. c � 2018 The Authors. Published by Elsevier B.V. r-review under responsibility of the ECF22 organizers. Keywords: Crack detection; distributed dislocations; inverse problem; finite plate; strain gauges 1. Introducti n Engineering structures are in general exposed to cyclic or stochastic mechanical loading. Exhibiting incipient cracks, particularly light-weight shell and plate structures su ff er from fatigue crack growth, limiting the life time of the structure and supplying the risk of a fatal failure. Due to the uncertainty of loading boundary conditions and the geometrical complexity of many engineering structures, numerical predictions of fatigue crack growth rates and residual strength are not reliable. Most experimental monitoring techniques, nowadays, are based on the principle of wave scattering at the free surfaces of cracks. Many of them are working well, supplying information about the position of cracks. One disadvantage is that those methods do not provide any information on the loading of the crack tip. In this work, the development of a concept for the detection of cracks in finite and semi-infinite plate structures under mixed mode loading conditions is presented. The concept is based on the measurement of remote strain fields by using strain gauges and the application of the distributed dislocation technique of linear elasticity [Bilby et al. (1968); Weertman (1996)]. As an approach, di ff erent from the FEM, cracks are modelled with a collocation of discrete © 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.: + 49 561 804 2505 ; fax: + 49 561 804 2720. E-mail address: ramdane.boukellif@uni-kassel.de 2210-7843 c � 2018 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ECF22 organizers. ∗ Corresponding author. Tel.: + 49 561 804 2505 ; fax: + 49 561 804 2720. E-mail address: ramdane.boukellif@uni-kassel.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.2018.12.015