PSI - Issue 2_A

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 Structu al Integrity 2 (2016) 664–672 Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia 00 (2016) 000–000 il l li t . i i t. tr t r l I t rit r i ( )

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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. 21st European Conference on Fracture, ECF21, 20-24 June 2016, Catania, Italy Effects of surface roughness on thermo-mechanical fatigue life of a P91 power plant steel S T Kyaw *1 , J P Rouse 1 , J Lu 2 , W Sun 1 1Department of Mechanical, Materials and Manufacturing Engineering, University of Nottingham, Nottingham, Nottinghamshire, NG7 2RD, UK 2Department of Mechanical, Materials and Manufacturing Engineering, University of Nottingham, Ningbo, Zhejiang, China, 315100 Abstract P91 martensitic steel has now been widely used for power plant components such as steam pipe sections and headers. With the shift to renewable sources, traditional fossil power plants are increasingly expected to operate under so called “two shifting” conditions (high frequency start up/shut down cycles from a partial load condition) to match market demands. Such conditions increase the potential for large thermal stresses to be induced in thick walled components, making thermo-mechanical fatigue (TMF) and creep-fatigue interaction a life limiting concern. It is important to investigate the behaviour of P91 power plant steel under cyclic creep-fatigue interaction conditions in order to estimate the component remnant life under various possible operating strategies. Specimens used for TMF testing are commonly hollow (unlike solid specimens used in isothermal tests) to allow for higher cooling rates (with insignificant radial temperature variations) by injecting air. It is difficult to polish the internal surface to the same extent as the external surface of the specimen (with a roughness (Ra) of 0.8μm). Concerns have been expressed as to whether this type of uncontrolled surface roughness could significantly affect the fatigue life of the specimen since most fatigue cracks often initiate at the surface of the material. In this work, the roughness profile of the internal surface of the TMF sample is measured using Alicona optical profilometer. Resultant surface profiles are idealised and used to simulate distributions of stress and plastic strain under fatigue load using multi-axial visco-plasticity model. Concentration of stress and higher plastic stain accumulations are observed at the peak region of the roughness profile and crack initiations are expected to occur at those regions. Using accumulated plastic strain as a failure criterion for the fatigue, shorter fatigue lifetime is expected for specimen with rougher surface relative to the polished specimen. Optical and scanning electron microscopy (SEM) has been used to investigate the nature of the cracks initiating from the internal and external (polished) surfaces of a failed TMF test specimen. © 2016 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of ECF21. Keywords: P91 steel, surface roughness, visco-plasticity model, thermo-mechanical fatigue 1. Introduction There is a trend in numerous industries to operate components in ways that ensure output is closely matched to demand. The reasoning for this is clear; by operating based on demand waste can be minimised and efficiency 21st European Conference on Fracture, ECF21, 20-24 June 2016, Catania, Italy *1 1 2 1 1Department of Mechanical, Materials and Manufacturing Engineering, University of Nottingham, Nottingham, tti i , , t t f i l, t i l f t i i i , i it f tti , i , ji , i , t iti t l i l l t t t i ti . it t i t t l , t iti l il l t i i l t t t ll t i ti condition i t t / t l ti l l iti t t t . iti i t t ti l l t l t t i i t i ll t , i t i l ti ti i t ti li li iti . t i i t t t i ti t t i l t t l li ti i t ti iti i t ti t t t t li i i l ti t t i . i t ti l ll li li i i i t l t t t ll i li t it i i i i t i l t t i ti i j ti i . t i i i lt t li t i t l t t t t t t l t i it . . t t t i t t ll l i i i tl t t ti li t i i t ti t i iti t t t t t i l. t i , t il t i t l t l i i li ti l il t . lt t il i li t i l t i t i ti t l ti t i ti l i lti i l i l ti it l. t ti t i r plastic stain l ti t t i t il i iti ti t t t t i . i l t l ti t i il it i t ti , t ti li ti i t i it l ti t t li i . ti l i l t i t i ti t t t t i iti ti t i t l t l li il t t i . t . li l i . . i i ilit t i ti i itt . : t l, , i l ti it l, t i l ti . i i t i i t i t t t i t t t t i l l t t . i t i i l ; ti t i i i i i 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. © 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 2452-3216 © 2016 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of ECF21. l i r . . i i ilit t i ti i itt . - t r . li

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.2016.06.086