PSI - Issue 13

ScienceDirect Available online at www.sciencedirect.com Av ilable o line at www.sciencedire t.com ienceDirect Structural Integrity Procedia 00 (2016) 000 – 000 Procedia Structural Integrity 13 (2018) 1285–129 Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia 00 (2018) 000 – 000 Available online at www.sciencedirect.com ScienceDirect 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. ECF22 - Loading and Environmental effects on Structural Integrity Fracture criterion for tested CFRP specimens under tension A.A. Lukyanchuk a *, A.G. Kalinin b* , A.V. Pankov c* , Yu.A.Svirskiy d* *Central aerohydraudynamic institute n.a. Prof. N.E. Zhukovsky (TsAGI),Russia, a andrey.lukyanchuk@tsagi.ru; b aleksey.kalinin@tsagi.ru; c andrey.pankov@tsagi.ru; d yury.svirsky@tsagi.ru The development of the theory-experimental methodology to evaluate the fatigue life is one of the essential stages to substantiate the strength and to verify the certification of aircraft from the POV of fatigue and service lives. To develop such a methodology, it is necessary to obtain the S-N curves for different stress ratios. However, the fatigue test by zero-to-tension stress cycle of an open-hole specimen manufactured of carbon fiber rei forced polymer (CFRP) until final fracture (broken into 2 parts) shows a big scatter of fatigue lives and sometimes it is impossible due to fibers long lives despite of fractured matrix. For example, in our research, the root-mean-square deviation of the logarithm of fatigue life S lgN was in the range 0.7 ÷ 0.9. In order to obtain reliable resource characteristics of the structure, at this kind of dispersion values, a lot of time and material costs are required. In order to solve this problem, the task was formulated to create a new fracture criterion, which will allow reducing dispersion of fatigue life. Our analysis showed that the fracture process starts from interlayer delamination at hole edge and propagates towards the outer side of specimen under test. The delamination initiation at the hole edge is proposed to be taken as failure initiation moment; then the data obtained are to be used to estimate the S-N curve. To fix the appearance of delamination, a special sensor was developed. A method was developed to detect the delamination initiation while monitoring the transverse displacement near the free edge of hole. This method provided a drastic decrease of fatigue life scatter up to S lgN = 0.2÷0.3 that is acceptable to estimate the fatigue life; at this, two modes of fracture process in CFRP are taken into consideration: initiation and propagation of delamination, which are characterized by different fracture mechanisms. © 2018 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ECF22 organizers. © 2018 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ECF22 organizers. ECF22 - Loading and Environmental effects on Structural Integrity Fracture criterion for tested CFRP specimens under tension A.A. Lukyanchuk a *, A.G. Kalinin b* , A.V. Pankov c* , Yu.A.Svirskiy d* *Central aerohydraudynamic institute n.a. Prof. N.E. Zhukovsky (TsAGI),Russia, a andrey.lukyanchuk@tsagi.ru; b leksey.kali in@tsagi.ru; c andrey.pankov@tsagi.ru; d yury. virsky@tsagi.ru Abstract The development of the theory-experimental methodology to evaluate the fatigue life is one of the essential stages to substantiate the str ngth and to verify the ce tification of aircraft from the POV of fatigue and service lives. To dev lop such a methodology, it is necessary to obtain the S-N curves f r di ferent stress ratios. However, the fatigue test by zero-to-tension stress cycle of an open-hole specimen manufactur d of arbon iber reinforced polymer (CFRP) until inal fracture (broken into 2 parts) shows a big scatter of fatigu lives and so times it is impossible due to fibers long lives despite of fractur matrix. F r ex mple, n our research, the root-mean-square deviation of the logarithm of fatigu life S lgN was in the range 0.7 ÷ 0.9. In ord r to obtai reliable resourc charact ristics of th structure, at this kind of dispersion values, a lot of tim and material costs are r quired. In order to solve this problem, the task was form lated to create a new fracture criterion, which will llow reducing di persion of fatigue lif . Our analysi sh w d that the fracture process starts from interlayer d lamination at hole edge and propagates towards the outer side of specimen under test. The del mination initiation at the hole edge is proposed to be taken as f ilure initiation moment; then the data btained are to be used to estimate the S-N curve. To fix the appearance of delamination, a special sensor was dev loped. A method was developed to detect the delamination initiation while monitoring the transverse displacement near the free edge of hole. This method provided a drastic decrease of fatigue life scatter up to S lgN = 0.2÷0.3 that is acceptable to stimate t e fatigue life; at this, two modes of fracture process in CFRP are taken into consideration: initiation and propagation of delamination, which are characterized by different fractur mechanisms. © 2018 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ECF22 organizers. Keywords: С arbon fiber reinforced polymer; open-hole specimen; delamination; fracture criterion; fatigue life; fatigue scattering parameter. © 2016 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of PCF 2016. Keywords: С arbon fiber reinforced polymer; open-hole specimen; delamination; fracture criterion; fatigue life; fatigue scattering parameter. Abstract To develop theory-experimental methodology for estimating the fatigue life of CFRP specimens, it is necessary to obtain experimentally S-N curves. For metal specimens, fracture of a specimen into two parts is used as the criterion of destruction, due to the fact that in the case of zero-to-tension stress cycle, the period of development of the crack is small in comparison with the period before its occurrence. However, during the fatigue testing of open- To develop theory-experimental methodology for estimating the fatigue life of CFRP specimens, it is necessary to obtain experimentally S-N curves. For metal specimens, fracture of a specimen into two parts is used as the criterion of destruction, due to the fact that in the case of zero-to-tensi n stress cycle, the period of development of the crack is small in comparison with the period before its occurrence. However, during the fatigue testing of open- 1. Background Keywords: High Pressure Turbine Blade; Creep; Finite Element Method; 3D Model; Simulation. 1. Background

* 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. 2452-3216 © 2018 The Authors. Published by Elsevier B.V. Peer review under r sponsibility of the ECF22 o ganizers.

2452-3216 © 2016 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of PCF 2016.

2452-3216  2018 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ECF22 organizers. 10.1016/j.prostr.2018.12.262