PSI - Issue 7

ScienceDirect Available online at www.sciencedirect.com Av ilable o line at ww.sciencedire t.com ienceDirect Structural Integrity Procedia 00 (2016) 000 – 000 Procedia Structu al Integrity 7 (2017) 391–398 Available onlin at www.sci n edirect.com ScienceDirect Structural Integrity Procedia 00 (2017) 000–000 ScienceDirect Structural Integrity Procedia 00 (2017) 000–000

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www.elsevier.com/locate/procedia 3rd International Symposium on Fatigue Design and Material Defects, FDMD 2017, 19-22 September 2017, Lecco, Italy Fatigue Crack Threshold of Bearing Steel at a Very Low Stress Ratio Kentaro Wada a *, Adeyinka Abass b , Saburo Okazaki c , Yoshihiro Fukushima d , Hisao Matsunaga c,d,e , Kaneaki Tsuzaki c,d a Graduate School of Engineering, Kyushu University, 744 Motooka Nishi-ku, Fukuoka-shi 819-0367, Japan b Konecranes Global Corporation, Koneenkatu 8, Hyvinkää FI-05801, Finland c Research Center for Hydrogen Industrial Use and Storage (HYDROGENIUS), Kyushu University, 744 Motooka Nishi-ku, Fukuoka-shi 819-0367, Japan d Department of Mechanical Engineering, Kyushu University, 744 Motooka Nishi-ku, Fukuoka-shi 819-0367, Japan e International Institute for Carbon-Neutral Energy Research (WPI-I2CNER), Kyushu University, 744 Motooka Nishi-ku, Fukuoka-shi 819-0367, Japan Abstract The aim of this study is to elucidate the effects of compressive mean stress on the fatigue crack threshold in SAE52100 bearing steel with Vickers hardness of 703. Tension-compression fatigue tests were carried out on specimens which have semi-circular notches, each measuring 2 a of 300 μ m in length. The threshold maximum stress, σ max, th , was seen to decrease at the corresponding reductions in stress ratio, R , of − 5, − 3 and − 1, at which points the fatigue limit was determined by the crack initiation limit. On the other hand, σ max, th at R = −10 was unexpectedly higher than that measured at R = − 5. The unbroken specimen at R = −10 possessed non- ropaga ing cracks, in which the maximum l ngth was 2 a of 535 μ m, a both ends f the notch. In order to clarify the reason for such peculiar phenomenon, the crack c osure behavior of th non-pr pagating cr ck was measured, using the unbrok n specimen at R = −10. The results indicated the existenc f crack closure which an arrest crack growth. 3rd International Symposium on Fatigue Design and Material Defects, FDMD 2017, 19-22 September 2017, Lecco, Italy Fatigue rack Threshold of Bearing Steel at a Very Low Stress Ratio Kentaro Wada a *, Adeyinka Abass b , Saburo Okazaki c , Yoshihiro Fukushima d , Hisao Matsunaga c,d,e , Kaneaki Tsuzaki c,d a G aduate School of Engineering, Kyush University, 744 Motooka Nishi-ku, F kuo a-shi 819-0367, Japan b Konecranes Global Corporation, Koneenkatu 8, Hyvinkää FI-05801, Finland c Research Center for Hydrogen Industrial Us a d Storage (HYDROGENIUS), Kyushu University, 744 M tooka Nishi-ku, Fukuoka-shi 819- 367, Jap n d Department of Mechanical Engineering, Kyushu University, 744 Motooka Nishi-ku, Fukuoka-shi 819-0367, Japan e International Institute for Carbon-Neutral Energy Research (WPI-I2CNER), Kyushu University, 744 Motooka Nishi-ku, Fukuoka-shi 819-0367, Japan Abstract The aim of this study is to elucidate the effects of com ressive mean stress on the fatigue crack t reshold i SAE52100 bearing steel with Vickers hardness of 703. Tension-compr ssion fatigue tests were carried out on specimens which have semi-circular tches, each measuring 2 a of 300 μ m in length. The threshold maximu stress, σ max, th , was seen to decrease at the corresponding reductions in stress ratio, R , of − 5, − 3 and − 1, at which points the fatigue limit was determined by th crack initiation limit. On the other ha d, σ max, th at R = −10 was unexp ctedly higher than that measured t R = − 5. The unbro en sp cimen t R = −10 possessed non-propagating cracks, in which ximum l ngth w s 2 of 535 μ m, at both ends of the notch. In order to cl rify the reas n for such a peculiar phenomenon, the crack closure beh vior of the non-propagating crack was me sured, us ng the unbroken specimen at R = −10. The results indicated th exis enc of crack closure which can arrest crack growth. 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. Copyright © 2017 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of the 3rd International Symposium on Fatigue Design and Material Defects. © 2017 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of the 3rd International Symposium on Fatigue Design and Material Defects. © 2017 The Authors. Published by Elsevier B.V. P er-review under resp nsibility f the Scientific Committee of the 3rd International Symposium on Fatigue Design and Material Defects. © 2016 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of PCF 2016. Keywords: Small crack growth threshold; Compressive mean stress; Crack closure Keywords: Small crack growth threshold; Compressive mean stress; Crack closure Keywords: High Pressure Turbine Blade; Creep; Finite Element Method; 3D Model; Simulation.

* Corresponding author. Tel.: +81928023902 E-mail address: ken@788.onmicrosoft.com

2452-3216 © 2017 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of the 3rd International Symposium on Fatigue Design and Material Defects. 2452-3216 © 2017 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of the 3rd International Symposium on Fatigue Design and Material Defects. * Corresponding author. Tel.: +81928023902 E-mail address: ken@788.onmicr soft.com

* 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 PCF 2016.

2452-3216 Copyright  2017 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of the 3rd International Symposium on Fatigue Design and Material Defects. 10.1016/j.prostr.2017.11.104