PSI - Issue 8

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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. Copyright © 2018 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of AIAS 2017 International Conference on Stress Analysis AIAS 2017 International Conference on Stress Analysis, AIAS 2017, 6-9 September 2017, Pisa, Italy Experimental analysis of tooth-root strains in a sun gear of the final drive for an off-highway axle A. Terrin a,b , M. Libardoni b , G. Meneghetti b, * a Carraro S.p.A., Via Olmo 37, 35010, Campodarsego, PD (Italy) b University of Padova, Department of Industrial Engineering, Via Venezia 1, 35121, Padova (Italy) Abstract The force acting on gear teeth can be influenced by several factors such as profile modifications, stiffness variations during meshing, inversion of the sliding direction at the pitch line, tip-to-root interferences, gears and shaft deflections and bearings clearan es. Moreover, in planetary gear sets the load can be shared unevenly among the planet gears due to manufacturing inaccuracies of the system. An accurate evaluation of the real load-time history experienced by the teeth is not straightforward and is affected by strong approximations even when advanced simulation software packages are used to create the theoretical model. Therefore, experimental analysis of the behavior of gears under in service load still constitutes a major step in the development of new transmission systems. In this work, three strain gauges were applied at different positions along the tooth root width of the sun gear mounted in the final drive of an off-highway axle. Strain measurements where then performed during a bench test of the complete axle and the signal was acquired by means of a telemetry system. Finally, the acquired data were used to assess the accuracy of software calculations and to identify the causes of overloads. © 2017 The Authors. Published by Elsevier B.V. Peer-revie under responsibility of the Scientific Com ittee of IAS 2017 In ernational Conference on Stress Analysis. Keywords: Strain gauges, Gear, Planetary gear set 1. Introd ction The actual pre sure distribution along the face of a tooth as well as among different teeth simultaneously in contact during normal operation of spur gears is strongly affected by the manufacturing and assembling accuracy of the shafts, the supports and the gear itself. Moreover, several aspects of the design as well as the operating condition of the system may influence the dynamic behavior of the gear pair. Among these, profile modifications, load, friction properties, speed, and inertia and stiffness of the rotating elements are the most important. Several numerical methods exist to calculate the compliances in gears and shafts and to estimate the amount of misalignment of mating teeth and the meshing stiffness during gears operation. Based on the results of such analysis, the designer may choose an appropriate set of geometry modifications to improve the pressure distribution for the design load and reduce the transmission error. For instance, crowning and helix modification are used to compensate for the effect of bearing clearances and shaft deformations, while tip and root relieves are useful to avoid interferences and abrupt variations of the load due to the passage from single to multiple tooth pair contact during the meshing period. Although calculation software packages are a very useful tool for the determination of an appropriate set of geometry AIAS 2017 International Conference on Stress Analysis, AIAS 2017, 6-9 September 2017, Pisa, Italy Experi ental analysis of tooth-root strains in a sun gear of the final drive for an off-high ay axle A. Terrin a,b , . Libardoni b , G. eneghetti b, * a Carraro S.p.A., Via Olmo 37, 35010, Campodarsego, PD (Italy) b University of Padov , Department of Industrial Engineering, Via Venezia 1, 35121, Padova (Italy) Abstract The force acting on gear teeth can be influenced by several factors such as profile modifications, stiffness variations during meshing, inversion of the sliding direction at the pitch line, tip-to-root interferences, gears and shaft deflections and bearings clearances. Moreover, in planetary gear sets the load can be shared unevenly among the planet gears due to manufacturing inaccuracies of the system. An accurate evaluation of the real load-time history experienced by the teeth is not straightforward and is affected by strong approximations even when advanced simulation software packages are used to create the theoretical model. Therefore, experimental analysis of the behavior of gears under in service load still constitutes a major step in the development of new transmission systems. In this work, three strain gauges were applied at different positions along the tooth root width of the sun gear mounted in the final drive of an off-highway axle. Strain measurements where then performed during a bench test of the complete axle and the signal was acquired by means of a telemetry system. Finally, the acquired data were used to assess the accuracy of software calculations and to identify the causes of overloads. © 2017 The Authors. Published by Elsevier B.V. eer-revie under responsibility of the Scientific Com ittee of IAS 2017 International Conference on Stress Analysis. Keywords: Strain gauges, Gear, Planetary gear set 1. Introduction The actual pressure distribution along the face of a tooth as well as among different teeth simultaneously in contact during normal operation of spur gears is strongly affected by the manufacturing and assembling accuracy of the shafts, the supports and the gear itself. Moreover, several aspects of the design as well as the operating condition of the system may influence the dynamic behavior of the gear pair. Among these, profile modifications, load, friction properties, speed, and inertia and stiffness of the rotating elements are the most important. Several numerical methods exist to calculate the compliances in gears and shafts and to estimate the amount of misalignment of mating teeth and the meshing stiffness during gears operation. Based on the results of such analysis, the designer may choose an appropriate set of geometry modifications to improve the pressure distribution for the design load and reduce the transmission error. For instance, crowning and helix modification are used to compensate for the effect of bearing clearances and shaft deformations, while tip and root relieves are useful to avoid interferences and abrupt variations of the load due to the passage from single to multiple tooth pair contact during the meshing period. Although calculation software packages are a very useful tool for the determination of an appropriate set of geometry © 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 * Corresponding author. Tel.: +39-049-8276751; Fax: +39-049-8276785. E-mail address: giovanni.meneghetti@unipd.it * Corresponding author. Tel.: +39-049-8276751; Fax: +39-049-8276785. E-mail address: giovanni.meneghetti@unipd.it

2452-3216 © 2016 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of PCF 2016. 2452-3216 © 2017 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of AIAS 2017 International Conference on Stress Analysis. 2452-3216 © 2017 The Authors. Published by Elsevier B.V. Peer-revi w under respon ibility of the Scientific Committee of AIAS 2017 International Conference on Stress Analysis. 2452-3216 Copyright  2018 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of AIAS 2017 International Conference on Stress Analysis 10.1016/j.prostr.2017.12.029