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Theses

Analyse du processus d’usure abrasive et optimisation d’engrenage aéronautique

Charly Lagresle 1, 2
2 SMC - Systèmes Mécaniques et Contacts
LaMCoS - Laboratoire de Mécanique des Contacts et des Structures [Villeurbanne]
Abstract : Powers transmissions are commonly used in many areas, including aeronautics. The studied system in this thesis is a helicopter gearbox. Its purpose is to transmit the power generated by the turbine engine to the main gearbox and to adapt the rotational speed of the input shaft. Aeronautical gears are light weight in order to maximize the power to weight ratio of the system. With thin rims, the mass of the system is reduced but its flexibility is increased. These types of gears, subjected to large number of revolutions and severe operating conditions, are more likely to be exposed to failures such as abrasive wear, scoring or micro-pitting. The first objective of this PhD thesis is the understanding and the simulation of the abrasive wear process for spur and helical gears. The material removal calculation is based on the well-known Archard equation, adapted to lubricated contacts. During the different phases of flight (take-off, landing, hover flight), the specific working conditions change. Consequently, the quasi-static gearing behaviour, the lubrication and therefore the quantity of wear need to be adapted. To this end, a new methodology is proposed to accumulate wear depths over several and different working conditions. This methodology makes it possible to analyze the kinetics and the intensity of the abrasive wear process and deduce the most severe phases of flight. The second goal echoes the first one. Following the identification of the problem of abrasive wear, a multi-objective optimization of the quasi-static behaviour of the thin rimmed gear is proposed. The goal of this optimization, based on the search of optimal tooth modifications, is to reduce potential sources of gear failures, in particular localized overpressures on tooth flanks or the Almen factor governing scuffing. Due to the complexity of the problem, a meta-heuristic multi-variable optimization algorithm (MO-TRIBES) is introduced. Multiple mono- and multi-objective gear optimization examples are provided in order to improve the quasi-static behaviour of the aeronautical gear : minimization of fluctuations of the transmission error under load, reduction of the maximal contact pressures, decrease of the scuffing risk factors. The ideal type of tooth modifications is discussed. Finally, by using the optimization module, the amount of wear is significantly reduced and a comfortable lifetime extension for the studied gear is provided.
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https://tel.archives-ouvertes.fr/tel-02902134
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Submitted on : Friday, July 17, 2020 - 6:48:34 PM
Last modification on : Saturday, July 18, 2020 - 3:37:59 AM

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  • HAL Id : tel-02902134, version 1

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Charly Lagresle. Analyse du processus d’usure abrasive et optimisation d’engrenage aéronautique. Mécanique [physics.med-ph]. Université de Lyon, 2019. Français. ⟨NNT : 2019LYSEI113⟩. ⟨tel-02902134⟩

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