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Étude d'amortisseurs non-linéaires appliqués aux roues aubagées et aux systèmes multi-étages

Abstract : This study deals with non-linear damping solutions for turbomachinery bladed disks. Structural dynamics is a major issue in the aircraft engine industry since vibratory phenomena are responsible for fatigue and failure risks. The use of damping technologies is quite common and among these, the friction devices are probably the most popular. Here, we are interested in circular friction dampers, called rings, for single piece structures.

Numerical methods have been developed in this view; these are mainly non-linear frequency domain methods adapted to cyclic structures such as the ones we are interested in. The modelling of contact interfaces and its influence on these methods are also addressed. Furthermore, a modal approach to deal with non-linear system is proposed. It makes it possible to calculate the modal parameters (eigenfrequency and modal damping ratio) of a non-linear system as a function of its energy (or vibratory amplitude). This method has several advantages among which the capabilities to evaluate directly the performances of a damping device and to address several types of dynamical responses (forced or free) in a unified manner.

These methods are then applied to study two types of damping devices. First, the damping of friction rings for single piece structures is investigated numerically on industrial case studies. The phenomenological aspects are described in details which allows the performances and limits of this technology to be estimated. Second, a study of energy pumping is proposed. Energy pumping consists in using a small, strongly non-linear, vibration absorber for the damping of a main (generally linear) structure. Here, the use of an absorber with hysteretic behaviour is investigated. Illustrated on a simple phenomenological system, the energy pumping phenomena - that is to say, an irreversible one-way energy transfer from the main system to the absorber - are studied by means of dedicated numerical methods.

Apart from the damping issues, we were also interested in the modelling and analysis of multi-stage bladed disks systems. This issue is quite new but tends to become a major one for the design of turbomachinery. In particular, existing methods to analyse the dynamics of such systems are currently of limited use. An original and efficient modelling approach of multi-stage cyclic symmetry is here proposed; a multi-stage assembly of cyclic structures can be modelled using one elementary sector of each stage and analysis can be performed on separated spatial harmonics. A non-linear application of this method is also proposed.

Finally, the first results of an experimental study of damping using friction rings are presented. The test rig, its design and associated technological features are presented in details. Following some experimental results obtained during the preliminary studies, a comparison with predictions from numerical simulations is proposed.
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https://tel.archives-ouvertes.fr/tel-00344168
Contributor : Denis Laxalde <>
Submitted on : Thursday, December 4, 2008 - 3:38:08 PM
Last modification on : Wednesday, November 20, 2019 - 2:27:22 AM
Long-term archiving on: : Monday, June 7, 2010 - 10:21:54 PM

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  • HAL Id : tel-00344168, version 1

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Denis Laxalde. Étude d'amortisseurs non-linéaires appliqués aux roues aubagées et aux systèmes multi-étages. Mécanique [physics.med-ph]. Ecole Centrale de Lyon, 2007. Français. ⟨tel-00344168⟩

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