Abstract
This paper deals with the study of squeal noise that can occur during the orientation phases of a windturbine. A study based both on experimental investigations and numerical simulations has been set up to have a better understanding of the phenomena involved in that squealing noise problematic and to analyze the influence of the friction material on squeal noise occurrence. This paper is focusing both on experimental and on numerical approach, more precisely on the development of a finite element model of the industrial test bench on which test campaigns have been carried out. The method used in that numerical approach is the complex eigenvalue analysis and the goal is to identify the contact instabilities that can occur and to follow their evolution regarding several parameters. It is important to precise that the bench to be simulated is an alternative translation test bench and so the classical disc in rotation is replaced by a flat beam in translation. The different parameters that are considered are the friction coefficient between the pads and the beam, the mechanical properties of the friction materials, the position on the beam and the beam profile. The friction coefficients have been measured during the test campaigns, some compressive tests have been performed to characterize the friction materials and the beam profile has also been measured, those characterizations are also described in this paper. Results of the simulation show the influence of the friction material regarding the pressure distributions at the interface of contact. Results also show the position on the beam and moreover its surface profile regarding the instabilities and the associated mode lock-in.
KEYWORDS - Squeal noise, friction, wind-turbine, friction material, surface profile.