Influence of the Gyroscopic Effects on Friction Induced Vibration in Aircraft Braking in System 2012-01-1804
Aeronautical brakes are subject to non-linear unstable
vibrations. In particular, two modes appear and present a risk for
the structure. Firstly, the whirl modes consist of a rotating
bending motion of the axle out-of-phase with the brake torque tube.
It is due to a coupling of two bending modes of the axle in
orthogonal directions. Secondly, the brake squeal mode resulting
from stick-slip or sprag-slip phenomena consists of a rotational
motion of the brake around the axle. Those vibrations are not
resulting from an external excitation but are friction-induced
self-excited. Hence, they are dependent on tribological phenomena
specific to carbon disks and are in particular controlled by the
friction coefficient μ.
In order to take into account the dynamical aspect in brake
design, Messier-Bugatti-Dowty wants to simulate modes and
acceleration g's levels. This article deals with the
improvement of such a model.
A finite element of the brake exists. It is able to reproduce
whirl modes and squeal mode. In order to improve it, physical
phenomena must be introduced. Here, the impact of gyroscopic
effects is evaluated. For this, an analytical model is built to
determine the consequences on frequencies and stability.