This is a pre-publication version of our paper:
Hamzeh, O.N., Tworzydlo, W. W., Chang, H.J. and Fryska, S., "Analysis
of Friction-Induced Instabilities in a Simplified Aircraft Brake", submitted
for publication to SAE Brake Colloquium in 1999.
Analysis of Friction-Induced Instabilities in a Simplified
Aircraft Brake
Osama N. Hamzeh,
W. Woytek Tworzydlo, and Hsien J. Chang
Computational Mechanics
Company (COMCO),
7800 Shoal Creek Blvd.,
ste. 290E,
Austin, Texas 78757,
USA
Slawomir Fryska
AlliedSignal Inc.,
Aerospace Equipment Systems,
3520 Westmoor Street,
South Bend, IN 46628
Abstract
The stability and dynamic characteristics of friction-induced vibrations
in a simplified aircraft brake model are investigated. A finite element
model equipped with nonlinear frictional contact algorithm is used. The
constitutive model of the interface is based on an extended version of
the Oden-Martins law. The interface material constants are obtained via
asperity-based homogenization methodology from the profilometric information
on the surface. Initial uncoupled analyses are performed to identify
the basic dynamic modes of the model. Frequencies of normal vibrations
of the model are found to be dependent on the interface stiffness and the
piston pressure. To study the dynamic behavior of the system, its
transient response is computed after a perturbation of the steady-state
sliding position. It is found that while the vibrations are subdued
in some cases categorized as stable, they grow in other, unstable cases.
It is also shown that the triggering mechanism of instability can be either
the velocity-dependent coefficient of friction or the dynamic coupling
of certain vibration modes of the system (even without velocity-dependent
friction). These two unstable modes exhibit different dynamic characteristics.
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Copyright ©
1999, 2000 Altair Engineering, Inc.