TITLE:
Behavioural Modelling of Lips Seal Made with Polytetrafluoroethylene Enriched by Glass Fibers
AUTHORS:
Ali Djeffal, Seif Eddine Bendaoudi, Mokhtar Bounazef, El Abbas Adda Bedia
KEYWORDS:
Composite Material; Friction; Wear; Glass Fibers; Design of Experiments; Modelling
JOURNAL NAME:
Modeling and Numerical Simulation of Material Science,
Vol.3 No.4,
October
24,
2013
ABSTRACT: Polytetrafluoroethylene reinforced with glass fibers is a composite
material widely used in industry mainly for the manufacture of seals at the level
of the rotary shafts of vehicles and stationary floor machines such as turbines
and compressors. However, due to elastic and viscous-plastic properties of this
material, it wears quickly under the influence of some external parameters
during operation. There are therefore material loss, increased clearance and
loss of sealing. This work summarises a series
of tests carried out with this material in order to analyse the variation of
the friction coefficient due to the roughness of the work piece brought
into contact with the PTFE, the linear velocity of contact between them and
material yield strength. To do this analysis, we used the method of
unconventional design of experiments to model the behaviour of material and
consequently make decisions to reduce this wear. The results are shown and
deeply analysed in the following text as a polynomial mathematical model,
graphs, contours and response surfaces illustrating the holding of this
material under the effect of the three parameters mentioned above. The previous PTFE samples enriched
with chopped glass fibers are not subjected to axially force this time, contrary
to the force applied radially. The advantage of this method is the
relative linear velocity at the contact sample-disc and the applied pressure
remains constant. Under the action of the weight “P” applied on the sample, it
comes into friction with the rotating disc whose roughness changes from
experience to another; it is expressed by the values of Ra. Tangential
friction force appears at the point of contact and is equilibrated by measured
force Fm on the lever. The calculation of the moment relative bench
axis caused by 2 forces gives the coefficient of friction. Knowing the values
of frictional force Ft by calculation and the weight P, we determine
then the friction coefficient.