No. 1, 1998 - Tribology in Industry

Fig. 1. The basic groups of sealirry joints of ntobile surfaccs
step is the selection of type of seals. The cornplete rnethod
is given in section 3. The parameters such as dimensions,
material, resistance, heat etc., are computed next,
for the selected type of seal.
This activity is based on the use of a catalogue of standard
parts, experimental results and analysis. If dimensions,
or resistance, heating, orwear are unacceptable, the type
of sealing connection should be changed. The structure
of construction elements, 3-D models of sealing parts
and their relationship are designed in the third phase. At
this level some changes of selected parameters are still
possible - even of the type of sealing as shorvn schematicallv
in Fic. 2.
neated; some types overlap in certairr ranges of use. This
fact clearly shows the uncertair.rties in selection process
due to poorly defined limits of application. The theory of
fuzzy reasoning can be used for solving problems of this
kind, This theory accepts poorly defined relationships
between elements and it approaches the process of human
reasoning. For any given case usually several seal
types could be used. but none is obligatory.
tsy the fuzzy reasoning theory an element,4 is the member
of the set X if the value of membership function
Itaft)= I , and is not the member of the set if pt.a@.) :0 .
The limits of any set are not flxed; cornmon regions may
exist. The range of membership function is from 0 to l.
of shape
of sealing
f ig. 2 Tlrc basic activ'ities of selectiott and nndellittg
o.[ sealittg joitrts
3. THE SELECTION OF Tl?E OF
DYNANIIC SEALING JOINTS
The decision which type should be selected depends on
fluid properties such as density, temperature, operating
pressure, chemical aggressiveness as well as operating
conditions like relative speed, friction losses, accuracy
and roughness of surfaces in contact. All these parameters
could be quantified by measurenents but the areas
of application for individual types elre not clearly deli-
/16(d)
Fig. 3 'l-ltc eratnplas of ntenbcnhip funcrion in tha fir:1,
set for contprcssion seals
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Tiibolop irt industty, V