Formula (1) is proposed for quantitative evaluation of functional condition at the
time moment T, as below,
−
=
э
э
T
t
T
fs
fs
1
, (1)
Replaceable non-repairable elements are subject to replacement with identical
elements upon expiration of specified term of operation (Fig. 3).
Figure 3. Alteration of functional condition of replaceable non-repairable
element throughout operation period T
Such elements may be characterized by their relatively low value and simple
design. For instance, they may include various fixing elements (bolts, pins, nuts,
gaskets, filters, bushings, piston rings, etc.).
Functional condition of such elements decreases until it reaches a zero value. At
that moment the element is replaced and the process repeats. The numeric value of
replaceable non-repairable elements for the T time moment may be calculated in the
way, as follows,
−
−
=
op
op
op
T
t
t
n
T
fs
fs
1
,
(2)
with n – quantity of replaced elements by time moment T;
э
t
T
n=
, (3)
Note: only integer number is taken into account.
Irreplaceable repairable elements are of similar features and construction to
irreplaceable non-repairable elements with only one clause. As a rule the irreplaceable
Т
fs
0
fs
T
t
FS
t
s
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