Note: Descriptions are shown in the official language in which they were submitted.
2152404
1 Rail~ay Rails
Inventor: Stefan Radulescu
BACKGROUND OF THE 1NV~W11ON
1. FIELD OF THE lNv~NllON
This invention relates to heavy-type railuay rails for
rolling stock capable of supporting an increased traffic on
the track.
2. PRIOR ART
In the domain of high-speed and heavy-traffic railuay rails,
several types of heavy-masse railway rails are kno~n in ~hich
such rails sustain increased loads as the area of cross-section
of rail and the moment of inertia of cross-section of rail are
increased as ~ell. Among the ~idely used rail types are type
UIC60, types 54E STAS 9592-74 and R65 STAS 11201-79 of
- 2152404
1 Roumania, types S60 and S64 of Germany, types 112 lbs and
155 lbs of United States. These types can be found in an
extented list of rail types given in ''Schueisstechnisches
Taschenbuch'', Edition 1968, Elektro-Thermit Corp., Germany.
Such rail types achieve increased loads solely by increasing
the moment of inertia of cross-section of rail, with the result
that the load of fatigue of rail increases at a lower rate
compared to the moment of inertia of cross-section of rail,
thus increasing the cost of rail~ay. This result is more
visible in case of heavier heavy-type rails.
Ho~ever, ~o rail type uith a masse greater than 51 Kg/l.m.
is kno~n in uhich the stress applied to the rail head is
decreased by increasing the moment of inertia of cross-section
of rail and by increasing a height bet~een the rail base and
the neutral axis of rail uhile the moment of fatigue of rail
base and the moment of fatigue of rail head are so balanced as
to obtain an increase of the endurance of the rail.
SUMMARY OF THE lNv~:NlloN
These disadvantages are overcome by the present invention
by creating a novel heavy-masse rail type. The present
21S2404
1 invention comprises a rail composed of a rail base, a rail
~eb and a rail head. It is an objective of the present
invention to provide a rail having an increased moment of
inertia of cross-section and an increased height from the
lo~er side of rail base to the neutral axis of the rail.
It is another objective of the present invention to obtain
a balanced stress in the rail base and in the rail head by
providing a rail in which the ratio of the moment of fatigue
of rail base divided by the moment of fatigue of rail head
i~ between 0.9 and 1.
It is further an objective of the present invention to
provide a heavy-type rail ~ith increased load of fatigue.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention ~ill be further illustrated by reference
to the accompanying drawing, in ~hich:
FIG. 1 is the schematic representation of a method of
implementation of rail~ay rails of heavy type ~ith
increased fatigue resistance, according to the present
invention.
21~2~04
DETAILED DESCRIPTION OF THE lNV NllON
The description is made uith reference to heavy-type
rail~ay rail, but this should not limit the scope or domain
of application of the present invention.
The present invention introduces new relations related
to endurance of materials, and of bars subjected to b~nd;n~
test, respectively. The general equation of b~nd;ng momentum
for a bar simple-st~nd;ng loaded ~ith a load of fatigue PO~
is given by the relation:
Mi = JJadydQ
The bPn~;n~ momentum is balanced by the sum of moments
given by unitary normal stresses ~ithin the bar. It is kno~n
that such stresses are null upon the horizontal neutral axis
and maximum at vertical extremities of the bar. It is derived
that:
MobSp = ~obc X Hc x w [Kg x mm] ( 1 )
Mobspt = aObt x nt x ~ [Kg x mm]
where: Mobsp is the specific moment of fatigue of the upper
side of rail head,
Mobspt is the specific moment of fatigue of the lo~er
side of rail base,
- 2152404
1 a0bc and aObt are the unity normal stresses of fatigue of
upper side of rail head and lo~er side of rail base, respectively,
HC is the height of rail head with respect to the horizontal
neutral axis of rail,
Ht is the height from the loYer side of rail base to the
horizontal neutral axis of rail,
~ )lm m2 is the minimum area element.
The present invention introduces the loading factor of fatigue
of cross-section of rail, defined as:
Riob=~ ( 2 )
Ri~6has a sub-unity value given by the ratio of the t~o
specific moments of fatigue. Developing the ratio in relation (2), it is
obtained:
obt = Ht ( 3 )
It is derived that Riob is alternatively given
by the ratio of squares of the heights of rail base and rail head,
respectively, with respect to the horizontal neutral axis of cross-
section:
Rio~ = ~ ( 4 )
With these relations it is derived:
Riob= ~
where: W~c is the modulus of toughness of rail head,
W~t is the modulus of toughness of rail base.
- 2152404
1 With the characteristics of laminated material for rail, uhich
generally is ~r = 90 Kg/m m2,it i8 obtained a maximum unity stress
of fatigue equal to aob = 3 ~r = 30 Kg/m m2, for a number of fatigue
cycles N ~- 107 , for rails ~hich do not exceed a certain average
height.
Considering ~obc = ~obad~ in relation (1), it is knoun from
the curves of Woehler that as the area of cross-section of rail
increases, ~ObaJ~ decreases, and this is the case of heavy-type
railuay rails. From relation (1) it is derived that
Mobadm = 2280 Kg x m m,~hich is used for dimensional
des; ,E~n; ng .
If has been discovered that ~hen the loading factor of
fatigue of cross-section of a railuay rail of heavy type
~ ith a masse of at least 51 Kg/l.m. is betueen 0.9 to 1,
the unity normal fatigue stresses in the lower and upper
cross-section portions are ~ell balanced and the lifetime
of rail, or alternatively, the sustained traffic, is
significantly increased.
A rail according to the present invention is composed
of a lo~er and upper cross-section portions determined by
the horizontal neutral axis of cross-section. The loading
factor of fatigue is given by the specific moments of
fatigue of the cross-section portions or by the squares
21~2404
1 of heights of the cross-section portions.
Refering to the draRing, the rail according to the
preferred embodiment of the present invention for increasing
the lifetime of heavy-type rails, is shoYn in FIG. 1.
The left side Rith respect to vertical axis Y-Y represents
the ~ul~d~ standard rail, Yhile the right side represents
the rail of the present invention. Each of these rails
i8 composed of a rail head 1 at its upper side, a rail
Yeb 2 at its center side and a rail base 3 at its loYer
side. The difference betReen the tRo rails is given by the
height h, located at the upper side of rail head of
standard rail.
The standard rail has the moment of inertia Iro and the
height Hco > Hto , Rhere Hco and Hto represent the heights of
cross-section Rith respect to its horizontal neutral axis Xo-Xo.
The upper side of rail head is increased Rith a height h,
Yhich makes Hc to slightly increase with respect to Hco.
HoRever, Ht increases significantly Rith respect to Hto,
considering the rising of the center of Reight, and the new
axis X-X, respectively. The increase of the moment of inertia
Ix is significant by increasing the height of the entire cross-
section, ~hile the increase of the loading factor of fatigue:
- 215240~
Riob = ~
is augmented by the significant increase of llt with respect
.to l7c.
There are further given three examples of calculus and
;he advantages obtained following the co~clusions above.
A. Rail type UIC60
General characteristics:
M = 60.34 Kg/l.m.; S = 76.86cm2;I~ = 3055 cm4; W~c = 335.5 cm3;
L~ = 150 mm; H = 172 mm; lqc = 91 mm; l~t = 81 mm
MobaJ~ = 2280 Kg x mm for ~r = 90 Kg/m m2,
with ~ob = 3 ar and N - 107cycles for the same characteristics
of material. It is obtained:
aobc = ~ = 2280 = 25.05K9/mm2
aObt = aObC x Ht = 22.3 Kg/m m2
In the case of a rail simple-st~n~;ng on two supports with
an opening of 1 m, the moment of fatigue is:
Mob = ~obc X W~c = 2505 x 335.5 = 840000 Kg x cm
and the load of fatigue is:
Pob = IOO~ = 33.6t
with Riob = H2 = 0.792 and Ps~ = 437Kg/cm2
B. Rail type UIC60' (modified)
- 21S2~04
1 The geometry of rail is modified by increasing the height of
rail head at the upper side ~ith a height h = 6 m m,
such that:
17' = H + h = 178 m m
The width of rail base is increased to 76.2 mm to make possible
a comparisson uith similar rails.
General characteristics obtained:
M'= 64.7 Kg/l.m.; S'= 82.44cm2;I' = 3460cm4; W' = 381cm3;
Lt = 150 m m; H' = 178 m m; ~ = 90.8 m m; ~ = 87.2 m m;
The position of the ne~ center of ueight, or the height
- of the horizontal neutral axis, respectively, is computed
through the method of static moments uith respect to the
upper side of the neu rail head. The moment of inertia I'
5 i8 computed with respect to the ne~ neutral axis. It results:
c = ~ = 2280 = 25.1 Kg/m m2
obt aOb~ x h~ = 24.1 Kg/m m2
Mob = ~obc X W~c = 2510 x 381 = 956000 Kg x cm
Pob = 1~ - 38.24t
R'~ = ~ = 0.922
~ = 38322444 = 464.5 Kg/cm2
C. Rail type R65
General characteristics:
- 21~2~0~
1 M = 64.93 Kg/l.m.; S = 82.65cm2;I~ = 3540 cm4; W~c = 358 cm3;
Lt = 150 mm; H = 180 mm; Hc = 98.7 mm; Ht = 81.3 mm
It i8 obtained:
~obc --Y'------= 98.7Xl = 23.1 Kg/m m2
aob~ = aobc X ~t = 19.03 Kg/mm2
Mob = aobc X W* = 2310 x 358 = 827000 Kg x cm
Pob = ~~d = 33.1t
Ri~ = ~ = 0.678
po~ = 33100 = 400 Kg/cm2
It is observed that for the rail of type UIC60' (modified)
a significant increase of the moment of inertia of cross-
section of rail is surprisingly obtained at the same time
~ith balancing the unity stresses of fatigue in the t~o
cross-section portions of rail, reA~-h;ng a load of fatigue
greater uith 15.5X than in the case of rail R65, even for
a masse and height of rail smaller than in case of rail R65,
a~suming the same characteristics of material.
The data presented as general characteristics for examples
A, B, C is taken from official national standards and from
"Sch~eisstechnisches Taschenbuch'' of Elektro-Thermit Corp.
~ 215240~
1 Although one embodiment of the invention has been
illustrated in the accompanying drauing and desribed in the
foregoing Detailed Description, it ~ill be obvious to those
skilled in the art that the invention is not limited to the
embodiment disclosed, but is capable of many rearrangements,
modifications and substitutions of parts and elements ~ithout
departing from the scope and spirit of the invention, and the
invention includes all such rearrangements, modifications and
substitutions.
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