Civil Engineering Reference
In-Depth Information
Table 3.13
Constants for calculating the force factor f
S5
(
3.69
)
Rope
d/d
a = 4/(p
f)
FC
IWRC
PWRC
EFWRC
ESWRC
Six strand
Filler
16
2.55
2.20
1.97
2.38
2.13
Seale
12.5
2.60
2.24
2.02
2.42
2.17
Warr.
14
2.60
2.24
2.02
2.42
2.17
W:-Seale
18
2.55
2.20
1.97
2.38
2.13
Eight strand
Filler
20
2.86
2.17
1.95
2.52
2.10
Seale
15
2.93
2.22
2.00
2.57
2.15
Warr.
17
2.93
2.22
2.00
2.57
2.15
W.-Seale
22
2.86
2.17
1.95
2.52
2.10
Spiral round 18 9 7 15 2.31
strand rope 34 9 7 21 2.33
FC fibre core, IWRC independent wire rope core, PWRC parallel-closed rope (parallel steel core
with strands), EFWRC wire rope core enveloped with fibres, ESWRC wire rope core enveloped
with solid polymer
3.4.3 Number of Bending Cycles
3.4.3.1 Simple Bending and Combined Fluctuating Tension
and Bending
With the constant tensile forces S and
the number of simple bending
cycles
and the number of combined fluctuating tension and simple bending
cycles
can be calculated with the Eq. (
3.55
) in Sect.
3.2
þ
b
2
lg
D
d
lg N
¼
b
0
þ
b
1
þ
b
3
lg
D
d
S
d
2
0
:
4
lg
R
0
1770
lg
þ
lg f
d
þ
lg f
L
þ
lg f
C
:
ð
3
:
55
Þ
With d is the nominal rope diameter in mm, D the sheave diameter in mm, S the
rope tensile force in N, R
0
the nominal tensile strength in N/mm
2
and l is the
bending length for l [ 10 d.
The constants b
i
are listed in Table
3.14
and the endurance factors f
d
,f
L
and f
C
in Table
3.14
a. In the Table
3.14
the constants b
i
for cross lay ropes has been
derived—Feyrer (
1981a
)—from the test results of Hugo Müller (
1966
). These
numbers of bending cycles Müller presented was the first for a far-reaching
complete field of tensile forces S and diameter ratios D/d. Because of their smaller
endurance the cross lay ropes will be seldom used for rope drives.
The numbers of bending cycles calculated with the Eq. (
3.55
), the constants of
Table
3.14
and the factors of Table
3.14a
are valid for up to a few million bending
cycles under the following conditions
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