Civil Engineering Reference
In-Depth Information
Fig. 2.4 Cross-section of a
spiral rope 1 9 37, wire
diameters d
0
= 1.35 mm,
d
1
= d
2
= d
3
= 1.25 mm;
wire cross sections
A
0
= 1.431 mm
2
,
A
1
= A
2
=
A
3
= 1.227 mm
2
; lay
angles a
1
= 0, a
1
= 14,
a
2
= -14, a
3
= 14
0
:
9703
2
1
þ
0
:
3
0
:
2419
2
45
:
61
r
z
r
t
;
1
;
2
;
3
¼
41
:
09
r
t
;
1
;
2
;
3
¼ 1
:
027
r
z
¼ 308 N/mm
2
:
2.1.5 Additional Wire Stresses in the Straight Spiral Rope
A straight spiral rope respectively a straight strand becomes longer and thinner
under a tensile force. The wire helix will be deformed and—beside the tensile
stress—there exist bending stresses, torsion stresses and radial pressures from the
small length-related radial force of the wires. The bending and torsion stresses
have to be calculated from the alteration in the space curve of the wire.
The space curve of a wire in a straight strand is in parameter form
x ¼
r
sin u
y ¼ r
cos u
ð
2
:
32
Þ
r
tan a
u
:
z ¼
u is the angle of rotation (running angle), a the lay angle and r
W
= r the wire
winding radius, Fig.
2.5
. The lay length is
h
W
¼
2
p
r
tan a
:
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