Civil Engineering Reference
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clamp
inductive elongation meter
wire rope
clamp
measuring length L = 2000 mm
Fig. 2.11
Arrangement for measuring the wire rope elongation, Feyrer and Jahne (
1990
)
80
Warrington 8 19-NFC-sZ
rope diameter d = 16.7 mm
met. cross-section A = 91.2 mm
2
nominal strength R
o
= 1570 N/mm
2
measuring length L = 2000 mm
800
kN
N
mm
2
60
600
1. loading
40
400
residual
extension
ʵ
b10
10. loading
10. unloading
20
200
0
0
0
2
4
6
8
10
‰12
rope extension
ʵ
Fig. 2.12
Stress-extension curves for a stranded wire rope with fibre core, Feyrer and Jahne
(
1990
)
rope tensile stress r
z
= 800 N/mm
2
and after nine loadings between r
z
= 0 and
r
z
= 800 N/mm
2
for the tenth loading and unloading.
The nine loading cycles should give nearly the same compression of the rope
structure as is found in practice after some time under working conditions (of
course with smaller tensile stresses and a greater number of loading cycles). It will
be anticipated here that after ten loading cycles the mean residual extension is 4 %
with a large deviation. A residual extension of approximately the same size was
found for wire ropes running over sheaves after 2 % of their life time as Woernle
(
1929
) already noticed. However a residual extension of 3 % was measured again
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