Wire Ropes Under Bending and Tensile Stresses - Wire Ropes: Tension, Endurance, Reliability - page 209

4

3

2

90%

1

10%

0

0 1 2 3 4 5 6

N/mm 2

global rope pressure p 0

Fig. 3.26 Ratio wire arc forces (F W1 + F W2 )/2F Wcal of Warrington-Seale ropes 6 9 36 sZ with
fibre or steel core, Häberle ( 1995 )

wires. Due to the dimensions of the force measuring elements, they normally
measure the force of two wire arcs at a time. Based on his measurements, Häberle
presented the ratio (F W1 + F W2 )/2F Wcal as the ratio between the measured and the
calculated forces for the wire arcs as shown in Fig. 3.26 and these results show a
wide deviation that decreases with the specific tensile rope force S/d 2 , respectively,
with the global rope pressurep 0 . Häberle considered the results as a normal dis-
tribution with the mean force ratio (F W1 + F W2 )/2F Wcal = 1 and with the standard
deviation

2

p

0 : 614
p 0

s 2 ¼ þ 0 : 146

and according to the addition theorem of normal distribution for the arc force of a
single wire F W /F Wcal , the standard deviation is

s ¼ 0 : 614
p 0

þ 0 : 146 :

Then for Warrington-Seale ropes 6 9 36 sZ running on the sheave, 10 % of the
wire arc forces on the bottom of the groove is higher than

F Wcal

0 : 614
p 0

F W10 ¼ 1 þ u 10

þ 0 : 146 ð 3 : 37a Þ