Wire Ropes Under Bending and Tensile Stresses - Wire Ropes: Tension, Endurance, Reliability - page 206

5

d

4

r ʳ

W − S. + SE

3

d = 24.1 mm

r / d = 0.581

W S. + FE

−

2

d = 27.8 mm
S/d 2 = 91

r/d = 0.504 N/mm 2

1

0

− 80 − 60 − 40 − 20 0 20 40 80

Grad

groove angle ʳ

Fig. 3.23 Relative pressure k/p 0 for the line pressure q max , Häberle ( 1995 )

3.1.7.3 Rope Pressure from Measurements

As described before, Häberle ( 1995 ) measured the rope pressure in a test sheave with
a longer piece of round groove that only consisted of force measuring elements. In
addition to the line pressure, Häberle also measured the pressure over the groove
angle c for some wire ropes with these elements. In Fig. 3.23 , the pressure relative to
the global pressure k/p 0 over the groove angle c is given for two wire ropes as an
example. This figure shows the relative pressure k/p 0 in the peak of the line pressure
q max when the rope runs onto the sheave. The bottom of the groove is well-suited to
the rope (r/d = 0.504) with the relative pressure being k/p 0 = 2.3 and for the rope's
relatively small diameter (r/d = 0.581) the relative pressure is k/p 0 = 4.7. The
maximum pressure in the groove is always a little displaced in the same direction as
the lay direction of the rope, Fig. 3.23 .
By using regression calculation, Häberle ( 1995 ) evaluated the pressures mea-
sured on the bottom of the groove for the fibre or steel core Warrington-Seale ropes
6 9 36 sZ which were used in the tests

0
@

1
A :

k ¼ 2 S

17 : 4
S

d 2 0 : 229 ð 1 e 4 : 52 ð r = d 0 : 5 Þ Þ

D d

1 þ

ð 3 : 33 Þ

With the maximum line pressure q max /q 0 from ( 3.28 ) and the pressure k 0 from
( 3.33 ), the maximum pressure on the bottom of the groove (peak pressure when the
rope runs onto the sheave) is

k max ¼ k q max
q 0

: ð 3 : 33a Þ