Wire Ropes Under Bending and Tensile Stresses - Wire Ropes: Tension, Endurance, Reliability - page 225

Fig. 3.39 Endurance factor f d for the influence of the rope diameter on the number of bending
cycles, Feyrer ( 2011 )

N i ð d; l ¼ 60d Þ
N Ei ð d E ¼ 16 mm; l E ¼ 60d E Þ :

f di ¼ ð 3 : 52 Þ

The endurance factor for the rope diameter of all those wire ropes with the
diameter d is the geometric mean of the endurance factors f di

n s

Y

n X

n n

lg f d ¼ 1 f d ¼ f di rsp lg f di ð 3 : 52a Þ

i¼1 i¼1

The advantage of this method is that the results of many different wire ropes
and test conditions can be merged and that a common endurance factor f d can be
found for the rope diameter d. As a result of the investigation the found endurance
factors for rope diameter is presented in Fig. 3.40 .
Figure 3.40 endurance factor f d for the influence of the rope diameter on the
number of bending cycles, Feyrer ( 2011 ).
The endurance factor f d is not a straight line in the double logarithmic chart.
Thus the relation cannot given exactly in the form with a constant exponent. A
simply form for the endurance factor f d is

b þ 1
b þð d = d E Þ a ¼

0 : 52
0 : 48 þð d = 16 Þ 0 : 3

f d ¼ ð 3 : 52b Þ