Wire Ropes Under Bending and Tensile Stresses - Wire Ropes: Tension, Endurance, Reliability - page 277

Analysis of the rope drive

loading sequence
bending length l

loading elements
loading elements w
per loading sequence

w w w

Calculation of the number of bending cycles

tensile forces

S

equa.
(3.85)

S

equa.
(3.87)

number of
bending cycles

N

equa.
(3.55)

N

equa.
(3.55)

corrected
number of
bending cycles

equa.
(3.89)

equa.
(3.88)

equa.
(3.88)

N

N N

corr

corr

corr

number of
working cycles Z
(Palmgren-Miner)

1 1

w i

ʣ

equa.
(3.92)

=

Z f z N korr i

Fig. 3.79 Course of calculations for the number of working cycles

The number of working cycles up to the rope being discarded or breaking is
calculated in stages. First the loading sequence and the bending length are derived
by analysing the rope drive. Then the rope tensile force and the course of the force
as well as the load collective are evaluated. The numbers of bending cycles can be
calculated from this and combined with the Palmgren-Miner rule to find out the
number of working cycles. The sequence of calculations for the number of
working cycles is shown in Fig. 3.79 .
The calculation for the wire rope drives is completed by calculating the limiting
forces needed for safe and cost-effective operation. The five dimensioning limits of
a rope drive can be calculated using the Excel-program ''SEILLEB2.XLS''.