Wire Ropes, Elements and Definitions - Wire Ropes: Tension, Endurance, Reliability - page 50

Fig. 1.40 Contour of a round
lay wire in the section
perpendicular to the strand
axis

y

=1

ʴ

r w = 1

˕ c

r c

X

Clearance between the round lay wires. The most important aim of geometry
calculation is to determine the clearance between two neighbouring wires. An
accurate calculation of the clearance based on ( 1.8 ) is to be found in Jenner's paper
( 1992 ). Griffioen ( 1992 ) also accurately calculated the distance between two
neighbouring wires by using a clearance angle with the vector method. This
clearance angle is the angle between the two straight lines coming from the centre
of the strand and they only touch the cross-section contour of two neighbouring
wires at one point each. Griffioen introduced with this clearance angle a new point
of view.
The clearance angle for round wires can also be calculated accurately based on
the contact angle u c as the boundary angle of the wire contour. To do this, the
contact angle u c for a straight line from the strand centre has to be used as a
tangent on the contour of the wire cross-section. The contact angle u c will finally
be found by iteration of the angle w in ( 1.11a ) as the maximum angle u max

u c ¼ u max w ! w c ð Þ

with the angle w c . Then the contact radius r c up to the contact point can also be
derived from ( 1.11b ) with the angle w = w c .
Using the contact angle w c from ( 1.11a ) and the number z W of wires in the wire
layer being considered, the clearance angle between the two neighbouring wires in
the cross-section is

:

p
z W

Du ¼ 2 u c ð 1 : 11c Þ

The clearance between two neighbouring wires is then

cos a :

p
z W

s W ¼ 2 r c sin u c ð 1 : 11d Þ