Wire Ropes, Elements and Definitions - Wire Ropes: Tension, Endurance, Reliability - page 52

1.6.3 Fibre Core

Experience has shown that the fibre core should normally be dimensioned to allow
sufficient clearance between the strands so that they do not press on each other during
the normal life of the rope. A very high strand clearance is required according to rope
way rules and, in relation to the strand diameter, this is about s S /d S = 9 % for a Seale
rope 6 9 19-FNC and about s S /d S = 12 % for a Seale rope 8 9 19-FNC.
Jenner ( 1992 ) evaluated the required fibre core mass of stranded ropes in
relation to the clearance between the strands. For his investigations, he considered
the cross-section up to the smallest distance between the strands of the fibre core
cross-section available, as well as 80 % of the wire gussets area in the contact zone
to the core. With the same intention, Sivatz ( 1975 ) recommended that the number
of outer strand wires be taken into consideration.
The density q of fibre cores under the specific tensile forces S/d 2 = 0 and S/
d 2 = 117 N/mm 2 , evaluated by Jenner ( 1992 ), is listed in Table 1.12 . The length-
related mass of a fibre core is in g/m

m F ¼ q A F ; ð 1 : 13 Þ

with A F as the cross-section of the fibre core in mm 2 and q in g/cm 3 as the density
of the fibre core, Table 1.12 . The cross-section for the fibre core in the rope is thus
as in Fig. 1.41

A F ¼ A g þ DA :

ð 1 : 14 Þ

Table 1.12 Density of the fibre core, Jenner ( 1992 )

S/d 2 = 0 N/mm 2 S/d 2 = 117 N/mm 2

Core

Density Standard deviation Density Standard deviation

q (g/cm 3 ) s (g/cm 3 ) q (g/cm 3 ) s (g/cm 3 )

SFC (polyprop.) 0.749 0.045 0.874 0.044

NFC (sisal) 1.053 0.106 1.233 0.062

Fig. 1.41 Fibre core cross-
section, Jenner ( 1992 )

wire
gusset

basic
cross-
section
A g