Wire Ropes Under Bending and Tensile Stresses - Wire Ropes: Tension, Endurance, Reliability - page 193

Table 3.1 Stress range and middle stress in wires during rope running over a sheave, Schiffner

( 1986 )

Wire position Ordinary lay Lang lay

Tensile side Compressive side Tensile side Compressive side

r m 2 r a r m 2 r a r m 2 r a r m 2 r a

N/mm 2 N/mm 2 N/mm 2 N/mm 2

1 139 467 560 343 128 287 504 513

2, 4 7 452 648 352 137 416 541 572

3 164 316 528 237 101 475 574 540

5, 13 531 776 110 685 591 968 121 642

6, 16 563 812 30 797 599 810 22 781

7, 15 522 690 102 780 552 652 33 923

8, 14 604 857 2 797 590 804 21 926

9 719 524 -115 557 937 798 -262 708

10, 12 1025 726 -446 803 915 914 -327 761

11 864 644 -305 754 779 871 -135 561

lubricated, r Z = 300 N/mm 2 ;

Parallel lay rope, six strand with fibre core; D/d = 28.8;

r = 0.53d; d = 0.076d; d S = 0.311d; h S = 6.19d; h W = 2.63d

and the middle stress

r m ¼ r 1 þ r 2 þ r 3 þ r 4
2

: ð 3 : 13 Þ

Schiffner ( 1986 ) calculated the range stress and the middle stress on the tensile
and the compressive side for wires in different positions. These stresses are listed
in Table 3.1 for ordinary and lang lay ropes. The positions of the wires considered
here are shown in the sketch accompanying Table 3.1 . The calculation has been
made for a third of the expected endurance. Where it was supposed that the friction
coefficient has been increased up to l = 0.15.
Table 3.1 shows that the maximum stress range occurs in the strands on the side of
the rope. This is true especially for tensile stress. For an ordinary rope, this maximum
stress lies in positions 8 and 14 with contact to the core and for the lang lay rope in
positions 5 and 13 between the neighbouring strands. The maximum stress range is
greater for lang lay ropes than for ordinary ropes. Nevertheless lang lay ropes have