File:Strength and other properties of wire rope. (1919) (14774141895).jpg

Identifier: strengthotherp1919121grif (find matches)
Title: Strength and other properties of wire rope.
Year: 1919 (1910s)
Authors: Griffith, J.H. Bragg, J.G.
Subjects:
Publisher: National Bureau of Standards
Contributing Library: NIST Research Library
Digitizing Sponsor: NIST Research Library

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tial that the specimen shallbe free from bends. A flat curvature to the specimen, while in-significant as regards the tensile strength, will effect elongationdeterminations during the earlier loads appreciably. Such imper-fect cables have been discarded in elongation tests. Another im-portant point in preparation of the specimen is that the force shallbe applied axially and that there shall be no lost motion due torelative slipping of wires or strands in the sockets. Indeed, ifsuch were the case, there would not be a uniform distribution ofthe load among the different strands. Zinc sockets were used in making the tests. The wires slip whenbabbitted sockets are used at loads as low as 25 per cent of themaximum strength. In preparing the cable for socketing, theends are first served or wound for about 1% inches with softwire (one-eighth inch clothesline rope was used) at the endsand at a distance from the ends equal to the length of the zinc Bureau of Standards Technologic Paper No. 121
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Fig. 3.—Typical fractures of wire ropes of 1% and 1% inches diametersThe zinc has been melted from the end sockets to show brooming of wires in preparing a test specimen Tests of Wire Rope 19 socket. In the present tests the length varied from 5 to 9 inchesa range of diameters of one-fourth to 1^ inches. Special m a range 01 diameters 01 one-iourtn to 1X2attachments were used on the few cables over 1 y2 inches in diame-ter tested in the Emery machine. (See note 5, p. 20.) After the cables were served as described, they were slippedthrough wedge-shaped cast-steel blocks, which acted later notonly as molds for the zinc surrounding the unraveled wires andforming the sockets but also as pulling blocks when these wereinserted in the wedge-shaped opening in the heads of the testingmachine. (See Fig. 6.) Solid blocks were used on the cablesabove seven-eighths inch in diameter. Split blocks were used forconvenience on the smaller cables. After the blocks were placed on a cable, the specimen

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