File:Papers - literary, sicentific, &c. (1887) (14786271453).jpg

Identifier: papersliterarysi02jenk (find matches)
Title: Papers : literary, sicentific, &c.
Year: 1887 (1880s)
Authors: Jenkin, Fleeming, 1833-1885 Colvin, Sidney, Sir, 1845-1927 Ewing, J. A. (James Alfred), Sir, 1855-1935
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Publisher: London : Longmans, Green, and co.
Contributing Library: University of California Libraries
Digitizing Sponsor: MSN

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f links, one for each joint, correspond-ing with each line of bearing pressure, and themselves joinedby other links, so as to form a frame which would be in equili-brium under the action of external forces equal to those in thehalf links. Thus any one of these forces may be looked uponas the equilibrant of the others, and as acting upon themthrough a series of links which are subject only to compressionor tension. In Fig. 4, p. 281, if the member h is jointed withmembers a, c, d, and e by four parallel pins, we might replace hin any machine by the four half links, in Fig. 4a, 1, 3, 4, and6 and a complete link 2, joining the intersection of 1 and 5 with In this frame it might be necessary to include at least one stiff bar orframe to meet opposite and equal couples. APPLICATION OF GRAPHIC METHODS 281 that of 3 and 4 ; this last link will be in equilibrium under theaction of the forces acting on t, as shown in the half links. Ina more complicated example the link 2 might be replaced by a
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complete frame, or by a rigid plate. Since the forces acting onone element either intersect at one point or in a series of pointswhich may be joined by other links, we may always designatethe point or points in question by the same letter of the 282 APPLIED SCIENCE alphabet as is used to denote the element. The geometricalintersections will be marked by capital letters, whereas the ele-ments are marked by italics. When there are several geome-trical joints for one element, these joints will be denoted by thesame letter, but distinguished from each other by suffixes. Thesubstitution of links or half links for an actual element maybe effected even when forces are 23arallel, if we admit joints at aninfinite distance. If, now, all the elements of a machine, in theirrelative positions at any one instant, be removed in succession,and replaced by their equivalent links or half links, we shallsubstitute for the original machine a self-strained frame of linkssuch that the stress in each link p

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