Scientific American Supplement, No. 648, June 2, 1888.Various
Science
Scientific American Supplement, No. 648, June 2, 1888.
Various
Science -- Periodicals
When failure in angles was first noted, the recorded load was 653,500 lb.,
or slightly more than four times the computed basis of load, which would
increase the above strains about one-fifth, giving a calculated flange
strain when angle failed of some 15,000 lb. per square inch, and bearing
area strain on end flange and web rivets about 80,000 lb. per square inch,
neither of which could possibly be true, or the web would have torn out
from the rivets, and the flanges be perfectly sound, well within elastic
limits, although in the last case it is to be noted that the horizontal
table of the flange was perfectly sound, the flange failure commencing
primarily with a long split along the weld of the angle iron root,
throwing the whole flange duty upon the vertical legs of the angle iron,
when a rupture strain was quickly reached. Had the angles been rolled from
a solid ingot, or on the German method of developing from a flat instead
of from the ordinary welded pile, the strength of this beam would have
been largely increased. The prime weakness in this beam was due,
therefore, to the mode of manufacturing the angle irons, which were weak
along the weld at the root. This was also shown in the end bracket angles
uniting the beam to the posts. The writer deduces from this experiment
that a plate web is an exceedingly stiff member, much stiffer than is
commonly supposed; that the customary method of proportioning
rivets--viz., the horizontal component between any two given points
divided by allowable bearing pressure per square inch equals number of
rivets required--is not true, and that the friction due to power riveting
has enormous value. This beam was reported to the company interested as
practically safe by the writer, on general considerations, before the
experiment was made, and the opinion reaffirmed after the experiment.
* * * * *
London Bridge cost $10,000,000. It is 900 feet long and 54 feet wide.
100,000 persons pass over it every twenty-four hours. The lamp posts are
made from cannon taken during the Peninsular War.
HYDRAULIC TUBE PRESS.
Forming metal tubes from circular plates by pressing or forcing them, by
the aid of mandrels, through dies or annular rings, though comparatively a
modern manufacture, is carried on to a considerable extent, and with the
improvements that are almost daily being made in it, and the rapidly
extending use of such tubes, this extraordinary process bids fair to
become a most important manufacture.
[Illustration]
The press illustrated here was designed and made by Messrs. Henry Bessemer
& Co., of Sheffield, for Mr. Samuel Walker, of Birmingham, for the
manufacture of tubes of large size, and also for making hollow steel
projectiles.
Public-domain text, read in full here on John Shaqi.
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