The research originated in an attempt to
re- establish the apparently critical ratio of width
to thickness which Barba found to give, in the case
of flat test -bars of mild steel, a maximum of extension on fixed or constant gauge -lengths, but the scope
of the investigation ultimately became much wider.
The main object of the experiments discussed
in this Thesis was to determine the nature of the influence of width of specimen upon the results of tensile tests of mild steel and rolled copper. The
test -bars were cut from 1/4-inch and 1/8-inch steel
boiler plates and from 1/8-inch copper plate, and were
machined to give widths varying from 1/4 inch to 4
inches, the range of the ratio width/thickness in the thinner specimens being approximately from 2:1 to 30 :1.
The results indicate the influence of width
of specimen on the strength, on the extension of
fixed lengths, on the extension of three types of
variable gauge-length, and on the reduction of area
and certain other quantities involving the final
transverse dimensions. For the most part, the
equations were derived from the results obtained from
the specimens of the high-grade 1/8-inch steel plate.
Further research on similar lines carried
out on 1/4-inch, 3/8-inch, and 1/2-inch mild steel plates,
all of which were rolled from slabs cut from the same
ingot, gave evidence definitely corroborative of the
views latterly expressed by the writer; but to
avoid unnecessary repetition no record of that investigation has been included in the present exercise.