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National Advisory Committee for Aeronautics, Wartime Report - The Strength and Stiffness of Shear Webs with Round Lightening Holes Having 45° Flanges

Tests were made of 18 shear webs with round lighten—
ing holes having 450 flanges. The purpose of the tests was
to extend the range of a previous investigation to larger
ratios of hole diameter to web depth and of web depth to
web thickness. Simple empirical formulas are given for the
streng-th and the stiffness of shear webs: these formulas
incorporate the results of the previous investigation.
Design charts are also giv;n to facilitate the application
of the results.

As part of a general investigation on shear webs, a
number of wet‘s with flanged, round lightening holes had been
tested and an empirical formula 1for the strength of the webs
had been obtained (refer rcnce l).1Although the number of spec-
imens =as fairly large, the range of some of the variables
quite limited in cor peris on with the range that might be
possible in actual construction. In the development of the
strength formula, an attempt was made to compensate for this
inadequacy of the test data by considering limiting cases in
order to find a ferrule that might give reasons ble accuracy
when extrapolated beyond the test_1ang e. In «iew of the
narrow range over vhich the formula was actually verified,
however, it was considered desirable to make at least a small
number of tests of webs having larger ratios of hole diameter
to web depth and of web deo h to web thickness