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A number of experimental results are given for unreinforced
circular; elliptical and square cut-outs with rounded corners, under
a variety of loading conditions. These results are then compared with
the infinite flat plate solution, using the complex stress function and
the method of conformal transformation.
It is generally considered sufficiently accurate for a plane stress
solution to be applied to problems of cut-outs in cylindrical shells,
provided that the cut-out dimensions are small compared with the
radius of curvature of the shell. In order to investigate this effect
of shell curvature, a number of experiments were carried out on cutouts
in two pressurised cylinders, and to obtain a wider range of loading
conditions, a further series of experiments was conducted using a plane
loading frame.
Two aluminium alloy cylinders, of 44 in. and 60 in. diameter,
were pressurised using air, and the stress conditions around the cutouts
examined using electrical resistance strain gauge techniques.
The plane loading frame enabled any combination of bi-axial tension
and shear to be applied to a plane sheet containing the cut-out under
examination. In this way the effects of body forces, which might arise in
such applications as aircraft and nuclear reactors, could be simulated.
The experimental results which are given generally show a close
agreement with the theoretical plane stress solution. |
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