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Buckling and Post Buckling Behaviour of Compression Loaded Isotropic Plates with Cutouts

An experimental study of the buckling and post-
buckling behavior of square and rectangular
compression—loaded aluminum plates with centrally
located circular, square, and elliptical cutouts is pre-
sented. Experimental results indicate that the plates
exhibit overall trends of increasing buckling strain
and decreasing initial postbuckling stiffness with iri—
creasing cutout width. Corresponding plates with
circular and square cutouts of the same width buckle
at approximately the same strain level and exhibit
approximately the same initial postbuckling stiffness.

Results show that the reduction in initial postbuck—
ling stiffness due to a cutout generally decreases as
the plate aspect ratio increases. Other results pre-
sented in this paper indicate that square plates with
elliptical cutouts and a large ratio of cutout width
to plate width generally lose prebuckling and initial
postbuckling stiffness as the cutout height increases.
However, the plates buckle at essentially the same
strain level. Results also indicate that postbuck—
ling stiffness is more sensitive to changes in ellipti—
cal cutout height than are prebuckling stiffness and
buckling strain.

An important structural component used in prac-
tically all aerospace vehicles is the rectangular plate
with a centrally located cutout. Cutouts commonly
appear in plates as access ports for mechanical and
electrical systems or are included to reduce the struc—
tural weight in components such as wing ribs and
spars. Often during vehicle operation, these members
experience compression loads. and thus their buck—
ling and postbuckling behavior are important factors
that must be considered in their design.

Investigations of the buckling behavior of plates
with cutouts have appeared in the technical litera—
ture since 1943. A summary of these investigations,
for both isotropic and laminated composite plates.
is given in reference 1. In-depth parametric studies
of the buckling behavior of square and rectangular
plates with central circular cutouts are presented in
references 1 through 3. Analytical and experimental
results are presented in these studies that indicate
buckling behavior trends for a wide range of plate pa-
rameters. The results and physical insight presented
in these references indicate that the buckling behav-
ior of compression—loaded isotropic and orthotropic
plates with cutouts is well understood.