Numerical Determination of the Effects of Boundary Conditions on the Instability of Composite Panels with Cutouts.
AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING
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An analytical study using the STAGSC-1 computer code was conducted to determine the effects of notches and unsymmetric boundary conditions on the load bearing capability and radial displacements of axially loaded cylindrical panels. The graphite-epoxy panel consisted of an 8 ply laminate with symmetric ply orientations. A finite element mesh refinement in the vicinity of the cutout was conducted in order to study the non-linear collapse analysis. In addition, the effect of different size cutouts with aspect ratios axial dimension of cutout divided by circumferential dimension of 2.0 or 0.5 was studied. Finally, analytic results for a 2 in. x 2 in. cutout with a varying set of boundary conditions were compared to experimental findings. It was found that as the surface area of the cutout increased, the buckling load decreased. Cutouts with aspect ratios of 2.0 were found to be capable of carrying higher loads than notches with an aspect ratio of 0.5. By comparing analytic results with experimental data, it was found that unsymmetric boundary conditions for the 2 in. x 2 in. cutout better approximated experimental data than when symmetric boundary conditions were considered.