Postbuckling analysis with progressive damage modeling in tailored laminated plates and shells with a cutout

An approach to modeling inplane damage progression in postbuckled laminated composite panels is shown to be accurate by comparison to experimental test data from other sources. A simple tailoring concept is shown to be very effective in increasing compressive buckling loads and ultimate loads for flat plates and curved panels with a central cutout. Effects of cutout size, the degree of tailoring, and inplane restraint on the unloaded edges are investigated. Optimal tailoring produces relative improvements in the flat plates ranging from 40% to 175% in buckling load and 190–240% in ultimate load capacity when compared to uniform plates with the same cutout sizes. In the curved panels, tailoring lowers the imperfection sensitivity and in some cases produces ultimate loads greater than the theoretical undamaged buckling loads. To the contrary, the ultimate load for the uniform curved panel is much lower than the undamaged buckling load. Relative improvements in ultimate loads range from a low of about 40% to a high of about 155% compared to uniform curved panels. Large differences in the damage initiation locations and damage progression patterns are shown between the flat and the curved panels. In summary, the tailoring concept investigated here can provide excellent improvements in ultimate load capacity in flat and curved panels with the largest benefits occurring in thin flat panels that are loaded far into the compressive postbuckling regime.