Test of integral composite panel in compression

The project POSCOS within the Swedish National Aeronautical Research program (NFFP) aims at methods development regarding strength prediction and sizing-methods for buckling-critical composite structures. The test results are reported for an integrally stiffened slightly curved composite panel loaded in compression (POSCOS-2). The panel was produced by SAAB AB, and the testing was performed at FOI. The test-results contain load-, strain- and full-field measurements using the optical system Aramis. The measurements show that the collapse load is approximately 2.5 times higher than the buckling load for the skin. It is also found that applying a limited number of load-cycles well above the buckling load do not cause any observable damage or measurable residual strain. The results presented can be compared with those for a similar test performed on a panel where aluminium-stringers were bolted to a flat composite skin (POSCOS-1).