POSTBUCKLING AND FAILURE OF STIFFENED COMPOSITE PANELS UNDER AXIAL-COMPRESSION

The postbuckling behavior of graphite-epoxy laminated stiffened panels has been studied analytically and experimentally herein. In this rese arch, the stiffened panels were analyzed using the nonlinear finite el ement method. The progressive failure analysis adopted the maximum str ess criterion and the complete unloading failure model. In the failure analysis, the considered failure modes were matrix failure, shear fai lure and fiber failure. The stiffeners were formed by the continuous l ay-up of the skin to improve the integrity of the stiffened composite panels. A shadow moire technique was used to monitor the out-of-plane deformation of the skin panel. Piezoelectric film sensors were used to detect the failure events during experiments. The analytical results on the buckling load, postbuckling behavior, and postbuckling compress ive strength showed good agreement with the experimental results. Para metric studies were conducted to show the effects of stacking sequence s and stiffener shapes on the buckling load and postbuckling compressi ve strength of stiffened composite panels, (C) 1998 Published by Elsev ier Science Ltd. All rights reserved.