Cocomat Design and Analysis Guidelines for Cfrp-stiffened Panels in Buckling and Postbuckling

One of the most important goals of the COCOMAT EU R&D project was the generation of a formulated set of guidelines which could be applied when buckling or postbuckling of CFRP-stiffened panels was considered. In this paper, issues of concern for composite materials are addressed, such as prediction of damage onset and propagation of defects during buckling and postbuckling, under static and cyclic loading. The design and analysis guidelines are the result of good cooperation between partners from the industry, universities and research centers, and are based on extensive theoretical and experimental research performed within the COCOMAT project. The analysis guidelines cover FE types and meshing, damage mechanisms, degradation models, recommendations regarding interface elements in the damage zone and ply failure models. Comparison between various analysis codes is also provided. Lessons learned concerning testing of structures in the buckling regime are presented. The sensitivity of conventional design to damage of various sizes has been investigated, and conclusions are drawn regarding design criteria. Two structural applications are also presented, where some of the above-mentioned guidelines were implemented at Israel Aerospace Industries (IAI).