Delamination is a commonly observed damage mode in composite laminate among various kinds of damages occurred in manufacturing and as a result of impacts of foreign objects. The Delamination causes decrease in the strength and stiffness of the composite plate which leads to failure of the structures. The reinforcement by stiffeners is one of the most effective ways to improve the stability of the laminated composite plates. In this present study finite element analysis is performed on the stiffened composite laminates with embedded circular delamination for the determination of critical buckling load. The buckling behaviour of graphite-epoxy composite laminates is investigated for an embedded delamination. The buckling loads are calculated and compared for both rectangular and I-section stiffener plates with delamination. The influence of plate length, stiffener height and layup sequence on critical buckling load is studied for both types of stiffener.

Keywords: Composite plate, Stiffener, Buckling load, Delamination.