CONSISTENT MIXED-MODEL FOR STABILITY OF STIFFENED PANELS WITH CUTOUTS

In contrast to the familiar Kirchoff approach, a simple, consistent, s hear flexible model for the stability analysis of stiffened panels has been developed in the context of hybrid mixed technique. This model i s composed of a quadrilateral plate element, as well as its complement ary skeletal grid element. The formulation is based on the Hellinger/R eissner mixed variational principle with independently assumed displac ement and strain fields. The proposed model has been utilized to devel op a general finite element code for determination of critical bucklin g stresses of stiffened panels for any case of in-plane loadings and b oundary conditions. The effectiveness and practical usefulness of this model have been demonstrated by a variety of numerical results for pr actical applications. In particular, design curves for buckling stress es of simply supported rectangular panels with central cut-outs and la teral stiffeners have been developed under in-plane load-type. These c urves provide a valuable insight into the behavior of stiffened panels and could be useful for design codes.