Critical buckling of stiffened panels with discrete point connections

Abstract

Point connections representing spot welds, bolts, rivets, screws, pins, etc. have been included in the powerful panel analysis and design computer program VICONOPT. The exact stiffness matrices of component structures are coupled by using Lagrangian multipliers to represent these point connections between the structures. The new approach gives a very quick and accurate analysis when longitudinal lines of point connections are used in panels which are loaded only in compression. In this case only one point connection needs to be modelled and only certain response wavelengths contributing to the buckling mode are used. Accurate solutions are also obtained for shear loaded panels but at a much greater computational cost. Illustrative examples include comparisons between results for line and point connections, indicating to designers how many point connections are required to produce an effective line connection. These comparisons cover both pure axial compression and pure shear loading cases for both isotropic and anisotropic panels. They suggest that for many panels, manufacturing costs could be reduced by using fewer point connections, with minimal reduction in the stability of the panel. The work presented here is of particular importance to aircraft panels where point connections are extensively used to connect component structures together.