BUCKLING ANALYSIS OF GEODESICALLY STIFFENED COMPOSITE PANELS WITH DISCRETE STIFFENERS

A computationally efficient analysis is developed to predict the buckl ing loads of geodesically stiffened composite panels with discrete pla te-like stiffeners under in-plane loads. The procedure accounts for th e contribution of the in-plane extensional and out-of-plane bending st iffnesses of the stiffeners through the use of a Lagrange multipliers technique in an energy method solution. The analysis is capable of pre dicting the buckling loads of grid-stiffened panels for a variety of s tiffener aspect ratios and stiffener laminate stacking sequences. It c an also be used to design panels with variable density grid stiffeners across the panel width. Results of the proposed analysis showed that the buckling loads of geodesically stiffened panels are predicted more accurately, especially in the case of panels with shallow stiffeners, compared to an earlier analysis that assumes the stiffeners to be bea m-like components. For plate-like stiffeners, laminate stacking sequen ce of the stiffeners is found to have a substantial effect on the crit ical load of a panel. It was demonstrated that the optimal stiffener i s not always unidirectional, and tailoring the stiffener ply sequence can lead to improvement in panel stability. It was also shown that pan els with a variable grid density can lead to designs with improved buc kling performance compared to uniform density panels.