Buckling of simply-supported rectangular Double–Double laminates
Erik Kappel
Abstract
The family of Double–Double (DD) laminates is in focus of the present study. Well established buckling-cases for rectangular plates are examined in this article from a DD perspective. It is shown that the DD conventions allow for beneficial reformulation of the available equations, which leads to drastic simplification. It is demonstrated that the lightest DD laminate can directly be determined for a specified buckling load. Permutation discussions and the corresponding evaluation of thousands of discrete solutions, known for conventional laminates, become obsolete. The developed DD-buckling equations are further examined from an invariant-based perspective using IQ=Q11+Q22+Q66+Q12 which reveals the important role of the 1/IQ3 term for minimum-laminate-thickness calculations.