Optimized Stiffened Composite Panels of Variable Fibre Tows

摘要

Variable Fibre Tows (VFT) are used to improve conventional Unidirectional Fibre Tow (UFT) designs for composite stiffened panels subject to buckling and strength constraints, and improvements in minimum weight and buckling capacity are calculated using a proposed two-stage optimisation strategy: first, a method to simplify laminates is formulated for panel level optimisation to establish dimensions for each structure, and second, each laminate level stacking sequence is optimised to satisfy manufacturing constraints and achieve higher critical buckling loads. Genetic algorithms are specifically coded to suit this two-level optimisation. To assess benefits of VFT, a range of UFT panels are optimised, and a typical panel is re-designed with VFT. Buckling and post-buckling of the VFT panel are analysed using non-linear finite element methods and compared with the UFT panel. The effect of stiffener support on the fibre path of the variable fibre tows is discussed in terms of design guidance, and the results show buckling loads are significantly increased by at least 50% and post-bucking capacity is improved by 11%.