Buckling optimization of variable-angle-tow panels using the infinite-strip method

A minimum-mass optimization strategy for variable-angle-tow panels subject to buckling and manufacturing constraints is presented. The optimization is performed using a fast-running optimization package that employs infinite-strip analysis for buckling and a gradient-based optimization method. A new variable-angle-tow-panel manufacturing method, continuous tow shearing, providing good quality, is considered in the optimization strategy where variable thickness occurs due to the shear deformation of dry tows. Optimum designs of variable-angle-tow panels are obtained and compared with panels without thickness variation. Different panel boundary conditions are investigated and discussed. The results show that boundary conditions have dramatic effects on optimum fiber paths. Over 20% mass saving is obtained for the optimization strategy with thickness variation compared with the design without thickness variation. The buckling strains are reduced to a practical level when the thickness variation is considered in the optimization. The buckling loads and mode shapes obtained from the infinite-strip method are in a good agreement with finite-element results. The optimization strategy provides structurally efficient solutions with good precision and low computational cost.