Metamodels for Optimum Design of Composite Stiffened Structures Under Torsion Loading

A metamodeling procedure has been elaborated for the optimum design of composite stiffened structures under the torsion loading. The presented methodology is based on the building of metamodels employing experimental design and response surfaces. A closed composite stiffened box geometrical variables has been sampled and torque versus rotation reaction curves have been extracted by employing the finite element method. In order to simplify approximation procedure all torque versus rotation curves has been approximated by three piecewise linear sections representing the prebuckling, postbuckling, and collapse regions. It was shown that employing the metamodels satisfactory accuracy can be achieved to describe the post-buckling behavior of the stiffened structures under the torsion load and to use these models in optimum design procedure. Experimental results on the torsion behavior have been accompanied for stringer stiffened cylindrical graphite-epoxy composite closed box structures and has been used in validation procedure.