OPTIMUM DESIGN OF STIFFENED CYLINDRICAL SHELLS WITH NATURAL FREQUENCY CONSTRAINTS.

The design optimization of axially loaded, simply supported stiffened cylindrical shells for minimum mass is considered. The design variables are thickness of shell wall, thicknesses and depths of rings and stringer, number/spacing of rings and stringers. Natural frequency, local and overall buckling strengths and direct stress constraints are considered in the design problems. Three different combinations of stiffeners are considered. In each case, the independent effects of behavior constraints are also studied. The optimum designs are achieved with one of the standard nonlinear constrained optimization techniques and few optimal solutions are checked for the satisfaction of Kuhn-Tucker.