Efficient Approximation Method in Minimum Weight Design of Stiffened Plate and Sheel Structures. 1st Report, Problems under Displacement and Stress Constraints.

Abstract

Taylor series approximation (TSA) has been used to form an approximate subproblem to the actual design problem for the efficiency. A new intermediate variable approximation method for stiffened plate and shell structures is suggested and minimum weight design under displacement and stress constraints is discussed. The approximation method of intermediate variables is considered for the thickness and geometric dimensions of the plate or shell and the stiffeners to construct a wide-range approximation model. For the displacement and stress constraints, it is found that the Taylor series approximation using reciprocal variables of thickness and geometric dimensions (RTSA) gives good approximations for the typical stiffened plate structures. The approximation method is also applied to solve the minimum weight design problems of stiffened plate and shell structures, and the results are compared with those of direct variable Taylor series approximation (DTSA) to illustrate the efficiency of optimization.