Minimum Weight Design of Plane Structures by SUMT

Abstract

In the previous paper, present authors investigated two techniques, which were named tentatively the linearization of constraint and the multi-step optimization, with the purpose of improving SUMT, and shown that those techniques had a good convergence property and a computational efficiency. In this paper the following technique is studied to make SUMT more efficient. The gradients of the constraint ∇g_j (x), which is necessary to make the constraint into the linear form, is derived by differentiating the stiffeness matrix of structure or the eigen value equation for buckling with respect to the design variables. Using this technique, the number of the structural analyses can be decreased. The extent to be applied the linearized constraint is reduced as the searching point approaches to the optimum. The computational efficiency can be improved in this way. The present technique combined with finite element method is applied to the minimum weight designs of the local structures of ship (transring strut and transring corner) with the constraints on allowable stresses and the perforated plates with buckling constraint.