Iterative univariate optimization of nonlinear trusses with fuzzy strain constraints

A univariate iterative method for the optimization of nonlinear trusses with fuzzy constraints is proposed. The method is based on the control of elemental strains rather than stresses and hence it is called the desirable strain design criteria method. The objective of the fuzzy optimization is to find a design so that the weight or volume of the truss as well as all of the constraints on the elemental strains and joint deflections are desirable and satisfactory according to the fuzzy designer expressions. Such expressions are mde in the form of fuzzy membership functions. Two illustrative examples, a 3- and a 10-bar truss, are optimized by the proposed method, where it is shown that in both cases the method monotonically converges to the highest desirability.