APPROXIMATE DISCRETE VARIABLE OPTIMIZATION OF PLATE STRUCTURES USING DUAL METHODS

This study presents an efficient method for optimum design of plate an d shell structures, when the design variables are continuous or discre te. Both sizing and shape design variables are considered. First the s tructural responses such as element forces are approximated in terms o f some intermediate variables. By substituting these approximate relat ions into the original design problem, an explicit nonlinear approxima te design task with high quality approximation is achieved. This probl em with continuous variables, can be solved by means of numerical opti mization techniques very efficiently, the results of which are then us ed for discrete variable optimization. Now, the approximate problem is converted into a sequence of second level approximation problems of s eparable form and each of which is solved by a dual strategy with disc rete design variables. The approach is efficient in terms of the numbe r of required structural analyses, as well as the overall computationa l cost of optimization. Examples are offered and compared with other m ethods to demonstrate the features of the proposed method.