Space frame optimization subject to frequency constraints

An efficient structural optimization methodology is presented for the design of minimum weight space frames subject to multiple natural frequency constraints. A powerful class of generalized hybrid c onstraint approximations which require o nly the first order constraint function d erivatives have been developed to overcome inherent nonlinearity of the frequency constraint. The generalized hybrid constraint functions are shown to be relatively conservative, separable and convex in the region bounded by the move limits based on the formula described in this paper. The optimization methodology is implemented in an automated structural optimization system which has been applied to solve a variety of space frame optimization problems. N umerical results obtained for three example problems indicate that the o ptimization methodology requires fewer than 10 complete normal modes analyses to generate a near optimum solution.

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