Adaptive Approximation-based Optimization of Composite Advanced Grid-stiffened Cylinder

An adaptive approximation-based optimization (AABO) procedure is developed for the optimum design of a composite advanced grid-stiffened (AGS) cylinder subject to post-buckling. The design taking account of post-buckling under ultimate load will be able to promote the structural efficiency compared to the conventional design in which only the linear buckling is allowed. The beam-shell offsets technique is utilized for modeling the stiffener-skin connection, and the Newton-Raphson method is employed for the post-buckling analysis. A few structural analysis efforts are carried out for establishing the Kriging model of the collapse load of the AGS cylinder for optimization to significantly increase the optimization efficiency. The multi-island genetic algorithm (MIGA) is utilized for global optimum search. An adaptive approximation framework is proposed to resolve the computational burden caused by the large domain of design variables, and it is demonstrated that much less computational expense than that of the traditional approximation-based optimization method can be achieved. The utility of making use of commercial optimization package iSIGHT in conjunction with the finite element (FE) code MSC.MARC to develop the preliminary design tool of the composite AGS cylinder is evaluated as well.