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Shapes and lay-up configurations of laminated composite shallow shells are optimized simultaneously to maximize the fundamental frequency by a simple genetic algorithm method. The surface shape is defined by a cubic polynomial and this makes it possible to express a variety of surfaces with inconstant curvature radii by varying the values of the coefficients for each polynomial term. The coefficients and the lay-up configurations of the laminated shells are directly employed as design variables, and constraints are imposed on the coefficients and curvature radii to maintain the shallowness of the shells. The frequencies are calculated by using the Ritz method due to its flexibility with surface shapes. The results of the present analysis agreed well with experimental and finite element analysis results in terms of frequencies and mode shapes. The obtained optimum solutions resulted in higher fundamental frequencies than for shells with commonly emplyed surface shapes and lay-up configurations.

Shapes and lay-up configurations of composite laminated shallow shells are optimized simultaneously to maximize the fundamental frequency by a simple genetic algorithm method. The shell shape is defined by a cubic polynomial and this makes it possible to express various shapes of shells with inconstant curvature radii by varying the value of coefficient for each term. The coefficients and the lay-up configuration of the laminated shell are directly employed as design variables, and constraints are imposed on the coefficients and curvature radii to keep shells shallow. The frequencies are calculated by using the Ritz method due to its flexibleness for shell shapes. Results of the present analysis technique agreed well with experimental and finite element analysis results in terms of frequencies and mode shapes. Obtained optimum solutions resulted in higher fundamental frequencies than the shells with general shapes and lay-up configurations.

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