Response surface method for optimum design of composite stiffened shells

The paper is focused on application of response surface method (RSM) in design of composite shells. The response surface method consists of two stages. In the first stage, an experimental design is selected in order to perform a deterministic computer simulation (finite element solution) in the sample points. The experimental design considered is based on a combination of the Latin hypercube approach and the D-optimal design. In the second stage, the approximation of the original functions is performed in order to obtain response surfaces. The original functions represent behavioral constraints (buckling, stiffness, collapse load, etc.) in the optimum design problem of the structure. Values of the original function in the points of experimental design are obtained by the finite element method. A global approximation by second order polynomial functions is employed. An example of minimum weight design of composite stiffened panel under buckling and post-buckling constraints is discussed. The design variables are the thickness of layers in the skin and in blade type stiffeners and the stiffener geometric parameters. A design example has shown that the response surface method is a computationally effective and powerful tool for the optimization of lightweight composite structures.