Optimal design of stiffened plates

A design methodology for the optimization of stiffened plates with frequency and buckling constraints is presented. The basic idea of the methodology is to consider a plate with a fairly dense1 distribution of stiffeners. Thickness of the plate and stiffeners, and the stiffener width are the design variables. Design variable linking is accomplished by the use of rational spline surfaces. The finite element method is used for the analysis. The plate is modeled using linear Mindlin plate elements and the stiffeners by linear Timoshenko beam elements. Both the plate and beam elements are shear-locking free by formulation, without requiring any special techniques such as reduced integration. Results for a square stiffened plate with three different stiffener layout patterns and different stiffener density1 are presented. The best four stiffener configurations which give the lowest mass are chosen and applied to 2:1 and 3:1 rectangular plates. It is concluded that the present design methodology gives good results, and that the stiffener pattern and stiffener density play an important role in reducing the mass of a stiffened plate.; 1Refers to the measure of the number of stiffeners and there spacings and NOT to the density of the stiffener material.