Manufacturing tolerances of fiber orientations in optimization of laminated plates

The paper deals with the effect of manufacturing imperfections in fiber orientations on the optimum design of laminate plates exposed to compression load. It is assumed that each dimensional imperfection cannot exceed one of two accepted values, called tolerances. In general, these are the largest allowed deviations of the design variable from its nominal value. The incorporation of tolerances is achieved by diminishing the limit values of state variables by the product of assumed tolerances and appropriate sensitivities. Therefore, the given method allows the introduction of tolerances into design in a relatively simple way and ensures safe results. The presented approach is a deterministic approximation of an exact stochastic solution of the problem. The paper is illustrated with two examples of the rectangular laminated plate design. The first one is maximization of buckling load for a given plate thickness. The second one is minimum weight (thickness) design for a given load. Numerical results show the reliability-based design to be important for structural safety when compared to the approach where tolerances are not considered