OPTIMIZATION DESIGN OF COMPOSITE PLATES WITH HOLES FOR INCREASED STRENGTH

Unlike in engineering structures, in nature, holes in bones are not normally involved in failure. This may be partly due to special material orthotropy distribution pattern in the vicinity of the hole. Material orthotropies have a dramatic influence on the strength of composite plates with holes. In this paper, a procedure for optimally determining the material orthotropies around a hole in a composite plate is presented. The material is assumed to have constant transversely isotropic elastic properties. Piecewise bilinear interpolation functions formed by quadrilateral elements are used to represent continuous material orthotropy distribution. Normalized Tsai-Wu failure index is minimized through genetic algorithm-based two-step optimization technique. The results show that the strength reduction due to hole in a composite plate can be dramatically alleviated by material orthotropy optimization near the hole. The optimized material orthotropies are similar in pattern to those found in bone around a foramen (blood vessel hole).

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