Design for the Maximum Natural Frequency of Laminated Composite Plates by Optimally Distributed Short Fibers

Abstract

A new design method is proposed for vibration of functional fibrous composite plates, which imitate micro structures of natural materials such as bones and shells. The material has local anisotropy induced by optimally distributed short fibers which are defined in each element of the finite element method. To design such locally anisotropic plates, the present optimum design method combines a genetic algorithm method (GA) with a layerwise optimization (LO) concept. The LO concept reduces a multi-layer optimization into iterations of a single-layer optimization, and the GA is used for the single-layer optimization to determine fiber orientation angles in each element. The fundamental frequency of the plates is chosen as the objective function to be maximized. It was revealed that the present plates give higher fundamental frequencies than conventional plates reinforced by parallel straight fibers. Further optimally distributed short fibers indicated specific orientations even though no constraint was imposed on those directions.