Optimum Design of Fibrous Laminated Sandwich Plates Subjected to Axial Compression

In the Case of Aspect Ratio Being Less than Unity

Abstract

Optimum material design is of great importance when designers try to utilize the ‘designable’ characteristic of fibrous composite materials for developing the best product in terms of cost, weight or the combination of these. In this paper presented is an analytical method useful for designing optimum fibrous laminated sandwich plates which can stand a given compressive load.
The sandwich plates considered in this study consisted of multidirectional balanced angle-ply laminated skin and isotropic core, and had a symmetric stacking sequence. The problem to be solved was the maximization of the core thickness ratio, which yields the minimization of cost of the plates, under the constraint of buckling load.
The proposed method was based on the flexural lamination parameter diagram which shows the feasible design region for a possible stacking construction of the laminated sandwich plates. The feasible design region became smaller when the core thickness ratio increased, and the region finally reduced to a point. The optimum solution was obtained under this condition.
It was found that the optimum stacking sequence of the skin was [(±θ)_n] and the optimum fiber orientation angle varied with the aspect ratio of the plate and the ply material, but it did not vary with the buckling load.
The optimum fiber orientation of the skin and the optimum core thickness ratio can be obtained easily by using the proposed method, but this method is limited to the aspect ratio less than unity.