Optimum Design of Composite Laminates against Delamination by Ranking

Abstract

In this paper, we describe a method for the optimum design of fibre rein forced composite laminates against delamination. The software developed based on this method designs laminates so that they are not susceptible to delamination when subjected to a bi-cubic distribution of inplane and/or bending loads. The laminated plate which is made of repeated sublaminates is assumed to be thin and of symmetric construction. Various layup schemes are evaluated based on the classical plate theory and quadratic delamination criterion for the interlaminar stresses developed in the laminate under load ing conditions. The optimum layup sequence which exhibits the least propensity to delaminate and the number of sublaminates required are obtained Further, a ply-drop round-off scheme is adopted to arrive at an optimum laminate thickness. As an example, a family of 0/90/45/—45 bi-directional lamination schemes are examined for different types of loads and the gains in optimising the ply orientations in a sublaminate are demon strated.