Optimal Design Methodology for Composite Materials with Particulate Fillers

The structure of composite materials which consist of a particulate filler and fluid binder are analysed. Composites are shown to have two main matrix structures. In the first, the fluid volume is less than the void volume of the filler and the composite strength accrues from both the natural bonding forces of the particulate mass and the bonding action of the fluid. The second characteristic matrix structure is when the fluid volume exceeds the filler void volume. Here the fluid essentially pushes the particles apart and reduces particle--particle interaction so that the composite strength is based largely upon the bonding action of the fluid alone. The two parameters which govern the structure of a composite are the proportions of fluid and filler and the natural voidage of the latter. A methodology is evolved to develop a composite with a desired matrix structure which includes a mathematical model to predict voidage of particulate size distributions in random mixtures. 22 ref.--AA