A FINITE-ELEMENT FORMULATION FOR COMPOSITE STRUCTURES BASED ON A VOLUME FRACTION MIXTURE THEORY

This paper is concerned with developing an advanced finite element for mulation for composite structures based on a volume fraction mixture t heory. The development is unique in that each node of the finite eleme nt mesh is assumed to have double the number of degrees of freedom ove r that of a single continuum. In particular, the degrees of freedom re present the displacements of the individual constituents, thereby allo wing for independent constituent motions. The behavior of the composit e is then determined by the governing rules for summing constituent va riables of the mixture. The primary advantage of developing such a the ory is that detailed information regarding the state of the constituen ts is retained while at the same time performing structural analysis. Hence, the mixture theory represents a marriage of micromechanics to s tructural analysis. The mixture formulation is shown to capture the me chanical behavior of a unidirectional composite under both uniaxial an d multiaxial loadings. Finally, an example of structural analysis is p resented for a composite plate with a hole in it.