The advantages of using graphite as reinforcement in aluminum composites have been addressed by several authors, e.g. Warner et al. . The addition of graphite has been demonstrated to improve the relation strength to density ratio because of the low weight of graphite. Also a significant hardening caused by the difference in the thermal expansion coefficient between graphite and Al matrix have been observed . Furthermore, the presence of graphite has been demonstrated to reduce the wear and abrasion of tools. The structural response of metal matrix composites (MMC) has been studied recently to evaluate the elastic and plastic performance by using Finite Element Method (FEM) [3, 4].
In this paper an analysis of the structural response of Al\graphite composites is presented. The analysis is based on the Finite Element Method (FEM) in the elastic and plastic regions. Several Al\graphite composites with different graphite contents were considered. A FEM model based on a unit cell was proposed and two different Al/graphite interface conditions were assumed: 1) strongly bonded interface, and 2) sliding-friction interface. Also, both regular and irregular arrays of graphite particles in the aluminum were considered in the model. The results in the elastic region are evaluated in terms of the effective elastic modulus and compared with some theoretical models in the literature . From these results it has been observed that when a friction-sliding interface is considered, a slightly smaller elastic modulus is obtained, compared with the strongly-bonded interface condition. Regarding the numerical simulation in the plastic region, the results were compared with theoretical models  and experimental data obtained from compression tests.