Numerical and theoretical modeling of the elasto-plastic response of aluminum-graphite composites during straining

One of the ways to improve the mechanical properties of Aluminum alloys is by dispersion of the metal matrix with small particles, such as Aluminum-Graphite (Al-Gr) composites. The elasto-plastic response of Aluminum-Graphite composites has not been fully understood. Hence, in this paper a numerical analysis of the elasto-plastic structural response of Al-Gr composites is presented. FEM models based on unit cells are proposed by considering two different Al/Gr interface conditions: (1) strongly bonded interface and (2) friction-sliding interface. The results from the numerical simulation in the elastic region are evaluated in terms of the effective elastic modulus and compared with existing theoretical models. On the other hand, the results from the numerical simulation in the plastic region are compared with experimental data obtained from compression tests, and with existing theoretical models that are based on the rule of mixtures. The results have shown that FEM models, based on conventional continuum theory, and existing theoretical models, based on the rule of mixtures, are not capable to predict with accuracy the plastic behavior of the composite. Therefore, a new empirical model is proposed instead, which is compared to the experimental results. After a calibration process of the model with a limited set of experimental data input, the new proposed model has shown a high accuracy in predicting the effective plastic response of the Al-Gr composite for different volume fraction of reinforcing particles.