Computational modeling of metal matrix composite materials

The mechanical behavior of an Al-3 wt% Cu matrix, SiC particulate reinforced model composite system was analyzed. The Computational Micromechanics approach was taken, i.e., a detailed representation of microstructure with the material characterized by a finite deformation, thermo-elastic-viscoplastic crystallographic slip theory. Individual matrix grains and reinforcing particles were represented, in the context of two dimensional repeating unit cell models and solutions were obtained using the finite element method. Microstructural performance under variation in reinforcement volume fraction, morphology, matrix strain hardening properties and loading state was investigated, as were the effects of residual stresses due to processing. Localized stress and strain patterns develop in the microstructures during deformation and are controlled by the positions of the reinforcing particles. Constrained plastic flow and matrix hardness advancement are major composite strengthening mechanisms. Both depend strongly on reinforcement volume fraction and morphology and the latter on the strain hardening nature of the matrix. Intense strain localization and development of high stresses within and around particles identify possible sites for fracture. Processing simulations were performed which resulted in the production of residual stress and strain fields. The residual fields shift yield stresses and strains and introduce differences between tensile and compressive behavior. The magnitude of these effects depends on the extent of processing. There is good agreement between the computed results for the macroscopic behavior of the composites and the predictions of approximate analytical models for composites based on phenomenological plasticity. Simulations were performed using the existing reinforcement geometry where the physically based theory was replaced with the phenomenologically based J{dollar}sb2{dollar} flow theory. Results are in good qualitative agreement with those of the crystal plasticity simulations at both microscopic and macroscopic levels. The J{dollar}sb2{dollar} flow theory composites have smoother and less localized stress and strain fields, features that depend strongly on volume fraction and morphology.