Mesofracture of metal matrix composites reinforced by particles of large volume fraction

Micromechanics analysis for metal matrix composites (MMC) reinforced by particles of large volume fraction is pursued in this paper. Particle reinforced Al₂O₃/Al MMC is made under a pressure-less filtration technique. Samples are tested in uniaxial tension, compression and three-point bending. The composite is modeled as identical elastic spheres linked by columns of elastic perfectly plastic matrix. Damage evolves in three mechanisms: the particle/matrix interface may debond if the interfacial energy release rate reaches a critical value; the ductile matrix may fail if voids expand to a certain degree; and the particle may break if the largest principal stress exceeds its strength. An averaging scheme is used to derive the macroscopic constitutive relation. Two random variables are adopted for the fluctuations of local stresses in particles and along particle/matrix interfaces. The predicted stress-strain curves, crack growth paths, and the composition of failure surfaces compare favorably with the testing data.