MICROMECHANICAL MODELING OF REINFORCEMENT FRACTURE IN PARTICLE-REINFORCED METAL-MATRIX COMPOSITES

Finite element analyses; of the effect of particle fracture on the ten sile response of particle-reinforced metal-matrix composites are carri ed out. The analyses are based on two-dimensional plane strain and axi symmetric unit cell models. The reinforcement is characterized as an i sotropic elastic solid and the ductile matrix as an isotropically hard ening viscoplastic solid. The reinforcement and matrix properties are taken to be those of an Al-3.5 wt pet Cu alloy reinforced with SiC par ticles. An initial crack, perpendicular to the tensile axis, is assume d to be present in the particles. Both stationary and quasi-statically growing cracks are analyzed. Resistance to crack growth in its initia l plane and along the particle-matrix interface is modeled using a coh esive surface constitutive relation that allows for decohesion. Variat ions of crack size, shape, spatial distribution, and volume fraction o f the particles and of the material;and cohesive properties are explor ed. Conditions governing the onset of cracking within the particle, th e evolution of field quantities as the crack advances within the parti cle to the particle-matrix interface, and the dependence of overall te nsile stress-strain response during continued crack advance are analyz ed.