Effect of microstructural architecture on flow/damage surfaces for metal matrix composites

Flow/damage surfaces are defined using a thermodynamics basis in terms of stress, inelastic strain rate, and internal variables. The most meaningful definition for viscoplasticity, surfaces of constant dissipation rate, is investigated for a unidirectional silicon carbide/titanium composite system using two micromechanics approaches; finite element analysis of a unit cell and the generalized method of cells. Damage, in terms of fiber/matrix debonding, is accounted for when a tensile interfacial traction is present. Three types of periodic microstructural architectures are considered; rectangular packing, hexagonal packing, and square diagonal packing. The microstructural architecture is observed to influence the shape and location of flow/damage surfaces and becomes more important as the fiber volume fraction increases.