Nonlinear homogenized properties of defected composite materials

The macroscopic response of elastic composite materials with periodic defected microstructures under large deformations is analyzed. The effects of microscopic instability and bifurcation are studied by using an updated Lagrangian formulation and frictionless self-contact between crack faces is accounted. Two special classes of homogenization problems are examined: effective contact and self-adjoint data. Numerical applications are developed by means of an FE approach with reference to a cellular material with diagonal microcracks and to a laminated microstructure with interface debonding. The strong role of crack self-contact nonlinearities and the influence of microscopic defects on the homogenized composite properties are pointed out.