Effects of the orientational distribution of cracks in solids.

We derive a theory for the elastic characterization of multicracked solids based on a homogenization technique. We consider a material containing a two-dimensional arbitrary distribution of parallel slit cracks which is elastically equivalent to a crystal with orthorhombic symmetry. We obtain explicit expressions for the macroscopic elastic stiffness tensor which is found to depend upon both the density of cracks and their angular distribution, here described by a suitable order parameter. For the isotropic case, we find that the degradation depends exponentially on the crack density. In addition, we show an unusual elastic behavior of a multicracked medium in the plane strain condition: for a negative Poisson ratio, we obtain an effective Young modulus greater than the actual value of the host matrix.