Fracture of disordered three-dimensional spring networks: A computer simulation methodology.

In this paper a computational technique is proposed to describe brittle fracture of highly porous random media. Geometrical heterogeneity in the ‘‘open cell foam’’ structure of the porous medium on a mesoscopic length scale ~;100 nm! is mapped directly onto a three-dimensional ~3D! elastic network by using molecular dynamics techniques to generate starting configurations. The aspects in our description are that the elastic properties of an irregular 3D-network are described using not only a potential with a two-body term ~change in bond length, or linear elastic tension! and a three-body term ~change in bond angle, or bending!, but also a four-body term ~torsion!. The equations for minimum energy are written and solved in matrix form. If the changes in bond lengths, bond- or torsion angles exceed pre-set threshold values, then the corresponding bonds are irreversibly removed from the network. Brittleness is mimicked by choosing small ~;1%! threshold values. The applied stress is increased until the network falls apart into two or more pieces. @S0163-1829~96!07146-9#