Stochastic homogenisation of free-discontinuity functionals in randomly perforated domains

In this paper, we study the asymptotic behaviour of a family of random free-discontinuity energies E_ε defined in a randomly perforated domain, as ε goes to zero. The functionals E_ε model the energy associated to displacements of porous random materials that can develop cracks. To gain compactness for sequences of displacements with bounded energies, we need to overcome the lack of equi-coerciveness of the functionals. We do so by means of an extension result, under the assumption that the random perforations cannot come too close to one another. The limit energy is then obtained in two steps. As a first step, we apply a general result of stochastic convergence of free-discontinuity functionals to a modified, coercive version of E_ε. Then the effective volume and surface energy densities are identified by means of a careful limit procedure.