  We prove the stability of a large class of unilateral minimality properties
which arise naturally in the theory of crack propagation proposed by Francfort
and Marigo in [Revisiting brittle fractures as an energy minimization problem.
J. Mech. Phys. Solids, 46 (1998), 1319-1342]. Then we give an application to
the quasistatic evolution of cracks in composite materials.
