Convergence of critical points for a phase-field approximation of 1D cohesive fracture energies

Variational models for cohesive fracture are based on the idea that the fracture energy is released gradually as the crack opening grows. Recently, Conti, Focardi and Iurlano proposed a variational approximation via Gamma-convergence of a class of cohesive fracture energies by phase-field energies of Ambrosio-Tortorelli type, which may be also used as regularization for numerical simulations. In this paper we address the question of the asymptotic behaviour of critical points of the phase-field energies in the one-dimensional setting: we show that they converge to a selected class of critical points of the limit functional. Conversely, each critical point in this class can be approximated by a family of critical points of the phase-field functionals.