Crack propagation in viscoelastic structures: Theoretical and numerical analyses

In the case of a brittle viscoelastic medium, the existence of a viscous dissipation affects the propagation of cracks. The paper first revisits the thermodynamic framework of Griffith's theory extended to viscoelastic media. A criterion for propagation is derived in the form of a threshold for the driving force of the phenomenon. Analytical and numerical implementations are presented. The driving force of propagation and the evolution of the crack length are found to be very sensitive to the loading rate.