Coupled time discretisation of dynamic damage models at small strains

Abstract: The dynamic damage model in viscoelastic materials in Kelvin-Voigt rheology is discretised by a scheme which is coupled, suppresses spurious numerical attenuation during vibrations, and has a variational structure with a convex potential for small time-steps. In addition, this discretisation is numerically stable and convergent for the time step going to zero. When combined with the FEM spatial discretisation, it leads to an implementable scheme and to that iterative solvers (e.g. the Newton-Raphson) used for the nonlinear algebraic systems at each time level have guaranteed global convergence. Models which are computationally used in some engineering simulations in a non-reliable way are thus stabilized and theoretically justified in this viscoelastic rheology. In particular, this model and algorithm can be used in a reliable way for a dynamic fracture in the usual phase-field approximation.