Viscoelastic crack growth process in wood timbers: An approach by the finite element method for mode I fracture

In this paper the effects of viscoelastic characteristics in wood timbers, on the creep crack growth process are studied through a new finite element approach in the time domain. In order to take into account the linear viscoelastic orthotropic behavior, we present an incremental formulation based on a rheological representation of creep tensor components. By using a relationship between stress and crack opening intensity factors, the general approach of path independent integrals is extended in order to calculate energy release rate and local fracture characteristics. Afterwards, fracture parameters are computed through a coupling process with the incremental viscoelastic behavior. The numerical algorithm is presented and validated through numerical as well as experimental examples.