Modelling of crack growth initiation in a linear viscoelastic material

Widespread application of viscoelastic materials the structures, which have to operate for a long time, requires better understanding of their mechanical behaviour and fracture properties. It has been observed that time dependence is of great importance in determining the rate of crack growth. The effects of viscoelastic characteristics on creep crack growth initiation are studied in the paper by using the finite element method. In order to define displacements and stresses around the crack tip in linear isotropic viscoelastic media new formulation in the time domain has been produced. We formulate a new constitutive equation in terms of the stress and crack opening intensity factors, using the correspondence principle by means of Volterra integrals. Afterwards, the fracture parameters are computed with an incremental viscoelastic formulation.