Delayed fracture of an isotropic viscoelastic material with a crack under cyclic loading

The delayed fracture of an isotropic viscoelastic plate is examined as a process involving the subcritical propagation of a straight normal-rupture crack during fatigue loading. Calculations are based on the modified delta(C)-model of fracture, it being assumed that the size of the prefracture zone ahead of the moving crack remains constant. This zone is also assumed to be small compared to the size of the crack itself. Solutions for a time-dependent crack length are given both for media which undergo quasi-viscous flow (an integral operator with an Abelian kernel is used) and for media whose creep curves have a horizontal asymptote (an integral operator with a kernel in the form of the fractional-exponential function of Yu, N. Rabotnov is used).