Mode I Crack Initiation in Orthotropic Viscoelastic Plates Under Biaxial Loading

Abstract

The subcritical propagation of a crack in orthotropic viscoelastic plate under time-constant biaxial external loading is investigated on the basis of generalization of the Leonov-Panasyuk-Dugdale crack model to the case of orthotropic materials satisfying a strength condition of arbitrary form. The crack is directed along one of the anisotropy axes with external loads applied parallel and perpendicularly to this axis. To find the rheological characteristics of the composite material, we apply the method of operator continued fractions. The relationships used to determine the duration of incubation and transition periods of crack propagation are deduced on the basis of the Volterra principle and the solution of the corresponding elastic problem. The influence of the biaxiality of external loading on the safe loading and subcritical crack growth is analyzed within the framework of the critical crack opening displacement criterion.