Kinetics of crack formation and growth on the material interface

A model of thermal fluctuation crack formation in aweakened bond region on amaterial interface is proposed. The weakened bond region is modeled by a bridged crack whose properties vary in time according to the thermal fluctuation mechanism. It is assumed that at least one of the materials is a polymer and the crack part occupied by bridges (the end region) is not small compared with the crack length. The stresses in the bridges and the kinetic dependence of the bond density in the crack end region are determined by solving a system of singular integrodifferential equations. The condition for the crack-defect nucleation is the decrease to the critical value of the average bond density on the corresponding part of the weakened bond region. Numerical results permitting one to estimate the crack nucleation time and the typical levels of external loads for the chosen material parameters are presented.