Capillary effect on subcritical crack growth - A model

A model of subcritical steady-state crack growth assisted by water vapor reacting with the material is studied. A water droplet is assumed to be sucked in into the crack by capillary effect, so that a bubble of moist gas (air) is present between the droplet and the crack tip. The water vapor is assumed to be transported by diffusion to the crack tip, where it is consumed by the reaction of rupture. The crack length is assumed to be well in excess of the lengths of the droplet and the bubble. A calculated example for glass is presented. It showed that the droplet in the crack can significantly affect the crack velocity under the conditions ensuring sufficiently large gas bubble length. This can be of interest for rock mechanics applications, considering the glass as a model of brittle rocks.