EFFECT OF STRUCTURE ON ENVIRONMENTALLY ASSISTED SUBCRITICAL CRACK-GROWTH IN BRITTLE MATERIALS

Subcritical crack growth in brittle materials is considered when it is thermally activated and water vapor affected. Effects of material str ucture on the crack growth were investigated. Special case of subcriti cal crack growth is examined when the crack growth is decided by water vapor enhanced rupture of some particulate strength controlling eleme nts of material structure. The water vapor is assumed to be transporte d to these elements through the material by diffusion in a gas filling a system of interconnected open pore channels in the material volume. Calculated crack velocity plots versus the stress intensity factor, t emperature and humidity are presented.