Energy Equilibria and Rate Process in Brittle Fracture

So as to treat brittle faracture by an atomic model, problems in the energy equilibria on the crack stability and those in the rate process are discussed, and new expressions are proposed. Newly derived critical condition of crack propagation for Griffith type through micocrack in brittle material is given as follows, $${\sigma _0} = 2{(E{\gamma _s}/1)^{1/2}}$$ where, σ0; critical tensile stress (threshold stress of subcritical crack growth) operated normal to crack surface and parallel to specimen length, E; Young’s modulus, Eγs; surface free energy of the material, 1; specimen length.