On propagation of small surface breaking cracks

In this paper the original Griffith's theory of the fracture of solids is r econsidered to evaluate its meaning in terms of the propagation of small cr acks. In the Griffith theory it is postulated that the work to form a new s urface involved in a crack in a solid has the same nature as for liquids. I n this paper it is shown that an additional stress intensity factor due to the surface tension for edge surface cracks can be taken into consideration . This stress intensity factor is dependent on the crack length as a root s ingularity and consequently rapidly increases as the length decreases. The model may assist in explaining the peculiarities of the kinetics of sma ll crack growth. It is distinguished from numerous existing theories in tha t it does not introduce any correction factors, empirical equations, charac teristic sizes or stages of-small crack propagation. The additional stress intensity from surface tension should be observable in the propagation of s hort surface cracks.