ABSTRACT
As early as the 1920s, the strength of glass and other brittle materials was understood to be limited by the presence of small cracks. Under stress, the small cracks would grow into larger cracks until reaching a critical size, at which point the material would fracture catastrophically. The fracture mechanics formalism he adopted in these two papers captured the dependence of the growth rate on the size of the crack and the stress. Wiederhorn also showed the crack growth rate depended on humidity in accord with an existing theory of delayed failure in glass. The recognition of the importance of the environment at the crack-tip to crack growth led to a series of studies of crack growth rate in electrolytes as a function of zeta potential, ionicity, and pH. Of these, only pH was critical in establishing the relationship between crack velocity and stress intensity factor.
