Flaw-insensitive ion-exchanged glass: I, theoretical aspects

Stable crack growth can be produced on residually stressed surfaces, provid ed that the residual-stress profile is carefully chosen. Once identified, t hese conditions will lead to strengthening and an insensitivity of strength to the size of the initial surface flaw. Theoretical calculations are perf ormed that involve choosing idealized forms of either the required toughnes s curve or the residual-stress profile. The results of this analysis allow the range of stable growth and the strengthening to be determined. Thus, in the material-design process, if the range of surface flaws in the stress-f ree surface are known, then the required stress profile or toughness curve for optimum performance can be selected.