STATISTICAL-ANALYSIS OF THE EFFECT OF SIDE-GROOVING ON THE MEASUREMENT OF BRITTLE-FRACTURE TOUGHNESS

Fracture mechanics specimens are commonly side-grooved to promote uniformity of the crack tip stress field, but this practice may affect the fracture toughness measured because of changes in the net thickness and in the constraint. This study, based on Weibull statistics, shows that, for brittle fracture, the difference between the fracture toughness measured with plain-sided and 20 percent side-grooved specimens results essentially from the difference in net thicknesses. It is also shown that the effect of constraint should not be evaluated from the load arrying capacity of the specimen, but rather from the distribution of stress intensity factor along the crack front. © 1990 Kluwer Academic Publishers.