EFFECTS OF NOTCH LENGTH ON THE DUCTILE FRACTURE OF A CENTER-NOTCHED LOW-CARBON STEEL PLATE

Ductile fracture of a thin-notched specimen deformed to plastic collapse was investigated by observing crack growth on the specimen surface. A correlation between the ductile crack growth and the initial notch length was obtained. It was found that: (1) the crack growth rate, da/depsilon, for the strain increment depends on the crack length, a, and the nondimensionalized crack growth rate, (da/depsilon)/a, is faster for short notch lengths; (2) crack opening displacement, delta, measured in the vicinity of the crack tip was also dependent on the crack length and the notch length; (3) the crack opening rate, ddelta/da, was inversely proportional to the crack length. Thus, the variation of crack opening displacement was found to have a good correlation with the crack growth rate.