Experimental Determination of the Dependence of Crack Extension Force on Crack Length for a Single-Edge-Notch Tension Specimen

Abstract

The single-edge-notch form of a plane-strain (or opening mode) crack toughness specimen is particularly economical in regard to available test material and testing machine capacity. The necessary calibration relation for a particular design of a single-edge-notch specimen centrally loaded in tension, was determined from a series of compliance measurements at crack lengths ranging from zero to one-half the specimen width. The accuracy of the calibration is estimated to be +1/2 percent in the range of interest. Agreement with concurrent results obtained by boundary collocation of an appropriate stress function is excellent. Alternative types of specimen are discussed, and the relation between necessary specimen size and the ratio of toughness to yield strength is emphasized.