The design of the specimen should be such that failure occurs in the test section. The acceptable ratio of the areas (test section to grip section) to ensure a test section failure is dependent on the specimen gripping method. Threaded end specimen may prove difficult to align and failure often initiates at these stress concentrations when testing in the life regime
of interest in this practice.A caveat is given regarding the gage section with sharp edges(that is, square or rectangular cross section ) since these are inherent weaknesses the slip of the grains at sharp edges is not confined by neighboring grains on two sides.