ABSTRACT
There is sufficient evidence to show that the response of paper containing a crack cannot be predicted by simple tensile strength, stretch, or TEA. For example, in Fig. 22 TEA is plotted against crack length for two different kraft sheets. Clearly, a ranking based on unnotched specimens (notch length = 0) would not represent the behavior of notched sheets such as sheets containing calender cuts or poorly bonded shives. Therefore, some sort of measurement of fracture toughness is required when fracture from a preexisting flaw is responsible for service failure. Based primarily on intuitive arguments about fracture mode, it has been widely suggested that the Elmendorf tear test, which involves out-of-plane deformations, is not the most sui table test when in-plane deformations are responsible for most service failures.
