Rivlin, Thomas, et al. (2) developed tear tests based on theoretical analysis of crack growth behavior. For flat sheet test specimens they defined a tearing energy or strength T, that is independent of the geometry of the test specimen provided the stored energy density of the specimen could be measured. Three types of test specimens were used: the strip or tensile specimen, the pure shear specimen and the trouser tear specimen. The relation for the tearing energy with the trouser specimen is:
T = 2ʎF/t - wE (X1.1)