Variable-notch one-size test method for fracture energy and process zone length

Based on the generalized theory of the size effect law allowing dissimilar specimens, this paper proposes a new version of the size effect method for determining the fracture energy G_f and effective process zone length c_f, which permits using specimens of only one shape and one size, but with different notch lengths. Cutting notches of different lengths on specimens of the same shape and size is an easy way to obtain specimens of different brittleness numbers, as required by the size effect method. Either linear or nonlinear regression of measured maximum loads of these specimens can give the material parameters G_f and c_f. An experimental program is conducted to verify the proposed method. The notched holed split-tension cylinder is found to be a suitable specimen shape, while the notched eccentric compression specimen is found to provide a barely sufficient range of brittleness numbers. The analysis in the paper also indicates that there exists an upper limit of notch (or initial crack) length for some specimen geometries as the limit for validity of the definition of brittleness number.