Some expressions for the strain energy in a finite volume surrounding the root of blunt V-notches

The paper gives some closed form expressions for the strain energy averaged in a finite size volume surrounding the root of blunt V-shaped notches under Mode I loading. The control volume, reminiscent of Neuber's concept of elementary structural volumes, is thought of as dependent on the ultimate tensile strength and the fracture toughness K-1C in the case of brittle or quasi-brittle materials. subjected to static loads. Expressions for strain energy density under plane strain conditions and Mode I loading have been derived from an analytical frame recently reported in the literature, which matches Williams and Creager-Paris' solutions in the particular cases of plates weakened by sharp V-notches or blunt cracks (U-notches), respectively In order to validate a local-strain-energy based approach.. a well-documented set of experimental data recently reported in this journal by Gomez and Elices has been used. Data refer to blunt and sharp V-specimens of PMMA subjected to static tension loads and characterised by a large variability of notch root radius (from 0 to 4.0mm) and notch angle (from 0 degrees to 150 degrees). Critical loads obtained experimentally have been compared with the theoretical ones, estimated here by keeping constant the mean value of the strain energy in a well-defined small size volume.