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A B S T R A C T A large bulk of static test results carried out on notched specimens are presented in a unified way by using the mean value of the strain energy density (SED) over a given finite-size volume surrounding the highly stressed regions. In plane problems, when cracks or pointed V-notches are considered, the volume becomes a circle or a circular sector, respectively, with R C being the radius. R C depends on the fracture toughness of the material, the ultimate tensile strength and the Poisson's ratio. When the notch is blunt, the control area assumes a crescent shape and R C is its width as measured along the notch bisector. About 900 experimental data, taken from recent literature, are involved in the local SED-based synthesis. They have been obtained from (a) U-and V-notched specimens made of different materials tested under mode I loading; (b) U-and V-notched specimens made of polymethyl-metacrylate (PMMA) and an acrylic resin, respectively, tested in mixed, I + II, mode; (c) U-notched specimens made of ceramics materials tested under mode I.The local SED values are normalized to the critical SED values (as determined from unnotched specimens) and plotted as a function of the R/R C ratio. A scatter band is obtained whose mean value does not depend on R/R C , whereas the ratio between the upper and the lower limits are found to be about equal to 1.6. The strong variability of the non-dimensional radius R/R C (ranging here from about zero to around 1000) makes stringent the check of the approach based on the mean value of the local SED on a material-dependent control volume.Keywords brittle fracture; critical radius; finite-size volume; notch; strain energy density. N O M E N C L A T U R Ea = notch depth E = Young's elastic modulus E 1 = strain energy on the control volume f ij , g ij = angular functions F(2α) = parameter to evaluate the strain energy density (blunt notches, R = 0) J = Rice's J integral l ch = characteristic length of the material K I , K U R,I , K V R,I = stress-intensity factor and notch stress-intensity factors for U-and V-shaped notches Correspondence: P. Lazzarin.

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