A comparison among some recent energy- and stress-based criteria for the fracture assessment of sharp V-notched components under Mode I loading

Abstract

Fracture assessment of components weakened by sharp V-notches is typically carried out by means of the Notch Stress Intensity Factors (NSIFs), which quantify the asymptotic linear elastic stress field in the vicinity of the notch tip. Since units of the NSIFs do depend on the V-notch opening angle, a direct comparison in terms of the NSIFs needs the constancy of the opening angle. A criterion based on the strain energy density (SED) averaged over a material-dependent control volume surrounding the notch tip has been proposed by the authors. When the control volume is small enough to make negligible the influence of higher order terms of Williams’ solution, the SED can be theoretically linked to the NSIFs.Considering Mode I loading conditions, the expression of the critical Mode I NSIF at failure as a function of the V-notch opening angle as derived according to the averaged SED criterion is compared with those given by two different versions of the Finite Fracture Mechanics (FFM) criterion, the former due to Leguillon, the latter due to Carpinteri et alii.Finally, the considered criteria are applied to components weakened by sharp V-notches under Mode I loading conditions in order to investigate the predictive capability of each approach. A number of experimental data taken from the literature are used for comparison.