Rapid calculations of notch stress intensity factors based on averaged strain energy density from coarse meshes: Theoretical bases and applications

In the presence of sharp V-notches the stress distributions are singular and the intensity of the stress fields is given in terms of the notch stress intensity factors which are largely used in the literature for fatigue strength assessments of welded joints and other notched components. Very refined meshes are necessary to determine directly the NSIFs from the local stress distributions. Refined meshes are not necessary when the aim of the finite element analysis is to determine the mean value of the local strain energy density on a control volume surrounding the points of stress singularity. The SED in fact can be derived directly from nodal displacements, so that also coarse meshes are able to give sufficiently accurate values for it. The link between local SED and NSIFs is discussed with reference to some typical welded joints and to plates weakened by sharp V-notches. The SED-based procedure is found to be useful to determine theoretical stress concentration factors for holes and blunt U- and V-shaped notches.