Equivalent Fatigue Zone in a Notched Elements Determined by Use of Non-Local Line Method with Weight Function

Abstract

The work presents non-local line method by which the equivalent fatigue zones were designated. These zones are one-dimensional efficient lengths in which operating stress variables cause initiation of fatigue cracks. The algorithm of the presented method considers the issues of multi-axial stress state, critical plane and weighting function. Calculations of stresses in the test element were performed by using the FEM assuming cyclic material properties, which are described with the model for multi-linear hardening. The empirical lifetime of elements with a notch was assumed to define length of the crack amounting to 0.1 mm. As the result of calculations, the dependence of effective length on nominal stress and radius of the notch was determined.

Recent advances on notch effects in metal fatigue: A review

“…Later, considering the fatigue failure requires a certain physical volume, namely, the fatigue failure process volume, Kadi et al, Pluvinage, and Krzyzak et al developed a volumetric approach. It is assumed that the corresponding fatigue initiation criterion is dependent on the effective stress as well as the effective distance.…”

“…Moreover, combining the local stress-strain field model with the Neuber rule, rain-flow counting method, and damage accumulation rule, they further extended the local stress-strain field approach into fatigue lifetime prediction under random loading paths. 120 Later, considering the fatigue failure requires a certain physical volume, namely, the fatigue failure process volume, Kadi et al, 121 Pluvinage, 122 and Krzyzak et al 123 developed a volumetric approach. It is assumed that the corresponding fatigue initiation criterion is dependent on the effective stress as well as the effective distance.…”