Energy-based low cycle fatigue indicator prediction of non-load-carrying cruciform welded joints

Abstract

A new uniform analytical formulation is proposed to predict the low cycle fatigue assessment indicator of non-loading cruciform welded joints under tensile cyclic loading considering the effects of plasticity and mechanical heterogeneity of the welded materials and geometry configurations. Particularly, weld toe of the joints is dealt with a notch rounding in order to avoid the notch tip singularity in accordance with generalized Neuber concept of Fictitious Notch Rounding (FNR). The relationship between elastic and plastic energy concentration factor of weld toe is firstly determined by the combination of notch stress and strain distribution with the increases of nominal loading, then the main parameters affecting the energy concentration factor are investigated by separating elastic and plastic stages. Stress and strain field intensities are finally expressed in terms of total energy values, which are linked to the nominal energy ones. The energy prediction function which takes into account the material and geometry factors is capable of providing a closed form analytical expression about the state of energy both under small and large-scale yielding for industrial facilities by the comparison against finite element analysis results.