Comparison of fatigue performances of gapped and partially overlapped CHS KK-joints

In this paper, a parametric numerical study is conducted to compare the fatigue performances of gapped and partially overlapped circular hollow section (CHS) KK-joints under different loading conditions. In order to obtain a more complete understanding of the fatigue performances of these two joint types, the maximum stress concentrated factor (SCF), the hot spot stress (HSS) and the predicted fatigue life for a set of selected gapped and partially overlapped CHS KK-joints which cover a wide range of geometrical parameters are determined and compared. For the gapped CHS KK-joints, their SCF, HSS and fatigue life are obtained by using parametric equations from standard design guidelines. For partially overlapped joints, since no reliable parametric equation is available, their SCF, HSS and fatigue life are obtained from a validated finite element modelling procedure. The comparison results showed that the partially overlapped CHS KK-joints are able to outperform their gapped counterparts under pure or dominating axial loadings while the reverse is true when the joints are subjected to pure or dominating in-plane bending loadings.