Finite element-based fatigue life prediction of a loadcarrying cruciform joint

Abstract

The aim of this study is to determine the stress intensity factor (SIF) and fatigue lifecycle of load-carrying 6 mm-thick fillet-welded cruciform joints subjected to fatigue loading conditions by means of finite element analysis (FEA). These joints are typical of automotive structures such as the mid-series rear axle of motor trucks which are sensitive to fatigue loading because of their construction and loading conditions. Finite element software was used to develop various cruciform joint models with varying geometrical dimensions, namely the depth of penetration and weld throat length, and simulation and analysis of the crack propagation were performed with 2D and 3D crack simulation software. The effect of the variations in the weld geometry with an induced crack at the weld root and weld toe on fatigue life was determined from the simulation results. The stress intensity factor values and lifecycles determined by the fracture mechanics approach were compared with the simulation results. It was shown that an increase in the depth of weld penetration and the weld size in isosceles triangles fillet weld shape for crack initiated in the weld root can decrease the stress intensity factor (SIF) and intensify the fatigue lifecycle. It was also found that linear misalignment had no significant effect on the SIF and fatigue life of cracks originating from the weld toe.

Keywords

• cruciform welded joint
• lack of penetration
• sif
• fatigue
• franc 2d/3d