Abstract
AbstractA new traction force approach (TFA) for weld root fatigue analysis of complex cruciform connections is introduced. The approach defines the local nominal weld stress by using a solid element model and connecting the welded parts only from the toe and root lines. This enables the peak weld forces to be distinctly defined. The TFA approach was validated with a fully connected solid element model. As a comparison, the same analyses were performed for a shell element model. The study shows that the approach that is introduced here gives a good estimate for the local weld force with a maximum error of 10% while the commonly used shell element model greatly overestimates the peak weld force, particularly for complex connections. The analysis of fatigue‐tested connections showed that by using TFA, instead of an approach based on overall nominal weld stress, the scatter range index is reduced from 3.71 to 1.98. The TFA approach is much more efficient compared to conventional approaches because of the low pre‐ and post‐processing effort.
Highlights
In welded structures, where scantlings are defined on the basis of stability or stiffness criteria, e.g., buckling, welded connections do not necessarily require matching strength with the connected member
The results show that FAT36 found from standards and recommendations for analysis based on the nominal weld stress match the local nominal weld stress results well
This paper introduced a new traction force approach (TFA) for efficient fatigue analysis of load-carrying cruciform connections in large complex structures
Summary
In welded structures, where scantlings are defined on the basis of stability or stiffness criteria, e.g., buckling, welded connections do not necessarily require matching strength with the connected member. If a high number of such joints exists, considerable production savings can be achieved by reducing the number of welded stiffeners and by using single bead fillet welds instead of, e.g., full penetration welds This often means that the joint becomes unsymmetrical and the fatigue strength of the connection is seriously affected as the fatigue initiation site changes from the weld toe to the weld root. Complex connections have a lack of symmetry planes, eccentricity of welds, thin intermediate plates, and stress concentrations as a result of the intersecting welds One example of such a connection can be found in cruise ships, where a rectangular pillar is welded to the deck and sides of the RHS profile are aligned with an underlying web, girder, and flat bar; see Figure 1. According to present fatigue design standards and recommendations, the nominal weld stress approach is the most commonly adapted approach for the fatigue analysis of a weld root.[1,2,3,4] The nominal weld stress is defined as the averaged stress at the weld σw 1⁄4
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