Multiaxial fatigue assessment of welded structures by local approach

The moving of vehicles on chaotic ground induces dynamic multiaxial loading on structures and mechanical components. As a consequence, early fatigue damage occurs especially in structural details such as notched areas and welded parts. A multiscale approach has been developed to design the structures against fatigue, starting from the dynamics of the vehicle and ending with the calculation of structural details using a local approach to assess the fatigue life. The methodology of the local approach developed is introduced. The evaluation of the prediction capability of this local approach is described. Finally, the application to the fatigue life assessment of welded elements is presented and compared to experimental results. The major parameters of the weld geometry that govern the material resistance against fatigue are pointed out. They concern geometrical features depending on the quality of the weld. Their influence on the weld durability is outlined and the way the proposed assessment method accounts for them in a quantitative manner is detailed.