Consideration of manufacturing effects on fatigue design for welded chassis components

The manufacturing process of chassis components determines variations in the formation of welded joints, which has a direct effect on the fatigue strength of chassis components in cyclic component tests. These influences are evaluated with the method “Design of Experiments” under fully reversed bending and axial loading at deduced T- and lap joints with a sheet thickness of 2.50 mm. Afterwards, the decisive geometry sizes are identified by measurements of the weld seam geometry and applied to FE models. By using the notch stress approach in combination with the stress-averaging method according to Neuber, the identified geometry sizes and their effects can be validated. For this purpose, the measured average radius is used for the weld toe and a radius of 0.05 mm for the weld root. Furthermore, the stress field at the notch is evaluated by stress values from a FE model to consider the stress gradient induced by the stress type. Thereby, the same design S-N line can be used for the fatigue strength assessment of weld toe and weld root failures.