Robustness Optimization of Welded Structure for Minimized Mass and Target Fatigue Life

There is increasing need to reduce CO2 emissions and energy consumption, rising motivation for light weight design of load carrying structures of vehicles. However, as the structures are designed lighter, the stresses and risk of fatigue at welds tend to increase. Fatigue of welds is sensitive to variation of manufacturing quality. In this presentation, the effect of misalignment of welds on the fatigue life of an example steel structure is studied together with minimization of the structural mass. This is done using robustness optimization by RAMDO software. The robustness optimization enables minimizing the mass of the structure and still achieving the target reliability for the fatigue life. Local detailed weld FE-model is coupled with coarse shell element model of the structure, and the coupled FE-models are used in the optimization. Two ten piece series of welded structures were manufactured, from which the distributions of misalignments were estimated after dimensional measurements by a coordinate measuring machine (CMM). Presenter: Petteri Kokkonen - Senior Scientist, VTT Technical Research Centre of Finland Ltd. Presenter: Peter Benzie - Senior Technical Specialist NVH, Altair