Optimization of Shell Fe Modeling Parameters in the Simulation of Weld Fillets Using the Structural Stress Method

The scope of the present work consists of the optimal parameters evaluation for simulating welded structures using shell finite elements. The design variables in the proposed formulation were defined as the weld leg length and thickness of the shell element representing the weld fillet. The main goal of the optimizations was to find a range of thickness/leg length which would not change significantly the first natural frequencies, and still deliver results similar to the ones obtained using a solid model. This kind of model is widely applied to dynamic problems in which the structural stress method (hot-spot approach) is employed for fatigue analysis. Sequential linear programming were performed in T-shaped structures with different structural details (FAT class). The structures of study were represented with constant section, different plate thicknesses and depths. An interior point algorithm was employed in the parametric optimizations performed. Different modeling techniques are suggested for each FAT class tested. A comparison with three well established methodologies presented in standards and the literature is also exposed. The differences in the results are compared for first natural frequencies, total mass and hot spot stress.