Finite Element Analysis and Response Surface Optimization of a T-Shaped Fillet Welded Joint under Transverse Loading

Abstract

Welded joints remain one of the most critical and failure-prone elements of fabricated structures, yet their design is still governed largely by empirical rules that do not fully capture the influence of weld geometry on the resulting stress and deformation fields. The present study addresses this gap by carrying out a detailed finite element analysis (FEA) of a T-shaped fillet welded joint subjected to transverse loading, followed by a Design of Experiments (DOE) based Response Surface Optimization (RSO) to quantify the sensitivity of structural responses to weld geometry. A three-dimensional CAD model of the T-joint was developed in ANSYS Design Modeler and discretized using a structured hexahedral mesh of 88,336 nodes and 18,360 elements, with mesh refinement at the weld toe and interface where stress concentration is highest. A fixed support was applied at the base plate and a transverse concentrated load was applied on the vertical member, and a linear static structural analysis was performed to obtain total deformation, equivalent (von Mises) stress, shear stress and normal stress fields. The weld height (P1) and weld base (P2), each varying between 4.2274 mm and 5.7726 mm, were selected as design variables for a nine-point central composite DOE, and response surfaces were generated for total deformation (P3), equivalent stress (P4), shear stress (P5) and normal stress (P6). The results show that the maximum total deformation of approximately 0.090 mm occurs at the free end of the vertical plate, while the maximum equivalent stress of 56.064 to 67.671 MPa, shear stress of 3.52 to 4.23 MPa and normal stress of ±20.4 to ±25.3 MPa are concentrated at the weld toe. Local sensitivity analysis reveals that weld height is the dominant geometric parameter, contributing 87 to 92 percent of the variation in deformation, equivalent stress and normal stress, whereas weld base has a comparatively minor influence. The findings provide a quantitative basis for the geometric optimization of fillet welded T-joints and establish a framework that can be extended to fatigue life prediction and thermal-structural coupled analysis of welded structures.

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