Laser welding is widely used in the automotive industry to join various materials due to its advantages of minimal thermal deformation and high productivity, applied in different joint


configurations, such as T-fillet and single-lap. The tensile properties of these joints are crucial for the stability of vehicle bodies, prompting research into both experimental and analytical evaluations. In particular, to experimentally evaluate the tensile properties of single-lap joints, a load cell-based force and crosshead displacement are generally used. However, the reliability of crosshead displacement data is affected by machine compliance and the specimen's dimensions, resulting in low reliability of displacement-related tensile properties such as structural stiffness. This can lead to discrepancies between experimental results and numerical analysis, which are critical for evaluating vehicle stability. Therefore, this study introduces a novel numerical modeling method for predicting structural stiffness using crosshead displacement during tensile testing of single-lap joints. Additionally, it presents modeling techniques to enhance the computational efficiency of the numerical model. Laser welding was performed on two types of materials, SPFC 590 and A6061, to make single-lap joint specimens. To evaluate the structural stiffness of these specimens, lap-shear tensile test was conducted. A three-dimensional numerical model based on ABAQUS software was developed, and a modeling method involving the application of an elastic modulus in the numerical model was proposed to enhance the correlation with the structural stiffness derived from lap-shear tensile test. Furthermore, modeling techniques such as optimizing mesh size and element type were suggested to enhance the computational efficiency.