Effect of specimen dimensions on mechanical behavior of resistant spot welded aluminium lap joints

A study was carried out to examine the effect of specimen dimensions on mechanical behavior of RSW welded joints. A full factorial Design of Experiment (DOE) approach was applied to the experimental process and analysis stages. Aluminium alloy AA5754 sheet in various thicknesses was used to form symmetrical and asymmetrical joints. Single lap shear test geometry with three dimensional changes; width, length and overlap at two-level, was tested throughout the project. The results demonstrated that for both symmetric and asymmetric stacks, the width of the specimen had a statistically significant effect on both failure mechanism and shear strength value of such joints; a strong interaction effect between length and overlap of the specimen on joint shear strength was observed. Although the strength variation is not substantial in engineering terms, the change in failure mechanism is significant and the results are useful in optimization of lap shear test standards and in comparison of joint strength obtained from different investigations with different specimen dimensions. It is also helpful in assisting structural and manufacturing engineers in design and development of RSW of aluminium for application.