An Experimental Investigation into the Fatigue Behavior of Spot Welded Tensile Shear (TS) Specimens

The resistance spot welds (RSWs) are extensively used in many industries especially automotive industry as a joining process of sheet metals due to its flexibility and adaptability to automation. In addition to easy automation capability, there are many more advantages that this joining process offers in the attachments of thin sheet body components, such as effectiveness, low cost and reliability. Despite all the favorable properties of this manufacturing process, the spot welded sheet metals are prone to mechanical fatigue failure especially under cyclic sinusoidal loadings. Therefore, understanding and elucidating the fatigue phenomenon of the RSWs are crucial during the design phase, in terms of estimating and preventing undesired failure conditions. However, in the design procedure, there exist considerable amount of challenges to be overcome to analysis and accordingly predict the fatigue failure in the sheet metals connected by spot welds, among them it can be counted electrode wear-down, non-uniform sheet metal forms, defected or incomplete weld nuggets. Many of these faults cause non-uniform stress distributions inside the sheet metal and make it difficult to estimate fatigue failure. Thereof experimental work, in most cases, shines as a viable option in the fatigue analysis. Within the scope of this work, an attempt is made to examine the fatigue phenomenon of the spot welded sheet metals experimentally. For this purpose, tensile shear (TS) type spot welded test specimens were utilized. A series of fatigue life tests were conducted on the previously prepared samples and the deformed test specimens were examined. The experimental results were compared with those of similar research studies available in the literature. It was observed that the outcomes of the present work are reasonably consistent with the literature results.