Fatigue Life Prediction for Adaptable Insert Welds between Sheet Steel and Cast Magnesium Alloy 2016-01-0392

Joining technology is a key factor to utilize dissimilar materials in vehicle structures. Adaptable insert weld (AIW) technology is developed to join sheet steel (HSLA350) to cast magnesium alloy (AM60) and is constructed by combining riveting technology and electrical resistance spot welding technology. In this project, the AIW joint technology is applied to construct front shock tower structures composed with HSLA350, AM60, and Al6082 and a method is developed to predict the fatigue life of the AIW joints. Lap-shear and cross-tension specimens were constructed and tested to develop the fatigue parameters (load-life curves) of AIW joint. Two FEA modeling techniques for AIW joints were used to model the specimen geometry. These modeling approaches are area contact method (ACM) and TIE contact method. ACM representation was used to calculate forces and moments for the joints and then calculated the structural stresses while TIE contact representation was used to calculate principal stresses for the joints. The load-life curves were used to construct the appropriate S-N curves based on ACM and TIE contact for different specimen configurations. Then both the S-N curves were used to predict fatigue life of AIW joints in the front shock tower structures. The test results and the prediction results were well correlated.