Hybrid joining in automotive applications

The objective of the ongoing Hybrid Joining Project, funded as part of the Automotive Lightweighting Materials Program, is to develop new experimental methods and analysis techniques to enable hybrid joining to become a viable attachment technology in automotive structures. This will be accomplished by evaluating the mechanical behavior of a representative structure consisting of a composite hat section attached to a metal sheet under bending loads. Three attachment methods are evaluated including riveting, adhesive bonding, and combination of riveting and adhesive bonding. Experimental results for quasi-static, fatigue and creep tests are presented. Quasi-static tests were conducted at room temperature and at -40°C. Joint failure was not observed for the quasi-static tests, however the attachment technique affected both the stiffness and failure mode of the structure. Some specimens incurred significant joint damage in the fatigue tests prior to catastrophic failure. Finite element models (FEM) can currently predict the behavior of the structure up to the point of damage in the composite. Comparison of experimental results and FEM is presented. The results and observations obtained from this project will facilitate incorporation of lightweight composite materials into automotive structures. Innovative design using dissimilar materials and effective joining techniques will result in reduced vehicle weight and fuel consumption.