Over the past several decades, significant gains in automobile fuel efficiency have been achieved through down-sizing, aerodynamic design and drive train improvements. As performance limits are approached in these areas, aluminum is being used to further reduce body weight by up to 40% compared to steel. In anticipation of the continued demand for more fuel efficient automobiles, aluminum sheet component unibody and extrusion and cast component space frame designs have been studied to address joining and structural performance. Joint geometries unique to specific body designs clearly illustrate the need for close linkage of the design and assembly functions.
Joining and assembly methods that provide static and dynamic structural integrity, 15 to 20 year durability and that can be integrated into robust manufacturing systems are key to aluminum usage for auto body structure. The applicability of a wide variety of joining methods from the more common resistance spot and arc welding processes to the newer methods of adhesive bonding, magnetic staking and riveting are examined. A review of the technical attributes and issues associated with each method is presented. Comparisons are drawn between the various joining methods on the basis of structural performance, environmental performance, manufacturing issues and economics.
