Joining techniques for aluminium spaceframes used in automobiles: Part II — adhesive bonding and mechanical fasteners

Concerns regarding the environmental impact of motor vehicles are driving automotive manufacturers to develop lighter, more fuel-efficient vehicles. Such a task is further compounded by customer demands for greater performance and more luxury and safety features, all of which tend to increase vehicle weight. Aluminium spaceframe body structures substantially reduce weight relative to traditional steel monocoques, whilst maintaining essential strength and stiffness. Such structures also present a considerable challenge for fabrication in volume production. This paper considers adhesive bonding and mechanical fasteners as potential techniques for the joining of spaceframe components in volume production. Production issues pertinent to the automotive industry are discussed in conjunction with a consideration of the physical properties of the joint produced. Comparisons are also made with welding techniques discussed in Part I of this paper. Whilst the findings show that processing problems associated with each technique differ in nature, the overriding issues remain common to all. No one technique discussed was found to provide an ideal combination of low cost, process reliability, consistently good quality, good microstructural integrity, high strength, and excellent impact and durability performance. However, whilst a definitive solution is not evident, it is concluded that a combination of techniques could be utilised to great effect. Such an approach could capitalise on the benefits of certain techniques, whilst at the same time minimising or eliminating some of their more significant shortcomings.