By increasing the strength of the steel, the thickness can be reduced while still retaining the same load-carrying capacity. However, to make full use of this in a vehicle structure application, attention must be given to the fact that the modulus of the material and the fatigue properties of welded joints remain essentially constant, even though the strength of the base metal is increased. The need for more integral solutions with fewer parts and joints becomes important and likewise a better understanding of the mechanisms that reduce the negative effects of joints on structure properties. Aluminium offers a weight reduction potential based on low density but has reduced modulus compared with steel. It is well established for applications in aircraft structures and is starting to be used for large ship hulls.
Automotive applications are mainly castings in the propulsion and chassis systems.
Potential in primary structures is limited by cost and further research is required. Fibre composites and sandwich materials offer high strength, low density and high stiffness but face limitations in terms of production technology and cost. These are also the main reasons for the limited use in automotive applications. Glass fibre composites for pleasure craft structures represent the volume structural application. Advanced military ship structures in carbon fibre composites are at the technological forefront.