Lightweight materials and structures - today and tomorrow
The present work gives fundamental overview about the modern lightweight materials and their applications for reliable structures like aircrafts, vehicles and trains. Almost all innovative products are also characterized by energy efficiency and sustainability of structures. In nearest future a lot of composites with carbon fibers and different laminates will be used in production scale. Lightweight materials such as aluminum and magnesium based composites will have a huge potential for the future development.
Another trend to reduce the weight of the structure is the increasing of stiffness by structured sheets, extruded Al-Panels or Al-Foam-Sandwiches (AFS). In the last one Al offers not only its low density and the good mechanical properties but also the advantage that it is extremely suitable for foaming due to the relatively low melting point. Furthermore, it offers the particular possibility of manufacturing a strong, large-area material joint-AFS, due to the utilisation of a similar material combination – conventional or structured sheets in the cover layers and aluminium foam in the core. The semi-finished AFS products can be processed flexibly in the still unfoamed condition as well as in the already finish-foamed condition. Investigations into the welding and the resulting joint properties are necessary so that the advantages of AFS can be used effectively as a material for welded structures. In the presented paper, systematic investigations were conducted into the weldability of AFS in the foamed and unfoamed conditions, mechanical-technological properties of the joints (joining nodes) were established and FEM modelling procedures were carried out.
The problem of joining for such type of similar and especially dissimilar materials can be solved preferably by means of Friction Stir Welding (FSW). The FSW developing to Impulse Friction Stir Welding (IFSW) and the influence of impulse parameter on the mechanical properties of the welded joints are discussed in the third part of the presentation.