Head of the group: Dr.-Ing. Wilfried Liebig
Composing the future of composites ...
Hybrid materials, i.e. composites or compounds, made or joint from several materials play a very important role in industrial application. The aim of hybrid lightweight construction is the mass reduction of lightweight structures and simultaneously the increase of performance of the construction, which is reflected in higher strength, stiffness or improved fatigue strength. In addition to steels with a comparably high stiffness and density both light metals like aluminium and magnesium as well as polymers feature a high potential for lightweight construction due to their low density. One major advantage of the last-mentioned material class is furthermore the excellent processability. A disadvantage of all lightmetals and polymers is the low stiffness which may be increased by reinforcements like ceramic or metallic fibres or particles increasing both absolute and specific stifness.
The combination of different materials in compounds or composites results in the evolution of an interface which is essential for the composite's performance as it provides the internal load transfer between the composite's components.
Future materials ...
The relevance of hybrid materials and lightweight structures in industry has increased during the last years. The BMW hybrid structure concept featuring an aluminium front end joint with a steel structure and the use of composites in aircraft industry are prominent examples. The composite use in aircrafts cumulates in the concept for A380 having a composite content of 25 %. In addition to glass fibre reinforced aluminium ("GLARE") GFRP are used fur structural parts. This content will be outnumbered by future aircraft concepts containing 50 % of composites in complete fuselage sections.
More than just a combination ...
The development of modern tailored composites and compounds depends on basic knowledge of their composition, their structure, their synthesis and their processing for each component. This previous history of a materials influences the microstructure, the interface evolution and potential microstructure defects, for example grain size or morphology and, furthermore, the character of the composite's components, their volume contents, their constitution and their metallurgical affinity. These facts suggest the physical properties of a composite material. Vice versa, it is possible to tailor the mechanical properties of composites.
Core comptence of the group is the deduction of correlations between processing, microstructure and properties for composites and copmounds. For that purpose, their mikrostructure is characterised using metallography and microscopy. The microstructure is correlated with mechanical properties obtained from different mechanical testing procedures. From these results theoretical material models can be derived which allow for the optimization of the material design as well as for a prediction of component's properties.