CD Laboratory for High efficient composite processing

Composites are plastics that combine the high strength of reinforcing fibres with the mouldability and lightness of a polymer matrix. Their properties depend crucially on the production process, which is to be optimised here.

The combination of lightness and resilience makes composite materials interesting for the entire mobility sector and for aviation in particular. However, the processes involved in the production of these materials are complex; residual stresses and deformations can occur and must be avoided. Process simulation is therefore a crucial component in the design of new materials.

Unlike most other materials, composite materials are only created during the production of the entire component. For example, entire fuselage segments of aircraft with a diameter of around 9 metres are produced using a single "mould": The reinforcing fibres impregnated with plastic resin are correctly aligned in the mould and then cured without any defects.

This process is very time-consuming and cost-intensive, so it is important to organise it in such a way that the end result is reliably good components: The aim is to avoid rejects, but it is also about optimising the process to reduce manufacturing costs.

To this end, the research team is first looking at the behaviour of the reinforcing fibres and the polymer resins during production. This involves properties such as compaction (compacting), mouldability (drapability) and permeability to liquids and gases (permeability). These properties are dependent on temperature and pressure as well as the time given for curing. How these process variables can be optimised is one of the research topics.

There is also a need for research into manufacturing techniques for the exact positioning and orientation of the reinforcing fibres. This is because even slight deviations from the desired orientation lead to a change in the material properties, for example a reduction in stiffness.

In order to be able to control ongoing processes, research is also being carried out into measuring methods for what actually happens in the mould: at what speed does the resin fill the mould, does it cure properly (e.g. without air inclusions), how does the permeability of the fibres change during the process, etc.?

Economic aspects are also taken into account: A new tool for cost modelling should be able to predict the costs of production at an early stage of development. This is important, as it determines whether the decision is made to invest in the development of a composite material or to work with metal.