Composite technology

Composites are composite materials created by combining two or more materials. They usually consist of a carrier material matrix and reinforcing fibres that give the material strength and stiffness. The matrix can consist of various resins, polymers, silicates, or ceramics, while glass, carbon or aramid fibres are often used as reinforcing elements. By combining different materials, the performance of products can be improved, weight reduction can be achieved, and at the same time, the desired mechanical, thermal or chemical properties can be guaranteed. In terms of application context, composites can be found in the aerospace, automotive, construction, electronics and medical industries.

The advantages of composite materials are diverse and make them attractive for numerous applications in different industries. The following benefits result from the use of composites:

Lightweight and energy efficiency: Using composites in vehicles, aircraft, ships and other means of transport can reduce the overall weight. This reduces energy consumption and greenhouse gas emissions.

Advanced design: Composites enable the design and manufacture of complex shapes and structures that are impossible with conventional materials such as metal. This leads to innovative designs, better performance and optimised functionality in various fields, such as mechanical engineering and aviation.

Corrosion resistance: Composites are insensitive to corrosion and chemical influences. Compared to traditional materials such as steel or aluminum, they require less maintenance and longer service life, resulting in cost savings.

Sustainability: Composites offer the opportunity to develop more sustainable products. By reducing weight in vehicles and aircraft, fuel consumption can be lowered and CO2 emissions reduced. In addition, composites can also be recycled and reused.

Improved performance and safety: Composites offer exceptional strength and stiffness. This makes them ideal for applications requiring increased stability and enhanced safety, such as crash elements in vehicle construction.

There are various manufacturing technologies for the production of composites

From traditional lamination processes to classical injection or pultrusion processes to automated tape laying processes Automated Fiber Placement (AFP), Automated Tape Laying (ATL) and Fiber Patch Placement (FPP), there are numerous options to meet the requirements of different industries. The selection of the appropriate manufacturing technology plays a crucial role in realising composite materials with the desired properties and meeting specific application requirements.

In hand lay-up, several layers of fibre reinforcements are impregnated with resin and draped over each other. This is followed by a vacuum build-up, which discharges excess resin and guarantees dimensional stability during curing. Afterwards, curing takes place under negative pressure and heat in an oven. Alternatively, prepreg can also be used. This is a pre-impregnated fibre semi-finished product, which makes manual brushing with the matrix material unnecessary. But even in this case, a vacuum build-up is necessary for curing in an autoclave or oven (for out-of-autoclave prepreg).

Injection or infiltration processes rely on the use of dry semi-finished products from which complex preforms are manufactured. The preforms are then placed in closed moulds and injected with resin (e.g. resin transfer moulding). Alternatively, the preforms are packed in a vacuum bag and connected with an infiltration set-up. In this case, a vacuum is built up via hoses connected to a vacuum pump, through which the liquid resin is sucked into the preform via a supply line until it is filled. Typical examples are the Vacuum Assisted Resin Infusion process (VARI) or the membrane-supported Vacuum Assisted Process (VAP®).

In addition to these processes, the main focus of Fraunhofer IGCV is on Pultrusion, Automated Fiber Placement, Automated Tape Laying and Fiber Patch Placement.

The manufacturing technology of pultrusion is a continuous process for producing fibre-reinforced plastic profiles. In this process, fibres are drawn through a resin bath and then through a heated moulding tool and cured into profiles in a continuous process.

Automated Fiber Placement (AFP) is a robot-assisted process in which tows (narrow, defined, cut-to-size semi-finished fibre products) are used in various forms (towpreg, prepreg, dry or tows with thermoplastic matrix). The robot places the tows specifically on a laying tool, whereby the tows are pressed onto the laying tool via a roller which is attached to the robot head. This enables the production of complex and final-contour preforms which, depending on the material, must then be cured in an autoclave, consolidated in a press or injected with resin and cured.

Similar to this process is Automated Tape Laying (ATL), which uses wider tapes instead of tows. This allows higher lay-up rates to be achieved at the expense of less complexity. With Fiber Patch Placement (FPP), only so-called patches are used instead of reel material. The length of these patches is limited to the gripper on the laying head of the Fiber Patch Placement system, but they enable the production of very complex preforms that cannot be realised with the previous systems.

Numerous parameters, such as material selection and material properties, play a role in the production of composites. Topics such as testing technology, the analysis of relevant data (efficiency and balancing) as well as studies on manufacturing and production planning are therefore also a central component of our research work in the area of composites.

In the area of efficiency and balancing of composite materials, we are working on enabling an ecological assessment of high-performance fibre composite structures. Models are being developed to estimate the energy and time-dependent demand for the production of components. The environmental and economic evaluation of different manufacturing process chains serves to find sustainable and economically sensible solutions.

Overall, composites research focuses on further optimising the properties and processes of these versatile materials to expand their applicability in diverse industries. To this end, we operate state-of-the-art research infrastructures, including laboratories and facilities for process simulation, prototyping and characterisation of composite materials - an essential contribution to testing and optimising manufacturing technologies.

Get detailed information about our research work in the field of composites through selected reference projects here.

Our experts work intensively on researching and developing innovative recycling processes for composite materials. Our goal is to extend the life cycle of composite materials and reduce their environmental impact. In this context, the topic of circular economy plays an important role. Because by recycling composite materials, a closed loop can be created in which waste becomes new raw materials and products. This promotes sustainability and contributes to a resource-conserving economy:

• Efficient, high-quality separation of fibres and matrix without material degradation.
• Single fibre characterisation
• Fibre preparation, surface functionalisation and recoating
• Textile semi-finished products from secondary fibres
• Debond on Demand
• Design to Recycling

More info on composite recycling | Contact: Jakob Wölling

We are also committed to raising awareness of the importance of composite recycling in industry and society. Therefore, we organise training opportunities to disseminate knowledge and information on sustainable composite recycling and build partnerships with industry partners and research institutions.

More info on further education in the field of composites!