Integrated lay-up process for sandwich structures with monolithic areas

The aerospace industry continuously strives to reduce emissions through greener, more efficient aircrafts. This development will probably be further accelerated with government plans for CO2 neutrality. We already see a high level of development activity across major industry partners with a focus on alternative propulsion technologies and the scaling-up of lightweight construction.

In this regard, composite sandwich structures are a quite versatile tool. They offer high mass specific stiffness (stiffness-to-weight ratio), rendering them suitable for the demanding weight-restricted applications on aircrafts. In previous articles, we have already given some insights on how Fiber Patch Placement (FPP) technology can automate the lay-up of a challenging multi-material mix including adhesive film, glass and carbon fiber directly onto honeycomb sandwich cores.

Certain components for aircrafts require exclusively non-electrically conductive materials to prevent the electromagnetic sensors from interference, ensuring a clear, strong signal transmission. This is particularly important for unmanned aerial vehicles (UAV’s) and urban air mobility (UAM’s) concepts with an increased number of sensors, but of course it also play a significant role in any commercial or military aircraft. The most common material for such applications in the commercial aviation sector is glass fiber. The principal design and construction of components that house electromagnetic receivers or transmitters are often identical: skins of material on non-metallic cores integrated with monolithic areas to fixate the component to the frame.

Today’s production process for these components is usually fully manual. The sandwich areas are placed on a ply-by-ply lay-up strategy by trained composite technicians. For the monolithic areas, many manufacturers are using pre-stacked kits to reduce the number of individual placements. However, those time savings are partially offset by the higher efforts to integrate the pre-stacked kit. No matter if with or without pre-stacked kits: the overall process is slow, expensive, and difficult to scale.

Cevotec’s Fiber Patch Placement (FPP)-based SAMBA production cells can handle these powerful, but complex lightweight components within one single system and process. Illustrated with a demonstrator part produced earlier this year, different sizes of plies and patches were processed in one integrated process for the sandwich portion and the monolithic area of the part.

In addition, the laminate design of the component was optimized. The skins of the sandwich structure are designed with as few plies as possible, whilst the monolithic areas are designed with pre-stacked patches. This combined approach is fully supported by the FPP-specific ARTIST STUDIO software. It shortens production time and offers flexibility for laminate adjustments in the development process whenever needed – with significantly reduced effort compared to today’s processes.

Bringing together the material flexibility with the recent advancements in design combinations, Fiber Patch Placement has become an important tool for manufacturers of high-performance, multi-material aerostructures. Typical savings for production time and cost range from 20% – 60% compared to today’s manual processes.

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About Cevotec:

Munich-based automation specialist Cevotec offers one of the world’s most advanced production systems for complex fiber composites. At the intersection of composites, mechanical engineering and software, Cevotec develops production systems and software based on Fiber Patch Placement (FPP) technology: SAMBA and ARTIST STUDIO. The systems, which are particularly suited for automated fiber placement on complex 3D geometries, process carbon fibers, glass fibers, adhesive films and other technical fibers. They can be used for a broad range of applications. Such flexibility is particularly appreciated by customers from aerospace and med-tech industries, who realize cost and time savings of 20%-60% when switching from manual processes to FPP.