Integral Foam Construction for Cabin Components

Commercial aircraft paneling currently consist of thermoset sandwich components containing glass wool packages for acoustic and thermal insulation purpose. The side wall panel production is an isothermal pressing process in which the aramid honeycomb core is covered by two glass-reinforced phenolic resin top layers. Due to the open structure of the honeycomb core a manual refinishing process is needed to obtain the required surface qualities. The application of a decoration foil on the front of the panel generates optic and feel that is wanted. Afterwards, a glass wool package for acoustic and thermal insulation is applied on its backside.  Furthermore, an additional glass wool package is mounted on the fuselage to ensure the necessary acoustic and thermal insulation properties. Glass wool packages are also to be found in the hull structure. In between both packages different additional systems are installed, e.g. riser ducts or electric wiring.  Due to adverse conditions, condensation formation in this area during the flight could be a problem. The insulation packages absorb the water which leads to weight gain and a high risk of mold formation.

In the scope of the aeronautical research project SOPHIA – Smart Processes and Optimized Designs for High Production Cadences (funding reference 20X1715D), a team consisting of two companies and four research institutes investigates new construction methods and production technologies for cabin components. To reduce process times and efforts regarding rework, assembly and maintenance, a thermoplastic design with high integration degree is pursued. The use of thermoplastic polymers offers numerous advantages over thermosetting design methods, considering the possibility of multiple melting , which permits the production of semi-finished products that can be stored indefinitely and formed, joined and decorated simultaneously or in a further process step. The use of thermoplastic particle foams further combines the high lightweight potential of these foams with the possibility of add-on part integration, e.g. insulation properties due to high pore fraction and duct implementation with sophisticated mold designs.

Combining the particle foam technology with hot press or thermoform processes enables efficient forming and joining processes. In particular, thermoforming process is characterized by by short heating- and cooling cycles. In these processes semi-finished products can be heated contactless by infrared radiators and subsequently formed in a cold tool. By using purely thermoplastic top layers forming, joining and decorating process can take place simultaneously, many process steps can be merged, thus, shorter process times can be achieved.

Within the framework of SOPHIA project, IVW is responsible for the investigation of flame-retardant polymers for top layer application. Focus lies on manufacturing of semi-finished products, development of forming and joining processes and process simulation. Selection of suitable polymers has to consider both, lightweight properties as well as ambitious flame-, smoke and toxicity regulations. Extensive investigations of matrix compatibility and process parameters were conducted. Currently, the topical focus lies on the investigation of the properties of open-pore inherent flame retardant polymer foams during hot pressing processes. During the contact of foam and mold the polymer melts and creates a skin. Thereby, a micro sandwich structure is generated. The influence of tool temperature, press force, and process time on the compaction and thickness of the resulting polymer layer will be investigated.

The process design and optimization is conducted in close cooperation with Neue Materialien Bayreuth GmbH, where the polymer foam properties are being investigated and customized.

 Project partner:

• Diehl Aviation GmbH
• Fraunhofer-Institut für Bauphysik
• Institut für Flugzeugbau, Universität Stuttgart
• Institut für Verbundwerkstoffe GmbH
• Neue Materialien Bayreuth GmbH
• Amphenol-Air LB GmbH

On the basis of a decision by the German Bundestag the project “SOPHIA – Smart Processes and optimized Designs for high Productions Cadences" is funded by the Federal Ministry of Economic Affairs and Energy (BMWi) (within the scope of the aeronautical research programme V-3, funding reference 20X1715D).

Further informationen:
Dipl.-Ing. Maximilian Salmins
Institut für Verbundwerkstoffe GmbH
Press & Joining Technologies
Erwin-Schrödinger-Straße 58
67663 Kaiserslautern
Phone: +49 631 2017-340
E-Mail: maximilian.salmins@ivw.uni-kl.de