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©Eurocopter, Patrick Penna
The increasing replacement of conventional metal structures with composites, and particularly carbon fiber-reinforced plastic (CFRP), has been an ongoing trend in airplane and helicopter engineering for years. In the area of high-performance fiber composites, sandwich structures are the preferred choice for light yet stiff designs.
The selection of the optimal sandwich structure is usually based on the different conditions associated with load-bearing capacity, production, and component design. The aerospace industry has long made use of ROHACELL® as a lightweight, structural core material that also reduces the cost of sandwich materials because of its process reliability.
• ROHACELL®, • Cover layer, e.g. CFRP, ++ very good, + good, 0 satisfactory
Criteria for the selection of the most suitable design include:
As an example, helicopter rotor blades are increasingly produced from sandwich composite materials. In this case, the ROHACELL® core assists with the placement of the UD-fibers and fabrics at the lay-up. With the defined oversize of the core the elastic behavior and the thermal expansion will generate an in-mold-pressure. It will consolidate the single layers when resin flow is starting. In the service the core stabilize the blade skins and spar from local buckling. ROHACELL® matches up the performance and the good fatigue behavior of the used composites material. To fulfill the aircraft service and production process requirements we create specifications closely with our customers. Thanks to our QM system according to AS/EN/JISQ 9100, we have established controlled production steps for foam production. We guarantee with a certificate that our material meets the specified properties.
ROHACELL® allows the cost-effective production of highly integral structures. The savings in subsequent phases, such as assembly, component testing (NDI), and coating, can be considerable. As an example, the surface quality of a foam sandwich structure (without the telegraphing effects that occur with honeycomb cores) can result in significant savings in the surface preparation for coating.
The various grades of ROHACELL®, such as WF, RIST, RIMA, and HERO offer optimized cell sizes for resin absorption, both in pre-preg processing and for resin infusion.
The PMI foam is able to withstand the typical curing temperatures of 180° C used in the aerospace industry up to compressions of 10 bar (depending on density) without significant creep. The high-temperature resistance of the material ensures that the curing pressure remains stable even in the presence of possible exothermal reactions, which guarantees the highest laminate quality. This results in reduced waste and stable processes that allow for efficient and streamlined component production.
Please contact our customer service staff for support with FEM calculation, the selection of suitable densities, and information about production parameters.
Our Sandwich Technology Center (STC Darmstadt and Shanghai) and our SHAPES production facilities (Darmstadt and Mobile) offer quick turnaround on prototype or pre-production series orders.
If you have any questions, do not hesitate to contact our regional expertsmore
The aircraft industry is facing new challenges related to production and maintenance costs. Evonik’s high-performance lightweight foam core “ROHACELL” enables to reach your target.more