One cubic meter of steel weighs 7850 kilograms. Aluminum weighs 2700 kilograms, while ROHACELL® can be as light as 32 kilograms – and is therefore a flyweight in contrast to metals. As a substitute for metal construction, so-called sandwich designs with ROHACELL® foam core are an important driver of greater resource efficiency and the avoidance of emissions.
The use of composite structures has been a trend in many industries for years. In this context, sandwich constructions are the preferred choice for light, yet stable construction. The structural foam ROHACELL®, based on polymethacrylimide (PMI) chemistry, is used as a core between fiber reinforced plastic skins. "Because ROHACELL® has excellent mechanical properties over a wide temperature range and at low densities, the high-performance structural foam is ideal as a core material for composite structures", says Kai-Martin Krüger, Head of Evonik's product line Performance Foams. In addition, lightweight constructions save more energy and thus contribute to environmental protection.
ROHACELL® is in great demand for a broad range of applications: from aerospace to sports, electronics and communication systems to automobiles and many other areas of application.
Urban air mobility
Although flying on vacation or travelling for business is currently almost impossible due to the pandemic, aviation remains one of fastest modes of transportation and is constantly being optimized. For a long time, the aviation industry has relied on the lightweight structural foam ROHACELL® as a light but robust alternative to conventional metal materials. For example, helicopter rotor blades are increasingly produced with the structural foam. The sandwich construction stabilizes the rotor blades and protects them from local buckling.
In the future, ROHACELL® will be used in autonomous air taxis.
In competitive sports it is not only physical fitness that counts, but also the right equipment. Whether you are building bicycles, skis or ice hockey sticks – composite structures with a ROHACELL® core and cover layers made of fiber plastic composites (e.g. carbon fiber reinforced plastic) are perfect for lightweight, robust and durable sports equipment. The structural foam core makes bicycle rims and skis lighter, while the combination with face skins made of fiber plastic composites makes them more resistant at the same time. Resistance is particularly important in sports like ice hockey. With ROHACELL® the sticks become more stable, so that they do not break even under rough playing conditions.
Electronics and communication systems
In flight operations, radar devices perform a variety of navigation and positioning tasks. The cover of radar or other antenna devices, also called radome, is usually designed as a composite structure. Due to high speeds and exposure to foreign bodies, the covers must meet the highest mechanical requirements, while at the same time not interfere with radar beams. The high-performance structural foam and its dielectric properties meet these requirements. For the same reason, it is also ideally suited for spacers in antennas.
By the way: ROHACELL® is also used in the loudspeaker membranes of mobile phones.
Lightweight not only provides advantages in the air, but also on the roads, the rails or at sea: ROHACELL® can be used in many modes of transportation such as ships, trains or automobiles. To protect the climate, environmentally harmful CO2 emissions require reduction worldwide. Lower weight cars, trains or even ships save fuel and lower emissions at the same time. Lowering vehicle weight is of particular interest for electric cars as this can make a significant contribution to downsizing the power train and improving the range. You will also find ROHACELL® in the fast lane of high-performance motor racing. Sports cars and Formula 1 vehicles already use sandwich construction to achieve further improvements in acceleration and handling due to lower weight.
In addition, there are many other areas of application for ROHACELL®. A special one is in medical technology equipment. ROHACELL® as a core in patient tables for X-ray and CT scans helps to reduce the necessary radiation exposure in diagnostic procedures, thus helping to avoid adverse impacts on human health while providing impeccable image quality that enables precise diagnosis. Even wind turbines, both traditional onshore and expanding offshore, with foam core in their blades are lighter in weight. Turbine loads in structures of this size are very high, so a blade with less weight reduces the load and extends the service life of the turbine.