Aircraft manufacture requires optimal design at low cost and makes corresponding demands on the composites industry. Sandwich components satisfy the requirement of low weight combined with the highest possible rigidity in, for example, spoilers, flaps and paneling. Evonik Industries, Germany, is now pleased to present its new product ROHACELL® HERO as a structural foam core for sandwich components, at Composites Europe 2014 (booth F20, hall 8b) in Düsseldorf. This light core material has been specially developed to meet the stringent requirements of aircraft manufacturers on damage tolerance and damage visibility after impact events such as bird strike or hail. Composite components using ROHACELL® HERO are also significantly less expensive to produce than counterparts with a honeycomb core structure.
High-rigidity components currently use honeycombs as core material. Due to the open hexagonal cells and low inherent rigidity, fabrication is complex and expensive. Foam cores, on the other hand, require only a simple one-shot manufacturing process and save on core filler or adhesive film; this reduces processing time, costs, and even weight. A direct weight and cost comparison has been carried out with a typical honeycomb design on a nose gear door of the Do728. By replacing the honeycomb core by a ROHACELL® HERO foam core and changing to an infusion process, the cost of the CFRP component was reduced by 25 percent and its weight by 19 percent.
Another problem with honeycomb structures is water accumulation in the cells during flight. The resulting increase in weight and, as a possible secondary effect, debonding of the covering layers necessitate repairs or replacement of the component. The foam design solves these problems, considerably reducing the airlines’ operating costs.
The required damage visibility for, for example, hailstones, runway debris, or tool drops has been confirmed by impact tests with impact energies of up to 35 Joule, carried out by the Fraunhofer IWM Institute in Halle. Even for damage inflicted with an open covering layer and at relatively high impact energies, the damaged area remains impermeable thanks to the closed-cell ROHACELL® foam; this means that spreading of the damage due to water penetration and further spreading by frost, as occurs in the honeycomb, is prevented. And in case of damage, repairing the foam sandwich is a simple matter.
Evonik, the creative industrial group from Germany, is one of the world leaders in specialty chemicals. Profitable growth and a sustained increase in the value of the company form the heart of Evonik’s corporate strategy. Its activities focus on the key megatrends health, nutrition, resource efficiency and globalization. Evonik benefits specifically from its innovative prowess and integrated technology platforms.
Evonik is active in over 100 countries around the world. In fiscal 2013 more than 33,500 employees generated sales of around €12.7 billion and an operating profit (adjusted EBITDA) of about €2.0 billion.
In so far as forecasts or expectations are expressed in this press release or where our statements concern the future, these forecasts, expectations or statements may involve known or unknown risks and uncertainties. Actual results or developments may vary, depending on changes in the operating environment. Neither Evonik Industries AG nor its group companies assume an obligation to update the forecasts, expectations or statements contained in this release.