Molded Carbon Composite Brackets Lighten Aircraft

DN Staff

February 17, 2010

3 Min Read
Molded Carbon Composite Brackets Lighten Aircraft

A new compression molding process coupled with high-performance carbon-reinforcedthermoplastic composites target lightweight applications, such as assemblybrackets, on aircraft.

Greene, Tweed & Co. of Kulpsville, PA, says Xycomp(R) DLF can be molded into highly complex shapeswith three-dimensional features such as ribs, bosses, gussets and flanges. TheDLF stands for discontinuous long fibers. Carbon fibers are used to reinforceone of three engineering thermoplastics depending on the application:polyetheretherketone (PEEK), polyetherketoneketone (PEKK), or polyetherimide (PEI).

Components are formed in a compression molding process called ProFusion(TM)that was developed by Greene, Tweed, whichinstalled one ProFusion(TM) press last year, and is installing twomore this year.

"This is all about metal replacement," says Tim Greene, global compositesproduct manager at Greene, Tweed.

Design freedom of the ProFusion(TM) process enables variedsection thickness or stiffening features that can be added in higher loadingareas or removed in lower loading areas to optimize weight savings. Xycomp(R) DLF components also offer molded-in insertsfor attachment points, heat sinks and bosses for integration of multiplecomponents and reduction of secondary operations such as drilling or bonding.Greene, Tweed also says performance isenhanced. Greater than 100 percent increases in torque and pull-out performancehave been validated versus bonded inserts, according to the company.

Xycomp(R) DLF components are up to 80 percentlighter than metallic materials and are said to offer superior matrix toughnessover thermoset composites.

Hundreds of brackets are used throughout airplanes, and havetraditionally been made of steel or aluminum. New aircraft designs, such as theBoeingDreamliner 787 and Airbus A350, use more composite materials and place amajor premium on weight reduction. Traditional composites, made with thermosetplastic as matrix materials, could not be designed with enough specificgeometry to be used in smaller, more complex components such as aircraftbrackets. The thermoplastics in Xycomp(R) DLF allow better flow than thermosets, but arestill constrained by high fiber loadings.

Temperature Control

Greene, Tweed's DLF material allows forspecified fiber lengths for optimal material flow and performancecharacteristics, and uses specialized temperature cycles to control heating andcooling of the compound in molds. No other details were available.

Greene, Tweed says the material showsexceptional resistance to aerospace solvents, high temperatures and highvibrations for extended component life and reduced maintenance requirements. Xycomp(R) DLF can be recycled and has exceeded allFederal Aviation Administration and airframe interior requirements withexcellent FST (flame, smoke and toxicity) performance, in addition to passing15 minute burn-through tests.

Another composite material, Xycomp(R) 4125, is used to make an aircraft seat assemblythat reduces weight 30 percent compared to an aluminum version. In statictesting, components made from Xycomp(R) 4125 tested more than 40 percent better thanaluminum components.

Greene, Tweed was founded in 1863 as anindustrial distribution business. It introduced the G-T Ring, for use in thelanding gear of the F-4 Phantom in 1964. The company specializes in thedevelopment and production of several high-performance materials, such as Chemraz,a chemical-resistant elastomer, effective in the most extreme temperatures. WRis a high-performance, wear-resistant, carbon-fiber-reinforced thermoplasticcomposite used in oilfield applications.
Molded Carbon Composite Brackets Lighten Aircraft

Molded Carbon Composite Brackets Lighten Aircraft_A

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