In its quest to reduce the weight of aircraft seats, a major seat manufacturer has switched a variety of seating elements from aluminum to a Tepex composite made with carbon fiber and Fortron polypheny-lene sulfide (PPS).
These elements, which include lumbar and thigh supports, armrest table covers, and shields for in-flight video screens, saw weight reductions of 40 to 50 percent.
Fortron PPS, which is available from Ticona, the engineering polymers business of the Celanese Corporation, was chosen over other polymers as the composite matrix because it is inherently flame retardant. It also has a low smoke index and a high limited oxygen index, in addition to creating an advanced composite having superior mechanical properties compared to aluminum.
The PPS-based Tepex composite is produced by Bond-Laminates GmbH in Brilon, Germany, as sheets having thicknesses of 0.2- to 5-mm and up to 20 layers. DTC in The Netherlands thermoforms the sheets into the seating components.
The lumbar support at the base of the rear portion of the seat is a good example of the savings that accrue with Tepex composites. This part, which measures 16 by 30 cm (6.3 by 11.7 in.), weights about 150 g (5.3 oz.) in the PPS composite and 280 g (9.9 oz.) in aluminum. The 130 g (5 oz.) weight saving adds up. Considering that an Airbus A380 has a standard seating configuation of 555 seats, the weight saving per aircraft could total 72 kg (158 lb.).
“PPS composites are easier and cheaper to process than aluminum, which undergoes many more production steps than the formed composite,” says Dirk Raudies, Technical Marketing Manager for Fortron PPS. “We estimate that parts made with Tepex generate an overall cost savings of about 20 to 25 percent compared to aluminum. Seating in new generation aircraft like the Airbus A380 calls for innovative concepts that combine safety and comfort on long-haul flights. As a high-tech plastic, Fortron PPS has become a basis for such developments because it is robust enough to replace metals yet lightweight enough to keep part weight low.”
According to Joost van Lindert, Managing Director of Bond-Laminates, the PPS composites are an excellent addition to the range of advanced thermoplastic composites Bond-Laminates offers: “The FST (fire, smoke, toxicity) properties of Fortron PPS combined with the high-strength fibers we use make Tepex a superior material for aircraft interiors and other applications where stringent safety requirements apply. Together with all the other advantages of thermoplastic composites – like very short cycle times, weldability, toughness and recyclability – this material will be a strong contender for many parts.”
“The use of Fortron PPS composites is in line with the growing application of all composites in aircraft, which has risen from 7 to 20 percent since the 1980s,” says Raudies. “Beyond seating, more than 1,000 Fortron PPS structural and other components have been developed for the aircraft industry, including keel beam ribs and the wing leading edge (J-nose). In all cases, the PPS composites speed production, lower weight and greatly reduce costs compared to established, conventional technologies.”
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