High-Performance Composites is read by qualified composites industry professionals in the fields of continuous carbon fiber and other high-performance composites as well as the associated end-markets of aerospace, military, and automotive.
Issue link: https://hpc.epubxp.com/i/332723
J U L Y 2 0 1 4 | 3 5 was asked by Airbus to investigate the use of thermoplastic composites (TPCs) in an aircraft fuselage structure. Fokker added torsion boxes (typically tails and/ or wings) as another application area. Material used was a new TenCate unidi- rectional carbon fber prepreg with Hexcel (Stamford, Conn.) AS4 fbers and Arkema (Colombes, France) polyetherketoneke- tone (PEKK) matrix. Processes used were automated fber placement, press form- ing and welding. Offringa says the result, unveiled in 2013, was a demonstrator fuselage panel of technology readiness level (TRL) 3 and a 12m/39-ft torsion box for a tail struc- ture of TRL 5. (Maximum TRL is 9, which means the part or structure is fully test- ed and operational.) Test results for the structure, he says, were encouraging. The TPC parts showed 10 percent weight sav- ings compared to thermoset materials, primarily because the thermoplastic's inherent toughness better prevents crack propagation and, therefore, allows the use of thinner laminates. Further, the stiffener and skin designs were segregated, which increased design freedom and promoted weight optimization. Consortium signatories forged the contract for TAPAS 2 on Jan. 20, this year. Currently in launch mode, the TAPAS 2 consortium is taking both of the TAPAS 1 structures further up the TRL scale. Of- fringa says "the technology is very prom- ising and worthwhile" and is confdent that thermoplastics will continue to prove feasible in commercial aerospace. For the torsion box, he says, the goals include generating allowables, qualify- ing materials and processes, develop- ing a "wet" box that can contain fuel and using a part architecture that features beams welded to skin. Offringa says TAPAS 2 hopes to have the technology for a dry box at TRL 6 by the end of 2015, and several airframers have expressed interest in real-world applications of the technology. The fuselage panel, it's hoped, will be matured to TRL 4 by 2017. The fuselage panel challenge, says Offringa, is manag- ing skin thickness, particularly for single- aisle craft the size of an Airbus A320 or a Boeing 737. "These laminates are rela- tively thin," he notes. "Design based on loading is thin, but local loads — for hail strike or maintenance tool impact — can cause a thickness increase. For these thin structures, a tough material will fare bet- ter. But the real question is, 'How thin a skin can we get that will comply with all requirements?'" In the long term, the hope is that TPCs can be proven a viable option for the successor to a narrow-body program. Of- fringa says that in addition to TPC, Air- bus is considering and looking closely at aluminum and thermoset prepregs. About 60 percent of TAPAS 2's €24 mil- lion budget will come from consortium partners, with the Dutch government providing the balance in the form of "risk-free" loans (e.g., the Netherlands Ministry of Economic Affairs is support- ing the ongoing partnership with a loan of €9.5 million). When revenue is derived from the project, the loans will be repaid to the Dutch government. 5-Axis Machining Centers For Composites Phone: 330.920.9200, ext 137 • Fax: 330.920.4200 • Website: www.quintax.com • E-Mail: sales@quintax.com L E A R N M O R E @ w w w. c o m p o s i t e s w o r l d . c o m Read this article online at short.compositesworld.com/TAPAS2. 0714HPC UpdateTapas-OK.indd 35 6/17/2014 10:45:59 AM