CompositesWorld

AUG 2018

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AUGUST 2018 30 CompositesWorld INSIDE MANUFACTURING separately, skins and stringers are then brought together for co-infusion. Wingskin layup is relatively straightforward and involves automated fiber placement (AFP) of the 0.25-inch Solvay PRISM TX 1100 dry fibers on an Invar tool, performed with a Coriolis Composites (Queven, France) AFP system using a KUKA Robotics 6-axis robot (Steps 1 & 2, p. 28). Meanwhile, says Gaydansky, the stringers are also laid up via AFP as flat preforms, about 100 mm wide and in varying lengths, using the same PRISM TX 1100 material. Each flat preform is then hot-formed to create an L-shaped preform. "After that, the two L-shaped halves of a stringer are connected together, resulting in a T-shaped stringer," says Gaydansky. "Further on, using special equipment supplied to us by Dutch-Shape [Borne, e Netherlands], the part is cut to speci- fied geometry and installed on the wing panel." Each stringer is supported on the skin by Invar tooling, which clamps together to maintain the desired T shape (Step 3, p. 28). Gaydansky says AeroComposit uses vacuum bag infusion: "e technology developed by our company involves the installation of two membranes," he notes. "Besides, we are practicing our own patented scheme of vacuum bagging. One might as well say that we have created still another version of infusion technology, specially adapted for building large-size primary structural elements." "After the stringers set is installed on the wingskin preform, it is wrapped in a number of auxiliary materials," Gaydansky says. "For bagging, we apply vacuum membranes, breathing and draining materials. Tubes are installed for resin supply and for vacuum level control. Finally, all is covered up with a vacuum-bag film which is secured and sealed along the perimeter of the preform, after which vacuum is applied." Infusion, he says, is done at 100°C, followed by cure at 180°C. AeroComposit uses a standard curing oven, supplied by a European manufacturer, that measures 6 by 22m. e entire infusion and cure process takes just less than 24 hours, followed by trimming, routing, drilling and cutting via a CNC machine (Step 4, p. 29) provided by MTorres. Finished wing- skins are nondestructively inspected (Step 5, p. 29). Meanwhile, in parallel, AeroComposit fabricates the C-shaped forward and rear spars. ese also are made with the PRISM TX 1100 material, laid up on a male mandrel, using an MTorres AFP system (Step 6, p. 29). Infusion of the spars typically takes 12 hours, using the same cure profile as the skins/stringers. e thickness of the spars ranges from 6-14 mm, and they benefit, says Solvay's Hill, from the steerability and low bulk of the material. "e microstructure of TX 1100 provides the ability for the tape to bond to the adjacent layer," he says. "In addition, the tape is able to manipulate without changing the form. As you steer the tape, you can recognize the limits of how much you can steer the tape by how much it starts to develop defects." is capability is impor- tant because, conventionally, composite spars are fabricated in sections, which are subsequently bonded or fastened together. is is necessary to accommodate direction and angle changes designed into the forward and rear sections of the wing. e steer- ability and low bulk of TX 1100, says Hill, allows AeroComposit to change directions and fabricate each MS-21 spar as one structure. Nondestructive testing (NDT) is performed with one of two systems (Step 7, p. 29). e first is an ultrasonic system supplied by Tecnatom (San Sebastian de Los Reyes, Spain). It applies phased arrays via a 7-axis robot, using converters that were specially designed and manufactured for the AeroComposit-Ulyanovsk facility. e Tecnatom system is equipped with an automatic head changer to minimize touch labor. e second NDT system is a mobile Omniscan machine produced by Olympus (Waltham, MA, US). is water-based system uses C-scans and reportedly can scan at high speed to check quality and integrity. Upper and lower wingskin/stringer struc- tures and front and rear spars, when cured, are then joined with the metallic ribs. "is is performed in a customized, automated assembly jig procured from MTorres," says Gaydansky. "is is high-precision assembly equipment that allows us to position and fix large-size panels to the pre-assembled structural frame, composed of spars and ribs. Here, mechanical fasteners are used for attachment. Fixation of wing panels to the structural frame is implemented with titanium fasteners." On the brink of big change This photo of a fully assembled MS-21 wing was taken at the 2012 Farnborough Air Show in Farnborough, UK. The wing was, at the time, in prototype stage. Since then, AeroComposit has manufactured 10 shipsets of the wings and wingbox (also infused) and has recently progressed to early production. The wing also has undergone static testing, with fatigue testing scheduled later this year. Source | CW / Photo | Jeff Sloan Comparable alternatives to styrenated products are available to those who wish to purchase them.

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