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The MS-21, a new single aisle airliner produced by Russia's United Aircraft Corporation, is the first passenger plane borne aloft by lightweight carbon-composite wings built without a costly pressurized oven called an autoclave.
[...] Under the new technology, instead of using fiber that is pre-impregnated with resin, parts are made from a dry-fiber engineered textile which is placed in a mould and then infused with resin under a vacuum.
The parts can then be cured in an oven without pressure, a process estimated to cost 25 percent more than metal. Ultimately, that gap needs to narrow significantly or disappear.
Boatbuilders and windfarm makers have used this method for years. Secondary airplane parts have also been made that way.
But although Canada's Bombardier partly used the technique for its CSeries, it was rare for flight-critical parts before the designers of the new Russian plane chose it for the wing.
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(Score: 3, Interesting) by kaszz on Wednesday May 31 2017, @07:26PM (6 children)
If the material is hardened without heat there must be some other factor that initiate the process to make it hard. Just vacuum is unlikely to do that by itself. Something is missing in the description.
And then, will this material handle long term rough handling? burning sun, freezing cold, pressure cycling, bending, cracking, brittlement etc? are failure mode gradual or rapid and thus catastrophic?
How about Bisphenol-A a hormone disruptive poison? vapor pressure into the cabin?
Recycling?
(Score: 4, Informative) by Anonymous Coward on Wednesday May 31 2017, @08:32PM (3 children)
> If the material is hardened without heat
Epoxy resin (the most common binder used in carbon fiber composites) is a two part catalyzing reaction. Depending on the specific formulation, some varieties cure (harden) very slowly when cold. Typically the "pre-preg" material (carbon fiber and epoxy combined together) is stored in a refrigerator until use. Other formulations require a certain heating cycle to develop full strength. If the finished part is being designed for a high temperature application, then special epoxy or other high temp materials will be specified, and these may require a cure at even higher temperature.
(Score: 3, Interesting) by LoRdTAW on Wednesday May 31 2017, @10:59PM (1 child)
Adding to this, the vacuum is most likely there to remove air from the material to allow the resin to fill all voids ensuring no air pockets exist to weaken the finished product.
(Score: 3, Touché) by mhajicek on Wednesday May 31 2017, @11:30PM
That and to squeeze the fibers together so there are minimum voids for the resin to fill.
The spacelike surfaces of time foliations can have a cusp at the surface of discontinuity. - P. Hajicek
(Score: 1) by khallow on Thursday June 01 2017, @02:06AM
Slow curing can be used for a variety of complex tasks. For example, I did a project (roughly rectangular base for a movable robot, so I was told) where due to the complexity of the project, I used a slow cure epoxy combined with 35-40 F temperatures (crudely, 2-5 C) to put on a layer with some complex structure. It took almost two hours at a time to place the layer's various pieces and make sure they were properly wetted by hand. With most epoxy formulations the thing will start hardening 15 minutes to an hour into the process. Then I brought up the temperature of the piece (applied together with some vacuum bagging) to roughly 85 F (30 C) to cure it. The first layer went on like a dream, but I messed the second layer up (poor planning, ran out of plastic peel ply which is necessary for vacuum bagging so the part doesn't stick to what is soaking up excess resin).
An example more along the lines of AC's comment is the construction of the Orion spacecraft by Lockheed Martin (as prime contractor). As I understand it, the base structure is constructed of preformed carbon fiber parts and flaps which are then soaked in epoxy resin and refrigerated, prior to construction. I gather through a carefully choreographed construction process, the structure is carefully put together in a series of cold phases each followed by a phase where it is baked in an autoclave to harden the current state of construction. Perhaps someone with more knowledge of the construction of this process could describe it further?
(Score: 1) by Roger Murdock on Thursday June 01 2017, @03:46AM
FTS:
They're just using an oven to provide the heat rather than an autoclave. There's still pressure and heat involved, just from separate sources. Without reading the article I assume they're talking about Resin Transfer Molding, where the vacuum that the part is subjected to draws resin through the formed part. It seems to be a popular method in industrial settings now.
(Score: 2) by engblom on Thursday June 01 2017, @05:09AM
Unless I have got my information wrong, heat does not make it harder, it actually makes it more soft and elastic, thus less brittle.