Результаты (
английский) 2:
[копия]Скопировано!
Other fabrication problems include getting a perfect bond between skin and core-if we do not, then bending stresses will tend to separate the two and lead to buckling. It's not always obvious just how thick to make the skins and cores, what kind of cloth to use, the optimal orientation of the fibers, and how gradually to distribute localized loads across a wide area. And finally, remembering our rule that an infinite number of very light things becomes infinitely heavy, it is important to use just enough resin, but not TOO much. To this end, one of the more advanced fiberglass fabrication techniques is vacuum-bagging, which uses the weight of the atmosphere as a giant press to force excess resin out of a layup. Most of the time, fortunately, we can get by with "hand layups" and relatively simple techniques. Indeed, the beauty of composite construction is that it's pleasingly incremental: you sculpt chunks of foam, glue them together, add fillets to inside corners and round those outside, then bond on fiberglass skins of sufficient thickness to satisfy the structural requirements of your application. Sometimes you mold structures around the objects to which they will mate; other times you do freehand build-ups of thickened epoxy and then shape them with a Dremel tool. The result is a kind of ugly thing with the surface texture of hardened burlap, dangerously sharp bits where once-soft fibers now protrude like needles, and a patchwork of blah colors resulting from the types of epoxy and hardener used as well as the various fillers . To clean this up once all the engineering issues are satisfied, you sand down the rough edges without damaging any more fibers than necessary, blend microscopic glass balloons into a fresh pot of epoxy, butter the fabric texture and overlapping edges with squeegees and other tools, and wait. Once that cures (a function of temperature and epoxy chemistry), you can finish the resulting object to any level of perfection ranging from butt-ugly to showroom-perfect depending on how much of your life you want to devote to it, then get intimate with another suite of toxic chemicals to prep / primer / paint the surface. It's all very messy, actually, but at every step in the process the thing you're building is editable-time and again, we tore into "finished" work with fearsome implements of destruction to correct mistakes, add fixtures, and even change our fundamental design as evolving specifications rendered earlier assumptions fallacious. This is not even remotely like machining: once you get used to working with composites, there is liberation in knowing that anything can be undone or fixed; rarely is it necessary to start over. Errors are not fatal.
переводится, пожалуйста, подождите..
