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      02-23-2012, 04:08 PM   #42
Judah
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Quote:
Originally Posted by mkoesel View Post
Sure, I understand that it can be done. But - unlike fiberglass - carbon fiber is woven. I think of fixing carbon fiber like fixing a damaged clothing garment. You can do it of course, but you typically have to mend it with a patch of some sort, and as a result it usually does not look or feel like new again. With fiber glass, its more like fixing a chip in a windshield - you just fill it in and no one is the wiser (well maybe it isn't quite that simple, but you see what I mean).


Yes, carbon fiber is woven into a fabric and so is fiberglass when used for structural purposes,( the same glass fibers just longer strands). Repairing CF is NOT like fixing a garment. I understand what you mean by, "like fixing a chip in a windshield" but that pertains to the repair of chopped FG which is very heavy on resin. Chopped fiberglass doesn't have near the strength of fiberglass fabric(woven). The same basic procedure used to repair multi layered FG is how multi layered CF is repaired. A great deal of the strength is in the resin and fabric orientation. The repair requires bonding to each individual layer and in some cases the core, resulting in a strong, smooth and almost invisible repair.
I'm not just stating that it can be done. What I'm saying is that it's not as expensive or as laborious as some people may think. There will be training but it's not rocket science.


Quote:
Originally Posted by mkoesel View Post
With steel or aluminum I can weld two foot-long pieces together and have the result be as strong as one equivalent-thickness two-foot-long piece. Even with fiber glass, I can fuse two pieces together and have something as rigid as the original. But I don't think the same is true for carbon fiber. If it were, then instead of producing huge sheets of the material to create large parts, they could just patch a bunch of smaller squares of it together like a quilt or something. There's obviously a reason why they don't do it that way - the rigidity of the part is largely dependent one continuous woven sheet of material.

With metal repair work, the limit is usually based upon cost. For cases where there is sufficient motivation, just about any steel part can be fixed (within reason - a fire would make it almost impossible, as would a near complete destruction of the part in a horrific accident or perhaps an explosion). Consider classic cars, for example. Even when left to rot for years, they are typically salvageable and restoreable (incidentally that's a big advantage of CFRP - no rust). Or, if someone wrecks their rare Ferrari GTO on a track, they will more than likely get it back going again some way or another.
This is really no different that CF chassis repair. When you look at autos of the past with CF chassis construction,(MP4-12C & Aventador) you'll find that the occupant cell is the CF structure and the impact zones remain aluminum, magnesium and/or steel. The impact zones are easily replaced or repaired. In the event of damage to the CF occupant cell see my comment above. However, if the cell is severely damaged to the point of no repair then chances are the occupants are dead. The cells are just that strong....
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