Aramid : speciality fabric

General Discussion
1

    I have been wanting to add a impact resistance to some boards we will be making for the coming winter. At first I thought I’d pick up some carbon fiber but after doing some research it seems it adds stiffness but not impact strength. An alternative I found is Aramid. Actually an Aramid/ Carbon mix. TAP:

"Carbon 45% Aramid 55% XC-1168
This fabric blends graphite for stiffness and Aramid for strength and resistance to damage from impact and fatigue. The hybrid twill weave of two-under and two-over allows the fabric to drape and conform to compound-curve shapes. It is the most resistant fiber to impact damage available today. It is 40% stronger and 25% lighter than graphite, and is half as stiff. Aramid is often used, with other fabrics, in high-stress areas. It works best with vinyl-ester resin, but also compatible with polyester and epoxy."

42-cabonkevlar.jpg

 

     Does anyone have any experience with this material? Any other suggestions appreciated as well. We do not vac bag so veneer is not an option, nor is vac bagging this or any material.  The idea is to add this to impact zones on the board only. Deck patches, rails etc. We do want a little flair here, but functionality is king. 

   Thanks for reading.

 

 

2

Better to use innegra

3

Hey Pico.

I’ve used it many times, and it takes a bit of care applying and cutting…

The carbon usually runs north to south or along the length of the board with the kevlar running perp. to the stringer… This results in a stiffer board than  plain S glass for example… If you’re just doing small deck patches however you can rotate the cloth 90 deg. and have the flexible kevlar running the length of the board…

Both the kevlar and the carbon need to be fully wet out, and this is something you need to practice… A dry lam of either is not a good thing… You mentioned that you will not be vacuum bagging it on, but I hope you’re aware this is the best way to apply this cloth other than a pneumatic press…  Some guys here hold down the cloth with saran wrap which might work ok…

It is also very hard to cleanly cut the kevlar while the carbon is easy to cut so you can end up with a ragged cut line…

I own a couple of pairs of Kevlar shears whick are designed for cutting the kevlar cleanly, they cost around $30 to $40…

It’s sometimes a good Idea to carefully tape down one end of the cloth then pull and straighten out the carbon as well as kevlar weave before applying resin. This looks better than having wavy lines in the cloth…

I’m going to use some red and black carbon kevlar twill for some deck reinforcing  inlay patches in the future.

I’ll be vacuum bagging a piece of  hybrid cloth slightly larger than the needed deck patch down to a surf board that is covered with plastic release film… Once the carbon kevlar inlay has hardened in the vac bag, I’ll peel off the patch and cut out a clean outline of the pre-laminated “top sheet” then glue it onto the blank much like a veneer…

This is kinda time consuming, but you end up with perfectly cut inlay perimeter lines and a top sheet that has the right amount of epoxy in the cloth… You could do this without a bag, but the inlay might end up a little resin rich…

If you want pure impact / puncture resistance,just go with 2oz. to 5oz, kevlar alone… Also try some innegra, it’s supposed to be great for this application…

I hope this helps

4

Like kiterider says, getting a clean cut edge is very difficult; and almost all these modern fibers/weaves are meant to be bagged. But I did some carbon/kevlar hybrid stomp patches by hand-lam back in early 80s, as did GL and others. So I know it can be done. If it is an add-on third layer it can be somewhat effective, at a cost of additional weight. Substituting it for an e or s glass layer didn't seem to make much diff in hand-lam (for denting/footwelling; puncture resistance improved). We're always testing all sorts of fiber combinations, I put up a picture of a twill that must be similar just recently. There's lots of aramids available now, and many hybrids.

Stiffness and stress risers resulting from transition points in lam schedule can also be problematic, that's another story....

5

    Any supplier of innegra? I’d like to get a small amount first of course so local would be best. SF area.

6

Shipping for a few yards is nominal, just get it direct from mfr. A quick search should find 'em, isnt it innegrity.com or something like that?

7

http://www.scenterprisesfiberglass.com/innegra-s.html

 

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