Unbonded Kevlar Seat?

[Toot]

I have been kicking around a few ideas for a seat and came upon the idea of using unbonded kevlar roving to fashion a sling-seat- just bond the edges of the kevlar to a frame. The idea is that it would be light and strong and the kevlar would be relatively damage-resistant if covered with a cushion.

The problem is, I know that kevlar absorbs water and, left unbonded, can break down over time. My question is- could this type of a setup last very long?

[frosh]

Hi Toot, It should work OK but it is an expensive solution I think. I have jeans and a jacket lined in pure unbonded kevlar and it withstands washing by machine no problem. I understand the main enemy is UV light. I don't expect it will break in the lifetime of your children and grandchildren.

[duluthboats]

An expensive misuse of the material unless you need a very strong, flame resistant seat.

Gary

[Toot]

Actually, my original thought was to use it for an aircraft, designing for a max of 12 G's. My second thought was for autoracing seats. Then I thought, what the heck? A 1.5 pound boat seat could be handy too.

Heck, it could save a lot of weight on a pocket cruiser if you did the berths that way....

Cheers!

[JPC]

Toot-

To experiment, if you haven't already, you might try Kevlar sail cloth (woven, not 3DLs or other loadpath designs). The weave is tighter than that meant for resin infusion -so it's more dimensionally stable to use 'naked', and you should be able to find lots of it for free. Most woven Kevlar sails that are being tossed in the dumpster will be old enough to have shed much of their Mylar laminate, so the non-breathability won't be so bad. However, I don't know if you would have bonding problems at your edges. Even with fabric designed for infusion and not 'used', it's my understanding that Kevlar is tough to bond to -but I think you know considerably more about this than I.

UV is the typical killer - both for the Kevlar, the laminate film, and the glue. The fabric shrinks, but will remain very strong within the range of seat bottoms.

If you don't think you'll find some at your local marina, check with a sail loft; they are probably receiving some retired sails when they sell new ones, or might have offcuts. Too bad, as I recently left a woven Kevlar genoa in the "swap" area of my marina - it probably had enough fabric to upholster a DC-3.

JPC

[Toot]

Thanks, JPC!

I'll check it out. You are right that kevlar can be difficult to bond. But the beauty of the bonded frame is that you can wrap it around a couple of times before bonding... you don't have to just bond to 2 faces of the frame... wrap that puppy a few times.

I doubt the mylar coating would be good for bonding, but it could definitely still provide an education and be worth playing around with...