read on here recently where someone said that carbon fiber may be stiff and brittle.
does kevlar keep it's load spreading properties when laminated with epoxy?
for instance, i can get 5.7oz E glass, 5.7oz carbon fiber, and 5.7oz kevlar.
if i was only interested in ding resistance, would kevlar be my best bet?
i've done searches and found not much other than how hard it is to sand and cut kevlar.
has anyone done any testing?
can anyone point me to a thread or other site that has info?
thanks
can't edt:
but i also learned from the archives that you have to keep kevlar out of direct sunlight.
paint it, veneer it, cover it somehow or it will break down...
hey chrisp, I used 6oz kevlar and epoxy to strengthen the underside of a hollow deck . It did the job and added minimal wieght. Ive also seen a board glassed totally in kevlar and it seemed to handle the sun ---its still around.............maybe heavily uv stabilised finish coat, not sure. carbon has great tensile strength,but when it does reach its breaking point ear-muffs are handy. A few years back, there was talk of nano-tube carbon fibre development , but I havn't seen it on the market as cloth yet
Ive heard pretty good things about “impact glass”. Some sort of glass cloth designed specifically for resisting impact. Not sure on the specifics, a different weave type and weight, dont think it drapes around curves as well as standard glass. Id be willing to bet that some of the SUP guys use impact glass for additional rail protection. This might be a good solution due to the cost and complications kevlar brings with it. If you look only at mechanical properties, then Kevlar is def your pic. Vac bagging kevlar will insure having it fully wetted, doesnt wet out easy like glass.
Kevlar floats in most resins, which is why you need to (should)bag it.
Most of the time you need to bury it behing some glass,
sanding it is an adventure in itself, ( it doesn’t like it much).
Think of carbon like concrete, really strong, but when it fails
it goes bang. Carbon, in a composite matrix teads to attract loads
as it is the stiffest material in the matrix. Everything but the
carbon gives, the carbon the takes the total load and fails,
usually with an explosion of very sharp black needles.
If ding resistance is your objective, I would consider
using a really light layer of kevlar between your deck layers.
I have seen a .25oz “veil” kelvar. Stick that between your
deck layers, (shouldn’t have to bag it under the top layer
in one shot) and it should be light enough and more
ding resistant.
Pete
I think I saw some hybrid fabrics at fiberglass supply that combined kevlar and glass, perhaps that would yield an interesting lamination. Probably still have to vac bag it though.
Kevlar has been around since the 70s and was used in surfboards almost as soon as it was introduced. Impossible to sand, so it must be under a layer of something sandable. UV degrades it, so it should be protected. Now there are many aramid fibers (the group kevlar belongs to) but Kevlar was the first.. A Kevlar laminate is most known for it's ductile mode of failure. It behaves almost like a metal sheet, bending and denting without fracturing. Boat hulls are a good application.
Carbon is just the opposite in terms of failure mode, as noted above it's a near-explosive event. Carbon's low specific gravity combined with incredible stiffness makes it THE choice for many multi-layer schedules where building laminate thickness/stiffness at lightest possible weight is the primary design criteria. I know some guys here who build aircraft using almost all carbon with vinylester resin, Race-car ''tubs'' and body work are other examples.
Carbon and kevlar are both frequently woven into hybrids with other fibers with complimentary physicals. Remember the ''carbon/spectra concept board'' I posted on here about 2 years ago?
For hand-lamming, e-glass is good stuff, and you'd have to put a layer of it over either the kevlar or carbon anyway; over the kevlar for sanding, over the carbon to ''toughen''.
I’ve been riding Dick Van Straalen carbon fibre boards for quite a while and I’m very impressed with their ding resistance.
A couple of times I’ve had people fall off right in front of me while travelling fast down the line on my 8’erand I’ve run over their boards while on overhead waves their has been very little damage.
The first time resulted in a light scratch and I went right over the top of the persons board.
The second time I ran over the guys board and it resulted in a small crack in the rail and I hit his board hard enough to crack both tabs on one of my sidebites.
After the wipeout I copped another set wave right on the board’s middle and came up from the pummeling in front of the rocks thinking…oh no…I’ll be seeing 2 4’ers but the board was in one piece. I was amazed.
Didn’t hear anything noise from my board but I did create some noise by venting at the guy who dropped in on me, went straight down the face and fell backwards off his board, leaving it as a speed bump for me on a barreling Noosa Boiling Pot screamer. Seen the footage of the Epic swell at Noosa a couple of months ago. It was the Friday of that swell.
Still the best waves I’ve ever seen at Noosa.
One interesting thing…remember seeing a My space interview with Rasta about his carbon boards and he says the only one he’s ever snapped was a carbon/kevlar mix.
Great explanation Mike! The failure mode of carbon is exactly why I never plan on flying in the new all carbon fuselage Boeing Dreamliner… I stuck some carbon/epxoy in a load frame a few months back just for fun and when it failed, man was it loud, and im glad I was wearing eye protection, little pieces of the sample exploded all over the room.
Hi Mike,
do you have any experience with other type of cloth like olefin? http://www.oneoceankayaks.com/Abrasion.htm has some info.
If anyone know where you can get these types of fibers, I’d appreciate it.
regards,
Håvard
http://en.wikipedia.org/wiki/Basalt_fiber
http://shop.r-g.de/Verstaerkungsfasern/Basaltgewebe/Basaltfasergewebe-180-g/m.html
Hello ChrisP
As a joke I named my workshop the Low Tech Lab. The more High Tech Swaylock's becomes the better the joke....
In 1986 I worked for a company named Fiberite located in Orange, California. I just did a search for Fiberite and the 3rd hit was a Safety Data sheet with the company's name and address. It's hard to look back and see that we were using Carbon fiber for Space Shuttles and race cars back in 1986. Kevlar for amored cars too....
Want to waste a bunch of time and money on High Tech cloth???? Go for it....Report back here.
Ding repair on a standard surfboard is easy. Let's keep it that way.....Add an extra layer of E Cloth for ding resistance.
.......Stingray...LowTechLab......
I have 2 8’er all rounder shapes from Dick Van with 2+1 set ups.
The carbon fibre/EPS board is so much better than its poly with resin tint stable mate I have not even thought of riding the poly board again.
It paddles better, is faster and more responsive and I just put it down to Dick making many boards in carbon fibre and dialling it in. Not a waste of $'s for me personally.
My carbon/EPS board is thicker than the poly and this may be a key difference that other board makers haven’t utilised to find the maximum potential of the material.
Still the best waves I’ve ever seen at Noosa.
haaa the best waves at noosa are long gone’’
but yea the best lot of consitant swell for 25 yrs at least.
**fellas’’ keep it simple to much tech damages the brain cells
**
Are you going back to the roots? PU/PE?
I dont know about surfboards and kevlar use but on racing yachts kevlar layers (on top of the carbon) are typically added in areas that were expected to have regular impact or wear and tear. The kevlar handles the impact/scraping better than the carbon. The kevlar is also left visible in these areas since any paint will just get chipped / scratched away anyway.
I have no experience with it but I seem to remember that RR had an epoxy formulation that they said was more flexible and more apt to handle impacts (less shattering maybe??). Sort of remember reading about it on their website which suggested using it on rental boards or similar. I would think that using standard glass and a different epoxy should be easier and cheaper than dealing with the expensive aramids, vac bag, etc ..and still give you some ding added resistance. May want to contact them and discuss the properties.
yoyo
thanks for all the info everybody...
the reason for the question was that i was mind shaping a timberflex board... 1.5 pound eps shape...
i was thinking of putting 1" kevlar tape along the apex of the rail on a shaped blank, letting it cure
then timberflexing with bamboo skins... my thinking was that the kevlar would first act as a stringer
to keep the rocker while vacuum bagging and, secondly, it would add ding resistence after whole thing
is said and done. 'cause without it, it's only 2 layer of 4oz fiberglass from the final lamination. unless i add more.
i thought the kevlar would add ding resistence without inhibiting flex...
Stingray, Huie, you guys are absolutely right... i guess it's just that sways disease trying to take a simple
process and make it complicated... ha!
Haavard I found that page about a year ago and bought a small amount of dynel from http://www.jamestowndistributors.com/userportal/search_subCategory.do?categoryName=Dynel&categoryId=625&refine=1&page=GRID James Town Distributors.
I used the dynel in a full frankenstein board. Ply perimeter stringered eps marko blank, corecell deck inlay, kevlar veil patch on the deck with the dynel on the bottom all bagged with peel ply and the works.
Even with breather cloth and the peelply the dynel sucked and retained too much resin. The board came out too heavy for all the money and work put into the board. The dynel was interesting stuff though. Under moderate vacuum the dynel fused to the eps. I ground off the glass on the rails to try to strip the board to salvage the blank and try something else, but there was no way the dynel would come off the bottom.
I was thinking about running strips along the rails over balsa or HD foam figuring it might be worth a shot for ding resistance.
**i have never left **
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