This looks cool.
http://www.railway-technology.com/contractors/transparency/parabeam/
Closed cell honeycomb could be pretty cool.
Where and when to use it, reinforced by what will be solved.
Since surfboards have to endure 50+ degree temp changes, would espansion/contraction rear it’s ugly head?
Nice!
Details;
Yes, honeycomb has been done and is I believe still being done.
But the Parabeam concept is sightly different. It is in effect a somewhat more similar structural concept to laminating Spheretex between layers of glass. The similarity of Spheretex and Parabeam refers back to the use of fiber. The disimilarity is honeycomb is a formed sheet structure. Of course Spheretex differs from Parabeam in several ways. Random oriented fibers v striated verticle structure, microballoon filled v not microballoon filled, though the resin can be mixed with microballoons. And other differences. But the point is Spheretex seems to fill the bill and is available now and is being tested by numerous shapers, glassers, and surfers.
As for the resulting laminate structure the concept is similar. Separate the layers of glass with a lite weight structure for added strength. This is where Parabeam, honeycomb and Spheretex cross paths. It’s the familiar old “I” beam structure concept in sheet form.
This stuff seems to expand to its thickness when laminated. Trapped between to shaped moulds would it conform to those shapes and would the strands that don’t expand fully due to the shape be as strong?
Well, at a glance;
First off, rails. It won’t bend to a radius r less than some multiple of the thickness, so you’d have to bead the rails or something similar, or else join top and bottom as was done ( not always successfully ) with the Aquajets.
The optimum manufacturing method would seem to be vaccum bagging onto female molds, top and bottom. heated molds ( for a thermosetting epoxy, for instance) might be a move. Another cute trick might be to inject an expanding foam into a top-and-bottom skin of it, inside a mold.
A ding in the stuff would be very interesting indeed, as it’d likely penetrate only the outer layer. I kinda wonder how resistant all those vertical ( or radial, perhaps, is a better term) pile/fibers would be to water passing by 'em. Repairs wouldn’t be a big deal, but draining it before putting the goo to it… that could get interesting.
Dunno - it’s interesting times, ain’t it…
doc…
Good question.
My first thought is that by compressing the Parabeam you can vary the flex pattern. This opens up a lot of possibilities. Provided the infill material is flexible I see on reason that it would compromose strength. But here is where materials need to be matched to one another.
I proposed a similar idea to Loehr a few years ago. It was based on a ramdom oriented Nylon fiber matrix use to manufacture lite strong concrete slabs developed in Japan. This matrix is similar to the 1" thick grill scrubbing pads based on 3m’s ScotchBrite.
I suggested blowing the foam into a mold that contained the matrix. In other words a super lite super reinforced blank.
I don’t know if the Parabeam could be used in a similar way.
We seem to have two possible directions to think about here. Hollow board v solid core. The hollow idea using Parabeam as a skin whereas the solid core using Parabeam as a foam filled core.
The biggest problem area with hollow boards as you pointed out is the rail and conforming the material to the curve is a big part of that issue. This has traditionally been done by making a mold with two halves and laminating them together right down the middle of the rail. But that puts a seam in the rail and that, as SurfTech found out, is the worst place for it. Flex the board and the rail opens up like a zipper.
And there is no known way to put an inner lap on the inside of a rail in a hollow board. If someone can come up with a way that would sure help. Perhaps an overlap pressed into place with an air filled removeable bladder.
I have heard rumors that the W.A.V.E. was popular with smugglers.
I would rather use a honeycomb, as it seems you wouldn’t get the same energy transfer/ flexibility options you have with honeycombs. Break strength and dent strengths from impacts with a larger area comes from the materials ability to distribute the load through out. Seems like the vertical strands would be stressed a great deal. It may hold up to the abuse, but then you also have to think about the time and cost to machine it. Building molds is expensive and unless you’re convinced of the technology and have reason to I couldn’t see anyone taking the time or risk to build molds. I could see it working as fairly flat skins, compounding to simple curves like concaves and then joing at the rails with another material. I think a ligthweight core would still ahve to be used. And then you have to think about what the flex and “feel” will be like. Anything can work if you take the time to problem solve it, but before you invest you’re time and money you have to be pretty damn convinced it would work. I saw that website a while ago, but I never pursued the stuff. Best way to know more about it is to try and get some samples of it, somethings wont come together until you have the stuff in your hands. Def could work though…
Hey Mark,
Re your nylon pad idea. There is a roof vent material made of what looks like the scrub pad but with more air space that I always thought could make a lightweight core. I could see a preshaped skins - glass / core /glass - being joined to rails as the pad would compress enough where needed under enough weight.
I have used parabeam in the past (in fact have a roll in the workshop), and I know that there are many varieties, but I wouln’t go near a surfboard with it in a million years!!!
I had the unfortunate job of building some large transit cases from parabeam cloth because some joker thought foam sandwich construction was too expensive! Ha
It won’t go round a radius and it is brittle as hell (resulting in many voids and ding repairs that wouldn’t occur with a proper sandwich construction) and soaks resin like a sponge.
I am sure it has many uses for flat industrial panels but don’t waste your time and money by trying it on a surfboard or in a mould.
Alaways good to hear from experience. Thanks M
“I would rather use a honeycomb, as it seems you wouldn’t get the same energy transfer/ flexibility options you have with honeycombs.”
Interesting statement. I agree you wouldn’t get the same options or effects, but also depends on the honeycomb. There are a wide variety of materials sizes etc. But on the face I’d estimate that regardless of the construction material, honeycomb is going to be much less flexible than Parabeam. The honeycomb structure has full contact top to bottom. Parabeam is individual fibers.
But given the new info I’m just going to drop it.
Right, good one. The one brand I know is Cobra. What do you think of the idea of blowing some foam into that?
M,
Hadn’t got that far into my braistorm but would think that would defeat the purpose of a lightweight core that allowed the two skins to slide a little without failing under a surfer’s weight. The cobra stuff is exactly what I was thinking and it already is attached to a thin filter frabic skin - although not well enough for a board’s loads maybe - but my thought was that a thin fabric / lam like that attached a little more securely to the cobra stuff would spread the load of some premade/shaped skins.
My thinking was that there would be no shaping involved as you could get a 2" pad of the stuff to compress where needed between the skins.
M, also I know nothing about blowing foam but I would think it would be hard to get foam evenly throughout the pad.
I was thinking about that foam insulation in a spray bomb can. Clark blank in a can.
Uhm- I think I see where you’re going with this… if you pumped some 2 part foam mix ( and do it cold, so it wouldn’t all expand and harden and make some interesting bulges) into a hollow shell, with one very big vent on the other end, then I guess you might get what you’re looking for.
Now, for a skin with some rebound in shear to it, what’s the matter with a somewhat heavier, stiffer foam sheet ( not especially thick) , sandwiched between a couple of laminations of fiberglass plus the appropriate resin? You’d wind up vaccum bagging deck and rails separately, but you could do a lap under the sheet and a lap over to tie dtop and bottom together fairly well. Granted, it’s older tech like someone I could mention is doing already, but it works. If you did it with the foam and the underlayer of glass/resin before going with the top layer of glass/resin, you could then finish shape the foam to get your nice rail contours and such, then vac bag on the glass you wanted on the outside. Another interesting thing is it comes in varying thicknesses and densities, so you could play those to tune the flexibility and rebound somewhat.
I should also mention that that ridge vent stuff, the ‘not quite a scrub pad but very similar’; it’s no fun to cut and how on earth you’d shape it is beyond me. Makes a nice prefilter for a dust collection system, though.
hope that’s of use
doc…