Rob:
Tow or just glass fiber is
something I've tossed around since deciding on sandwich
construction. My idea was a sort of sewing machine with a gang of
what amounted to sewing awls (mounted needles with spools of
whatever thread) resulting in something like a piece of fabric
that has been sewn and the for the lower thread ran out. It
would be simple to construct and could be operated more or less
manually. A pair of air cylinders to drive the needle head up
and down actuated by a manual valve. Push the sheet of foam or
pull it to the next stop, trigger the head, and continue. The
only problem of course is that the shear forces are angular rather
than straight so ideally the holes would be on a 45 each way along
the long axis. Effectively the result would be a sort of truss
enhancing the ability of the core to take shear loads.
A bit nuts ;-) ........ so I
didn't mention it before you mentioned "sewing a sheet" with
tow. My thought mentioned in an earlier post "wrapped foam
plank" was another approach to the same result, as the wrap would
be on the bias. It would add great stiffness.
H.W.
On 11/12/18 5:13 PM, Rob Denney
harryproa@gmail.com [harryproa] wrote:
1' x 1' would be plenty, but hold onto it for a while, please. I am not going to get any tests done for a little while, partly due to work pressure, partly due to the engineer not having time to do the number crunching. However, anyone who wants to do their own testing should let me know and i will describe the test regime for each parameter. Eventually, I will get this on the web page.
Went for a sail on Rare Bird on the weekend. It is in remarkably good nick after 10 years of sitting in the water. The crew were pretty switched on and we chatted about improving core performance. One solution was to weave tow through the air holes in the foam. Done a metre or so of tow at a time, it was "fairly quick" to sew a sheet. The improvement in core properties is, apparently, immense. H60 with tow performs as well as H100 under many loads. Something else to try.
On Wed, Oct 31, 2018 at 9:00 AM hannaberryworkshop@gmail.com [harryproa] <harryproa@yahoogroups.com.au> wrote:
Rob,
What size sample would you need?
I have a few different thicknesses and densities being sent to me now. They will send a 1'x1' piece for free. Beyond that they charge a small fee.
Still waiting on the per sheet prices, but they did say that they preferred to sell it "by the box" which would be 32 sheets. (Buy less than a box and the price per sheet goes up)
__._,_.___
Posted by: StoneTool <owly@ttc-cmc.net>
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