On Fri, Apr 24, 2020 at 12:36 AM a8b7k57g@protonmail.com [harryproa] <harryproa@yahoogroups.com.au> wrote:
PICS!Will do. Attached is a screen shot of what i am thinking of. The blue and grey corrugations are glued together, probably during the cure of the grey sheet, then if required, the red flat sheets are laminated on each side. Lots of variations with fibre direction and type, and on long skinny hulls whether corrugations in both directions are required. Big problem for hulls is how to infuse it all in one shot. However, as I am not paying for labour, it may be worth doing it in multiple shots to reduce costs.Rob, what are the economics of this? Even with zeroing labour...You have 4 sheets of glass and resin, but 2 are corrugated, so add 10% to that surface area. = 4.2 m^2 of whatever GSM glass, plus whatever times 50% fiber ratio at 12$ a kg.you are at almost 11$
perhaps stacked foam? thin h100 on the top and bottom, and h45 or structural XPS for core?I imagine you have thought all through this, but I am curious.
Me too!
I laid up the corrugations. One of 200 gsm cloth, fibres running along and across the corrugations and one of 400 double bias, fibres running at +/-45 to the corrugations, then realised there was a much better way, allowing the whole panel to be built in one shot, though not easily infused. Infusion is probably not ideal for the corrugations as the thicker they are, the stiffer they will be.
Glass costs near enough $AUS5 per kg, regardless of areal weight, plus $12 per kg of resin. So each 100 gsm cloth and resin will cost 50c +$1.20 per sq m. Plus 20% (for the corrugations and doubled for the two corrugations required, a sq m of 100 gsm double corrugated glass will cost ~$4.10 and weigh 480 gsm.
12mm H80 pvc foam is ~$AUS25 per sqm and requires an additional 200 gsm ($2.40) of resin each side so it weighs 1.4 kgs per sq m and costs $27.40.
To match the foam weight, the corrugations are 300 gsm (1.4/0.48). To match the cost, 650 gsm (27.4/4.1)
If the corrugations are stiff enough not to need faces, they will be lighter and cheaper, albeit ugly (not a problem for hidden bulkheads and things like floors where either one side or neither side is visible), harder to build and challenging to fillet and tab.
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Posted by: Rob Denney <harryproa@gmail.com>
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