I can see a lot of uses for a panel like this. I plan on testing a 6oz flat tow surface skin, backed up with a 6oz woven biaxial ply, 1/2" foam core and the same schedule on the opposite side. That would make for a panel stiff enough for a car body if properly supported to the frame underneath. I would estimate about .42lbs per square foot. As always, really informative videos.

@ExploreComposites

3 жыл бұрын

That is a nice panel type for so many things! I ran it through my spreadsheet for two 6oz plies sandwiching 1/2" 5lb core and it comes out a bit heavier at about .56lbs per square foot with infusion. A lot depends on how much resin the core sucks up. 3 or 4 lb. core would help and you'd probably get a lighter panel with bagged wet layup (like Sample #15) than with infusion - because you could use filled resin for the core bonding - and not every little area will be forced full of resin - might be able to get into the sub-half-pound range. Infusion is great for manufacturing, but it's really easy to overshoot your weight estimates!

@TWX1138

3 жыл бұрын

I can see a direct application, lightweight yet strong automotive truck canopies and tonneau covers. Heck, for tonneau covers one could almost make the thing on a flat table that's larger than the largest truck bed opening, to then be cut-down and possibly cut to trifold shape. If there's a need for a one-piece tonneau cover to bow upwards, use a glass table and support it taller at the perimeter so that the center bows downwards so when the part is turned over, it bows upward.

We used Nu-Tac on the mold surface only. I don’t think I’ve ever had a can not spray out poorly except for the first use.

@ExploreComposites

3 жыл бұрын

I've used it before and it was less splattery - just grabbed it here and was surprised by the mess. In your experience does it leave a nice surface? What do you use for the rest of the layup? I think it has a longer open time to tack than the 3M 77.

@rickjames8510

3 жыл бұрын

@@ExploreComposites It would leave splotches and streaks if too much was applied. It would come off if the part was buffed in post process. We learned to just spray it heavy in cut-off areas and lightly on the part surface.

Just confirming my math, the 20mm M80 Corecell initial weight for the one square foot section would have been approximately 158g/5.6oz? That means the resin+fiber added ~409g/~14.4oz? I assume the greater resin weight was due to infusion into the core moreso than the carbon fiber. It would be interesting to see a panel like this made with gelcoat fiberglass on the mold/table side and carbon fiber on the topside, since the core in between might reduce problems with dissimilar materials and provide greater resistance to aging from sunlight and allow more conventional repairs to damage to the fiberglass side.

@ExploreComposites

3 жыл бұрын

Yes, the core is about 158g / 5.6 per square foot. The resin to fill the grooves and bond the core to the skins is about the same. Estimated resin ratio by weight in the skins is 40%, but realistically that is probably low. My estimate is that total resin was 235g / 8.3oz with 143g / 5oz of reinforcement weight. Laminate Sample #7 shows a similar panel in glass but without sliced core. I try to avoid mixing resin systems in the samples, but there are cases where you might want glass on one side and carbon on the other - or more likely a mix of each. There are UV resistant epoxy compatible gelcoats and it is also possible to do epoxy laminate on a polyester gelcoat and skincoat - but things can go badly and as a general rule it is better to avoid! With the exception of gelcoat, it should be similarly easy to fix carbon and glass - but you want to repair with a similar process to what was used to build the part. Infused and prepreg parts are often repairable with bagged wet layup, especially epoxy - and it's often way more practical.

Have you thought about lightly insulating thicker parts (e.g., with loose aluminum foil or a shop towel) when pulling resin in a cold shop?

@ExploreComposites

3 жыл бұрын

Yes it is a good idea and I do it sometimes with thick breather cloth or that shiny insulation on a roll. Hard to take video through it though!

I’ve. Done a fair amount of hand layups of windsurfers and I get better results with less air trapping might be a little heavier but without the inherent weakness of trapped air

@ExploreComposites

2 жыл бұрын

Yeah you can do a lot of good laminating without a vacuum bag - especially thin reinforcements like on a windsurfer. Infusion is just nice as a manufacturable process - and it's easier to infuse huge stuff than to hand wet and roll. Also, very little of what I do in these videos is perfect textbook compotes work - I want to show things that can and do go wrong with each process. I just try not to have any total throw-away samples!

Could a double-sided smooth part be made by using a sheet of glass for the top instead of using the traditional peel ply etc?

@ExploreComposites

3 жыл бұрын

Yes... You'd have to be careful not to break the glass especially demolding, but given that the flow media is the core it should work fine. A hard plastic, aluminum or fiberglass plate might work better than glass - but you won't have the comfort of seeing the resin progress! See Laminate Sample #19 for a mini version of this: kzread.info/dash/bejne/iXpqy8OTes-rgJs.html

@TWX1138

3 жыл бұрын

@@ExploreComposites Thanks! I'd forgotten about that sample. Makes me wonder about the viability of making complex shapes if one can use a fiberglass mold, careful cutting of the foam to make it conform to the mold, and some kind of plastic that could be heated for shape prior to the infusion.

Hi, i wonder how to avoid get groove imprint on surface, vaccum did not not suck carbon fabric into those grooves?

@ExploreComposites

3 жыл бұрын

It didn't here, but the grooves are very thin. I think with polyester or VE resin that shrinks more there is a risk of print. Skin thickness makes a difference too.

@karbonfiberkompozit4821

3 жыл бұрын

@@ExploreComposites you are right actually, multiaxial fabbrics are cros to groove direction, make thickness, thank you but if we make infusion same core but single layer fabric both side, what will do you think happen

I'm learning these things.. Did you discover uv stable epoksi? And here op in datasheet should not be 85 m3 (kubik) insted of skwere

@ExploreComposites

3 жыл бұрын

You are totally right about m^3! Ooops. Too bad you can't edit KZread videos. There are UV additives for epoxies - they aren't really good for laminating - but mostly people use coatings like gelcoats or paint systems. There are plenty of epoxy-compatible gelcoats but they may take some experimentation to be confident.

@drankenkorps

3 жыл бұрын

@@ExploreComposites well im studying for boat build...itc. you make good videos very good! but please use all metrical units.

Wow awesome videos, thank you very much! Just to confirm, you don't need these grooves if you use flow mesh and just perforated core like with sample #7 (Epoxy Infused E-glass with Corecell Foam Core)? 1.5kg/m² seems like a lot of weight to add.

@ExploreComposites

3 жыл бұрын

Yes - grooves or surface flow media. Grooves do add a bunch of weight and are best for heavy skins that need lots of resin delivered fast - from big enough feed lines!

How would you "finish" the edges?

@ExploreComposites

2 жыл бұрын

Ideally you could flange the part when you mold it, bringing both skins up forming an "L" which would finish the edges. Alternately you could put radii on the edges and laminate a few plies of something +/-45 (double bias, woven cut into 45 degree strips) over the edge to tie the skins together. Its not done, but lots of those details are shown here: explorecomposites.com/articles/design-for-composites/composites-details-edges-holes-and-joints/

Can you give the formula resin needed

@ExploreComposites

Жыл бұрын

Generally with infusion, I start with resin weight = dry fabric weight. You can calculate resin uptake from core data sheets sometimes but curvature changes things. I have some basic spreadsheets for calculating plumbing volume based on hose lengths and under-bag flow media areas. Really testing is the best way to know for larger parts - but it is common to still be a bit wrong even with pretty involved estimating!

it is symmetrical, has the same quantity of carbon in 0/90 directions...