Infused Panel Laminate with core.

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#1

Hi all, first time poster… and whilst I’ve played around with a few different techniques, I’ll be soon attempting my first infused project, with a core… Disclaimer; I’ve searched around & had a good read, but still a little nervous and after some clarification…

Project:
CF Internal door skins to replace the existing MDF panels in a early 1930s Lagonda Rapide. Client wants panels that weigh less, and increases the side impact protection (or as much as one can do for such an era of vehicle).
Final composite panels will be covered in new leather, so aesthetics are not critical.

Build Layers
1 - 3k CF
2 - 3K CF 45 degree offset
3 - 3k CF
4 - 5mm structural core (Divincell or Klegecell)
5 - 3K CF
6 - 3k CF 45 degree offset
7 - 3k CF
8 - Mould/laminate based treated with wax/PVA etc.
I may possibly replace layers 1 & 7 with e-glass, for a slightly more robust finish, and less “shatter” in the event of fracture or failure…

Now, whilst I’m competent with a non-cored infused process, having never performed an infusion with a core, I’m nervous about ensuring the bottom side (layers 5-7) of the laminate structure is not left with any dry spots, and that it is completely wetted out during the infusion process.

I’m yet to purchase the core, but imagine that it will require some “channels” to allow the resin to flow to those bottom layers. (Layers 1-3 are not a concern due to infusion mesh aiding the process, and the ease of being able to visually monitor the resin take up).

Apart from laminating the job on a sheet of glass (for visual inspection aid), are there any suggestions as to how I can ensure those bottom layers are correctly infused? Or am I worrying too much/missing something obvious??

I can go down the path of a wet layup, but find the infusion process much “cleaner”… Or alternativly should I lay up the bottom layer first, then at the core/top plys in a second process…

Thanks inadvance, there’s a great plethora of usefull information amongst this site.

James

#2

Just perforate the Divincell and no worries… those are not very thick panels. I’ve done tons of parts that way and the perforations would allow the resin to penetrate the bottom no problems. You should do some test panels to see for yourself, just leave a good break at the vac source to give resin time to flow.

One thing against foam core was it’s ability to soak resin and increase weight. If it’s not an issue than have at it. There is also 6mm end grain balsa that might not absorb as much resin? I’ve also seen plastic honeycomb with a membrane for infusion which might be another alternative. The other option is to have no core and use a rib type structure which takes a bit more work to make the tooling but would weigh considerably less… say 30-50% at least.

Sounds like a cool project. I’d like to hear more. Are the pannels flat? There is also kevlar if you want more resistance to impact?

-=Sam=-

#3

Surface resin on foam and balsa are pretty similar.

Balsa will give a stiffer result, though, although it is heavier as well.

Shattering will not be a big problem, as it is leather covered.

If you are worried on resin flow, make sure your foam is perforated, and has a slight impression of chicken wire pressed in (you can do that yourself easily, chicken wire is everywhere…)

#4

Thanks Sam & Herman, layed up the first panel this morning via a wet hand layup… Local supplier couldn’t get the appropriate resin in time, so choice was limited…

Not 100% happy with how that went, the warm weather here in Oz gave my pot life a shorter than hoped lifespan… 30mins wasn’t quite enough… (Using FGI R180 with the “slow” hardener).

Has anyone tried placif an ice pack under a tub of mixed resin? Wondering if that may buy an increase in work time?

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#5

I use Soric on my infusions. Has the channels already in it but I do parts with curves to it that balsa and foam cant quite conform to.

#6

Further on topic, I am also working on a similar project.

Has anyone attempted this one step process with traditional aluminium or nomex core? Cell size 1/8 and 1/8 thick core. My concern is also complete saturation and weight (via resin filling cores) or should I just stick with a foam core

Thanks for the advice!!

#7

Thanks all for the various replies.
I wasn’t able to get my hands on a suitable infusion resin in time, so was semi-forced to use a hand layup process instead. Having not layed up such a large surface area in warmish weather threw in a few challenges, but we got through it ok… The joys of a backyard makeshift workshop…

The 1st panel was on done at around 25 degrees (with temperature increasing over 30 later in the day), but suffered a little with potlife & poor bag sealing… Managed to pull ok vacuum, but a tiny leak somewhere caused a small headache - cured reasonable quickly. In the end it was ok… ~1200 grams finished panel weight.

The 2nd panel was layed up at around 20 degrees, into a cool night… Took a lot longer to cure, but bagging was much better sealed… Possibly pulled a bit too much resin out - though the weight difference between the two is around 50 grams? ~1150

A few imperfections (pin holes/print though etc), but the “customer” was happy, so thats the important bit!

From a highly untechincal testing method, and from curiosty, I decided to make a few test “cards” ~A4 in size, to assertain some basic strength ratings… I’m light as a feather @ over 100kgs (& 6’3)…

1 ply carbon, 5mm core, 1 ply carbon - broke when i stood on it between 2 bricks…
2 ply carbon, 5mm core, 2 ply carbon - held, but felt compromising when stood on between two bricks…
3 ply carbon, 5mm core, 3 ply carbon - held, and jiggled around whilst loading full weight on panel with 1 foot…

Also now that the important bit is out of the way, I’ll have a play around with some core infusion during some spare time in the coming weeks/months… Sound like I’ll have a few more projects later on in the year…

Again thanks,

James

#8

I thought about this as well… Infusing with a honeycomb core will just result with lots of resin saturating out the core, (Unless the core has a film of sorts over it)…

Could be done using either prepreg (but I imagen an oven of sorts would be required to cure product), or laminating in multiple stages (but becomes a mechanical bond rather than a chemical bond, so arguably a weaker structure.

They are the reasons I went down the path of a closed cell foam core…

#9

On heat: An ice pack could definately help, but I am a bit wary for condensation.