Question on sandwich cores

General Composites Discussions Composites Talk
#1

I am planning to use a honeycomb sandwich core but was wondering about the strength of the core when used vertically.

If I were making a CF bookcase, the CF covered core could easily be used for the shelves, but what about the vertical walls of the bookcase? All the load would be pushing down on the sideways oriented
honeycomb, does this make sense? Kinda like crushing a can on its side vs standing it up.

Also, I’m not really making a bookcase. This is for a V-mount configured radiator and intercooler. How do I determine if my core is strong enough before actually laying the pieces up? The water filled radiator and the intercooler are pretty damn heavy, plus vibrations from the engine/road, and engine heat…maybe I should go back to the original plan of using aluminum sheets.

Thx!

#2

Good question, maybe we should / could test those honeycomb panels we made in the classroom?

#3

Why not sheets of carbon? A sheet of carbon will yield higher strength than a sheet of aluminum of similar thickness.

#4

Use core material everywhere, except to the edges or where bolts will pass through.
It will be more than strong enough with the proper layup schedule of carbon.

#5

If you are looking for part that will perform reliably in the application you have outlined, then I think you would be far better choosing aluminuim.

On the other hand if cosmetic appearance is more important then you could almost certainly get carbon to work well, but this would be much more costly then aluminuim, and unless you are very experienced making these type of parts, it would be a very good idea to over engineer to ensure durability, which may well mean it would be heavier than a properly designed and made aluminuim part.

#6

Use potting compound at the insert locations to transfer the load to the skins. It should be stiff enough with the skins.

#7

TET,
Could you explain more about using core up to the edges? What would I do at the actual edges?
I think I understand for the bolt holes, maybe layup a piece of tubing or rubber bushing or something.

Classicbike, I agree with you totally on all points. I’m thinking of vacbagging first with cloth or mat and then overlay in CF. I may double up with more core in some areas to provide a lip where mounting tabs can be placed. If it’s too heavy I will start over or switch to aluminum…and then overlay with CF!

Bill E.
Can you explain the use of potting compound? What it is and how it will handle the stress?

Here’s some pix of someone else’s car. He doesn’t appear to have the vertical walls on both sides of the rad/IC which would prevent air from escaping past.

Thanks to everyone!

#8

Aluminum honey comb with 3 layers of 8.8oz glass on each side is unreal stiff/strong.

We recieved several test cores covered in glass from www.plascore.com

All of them were unreal. I think Id be more worried about the resin instead of the core.

#9

Might want to lay a layer of S-glass between the aluminum and CF to keep the aluminum from corroding.

#10

Noted, thanks!

#11

With Honeycomb (where did you get it from…:rolleyes:) you will need to bevel the HC edges and edge seal with reinforcements like the paper core mat or moisture will paly havic with delamination.

I have special fasteners for honeycomb shown on one of my post on here somewhere…

#12

Seems an awfully big intercooler core, your motor must be producing serious power to need a core thats bigger than those used on WRC rally cars.

#13

That is a large I/C, but they come larger. The SR20 in that S14 could easily be making 500hp. Even an I/C of that size can get heat soaked pretty quickly. I also drive one of those and I make around 400whp.

Rally cars are HP limited and also have the luxury of using race gas only, alcohol injection, intercooler spray bars, better tuning etc…

#14

One of the greatest engines ever made…true story.

#15

Oh, you know, some guy was moving to Tennessee or somewhere out there:-)

These special fasteners I MUST see!

#16

…now maybe not for a year or two now…but so. MO. is looking better!:rolleyes:

#17

Good! I actually hope you can stay!

Thanks for the pix, I saw these in another post while I was searching yesterday.

But…I have decided to go with an aluminum frame using 1"x1" tubing, and then possibly just making the (removable?) walls out of fiberglass or carbon.

The idea is to be able to lift the entire IC and rad assy. out together. So I came up with the cage/cradle idea.

I may want to wrap the tubes in carbon…What else can I use to insulate the materials from each other? Etching primer or whatever its called that the automakers dip their panels in? Rustoleum?

#18

So after some delay, here’s how it turned out. I can lift the IC, RAD, and OC + rad fan all as a unit!
My aluminum TIG skills suck…
I’m gonna wrap the tubes in CF.




#19

These two are older pictures, before the OC mount and additional tubing was added.

#20

Awesome workmanship! “Tiging” is just soldering alum…:rolleyes: