Typical Layup Schedule

General Composites Discussions Composites Talk
#1

What all do you guys use in the lay up of a carbon fiber hood. Very few on the market use a core material. I’m just curious because the hood I want to make I want light as well as good looking. I plan on using a fiberglass replica of the frame underneath, but I was thinking a layer of carbon then a layer of core material, backed by a layer of woven e-glass.

Is that typically how it’s done? Or just lots and lots of CSM?

Also, are steel mounting points necessary? Or can wood with threaded inserts be used for weight savings?

#2

Where do I start…

Is this for a street or full race hood? It matters…

Yes to one 0 degree layer of CF and then a layer of -45, +45 degree 10oz FG. Then some core material (perf paper or honeycomb) and couple top layers of more 10 oz FG at differnet directions.

Why hinge it, just use hood pins if lightness matters…

#3

Well…it’s a street hood mainly, but It’ll see a few passes down the 1320. The hinges would be for simplicity, and the fact that hood pins only are for real race cars and I don’t want to seem like a poser.

I’ve never seen the perf paper you speak of…any links to it? This material works with VIP?

#4

With a core, make sure you coat the top well if you are only using one layer of CF. It is a very pourous material, and when it rains, it will soak into the core!!!
Hell, I’d say 2 layer top, and 2 bottom, of CF.
If you use honeycomb core, use a hard insert for the mounting points, wood, or anodized metal. Otherwise the core will squish when you tighten the bolts.

#5

About the actual core used, what thickness would be best considering 2 layers of carbon on each side (or carbon->carbon->core->kevlar->carbon maybe?)?
I understand as you go thicker, the panel stiffness increases hugely, but what about getting the core to mold to curves?

For instance, here is a review of the same model car as mine.
Scroll down the page and you can see the bonnet (hood) bulge.
Click -> http://autospeed.drive.com.au/cms/A_1805/article.html?popularArticle
It also has a compound curve to it.

Would paper or nomex honeycomb conform to curves like that?
Up to what thickness?
Or would scored foam be better? Grid scored?

PS Appologies if it seems like im trying to hijack someones thread. Im not. Just so much to learn :eek:

#6

No appology needed! I’m here to learn as much from others as I can. I too have the same problem because mine will not be a flat “bonnet” if you will. It will be similar to the ram air trans am hood. I’m interested in a lightweight core that conforms well or maybe should I just leave the core otu of the area where the scoops will be in the hood?

Ps…I don’t like Fords much…but I think that is a hot car. :slight_smile:

#7

Ok…so I found this post by dual twill over on the fiberglast board

SKIN
1 layer kevlar hybrid
1 layer of 5.7 oz 3k plain weave
Core Material
2 layers 5.7 oz 12k plain weave

Frame

3 layers of 5.7oz 3k plain weave

That is how he laid up the hoods that he did for the race cars. Any problem doing the same thing for a street hood? Or should I have more layers?

I may do one hood with just fiberglass and not the carbon fiber to test before I spend the money on the carbon.

Let me know what you guys think!

#8

For a street car you will need more layers as they take more abuse over time.

Good thinking, use FG before spending the big bucks and finding out the amount of stiffeness that you are looking for.