automotive composite shell advice

General Composites Discussions Composites Talk
#1

Hi,

Hoping i can gain some advice or idea’s for one of my race cars.

We are in the process of building a composite shell for a GT production car. The production car we are using, uses a sub-frame chassis. Rules stipulate that the original sub-frame of the car must be retained. So ALL outer panels of the car will be replaced by composite structures to lose as much weight as possible.

Most of the panels and doors will be a simple task to mold and produce, however…

The roof, rear quarter panels and side of the car is a one piece structure. It’s spot welded to the inner sub-frame panels of the car. This will prove to be a difficult task.

Quick paint brush Image :slight_smile:

We plan to mold this is sections. Starting with the roof and pillars which we would flange off 90 degrees with alignment aids for the next mold. After the mold is complete, flanges would be removed and the next mold would be made, rear quarter panels. So on and so forth…

The tooling will be made with a high quality epoxy and woven/MA s-glass, suitable for room temp VIP layups.

We would hopefully end up with an muti-part “exploding” composite mold.

The shell will be made out of:

0/90 carbon fibre
+45/-45 carbon fibre
lantor soric (core)
0/90 kevlar
+45/-45 carbon fibre
(Would really like some advice on this!) [Kevlar is required to shield]

I want to achieve a light and safe shell, but don’t want to over do it. The car already has a steel sub-frame and full chrome-molly roll cage.

Once the tooling is finished and removed, spot weld will be drilled out and the outer shell removed. The composite shell would be made and glued on with an appropriate structural adhesive.

However because of the shape of the shell, i don’t think we could make a one piece structure.

Also very worried with the size of the shell, a VERY large part to infuse. No autoclave access, so that’s ruled out :frowning:

My Questions:

[ol]
[li]What do you think of the outer shell layup? If you disagree what do you think would be best suited?[/li][li]After/IF the shell is manufactured as one piece, would we be able to trim the shell into sections and re-bond with and adhesive or would this ruin the structural properties?[/li][li]Should the mold be made as a multi-part mold or just made separately for different sections?[/li][/ol]
Thank you for your time, and help and advice would be appreciated! :slight_smile:

#2

I wouldn’t worry about the size. If you search youtube you can see people infusing hulls large enough for multiple people to stand in. You will have to correctly place resin inlets and vacuum lines though to ensure complete coverage of resin flow but I can’t help you out much there.

[ame=“http://www.youtube.com/watch?v=g58x8atklaQ”]YouTube - World Cat 320CC Hull Infusion[/ame]

#3

The layup for the parts sounds like it would be fine. I would put some kevlar around the wheel arch area (but not upto the very edge to avoid fraying). This is just so that a little light door to door rubbing doesnt make the body apart. So you could atleast finish the race.

I would make the roof and rear quarter panels seporate so they can be replaced indervidually as you get body damage. This will reduce cost of damage and make carrying spares easier.

With race car bodywork you need to remember that you may need to have more plies in some areas than other area to keep the weight down but actually make the parts stronger where they actually need to be.

#4

Thank you for the replies!

Will run an infusion test and time flow rates to see what type of pot life we would go for.