Carbon Fiber Anyone???

[11Budlite]

Interesting read: http://www.lowcgen.co.uk/presentations/thurs04.pdf

 

Bruce :7drive:

[shiva]

Nice paper, really liked it thanks.

 

One thing that could be interesting in my build is using epoxy bonding for the side panel instead of regular rivets.

 

There is a 60% increase in frame rigidity compared to rivetted panels. Well according to them. Page 29

 

Seams like a cheap and easy way to add even more stiffness to the chassis.

 

Anyone got more info on what kind of epoxy one could use to achieve similar results?

[Ian7]

Best stuff (at least best in an affordable environment) for bonding skins to tubes is Hysol.

Easy to mix and apply. Absolute b*gger to get off years later, so it must work...

Contact Aircraft Spruce in California or Georgia.

[Birkin42]

Pretty neat stuff.

I did notice that the size of composite tubes they made were much bigger then the typical 1 x1 tube used in a 7 space frame. This on its own would add a lot of strength/stifness, but takes up a lot of extra space.

It seems like it saves a fair % weight, but seeing that the typical 7 space frame is just over 100 lbs, how much overall weight of the car is it really saving. The 100 lbs for the steel frame includes the suspension anchors which on the composite car requires bolt on metal brackets with imbedded metal plates in the composite anchor too. 4 x's the cost of the frame to save about 50 lbs may be expensive, though if you are going for the ultimate 7, it might not seem bad to some.

Not sure how user friendly a composite frame would be to the home builder that wants to customize his build, but would be a great basis for the next ultimate 7 from Caterham.

It will be interesting to see who this technology will evolve in the coming years.

 

In terms of bonding aluminum panels on to a steel frame, this should add some stiffness, but your ability to repair a panel or the frame in the future could be a problem.

[shiva]

I guess that maintenance would then get a problem. Having to remove/replace a panel would then get a bigger challenge. Heating the bonding would probably help since most of the bonding glue I've seen are rated to 300F or so.

 

If has is pros and cons I guess. One thing is sure, having NOT to drill the frame for the rivets would probably be a good thing. Help keeping structural integrity while also give more rigidity.

 

I'll see when I'm there I guess. Almost every seven where drilled and riveted anyway.

[rv-4mike]

In my opinion it misses the whole point of using molded composite in the first place. The advantage of molded composite is that you can get a very complex shape, put the strength where needed, etc... In other words a molded monocoque eliminating the frame altogether.

 

If you want to build a space frame and increase stiffness/reduce weight, use 4130 steel rather than mild steel. Save the carbon and the $ for a more reasonable application.

 

Unless of course you are one of those types that just has to have it for the bling factor.

[BusaLoco]

RE: Monocoque: In other words a molded monocoque eliminating the frame altogether.

You sure got that right! ... The boys at Lotus got it right a long time ago!

My son is an aircraft structures mechanic.

He just looked at this complex structure, scratched his head and asked ... Why?