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My Carbon Fibre 280z!

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@rturbo 930 No idea lol. We're thinking its the T3 suspension that help load things off a bit. But yeah, full tank, all fluids in, and I still have sound deadening at the front (Trunk was cleaned up). 

 

@seattlejester Didn't think much into it. Just grabbed the doors as soon as I was told about the ridiculous cost to paint the car.

 

@Neverdone They definitely came up to mind. It's due to safety but a customer can still order the doors in carbon if they wish. Carbon was just the route to go to, funny enough, to save money lol.

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Posted (edited)
19 hours ago, seattlejester said:

Having played with that honeycomb aluminum, that material is pretty interesting. Lots of structure in the comb direction, you could stand on the material. Super trippy standing on the edge of aluminum foil thick material. Any side load though and it would collapse to the couple sheets thickness of aluminum foil that it was. It used to be pretty prohibitive to find, our supplier was a friend's dad who worked at boeing who bought it from their surplus section. 

 

It can support a ton of weight in the tubular direction. The question we had in our application was getting it to fit around curvatures, how to make it thin enough without shredding it, and how to try and keep the resin out of the combs as that would be overall additional weight. Thoughts of adding foam to keep the combs from collapsing, but in the end just a fiber glass structure core was used to support load. 

 

Huge aside, but you don't get a chance to talk about that material too often. 

 

For the doors, is it because to do it right there wouldn't be much weight savings? Add carbon, add core material, add resin etc. Therefore people who consider it as a weight savings aren't really planning on doing it right?

 

 

yeah, getting aluminum honeycomb, or honeycomb in general, to lay nicely over complex compound curves is inherently a challenge. It has massive compression strength. Shear, not so much, like you mention. Depending on the complexity of the geometry, you can sometimes carefully scarf, and bevel, core to make them flex, bend, or conform better. Sometimes you must cut the core into many sections and lay them side by side, instead of one continuous piece. It definitely can be tricky.

 

Getting resin within the combs themselves shouldn't happen, if you're using the proper materials that these were designed around. Prepregs. If you're using these types of cores, you should NOT be using hand layup. That defeats the purpose. Very much like a laminate that includes both chopped strand mat, and a carbon fiber skin. That is not a "carbon" laminate. That's mostly fiberglass and the carbon is doing very little, if anything, to the structure of the layup. You see virtually no weight savings over the "fiberglass" versions...and the carbon isn't even allowed to do its job... It's simply a more aesthetically pleasing cover, which there's nothing wrong with...just stop calling it a "carbon X".

 

If you're using prepregs and honeycomb it is a breeze. The prepreg fabric only has enough catalyzed resin for itself, so you must use a sheet of "film adhesive" (a literal sheet of catalyzed resin) to join the fabrics to the core. The film adhesive is just enough resin to, in a perfect world, form a little meniscus over the top of each of the combs, holding a firm and uniform bond between the skin and core. If it is too resin rich, the laminate becomes heavier (like you said) and brittle. Resin rich comes from hand layup.

 

In a perfect world, when you test the physicals of the laminate, the core itself will fail, and the skins will not delaminate.

 

high density foams are a wonderful material, and work well in combination with honeycombs, but as you can see from even my brief touching on the topic...there is a lot of variability, and tailor-ability to composites....which is one of its greatest advantages. If you understand the materials, and how they are designed to be used, you can customize the laminate to do exactly what you want, where you want. Only robust in those areas that need it, or strong in a certain force, while others areas that don't need said requirements can be as lightweight as possible.

 

I think the main reason behind most doors being metal is simply it's the best bang for the buck. It's wonderful at dispersing load, and provides good intrusion protection. You will absolutely see a weight savings with a carbon, cored, door over its metal counterpart - but doing so would add exorbitant cost and effort. As far as physical performance, the carbon door would be superior in virtually every way, but only if properly constructed. If not properly constructed, it could be devastating.

 

I was extremely lucky to learn from, quite frankly, one of the Composites wold's leading authorities, Henry Elliot. Now a head consultant for the Oracle Team USA Americas Cup team. 

 

I oringinally had planned to make full carbon, FIA legal, composite doors while at school. When I told him about the project, he raised his eyebrows big time...

 

Basically told me not to do it....he told me that the juice was not going to be worth the squeeze.

 

"if ten pounds is what makes or breaks your race, you're on an entirely different level of skill.....Don't sacrifice safety for weight, that's not how composites are supposed to work."

 

"don't sacrifice safety by chasing numbers."

 

is essentially what he told me.

 

 

 

 

If you aren't going into making doors with these thoughts in mind, you shouldn't be making doors.

 

That's my humble opinion.

Edited by OldAndyAndTheSea
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That is super interesting. Our core was pretty thin to start with, but if it was a thicker height I can see how you could shape it instead of trying to curve it with the right tools.

 

That makes a lot more sense on how one is supposed to go about it. Do you cap the ends in any way or is it just a sandwich of sorts?

 

We played with this material maybe 13 years ago? There was only one shop that had prepreg sheets and they only sold it in 1x1 or 1x2 sheets locally we wanted like a 1x3 or a 1x4 with some curves so that wasn't really going to work, we didn't have credit cards being younger back then either meaning no online purchases, kind of interesting how things change. We ended up doing some fiber glass strengthening beams and some type of core mat and hand laid layers of carbon for our little project. 

 

I digressed a lot though, but I appreciate your thoughts. My only foray into this may be some hand laid carbon for a hood at some point, doors are way beyond what I think I am able or willing to do.

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Posted (edited)
14 minutes ago, seattlejester said:

 

 

That makes a lot more sense on how one is supposed to go about it. Do you cap the ends in any way or is it just a sandwich of sorts?

 

I digressed a lot though, but I appreciate your thoughts. My only foray into this may be some hand laid carbon for a hood at some point, doors are way beyond what I think I am able or willing to do.

 

Typically any ends are covered by the laminate, exposed core is a risk to the core itself, not unlike any other circumstance, and should be thought about in the same way. The core is usually prepped, with beveled edges, at usually around a 45 degree angle (or at around a 2-5mm radius - material thickness depending) to allow for easy conformity of the fabric over the core's surface. 

 

Sometimes the ends aren't capped, but those situations are less common I find. ..but again, there's that tailor-ability coming into play. If you want caps, you can have caps. If you don't need caps, you don't have to have them. You have freedom of choice. Unfortunately freedom can sometimes be dangerous too. haha.

 

I love answering any composites related questions. Unfortunately there is a lot of misunderstanding of these materials. I'd like to help clear that up, to make the industry, as a whole, better.

 

I do apologize for any tangential trajectory that my comments may have taken things however. haha.

Edited by OldAndyAndTheSea

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