yes i know Interior/Exterior section but ... wouldnt this also provide performance gains ? we all know it is sexy and light weight ... but ive noticed that it also seems to releive heat ... quite good too (i have the oem style .. vented ones i know is self explainatory )... its honeycomb design is the main reason for its heat dissapation .... so i guess it helps at least in re: to therman dynamics ... please discuss

Doesn't relieve heat that well...mine is cracked to shit because of the heat.

Originally posted by sonikbewm
Doesn't relieve heat that well...mine is cracked to shit because of the heat.

Same here ^^^^^^

The Carbon fiber on the market for cars, is weaker than fiberglass because they are using it as a styling and not for function. It has to do with the resins used. Structural carbonfiber is baked in a autoclave, none of the street stuff is. Beside, most people don't even look at carbon fiber anymore, there is to much of it.

It has more insulation value than steel, and with the street stuff the resins will break down over time do to heat cycling. I have seen some of the older stuff starting to break down from heat cycling.

well thats weird .. i had my stocker hood on for about 3 yrs before i got this ... it never saw it causing that heat mirage effect before .. but sure enough ive noticed it quite a few times on the C/F and this is after normal driving ...

on a side note when my hood is up u can actually see light through the c/f ... can this have something to do with it ? cause it seems like common sense that if your eyes can see through it than the heat can escape through it ...

Yes, the thermodynamic properties of carbon fiber laminates are directly defined by the type of resin used. Brake rotors that are made from carbon fiber use a special very expensive epoxy resin manufactured by Huntsman, and consolidated in an autoclave.

Most aftermarket carbon fiber parts are hand laid, and made from polyester resin (poor interlaminer strength, and high temp. capibility), and if anything vacuum bagged. Composite strength is inversly proportional to resin content.

If anyone has any specific carbon fiber questions, PM me. I'm the Body and Composites section leader for the AU Formula Team.

Originally posted by WickedESi Composite strength is inversly proportional to resin content.

Not sure who told you that, but that is not correct. Strenght vs resin content is not inversly proportional or even linear. With Polyester Resin and Fiberglass maximum strength will between 9% and 14% and begin to drop off on either side of that range. Resin rich is not as bad as resin lean. You might want to check with your professor that told you that and varify that.

Originally posted by AFX_Manufacturing

Originally posted by WickedESi Composite strength is inversly proportional to resin content.

Not sure who told you that, but that is not correct. Strenght vs resin content is not inversly proportional or even linear. With Polyester Resin and Fiberglass maximum strength will between 9% and 14% and begin to drop off on either side of that range. Resin rich is not as bad as resin lean. You might want to check with your professor that told you that and varify that.

I was sparing the details when saying it was inversly proportional. Obviously if you had no resin you would have just a peice of fabric.

The "strength" of a composite is a linear relationship, as resin is reduced tensile stress compacity increases (a peice of fabric with no resin being the greatest), as fabric content is reduced strain compacity increases (a chunk of expoxy being the stiffest). This is known as the Rule of Mixtures.

In order to acheive an optimal laminate you only want enough resin to bond the fibers together, and no more (you then start to loose the tensile strength of the part). I would post the typical stress/strain curves of fiber, resin, and a cured FRP composite, but I don't have a scanner here.

The best properties are usually obtained around 0.4:1 resin to fabric ratio, and by contact molding (hand layup, no vacuum consolidation), you generally won't see better than 1.25:1, most manufacturers can't afford an autoclave and pre-preg carbon.

All numbers come from Simon McBeath (Formula 1, and other competition series composite manufacturer).

Originally posted by WickedESi
I was sparing the details when saying it was inversly proportional. Obviously if you had no resin you would have just a peice of fabric. The "strength" of a composite is a linear relationship, as resin is reduced tensile stress compacity increases (a peice of fabric with no resin being the greatest),

That in not right. It is not linear. It is a bell curve. I can rip apart a peice of carbon fiber or fiberglass with my hands, but if you add resin I can't.

Originally posted by WickedESias fabric content is reduced strain compacity increases (a chunk of expoxy being the stiffest).

That is not correct either. Pure resin has no shear strength without fabric, it also has poor compression resistance, it is brittle.

Originally posted by WickedESi This is known as the Rule of Mixtures. In order to acheive an optimal laminate you only want enough resin to bond the fibers together, and no more (you then start to loose the tensile strength of the part).

That is correct, and also contadicts Originally posted by WickedESiThe "strength" of a composite is a linear relationship, as resin is reduced tensile stress compacity increases which you posted above.

Sometimes text books suck. The worst engineers in the work are the ones that got straight A's in college. That usually ment they were book smart, but had no common sense. Of the guys I was in Chem E with the ones that worked jobs that required hands on have now advanced further in their jobs, than those that only read the books and studied all the time. Experience means alot. The best example of this I can think of is this.

Story from my Youth by Gary When in collage during the summers I worked construction, usually in the local paper plant when they would shut down the machines. I was working a shut down on a paper machine, and we were installing a new coater. The young engineer on the job was ask by a foreman where he wanted a beam installed on the buildings superstructure. The engineer kept pointing to the blue prints, and saying "There, there" as the foreman kept asking where. Finally the foreman grabbed the engineer by the head and turned up and pointed at the real superstructure and said, "Where do I put the beam." The engineer turned back to the blue print and before he could say anything the foreman said, "Look at the date on your blue print dumbass it is 1927. The was rebuilt in 1947, 1961, and 1974 that beam on your blueprints hasn't been there for 50 years get your head out of your ass and tell us what you want us to do." The moral of the story is to be a good engineer you have to look at the real world along with the books to be effective.

Originally posted by oRACLe063
well thats weird .. i had my stocker hood on for about 3 yrs before i got this ... it never saw it causing that heat mirage effect before

Your factory hood should have had a heat insulator under it, plus steel reflects heat.

Originally posted by oRACLe063.. but sure enough ive noticed it quite a few times on the C/F and this is after normal driving ... on a side note when my hood is up u can actually see light through the c/f ... can this have something to do with it ? cause it seems like common sense that if your eyes can see through it than the heat can escape through it ...

Not following your logic here. I can see through the windows in my house, but when it is -10 below outside, my house is still 70 degrees when standing in front of the window.

Originally posted by AFX_Manufacturing Not following your logic here. I can see through the windows in my house, but when it is -10 below outside, my house is still 70 degrees when standing in front of the window.

Agreed. Light and Heat are two very different things, even if they can generate each other they are very different forms of energy.

"Not following your logic here. I can see through the windows in my house, but when it is -10 below outside, my house is still 70 degrees when standing in front of the window."

yes this is true ... your window is transparant .. this is not ... this is supposed to be a soild object yet light makes it through meaning its porous ... heat will escape by the easiest means nessicary ....

Originally posted by oRACLe063
"Not following your logic here. I can see through the windows in my house, but when it is -10 below outside, my house is still 70 degrees when standing in front of the window." yes this is true ... your window is transparant .. this is not ... this is supposed to be a soild object yet light makes it through meaning its porous ... heat will escape by the easiest means nessicary ....

Transparent and Solid are different terms. Solid, Liquid and Gas are the three states of matter. Transparent and Opaque are weither or not a material can reflect or allow light to pass through.

Your carbonfiber hood is not porous, it is solid. If it was porous water would go through it, and that doesn't happen. The hood has transparent parts that allow light through, but its solid state will still block heat from escaping.

Consider that composits are reinforced plastics, nothing more. The resin is the plastic, and the carbonfiber or fiberglass are the reinforcements. Something else to consider is that fiberglass is used as insulation in houses because it blocks heat from escaping your house. If you put carbonfiber into rolls like fiberglass it would do the samething. I can make a fiberglass hood and not put any gel-coat in and it would be come a very hazy transparent object. It will still block heat, it will still be solid, but it will allow light to pass through.

not to jack the thread n shit but.

Where can you get carbon fiber? A fabric or canvas store?

EDIT: wow that sounds stupid after reading the above post :P

DOh!

Originally posted by Blizare
not to jack the thread n shit but. Where can you get carbon fiber? A fabric or canvas store? EDIT: wow that sounds stupid after reading the above post :P DOh!

You can find it at industral supply companies. The best source for small quantities for someone just using it as a hobby is http://www.fiberglast.com We purchase large quantities for production of parts, but these guys are good if your trying to make something small.

thanks a lot.