Fabricating Structural Components from CF/CKevlar/etc
 

Anyone have experience with this? Among the things Ive been looking into/researching, this is is one of them. Of course, the easiest would be the panhard bar and rear lower control arms. So, anyone have experience with composite structural pieces?

Re: Fabricating Structural Components from CF/CKevlar/etc
 

The alignment of the fibres, weave, number of layers, type of epoxy and how well it is vacuum bagged/compressed will have a huge impact. Unless you have this all figured out structural items where failure causes a crash are not a good idea.

I have done some work with CF and I am prepping to make a STB at the moment BUT I would not ever consider things like a PHB or LCA, if they fail you will have BIG problems (failure = crash, maybe death...). Unless you have everything all figured out on alignment, layers etc. they likely will fail. Something like a STB fails and all I have is a mess--it can also be overbuilt to add some margin.

I have also used it to reinforce, if you do a look on here you will find the CF cowl I made. If you are going for the look you can always just wrap it but watch out for galvanic corrosion.

Here is the link... https://www.thirdgen.org/forums/fabr...-progress.html

A good place to get materials is an aircraft supply or boat supply. They should also have structural rated epoxies.

Re: Fabricating Structural Components from CF/CKevlar/etc
 

the easiest/safest way would be to uses an aluminum core and use the composite as a bulk of the control arm.

i do know a bit about coaxing strength out of a weaved material.

i think one way to do it would be to use alternating regular cloth, cf 'tape', cloth, 'tape', cloth, it would keep the weaves mostly perpendicular. another would be tow, cloth, tow, cloth. there are a few ways.

i think the failures are most likely to come at the ends. a full composite control arm would be more difficult than a metal cored one.

Re: Fabricating Structural Components from CF/CKevlar/etc
 

How would you plan to confirm the tensile strength of your composite pieces vs the standard equipment ?

Re: Fabricating Structural Components from CF/CKevlar/etc
 

could go as complicated as a load cell or.. weigh single brick, then pile brick after brick onto control arm situated in such a way that only the ends are supported (wouldnt be a difficult rig) until crack, snap, etc.

though, if you think most of these manufacturers actually load test the control arms:lmao: (yes, i see the reason for testing composite pieces. its not something thats lost on me)

Re: Fabricating Structural Components from CF/CKevlar/etc
 

Oem does test their parts. Aftermarket isn't worth a piece of scrap.

Re: Fabricating Structural Components from CF/CKevlar/etc
 

considering theyre looking for the cheapest ways to make the control arms... i dont doubt oem's do. aftermarket though? nope.

Re: Fabricating Structural Components from CF/CKevlar/etc
 

Unless you have access to hydraulic presses and vacuum bagging systems you wont be able to make suspension components.
Kevlar isnt realy suited for ridged applications. Its main use is for puncture resistant applications. The problem with carbon fiber is it doesn't hold up well to impacts. I.E. its not durable. Its very strong up to its breaking point. But once it takes a load more than that point it shatters. Think of driving over a large pothole, and boom your suspension falls apart. In a solely racing application it could have its advantages.
But I think the main reason you wouldn't want to do this is cost. For quality carbon fiber cloth your looking at about $40 a square yard. Not to mention resin to hold it together.
I think your best bet if your looking for weight savings is aluminum. Its easyer and more forgiving to work with. And more cost effective.

Re: Fabricating Structural Components from CF/CKevlar/etc
 

i know cost is a major issue on this site but cost isnt why it entered my mind.

pfadt unveiled something very similar to what im tlaking about for the 2010+ camaro right before they closed:

http://spectre23.files.wordpress.com...pfadt-arms.jpg

metal core, composite reinforcement. i would guess its about 1/3-1/2 the weight of a full aluminum control arm.

vacuum bags and the like are easy to find and such. i also know of the limitations. racing teams generally fabricate carbon pieces that have a unidirectional strength (up/down or side to side). the pieces can have omnidirectional strength but the penalty with that is weight and complexity.

Re: Fabricating Structural Components from CF/CKevlar/etc
 

Ok I understand your direction better now. I thought you were talking about complete suspension components from carbon.
I have quite a bit of experience building composite gliders using all the big materials (carbon, Kevlar, fiberglass). If you have any specific questions about this topic I would be happy to help. The main issue I see you having is the joint between the aluminum and carbon components. As in my experience bonding a composite material to a metal is very difficult. Because the composite often flexes while the metal doesn't. The weak point being the glue joint, breaks. However if cost really isn't an issue their are some industrial adhesives that will work quite well.

Re: Fabricating Structural Components from CF/CKevlar/etc
 

i would absolutely LOVE to be able to fabricate a fully carbon suspension that is strong enough to take oem type abuse and more. unfortunately, i dont have the means to go that far (knowledge/experience, tools, etc)... yet. one substance, carbotanium, would probably be awesome to use for suspension pieces. dont want to see prices on it though..lol.

most of my 'how the hell would i do this' questions relate to melding the 2 together. one idea is to use an aluminum rod (7075 most likely) threaded on both ends, wrap the center with c/f to the thickness desired then thread on the ends or some such. chromoly could be an option as well.

Re: Fabricating Structural Components from CF/CKevlar/etc
 

nighthawk, can we get a weave to optimum use sort of list?

Re: Fabricating Structural Components from CF/CKevlar/etc
 

You may want to check out uscomposites.com . They have all kinds of carbon, kevlar and fiberglass along with different types of resins, And for a project like you are thinking about I would recommend using carbon sleeves, the more layers you have the more rigid and strong it will become. I personally would get an aluminum rod well waxed with release wax and use the kevlar sleeve first then multiple layers of carbon fiber, the Kevlar will give the piece more strength once impregnated with epoxy resin. And use vacuum forming to infuse the resin with fibers. Most problems are caused because of to much resin being used, And vacuum forming eliminates the over use of resin in a piece, If you don't have a vacuum pump you can pick on up at harbor freight for around $100, I use the one for evacuating A/C systems for my projects, the better and stronger the vacuum the stronger the piece will be.

Re: Fabricating Structural Components from CF/CKevlar/etc
 

I agree that carbon sleeves are the way to go. If I were making a control arm I would alternate layers of carbon sleeves with 12k carbon tow wrapped around whatever your using as a form. And keep that up till the thickness you want is achieved.

Re: Fabricating Structural Components from CF/CKevlar/etc
 

almost forgot about the sleeves. wouldnt the better idea be to leave the metal piece a part of the piece as a whole?

the biggest design/engineering issue i would think would be to have end that wont separate under stress like was an issue with teh CF driveshafts. it was why i put the idea of a metal core out there.

the carbon 'twine' was part of my original ideas. the tow at alternating angles i would think would help strengthen the piece as well.

uscomposites shipping prices are insanity..

Re: Fabricating Structural Components from CF/CKevlar/etc
 

what about using prefabricated tube?

here are the ends i would use:
http://umiperformance.com/catalog/im.../0011a_LRG.jpg

Re: Fabricating Structural Components from CF/CKevlar/etc
 

I would think leaving the aluminum rod would be best, But I will admit making suspension parts is not anything I have ever done or would do. I mostly do body panels and such,

yes alternating the weave does make it stronger, I use the 1/4 method

Yes if your not buying a big quantity the shipping price is a bit high. I was just giving an example of a good place that sell good quality fiber and resin.
you could buy it off ebay , but your never sure what quality your going to get.And that matters to me at least.

Re: Fabricating Structural Components from CF/CKevlar/etc
 

This is where I buy all my composites,
www.acpsales.com

Prefabricated tube would take a lot of the questing out of the equation on your part. However it might be difficult to find the exact specifications you want in a premade tube.

Re: Fabricating Structural Components from CF/CKevlar/etc
 

bend stiffness and torsional strength are the most important ones, i think:


90 Degree "Hoop" 0 Degree "Zero" /- 45 Degree "45's or Angled"

Fibers Wrap Around Circumference Fibers Run Along The Length Fibers Twist Down The Length
Provides Crushing Strength/Stiffness Provides Bending Strength/Stiffness Provides Torsional (twist) Strength/Stiffness

http://www.rockwestcomposites.com/ck...jpg?1376004328

Re: Fabricating Structural Components from CF/CKevlar/etc
 

It depends on what components you are talking about. If you are talking about rear LCA and panhard rod then all your are worrying about is axial load.

The problem is these components see compressive loads that are just as high as the tensile loads. So you are going to have to make some pretty stout tubes to handle the buckling.

Honestly, if I were to do this I would start by making just one rear LCA and running that. If you have a failure it would likely not lead to a serious crash this way.

Here are some challenges to think about.

1. How are you going to test? For "home built" projects I would test every part made with a comfortable safety factor. Make sure to test for all in service conditions (cold wet, hot wet).

2. What about corrosion? Since cost is not an issue, I would recommend using titanium ends to avoid this issue.

3. How are you going to attach the carbon fiber tube to the ends? Bonding is an option but requires a good amount of surface prep. I would add some chicken fasteners for sure.

Re: Fabricating Structural Components from CF/CKevlar/etc
 

I would say use titanium for suspension parts. Its a lot more like steel, where it will bend before breaking.
A bent suspension component is bad a shattered composite one could be catastrophic.
Then use CF for body panels.

Re: Fabricating Structural Components from CF/CKevlar/etc
 

1) simple load teast rig could be made. wouldnt take a lot. just need weights of some sort and a fixture to load the arm with that weight.

2) corrosion is only an issue if the aluminum or steel comes directly into contact with the cf. a threaded metal sleeve wrapped in fiberglass then inserted into the tube would work.

3) ^