I’m working on a f/x project for school and wanted to either be told or sent in the right direction on making THIN carbon fiber panels with the best crush resistant reinforcements materials (foam? making ridges?)…any other threads I should check out?
What would be the least amount of layers to make really strong crush resistant costume armor using carbon fiber and epoxy resin?
What materials and/or techniques could I use to reinforce the carbon fiber?
Thank you for the help!
Will the body armour experience actual load, or is it purely a costume?
It will experience actual load, I plan on have some folding wings and other external effects held inside …it’s complicated stuff but I’m not experienced with “strengthening” carbon fiber. I’ve make some fiberglass pieces before and I really used too much cloth and resin and made some too big, too heavy props. I’d like to avoid doing that again.
I think without knowing what load is going to be applied, it’s impossible for us to say what will be strong enough, as strong is a relative term.
But in general, if crushing forces are at play then foam cores aren’t ideal. You would really need a solid core like marine ply, or a solid laminate. The marine ply would no doubt be way too heavy, so it really means you need a solid laminate if the load is actually high. But then it’s also very hard to say what thickness laminate you would need, so layers and cloth weights becomes difficult to recommend.
Realistically, anything below 2mm thick wouldn’t really be considered structural. So you are going to be looking at at least 2mm. Over 5mm is going to be extremely strong, and I would be astounded if any wearable prop needed such strength. So your ballpark figure is between 2-5mm as a best guess, but there’s a massive difference between those numbers. My gut feeling says 3mm would be overkill, but I don’t know anything about the project…
A lot of bullet proof vests are made with Kevlar or Inegra fabrics. I believe carbon is weak on shear strength…
Although carbon fibre looks great and is strong if you want thin but crash resistant armour then best is fibreglass and kevlar using epoxy resins.
The thin carbon will most likely let you down. Maybe there is some fake carbon/black fibreglass you could use?
I am with the above. Kevlar.
If you really want body armor that works, you would use ballistic ceramic plates. 
OK, thanks guys!
Keep in mind that Kevlar is only stronger than carbon in the event of failure. Bullet proof vests and other body armour use Kevlar because it has decent elastic strength and will continue to absorb energy after it has exceeded it’s plastic strength. Carbon on the other hand will take more energy to break, but once it has broken it won’t absorb any more energy at all.
Kevlar also has shocking compressive strength, which may be a factor in this application. Again, without knowing the ins and outs, it’s hard to recommend.
I do agree that fibreglass is potentially a better option, but only if it is S-glass. If it’s e-glass then the only benefit is cost saving. S-glass is stronger than carbon, but not as stiff.
Like Hanaldo says you have a few things to weight up, is it really getting heavy hits? Flexing absorbs impacts too.
Fglass/kevlar mix would be more comfortable to wear with it being more flexible and moving with your body a bit more than rigid carbon.
I agree with what Honaldo says about needing more info on the sort of pressure it will be under before being able to offer meaningful guidance.
As a very general point, for making cf parts with fewer layers but higher rigidity, I find that a 4x4 Twill weave fabric will produce stiffer parts than your typical 2x2 twill or plain weave. It’s also twice the price so not ideal if cost savings is the goal.
I would also add that the part design makes a huge difference. A single layer in a pipe shape will be noticeably stiffer and stronger than a flat panel or sheet.
I would usually say that you should use as many layers as needed to achieve the desired strength. Why is minimizing the number of layers important here? If 6 layers produces enough strength and 4 doesn’t then why not use 6 layers?
Perhaps some pics of the part design and more specific info on how it will be used might help people offer advice that is actionable.
Cf, fiberglass and Kevlar are all strong in different ways. If it needs to stop bullets then Kevlar is the way to go. If it needs to not bend, then cf is your best bet, if it needs some flex before it breaks, then fiberglass might be the right choice…