Helmet layer questions

General Composites Discussions Composites Talk
#1

Hi everyone,
First post after reading what seems like 1,000… thanks for all the great info…

Ok, about me… huge melon on my shoulders. I was the kid in pee wee football who HAD to wear the XXL helmet.

Anyway, I have 4 helmets at home and none fit. So I thought why not, I’ll make one myself. I want it to be light and thin as possible. I found a foam called Poron XRD that I will use for impact protection.

Ok, I’m concerned about the shell. I’ll be infusing…

  1. Should I use a CF/Kevlar blend to provide impact protection, or just straight CF. I’m reading everyone is having trouble trimming the Kevlar.

  2. Should I go with a heavyweight fabric like a 12k 19.7oz over soric like so
    12k
    soric
    12k

  3. Or is the lighter 3k 5 oz fabric with more layers stiffer, stronger, lighter? Like so?
    3k
    soric
    3k
    soric
    3k

  4. And then finally, the edges of the fabric after the helmet cures… I want a nice round edge. I was going to trim with a dremel and diamond disc, but how can I get a nice round edge without seeing the soric? Spray some resin, black pigment… not sure??

Thanks again for all the great info and I’ll definitely put up pics of when I’m done…

#2

I have no idea how much material you should use.

When it comes to impact strength more layers in many orientations is better than a few.

I’m not sure that using a core material between the carbon layers is a good idea. That will reduce the puncture resistance and impact strength. Having all the layers together will maximize the puncture resistance and impact strength.

I’m not sure making your own helmet is a good idea…unless you do a lot of careful testing. I guess it’s your head though. :smiley:

I now feel like I need to write a disclaimer. :smiley:

#3

I’m not sure that using a core material between the carbon layers is a good idea. That will reduce the puncture resistance and impact strength. Having all the layers together will maximize the puncture resistance and impact strength.

Most core materials will absorb some off the impact, and will not puncture when a full fibre laminate would. SP has some comparisons in their documents.

#4

Heck I’ll disclaimer up!! This is all hypothetical!

What is sp? Is that the soric manufacturer??

What do do you all think about the edges? How can I get a good solid edge around the base of the nugget protector? Hypothetically or course…
Thanks

#5

SP, manufacturer of ampreg resins, corecell, etc. Gurit brand.

#6

We did a helmet (skateboard) for a pro skater who wanted it in carbon and custom made to his head. We had to make 5 units and sed to UL for testing where they destroyed them to test for safety. I do 't recall what the charge was though and I can’t really disclose the lay-up as the skater owns the info, not us…

What I will say is the helmet has to be designed to absorb the impact to a certain degree and like any other helmet there is a breaking point in which it is suppose to crack to absorb the impact when the severity of it warrants.

This isn’t something to guess at OP, every helmet has different standards as well depending on the application and the tests differ based on te application.

What is the helmets application, football? Motorcycle? Road bike? Sports? Snowboard?

#7

> Thanks… Yes its for snowboarding. And I actually spoke withx 3rd party lab and testing isn’t so bad… It was 8 units and only $625 to certify… So I’m just trying to get to a starting point really. I’ll be able to construct it in solidworks as well as simulate impacts…
>
> So hypothetically if you were to build another belmet… Would use core materials or straight cloths? And multiple layers of lighter cf or less layers of heavier?
>
> Thanks for the conversation!

#8

I would not use a core material…the lay-up sequence is stepped, imagine several layers of thin laminate, several layers of thick, then several layers of thin again, then thick, so on and so on…

Good to hear you looked into testing, you should def get that done to make sure it passes.

#9

Cool. I’d like to see that data but I couldn’t find in the Lantor site. Where can I get it?