Making CF motorcycle body armour.

General Composites Discussions Showcase
#1

So after crashing aBMW 2012 GS bike head first into a tree which totalled the headlight and instrument cluster I have been thinking about how I was glad I hadn’t been skewered by the branch.

Now I have the Forcefield chest armour (http://www.forcefieldbodyarmour.com/product/race-lite-chest-protector/2351) which is great for absorbing impact but not preventing penetration of sharp things.

With that in mind I decided to make an over lay for the Forcefield which I could take on and off as required.

Forcefield chest armour.

First of all I measured out the required fabric using my template.

Make sure to protect your very expensive carbon fibre by using masking tape to secure the warp and weft when you cut the bolt.

I will be using three layers this time. Layer one 1 x 200 g/sqm plain weave carbon, Layer 2 1 x 330 g/sqm high modulus tri-axial carbon fibre, Layer three 1 x 200 g/sqm plain weave carbon

The wrap on the mould for the e-glass prototype created a terrible finish which was very resin rich. This time I coated the cardboard with PVA (Polyvinyl alcohol) to allow for an easy release.

To get round it being rather cold in the UK, to help increase the fluidity of the epoxy and to speed cure times I setup a heatgun with temperature sensors.

I then built the layup again with SP systems 106 epoxy and used the heatgun to ensure full wet out. I then squegeed out the excess resin.

#2

I put the layup on top of my boiler to give it some extra heat while it cured over night.

The next day it had reached a workable cure.

I trimmed the excess fabric off.

I used some pliers to grab the edge of the cardboard and with a hard yank it released nicely.

I covered the presentation side with masking tape to protect it.

I filed the rough areas on the rear and then took wet and dry sand paper to it to create a matt surface for the velcro.

#3

Time to remove the protective tape.

Shiny, shiny.

Add the velcro but this time vertically as it prevents it peeling off when you pull the plate off side ways.

And your done! Looks nice, weighs about 180 grams and is rock solid.

#4

I’m not sure you get much protection from impact and penetration with Carbon Fiber I would think Kevlar would have been a better choice.

#5

I agree with the above, make another using Kevlar and you could have an outer layer of carbon for looks :slight_smile: the carbon only guard could splinter on impact. please do not see these comments as negative just constructive.
Regards Chris

#6

I’m also thinking make for my, a composite protections,
This is mine:
http://motorcycle-gear-online.com.au/exfiles/products/fox_titan_suit.jpg
Good, but heavy.

One of the problems I see is that composite protections, vs plastic, are very thin and rigid, then, you could cut with them in a impact!

Regards.

#7

Having had a few carbon splinters, I’d be very reluctant to use it for impact protection on my chest. They’d have no trouble stabbing most of your vital organs. Might be an application better suited to plastics.

#8

carbon on impact will splinter just look at some of the f1/racing car crash pictures!
however there is no need to start over! simply add a few layers of kevlar to the inside of your nice shiny carbon piece!
it will be a little heavier but its alot easier and nicer looking than making a whole new piece

#9

As the overlay is just designed to resist penetration and to provide a hard outer I am not too concerned with explosive splintering of the CF as it won’t be under any load when it is struck. In addition the energy absorbing armour should protect me from most splinters.

Anyway I created a test panel using the same layup and got to testing.

I tried recording the impact using a GoPro at 240 FPS but it wasn’t as useful as I thought. The sample was placed on similar impact foam as used in the chest protector. The impact was created using the corner edge of a Facom engineering hammer.

No way of calibrating the impact force but I hit it as hard as I reasonably could while having enough control to not smash the GoPro up.

Front side.

Rear side.

Splinters in foam.

I also tested other samples including e-glass, CF/kevlar and a thick CF layup. I have decided to try the following as the next sample:

Plain weave 200 gsm CF
175 gsm plain weave Kevlar
-45/+45 bi-axial 270 gsm CF
175 gsm plain weave Kevlar
-45/+45 bi-axial 270 gsm CF
175 gsm plain weave Kevlar
Plain weave 200 gsm CF

I have allot of carbon hanging around but little Kevlar thus the high number of carbon layers. I will get testing and report back.

#10

So I tested the new layup …

Impact of a hammer blow with roughly similar force to the previous piece.

Only just penetrated.

When the hammer fully penetrated the sample it went through the foam to the floor. To prevent hammer damage I doubled up the foam so I could try hitting it harder. This was also a slightly more representative test of the energy absorption capabilities of the chest protector it would be mounted on.

These blows were as hard as I could possibly beat the sample while using the hammer. My arm was not feeling 100% afterwards so I must have been doing it right :cool:

Well the hammer got through. I have decided to replace one of the bi-axial carbon layers with a doubling up of all of the kevlar layers. I will give this a test and if still no dice I will put in an order for some heavier weight kevlar fabric.

#11

you should better use ballistic type of kevlar for maximum protection from penetration

#12

And make sure you use as little resin as possible. The part should delaminate on impact, which is when the most energy is dissipated. Aim for a 20% resin ratio if at all possible.

And be careful with hammers. I recall having made a test panel for a carbon / aramide boat I was building. The guy who owned the workshop put the panel in a vice, and smashed it with a hammer. The part survived, and threw the hammer back to the guy, hitting his eyebrow. A couple of stitches at the doctors were the result… Now some 17 years later you can still see the scar. (I happen to run into him every now and then)

#13

Interested to see the progress on this. Glad you looked into adding kevlar, the thought of plain carbon is a scary one!

Also herman how would you reach a 20% resin ratio? Surely not possibly with wet layup?

#14

Having done a bit of research it seems my carbon/kevlar alternating layers is probably reducing the effectiveness of the kevlar. I have just laid up:

1 x Plain weave 200 gsm CF
1 x -45/+45 bi-axial 270 gsm CF
6 x 175 gsm plain weave Kevlar
1 x Plain weave 200 gsm CF

Will give it a test once it has cured.

I also tried bonding a low temp thermo plastic to the exterior of a cured part and also to dry carbon using small granules and a heat gun. It is showing mixed results as it is tricky to get it to bond. However it is showing great impact results so it is worth further work.