Impact resistance? Front bumper bar.

General Composites Discussions Composites Talk
#1

Hey guys, first post here.
A bit of a background on me. I don’t have a huge amount of practical experience with composites, just a few repair jobs here and there with fibreglass and carbon fibre. I have read a fair bit and I’m a very practical person and tend to pick up skills like this reasonably quick, so I have no problem trying to tackle something a bit bigger/more advanced.

Anyway, to my question. For work I drive my subaru outback along rural roads at dawn quite regularly, resulting in frequent animal strikes (smaller things like possums and wallabies mostly) and the front bumper is just taking a beating!
So what I would like to do is make a new one, with a bit better ground clearance and the ability to not break as often as the current plastic one.
The actual design isn’t a problem, what I’m wanting to know is if a carbon/kevlar blend would be sufficient to handle animal strikes? I will probably incorporate a small amount of metal behind/inside the composite in the high impact areas also. Does this sound ok?

My next option is a full metal bullbar, but they cost in excess of $2.5k for my vehicle and add a fair amount of weight to what is essentially just a car…

Open to all suggestions here! Thanks!

#2

Hello there,

Is it just for keeping the front of your truck safe or do you want it to look good also?
If you’re not worried about raw carbon looks, leave carbon out of there as it has no real place (normally) in an impact strength or impact resistance application: Kevlar and glass are the ones you should go for.
Glass, particularly S-grade glass has excellent impact properties due to its ability to bond to resins better than Kevlar and in certain instances is much better. However, shearing Kevlar fibres is very difficult and is therefore used a lot in impact applications. It can be pretty useless on its own, so combined with other materials, its properties are exploited.
You’ve actually got two scenarios in your application – hitting an animal once and then hitting another ten down the road so repeated impacts are important: I would go with Kevlar and glass together.

#3

It’s definitely multiple impacts :wink:

Didn’t realise that glass was used in impact applications. Always thought it was carbon for stiffness and kevlar to stop it shattering! Glass is cheaper so I don’t mind that :wink:

#4

Can’t you just slow down a bit?

Poor little possums and wallabies!

#5

So just so you know, impact strikes are pretty tough on composites. More so on cored composites. Carbon doesn’t like them… kevelar is a bit better. Mixed hybrid layups would be best.

I think you’d be better off with

#6

I probably would be better with something like that, but it’s not at all a cheap option as none of the major bar manufacturers in Australia make them… I would prefer a proper bar, but my wallet disagrees :wink:

#7

Or these might work.

#8

I like the second one, it has cleaner lines…