Designing motorcycle parts - pros/cons of aramid/polyester reinforcement?

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#1

Hi folks,

I was just wondering about the various pros & cons when designing a motorcycle part like this: http://www.oppracing.com/product_display/3079-macmoto-series-airduct-sbk-right-gsxr1000-20052006/

It’s basically a few pieces forming an entire front fairing with ram air ducts.

They have used Kevlar, but I’m wondering if it’s really worth it, or whether you could achieve 90% of the result at 10% of the cost using something like Innegra?

Probably the main consideration is to ensure that the part won’t break up in a crash, but a secondary benefit could be that the part takes minimal (or zero) damage in a crash.

But a part is only as strong & durable as the weakest material, in this case that would be the plain carbon fibre?

Say for instance that a part was crushed, it would surely deform and crack? Obviously the same would happen if Innegra was used, but to what extent would the Kevlar part have an advantage, if any?

Also how much of a factor would delamination be? Comparing the effectiveness of a carbon/Kevlar hybrid and a part using a sandwich layer of Innegra? How close would the performance be if you then compared a Kevlar hybrid with an Innegra hybrid?

If you were building a part like that, would you go to the expense of using Kevlar?

Thanks for any insights, looking forward to your responses.

#2

Use Diolen. It is actually better for abrasion and is cheaper than Carbon Kevlar.

#3

And keep in mind: When you drop the bike, it will get damaged.

#4

Ah, Diolen - cheers.

So any of these reinforcement materials are really just to stabilise the part (so it doesn’t splinter off when crushed for instance) and to add abrasion resistance in the case of Kevlar and Diolen?

In the event of a big crash where you’d expect parts to get crushed and cracked, the aramids won’t actually provide any damage resistance beyond what the Innegra would? The main benefits would be abrasion resistence? In which case you’re still going to bin (or repair) the part if it gets all scuffed up or has a hole worn though it…?

If that’s the case, I’m wondering why go to the trouble of using a surface layer of hybrid fabric like Diolen or a carbon/kevlar hybrid, why not just use plain carbon which most people would prefer the look of anyway, and put the Diolen or Innegra in the middle?

#5

Diolen looks similar to carbon fibre but deeper black in colour. I’ve heard it is best to use on inside due to good tensile strength

Edit: just realised diolen comes in different colours. I was referring to the black stuff obviously :slight_smile:

http://www.easycomposites.co.uk/Products/Kevlar-Aramid-Others/Black-Diolen-200g-1200mm.aspx