Carbon fiber helmet safety?
#1
07-15-2009, 02:41 PM
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Carbon fiber helmet safety?
I'm interested in a half helmet (I know... safety and half helmet in the same sentence, but just go with it), and was wondering if the carbon fiber shell offers better noggen protection than the traditional plastic shell (which might be slightly thicker). ???
#2
07-15-2009, 02:47 PM
I don't know any data, but I can tell you that the ACC helmet I have is small, light, and seems fully capable of protecting my noggin from the types of things I worry about - head bounce and some sort of a direct impact. It was well worth every penny and is much more comfortable for long rides.
#3
07-15-2009, 03:06 PM
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stronger
On the ACC site they have comparison charts and the kevlar carbon fiber combo
is the strongest.
ACC uses a modified resin transfer system, this process involves basically the same process as the non-pressure laminate, a female mold is sprayed with gel coat, Multiple layers of fiber are put in the mold but then pressure is applied at 75psi inside the mold. Resin is then injected in exactly the right amount and the helmet is heated to cure. By injecting the resin we can achieve a 40% resin to 60% Fiber ratio, which is optimum for helmet shells. The result is a laminate that yields all the structural integrity that the materials were meant to have.
Now that you know about the process you may be asking what's the difference between Fiberglass, Carbon Fiber and Kevlar. Everyone knows basically what fiberglass is, extruded glass. 95% of all helmets are made from fiberglass be it mat (random fibers) or woven fabric. They are all basically the same. One key factor is fiberglass is cheap. When talking about DOT and non-DOT helmets they are all basically made from Fiberglass. The non-DOT helmets being made cheaply and without the aid of high pressure.
Carbon fiber is made by superheating an acrylic fiber yielding high strength to weight and high stiffness to weight properties. When engineered properly Carbon Fiber composites can achieve the strength and stiffness of metals at a significant weight savings, these two factors are key to the manufacture of a helmet.
Kevlar is made by dissolving a polymer in a solvent and extruding the fiber and then spinning. While Kevlar has properties similar to Carbon Fiber it lacks compressive strength. The combination of 50% Carbon Fiber and 50% Kevlar results in a laminate with flexural strength about three times that of Kevlar alone.
Below is a comparison of typical fiber properties of some of the materials we use.
Material Stiffness (MSI) Tensile strength (KSI) Density (g/cc)
Fiberglass 10 500 2.55
Carbon Fiber 42.3 770 1.78
Kevlar 13.9 450 1.44
All this may be a bit confusing but it's important for you the customer to know what we are trying to achieve in our Non-DOT and DOT certified helmets
By using Carbon/Kevlar and our high pressure laminating process we can produce a helmet shell with far superior strength to weight ratio. The stiffness (42.3 MSI) of Carbon Fiber being a contributing factor to that strength and weight based on its density (1.78(g/cc)
is the strongest.
ACC uses a modified resin transfer system, this process involves basically the same process as the non-pressure laminate, a female mold is sprayed with gel coat, Multiple layers of fiber are put in the mold but then pressure is applied at 75psi inside the mold. Resin is then injected in exactly the right amount and the helmet is heated to cure. By injecting the resin we can achieve a 40% resin to 60% Fiber ratio, which is optimum for helmet shells. The result is a laminate that yields all the structural integrity that the materials were meant to have.
Now that you know about the process you may be asking what's the difference between Fiberglass, Carbon Fiber and Kevlar. Everyone knows basically what fiberglass is, extruded glass. 95% of all helmets are made from fiberglass be it mat (random fibers) or woven fabric. They are all basically the same. One key factor is fiberglass is cheap. When talking about DOT and non-DOT helmets they are all basically made from Fiberglass. The non-DOT helmets being made cheaply and without the aid of high pressure.
Carbon fiber is made by superheating an acrylic fiber yielding high strength to weight and high stiffness to weight properties. When engineered properly Carbon Fiber composites can achieve the strength and stiffness of metals at a significant weight savings, these two factors are key to the manufacture of a helmet.
Kevlar is made by dissolving a polymer in a solvent and extruding the fiber and then spinning. While Kevlar has properties similar to Carbon Fiber it lacks compressive strength. The combination of 50% Carbon Fiber and 50% Kevlar results in a laminate with flexural strength about three times that of Kevlar alone.
Below is a comparison of typical fiber properties of some of the materials we use.
Material Stiffness (MSI) Tensile strength (KSI) Density (g/cc)
Fiberglass 10 500 2.55
Carbon Fiber 42.3 770 1.78
Kevlar 13.9 450 1.44
All this may be a bit confusing but it's important for you the customer to know what we are trying to achieve in our Non-DOT and DOT certified helmets
By using Carbon/Kevlar and our high pressure laminating process we can produce a helmet shell with far superior strength to weight ratio. The stiffness (42.3 MSI) of Carbon Fiber being a contributing factor to that strength and weight based on its density (1.78(g/cc)
Last edited by WillieC; 07-15-2009 at 03:09 PM. Reason: spelling
#4
07-15-2009, 03:17 PM
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Well, for what it's worth.......
I have one of the ACC Headtrip helmets (non-DOT). As per the manufacturer, the only DOT test it didn't pass was the puncture test. Last June I was in a near-fatal accident and the thing that saved me was the helmet. I was launched through / over the fairing and through the back glass of the vehicle and proceeded to crumble backwards onto the road (no, it wasn't my fault - LOL). In any case the helmet came through with flying colors to the point that I repainted it the same color as my bike during my bike rebuilding process and continue to use it today.
If I ever need to get another helmet for any reason, I'm heading back to ACC.
Brian
I have one of the ACC Headtrip helmets (non-DOT). As per the manufacturer, the only DOT test it didn't pass was the puncture test. Last June I was in a near-fatal accident and the thing that saved me was the helmet. I was launched through / over the fairing and through the back glass of the vehicle and proceeded to crumble backwards onto the road (no, it wasn't my fault - LOL). In any case the helmet came through with flying colors to the point that I repainted it the same color as my bike during my bike rebuilding process and continue to use it today.
If I ever need to get another helmet for any reason, I'm heading back to ACC.
Brian
#5
07-15-2009, 03:23 PM
Well, for what it's worth.......
I have one of the ACC Headtrip helmets (non-DOT). As per the manufacturer, the only DOT test it didn't pass was the puncture test. Last June I was in a near-fatal accident and the thing that saved me was the helmet. I was launched through / over the fairing and through the back glass of the vehicle and proceeded to crumble backwards onto the road (no, it wasn't my fault - LOL). In any case the helmet came through with flying colors to the point that I repainted it the same color as my bike during my bike rebuilding process and continue to use it today.
If I ever need to get another helmet for any reason, I'm heading back to ACC.
Brian
I have one of the ACC Headtrip helmets (non-DOT). As per the manufacturer, the only DOT test it didn't pass was the puncture test. Last June I was in a near-fatal accident and the thing that saved me was the helmet. I was launched through / over the fairing and through the back glass of the vehicle and proceeded to crumble backwards onto the road (no, it wasn't my fault - LOL). In any case the helmet came through with flying colors to the point that I repainted it the same color as my bike during my bike rebuilding process and continue to use it today.
If I ever need to get another helmet for any reason, I'm heading back to ACC.
Brian
Not to be disrespectful but... What are you, nuts?!?!?! Threre is no way you should still be wearing that same helmet! They are engineer for one good wacking. The energy produced by the impact with weaken the helmet. Do youself, and your family a favor... replace it.
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#10
07-15-2009, 07:05 PM
Road Master
Well, for what it's worth.......
I have one of the ACC Headtrip helmets (non-DOT). As per the manufacturer, the only DOT test it didn't pass was the puncture test. Last June I was in a near-fatal accident and the thing that saved me was the helmet. I was launched through / over the fairing and through the back glass of the vehicle and proceeded to crumble backwards onto the road (no, it wasn't my fault - LOL). In any case the helmet came through with flying colors to the point that I repainted it the same color as my bike during my bike rebuilding process and continue to use it today.
If I ever need to get another helmet for any reason, I'm heading back to ACC.
Brian
I have one of the ACC Headtrip helmets (non-DOT). As per the manufacturer, the only DOT test it didn't pass was the puncture test. Last June I was in a near-fatal accident and the thing that saved me was the helmet. I was launched through / over the fairing and through the back glass of the vehicle and proceeded to crumble backwards onto the road (no, it wasn't my fault - LOL). In any case the helmet came through with flying colors to the point that I repainted it the same color as my bike during my bike rebuilding process and continue to use it today.
If I ever need to get another helmet for any reason, I'm heading back to ACC.
Brian
BTW - Love my helmet!!