Roll Cage question .......

[Trevor]

Another approach I've been wondering about is a spyder section made from carbon fiber with carbon fiber matrix/foam core. The relative strength compared to other materials including chrome moly steel is shown in the link below.

This approach could potentially provide significant upgrade to the overall strength of the driver/passenger area without the intrusion of an internal cage with its inherent safety risks. As mentioned before the potential improvements to overall chassis stiffness could also be significant.
Apart from the difficulties of manufacturing such a component in carbon/carbon, the other issue would be to find a way to provide a mechanically strong interface between the spyder and the base of the front pillars and to the rear bulkhead.

 

[Trevor]

Before I get shouted at by everyone on here, I realize the demo in the link is not very meaningful as there is a lot of info missing and what is being measured doesn't really address the suitability due to impact. A deeper discussion/analysis is required. However considering some of the impacts sustained by the tubs of the cars involved in the crashes at the start of the Mugello GP, Indy car etc, a carbon fiber approach has merit.

 

[Randy V]

Carbon Fiber by itself is very lightweight and very strong, but it has very poor impact resistance. Reinforced with Kevlar and/or fiberglass (depending on structure being made) - much better..

 

[Howard Jones]

When considering a Carbon tub such as an IndyCar or WEC prototype tub, the first question that comes to my mind is this.

Given the nature of a carbon-formed structure being inherently less resistive to second-order impact and loss of structural rigidity when damaged, it seems to me that once damaged in a shunt in many cases the entire tub is rendered unusable. More importantly, it could lose a large portion of its strength after the first impact in an ongoing shunt.

I am thinking that in many ways a carbon tub is often a nonrepairable component. Do you really intend to throw it away once it is significantly damaged, unlike a space frame chassis that can in most cases be simply repaired by cutting off the bent stuff and welding back on nice new tubing?

When considering the second-order impact question I believe there is a better chance that a bent up space frame chassis will retain at least a good portion of its strength, even if bent up. My mind goes to a badly cracked up carbon chassis being greatly compromised and not holding up to a second hard impact.

 

[Chris Black]

well, you should at least put some real padding around your rollcage tubes. For a road car, I'd go just for a roll hoop and not a full cage.

 

[Ben Hedrick]

Great articles. Both! Wow! Very educational. Thanks Frank!

 

[Neil]

well, you should at least put some real padding around your rollcage tubes. For a road car, I'd go just for a roll hoop and not a full cage.

Without any fore and aft bracing this "roll hoop" is not likely to be of much help.

 

[Bob]

Im no expert for sure,

Have been saved by a roll cage a couple times.
Both in a modified open wheel race car.
Steering shaft almost got me was solid put a collapsible in after.

Have survived a head on doing 65 in a stock 1st gen Dodge other guy hit ice and came in my lane going about the same speed killed him instantly...

Can see both sides of the discussion scary to think of getting hit in a 40 by something bigger.

Wouldn't be much left of the car or driver....

 

[Devin]

A great example of an integral safety cell.

What a pity that the 1/8" thick gussets can't be used on a GT40 cage due to the lack of a perimeter tube around the roof area.
No one seems to be saying it but ....

In my opinion, the GT40 design just doesn't lend itself to the creation of a safety cell without the inclusion of additional steel work that's cosmetically undesirable.

Just not cosmetically undesired but as a taller with longer legs individual (and not exactly young) any other obstruction would further make it even more difficult to enter and exit the vehicle.

I would also emphasize the attitude of driving it like a motorcycle (as I do with my cobra replica) and not take additional risks or chances beyond what is reasonable.

 

[joe]

If you roll and the A-piller hoop bends back as it did in one of the crash seen pictures earlier in the thread, don't you have bigger concerns? That hoop did provide some protection that afforded the driver a little bit more of a chance than relying on the A-piller and windshield support alone...didn't it? I'm considering a front hoop in a build I have been talking with Chris at Ardern cars about. It will make it to the track eventually, but I don't drive any of my cars at 10/10th's.

 

[Neil]

Another approach I've been wondering about is a spyder section made from carbon fiber with carbon fiber matrix/foam core. The relative strength compared to other materials including chrome moly steel is shown in the link below.

This approach could potentially provide significant upgrade to the overall strength of the driver/passenger area without the intrusion of an internal cage with its inherent safety risks. As mentioned before the potential improvements to overall chassis stiffness could also be significant.
Apart from the difficulties of manufacturing such a component in carbon/carbon, the other issue would be to find a way to provide a mechanically strong interface between the spyder and the base of the front pillars and to the rear bulkhead.

Crash protection is more than a function of material strength, it depends mainly on energy absorption. A high strength material that deforms and then springs back absorbs little energy. A lower strength but tough material that is deformed into its "plastic range" absorbs more energy and this provides protection. The object is to have deformation but not so much that it intrudes into the cockpit where the driver sits.

 

[Randy V]

Crash protection is more than a function of material strength, it depends mainly on energy absorption. A high strength material that deforms and then springs back absorbs little energy. A lower strength but tough material that is deformed into its "plastic range" absorbs more energy and this provides protection. The object is to have deformation but not so much that it intrudes into the cockpit where the driver sits.

Great video! Thanks for posting it!

 

[Neil]

Great video! Thanks for posting it!

I was not the original poster of the video, Randy.

 

[Randy V]

I seemed to have missed it 2 years ago when Trevor posted it and your post bubbled it back up.
Either way it was quite enlightening!

 

[Liam39]

After reading this thread, I swapped my 6 point roll cage for a 4 point.
Now I just have to work out how to upload photos to this forum...

 

[joe]

Isn't a difference of your head possibly hitting the a-pillar tube if it collapses...or the ground? There might be an argument that the front hoop has the ability to do more good than harm.

 

[Frank Catt]

No Joe, your body / head will move far more than the steelwork wil.

 

[joe]

Head to a-pillar? Your head and upper body can move that far if you are wearing a 4/5 point harness?

 

[Paul Hendrickx]

Head to a-pillar? Your head and upper body can move that far if you are wearing a 4/5 point harness?

why then have motorsports federations, made compulsory the Hans helmet retaining system? to avoid head injuries

Paul

 

[Neil]

why then have motorsports federations, made compulsory the Hans helmet retaining system? to avoid head injuries

Paul

Actually, the HANS device is primarily designed to reduce neck injuries where the G-forces pull your skull forward, off the end of your spine. They are a good idea.