Side intrusion bars

[Zedn]

Originally Posted by xlr8tr

well said- or a guardrail, or wall, or.....

I think we are talking about different things. Im talking about side impact from a vehicle.

That may happen if you slid sideways into a pole or similar. If you are in this position then the bolts will be least of your worries. For that sort of collision you actually want the side intrusion bars to deform a bit to absorb energy.

First of all you are assuming that the side impact is a very narrow object that only impacts the door. In reality this is very unlikely to happen due to the size of cobra door (or ferrari).

If a car is hitting you from the side you are in most cases going to be crossing an intersection where you are both crossing paths (such as someone running a red light). In this case there will not be trees or walls in that direction, there will be road. If it is a T intersection it will be very unlikely they will t bone you. You will t bone them or run up the back of them.

This link will show you why i talk about tyres. Select tab for side impact test and press play. Notice what the car does when tested. The impact is absorbed by both the friction of the tyres and crumple zone of the front of the other car.
ANCAP - Crash Testing Explained.

You also need to consider what is going to happen to the driver. In a cobra, the top edge of the door is quite low. When the car is hit from the side the driver will be whipped towards the incoming car. If it is a 4wd it may go over the bars.

There is much more to crash science than a point load in the middle of a side intrusion bar. The shear capicity of each bolt in the striker is several thousands Kgs. The full impact is also not applied only on the bolts it is also carried by the hinges and any other part of the car that is hit.

There is also the thicknes of the striker plate/latch to consider as it is probably less than the bolts

[PeterAllen]

Zedn - I agree with what you are saying but I think you are talking about a best case impact scenario. If I'm in the position of starting to fit the intrusion bars I would like to think I could design for the worst case scenario and work down based on the limitations I encounter.

After reading John Wilson's newsletter I understood I should ensure the intrusion bar does not inhibit the ability of the door and hinges to hold the door in place in an impact. However, when I spoke to someone at the Transport Dept today they were telling me to attach it to the hinge and the door latch. Am I reading John's newsletter correctly? - I'll check the actual ADR later.

I don't want to be morbid about this but did anyone see the Daytona after Brock's crash, or any Cobra with a pole side intrusion, to see if the hinge and/or latch were torn from the fibreglass door. I'm not disputing the strength of the bolts; I'm just trying to understand the weakest point in the whole door structure. Does fibreglass act as a good impact attenuator or does it tend to shatter?

You are correct that the occupant of any severe impact will experience hyperflection of the neck in the direction of the impact and that's why most race cars have halo head rest and those neck thingo attached to their helmets and held in place by the seat belt. Since the introduction of headrest the term 'whiplash' seems to have disappeared in relation to rear impacts - all a little off the topic of intrusion bars.

[Zedn]

Originally Posted by PeterAllen

Zedn - I agree with what you are saying but I think you are talking about a best case impact scenario. If I'm in the position of starting to fit the intrusion bars I would like to think I could design for the worst case scenario and work down based on the limitations I encounter.

After reading John Wilson's newsletter I understood I should ensure the intrusion bar does not inhibit the ability of the door and hinges to hold the door in place in an impact. However, when I spoke to someone at the Transport Dept today they were telling me to attach it to the hinge and the door latch. Am I reading John's newsletter correctly? - I'll check the actual ADR later.

I don't want to be morbid about this but did anyone see the Daytona after Brock's crash, or any Cobra with a pole side intrusion, to see if the hinge and/or latch were torn from the fibreglass door. I'm not disputing the strength of the bolts; I'm just trying to understand the weakest point in the whole door structure. Does fibreglass act as a good impact attenuator or does it tend to shatter?

You are correct that the occupant of any severe impact will experience hyperflection of the neck in the direction of the impact and that's why most race cars have halo head rest and those neck thingo attached to their helmets and held in place by the seat belt. Since the introduction of headrest the term 'whiplash' seems to have disappeared in relation to rear impacts - all a little off the topic of intrusion bars.

Im not sure what you mean about the newsletter. It says that it must be designed so that the bars cannot enter the vehicle without destroying the body work around the hinge and lock. I interpret that as destroying the subframes that the hinge and striker plate are mounted to on the car (not the door).

If the bars and latch are not integral then the bars will be able to enter the cabin.

I think the best way is as i originally said with the hinges mounted to steel plate and intrusion bars welded to the plate. Same on the other side with the latch bolted to it. For your adjustment, perhaps you could slot the holes in the plate and use a bolt and nut. Or slot the holes in the hinges and tack nuts onto the steel plat in the door.

Effectively you should be able to open and close the intrusion bars without the door there. That way the door is just glassed on to the frame for the intrusion bars.

[PeterAllen]

Originally Posted by Zedn

...If the bars and latch are not integral then the bars will be able to enter the cabin....

Yep... agree entirely, but, and this is the point I can't quite get, by attaching the bar to the hinge/s and the latch you would be at risk of damaging them if the intrusion bar was impacted. As the hinges and latch are a separate ADR (to which my car already complies) to the side intrusion ADR then the intrusion bar should not function so as to inhibit the performance of the hinges and latch - that seems to be the way the rules read. I'm not saying I agree with it just that is how they read.

The RTA advised to go with your idea and if my engineer agrees I'll get it in writing from the RTA and move on to my next anxiety attack. Thanks all.
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[Zedn]

Originally Posted by PeterAllen

Yep... agree entirely, but, and this is the point I can't quite get, by attaching the bar to the hinge/s and the latch you would be at risk of damaging them if the intrusion bar was impacted. As the hinges and latch are a separate ADR (to which my car already complies) to the side intrusion ADR then the intrusion bar should not function so as to inhibit the performance of the hinges and latch - that seems to be the way the rules read. I'm not saying I agree with it just that is how they read.

The RTA advised to go with your idea and if my engineer agrees I'll get it in writing from the RTA and move on to my next anxiety attack. Thanks all.
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I think you are misinterpreting it.

They cant interfer when in working condition not after an accident.