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Trevor Booth · 06-16-04, 09:04 AM

From the slide rule department.
The notable feature of the crash test is the rupture of the fuel cap allowing escape of fuel. A foam filled tank will go a long way to prevent this occurrence. The foam whether 10% or 15% will retard the velocity of the fuel and hence the energy to rupture the cap. A screw in type cap below the traditional QR cap will not allow fuel to escape. It is also to be noted that the vehicle had bag tanks which perform particularly well in a frontal impact. If you have a rigid alum tank it may well rupture in any event. Foam filling will reduce the energy level of the fuel in an impact situation. IMHO any side mounted tank should be of the fuel cell type. The crash test would have produced a decel in the order of 25-30g and when you look at the wheel posn the tub does not appear to have suffered a great deal of deformation. An overhead shot of the impact would indicate the level of deformation more clearly than a side view. On the subject of crash worthiness for replica vehicles it is not difficult to evaluate with the power of modern computers by non linear analysis, however the cost is high. It is not feasible to retrofit some form of crash worthiness device to an existing vehicle. The energy of a frontal impact is absorbed throughout the whole of the vehicle, modern day vehicles crumple under the back seat and rear passenger area floor to absorb some of the energy. Rear engined cars have a unique set of circumstances in as much as you have a veritable block of cast iron behind you which suddenly becomes 20-30 times it's mass ( rushing out to have a look at those engine mounts :-))). IMHO tube framed vehicles are unlikely to exhibit the same amount of crashworthiness as a mono tub. The whole purpose of crashworthiness is to limit the amount of energy imparted to the occupant. Some of the injury criteria are, deceleration of the head 75-80g for 3 milliseconds, compression load on the femur - 10 Kn (~1000 kg, 2300lbs). compressive deflection of spine relative to sternum - 75mm,
Tension in the neck - 3300N (~330kg). Any more than this and you may not survive!! It is not uncommon for car makers to crash 5-6 cars cars before they get it right.
Hopefully a video of a computer modelled chasssis rail is attached. This was broken down into 8000 elements for modelling.

06-16-04, 09:04 AM	#12 (permalink)
Trevor Booth nota2266 Lifetime Premier Supporter Join Date: May 2004 GT40: Kurrajong, Australia Posts: 347 Rep Power: 8	Re: GT40 Crash Test 1967 From the slide rule department. The notable feature of the crash test is the rupture of the fuel cap allowing escape of fuel. A foam filled tank will go a long way to prevent this occurrence. The foam whether 10% or 15% will retard the velocity of the fuel and hence the energy to rupture the cap. A screw in type cap below the traditional QR cap will not allow fuel to escape. It is also to be noted that the vehicle had bag tanks which perform particularly well in a frontal impact. If you have a rigid alum tank it may well rupture in any event. Foam filling will reduce the energy level of the fuel in an impact situation. IMHO any side mounted tank should be of the fuel cell type. The crash test would have produced a decel in the order of 25-30g and when you look at the wheel posn the tub does not appear to have suffered a great deal of deformation. An overhead shot of the impact would indicate the level of deformation more clearly than a side view. On the subject of crash worthiness for replica vehicles it is not difficult to evaluate with the power of modern computers by non linear analysis, however the cost is high. It is not feasible to retrofit some form of crash worthiness device to an existing vehicle. The energy of a frontal impact is absorbed throughout the whole of the vehicle, modern day vehicles crumple under the back seat and rear passenger area floor to absorb some of the energy. Rear engined cars have a unique set of circumstances in as much as you have a veritable block of cast iron behind you which suddenly becomes 20-30 times it's mass ( rushing out to have a look at those engine mounts :-))). IMHO tube framed vehicles are unlikely to exhibit the same amount of crashworthiness as a mono tub. The whole purpose of crashworthiness is to limit the amount of energy imparted to the occupant. Some of the injury criteria are, deceleration of the head 75-80g for 3 milliseconds, compression load on the femur - 10 Kn (~1000 kg, 2300lbs). compressive deflection of spine relative to sternum - 75mm, Tension in the neck - 3300N (~330kg). Any more than this and you may not survive!! It is not uncommon for car makers to crash 5-6 cars cars before they get it right. Hopefully a video of a computer modelled chasssis rail is attached. This was broken down into 8000 elements for modelling.