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SAE TECHNICAL
PAPER SERIES 983061
Barrier Testing
Peter G Wright
Fédération Internationale de l’Automobile (FIA)
Andrew Mellor
Transport Research Laboratory (TRL)
Reprinted From: 1998 Motorsports Engineering Conference Proceedings
Volume 1: Vehicle Design and Safety
(P-340/1)
Motorsports Engineering
Conference and Exposition
Dearborn, Michigan
November 16-19, 1998
400 Commonwealth Drive, Warrendale, PA 15096-0001 U.S.A. Tel: (724) 776-4841 Fax: (724) 776-5760
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983061
Barrier Testing
Peter G Wright
Fédération Internationale de l’Automobile (FIA)
Andrew Mellor
Transport Research Laboratory (TRL)
Copyright © 1998 Society of Automotive Engineers, Inc.
ABSTRACT This was achieved by conducting full scale impact tests
using an instrumented trolley of appropriate mass fitted
Motor racing circuit barrier systems have traditionally with a Formula 3000 nosecone. A well designed barrier
been tested by impacting them with, typically, a 780kg, should absorb the kinetic energy of an impacting car in a
450mm x 450mm flat impactor, at a velocity of 12m/s controlled manner whilst ensuring the car does not
(43.2kph). Since the adoption of energy absorbing nose- rebound back onto the circuit.
cones on Formula1 and other single-seater racing cars,
which are subject to an FIA impact test into a rigid barrier, DESCRIPTION OF BARRIER CONFIGURATIONS
it has become necessary to develop a more appropriate
barrier test to take into account the compatibility between Five methods of barrier construction were evaluated as
the sharp, rigid nose-cone and the relatively soft tyre bar- follows:
riers that are used on circuits world-wide.
1. Method of fixing the tyres together, using straps
The FIA commissioned the Transport Research Labora- or bolts.
tories (TRL) in the UK, to carry out a series of barrier 2. Incorporation of a physical gap between rows
impact tests using a Formula 3000 nose-cone mounted of tyres.
on the 780kg impacting trolley, at speeds of 16.7m/s
3. Fitment of inserts inside the tyres, plastic tubes and
(60kph) and 22.2m/s (80kph). The 14 tests evaluated the
foam cylinders.
performance of existing and modified barriers, and two
types of proprietary barrier, the results of which are not 4. Addition of mass by fitting smaller tyres inside
reported in this paper for reasons of commercial confi- the
dentiality. A modified barrier provided the best solution primary tyres.
and was five times as effective as a commonly used 5. Fitment of conveyor to the face of the barriers.
existing barrier design.
The methods of construction were evaluated by testing a
The mechanisms by which barriers absorb energy are total of eleven different configurations of barrier, as
analysed and recommendations made concerning the described in Table 1. Barrier 11 was found to be the best
design of barriers; the design of nose-cones to make solution and the construction of this barrier is detailed in
them more compatible; and for barrier test specifications. Appendix A.
INTRODUCTION
The objectives of the test programme, carried out at the
Transport Research Laboratory (TRL), were
1. To develop a better barrier test specification.
2. To evaluate existing barrier types.
3. To develop improved barriers.
4. To evaluate proprietary barriers.
1
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Table 1. Barrier configurations.
FIA test No: V (kph) Rows of Gap Connections Conveyor Inserts
tyres
1 60 3 None Straps None None
2 60 3 None Bolts None None
3 60 3 None Bolts None None
4 60 2+1 600 Bolts None None
5 60 3 None Bolts 1 None
6 60 2+1 600 Bolts 1 None
7 60 3 None Bolts None Plastic tubes
8 60 2+1 600 Bolts 1 Inner tyres
10 60 3 None Bolts None Foam Cyls.
11 60 3 None Bolts 1 Plastic tubes
12 80 3 None Bolts 1 Plastic tubes
13 80 Triple: 3 None Bolts 1 Plastic tubes
TEST PROCEDURE AND INSTRUMENTATION During the tests, both the barrier and the nosecone
absorbed kinetic energy from the impacting trolley. It was
The barriers were positioned, free standing, in front of a found that in every case, the barrier was softer than the
massive concrete block and impacted at 90o (frontal) by nosecone and the barrier ‘bottomed out’ before any
a trolley fitted with a ‘F3000' nosecone. The mass of the deformation of the nosecone occurred. Nosecone defor-
trolley was 780kg and the impact velocity was 60km/h for mation occurred as it impacted the concrete block at the
all tests except for tests 12 and 13 for which the impact rear of the tyre barrier. Analysis of the results clearly
velocity was increased to 80km/h. The acceleration his- showed that the trolley displacement had exceeded the
tory of the trolley was measured with two fore-aft acceler- thickness of the barrier when the nosecone began to col-
ometers and the tests were filmed using high speed lapse. The nosecone was, therefore, required to absorb
cameras at 1000frame/s. any kinetic energy not already absorbed by the barrier
and subsequently the residual damage to the nose cone
RESULTS was inversely proportional to the effectiveness of the bar-
rier.
The acceleration of the trolley was recorded during the The mechanism by which a tyre barrier absorbs energy is
impact, and by integration the velocity and displacement complex, and various mechanisms are involved. The
of the trolley were determined. Analysis of the high speed important ones are: elastic deformation, plastic deforma-
film was used to validate these results, and the average tion, friction, momentum transfer and damping. By con-
deceleration of the trolley through barrier and the peak sidering the characteristics for each mechanism, it was
deceleration of the trolley were calculated. A summary of possible to evaluate the prominent mechanisms for each
the results is shown in Table 2 and the instrumentation barrier. It was found that most barriers absorbed the vast
and photographic results from tests 1, 11 and 13 are pro- majority of energy by plastic deformation. The tyres were
vided in Appendix B. seen to recover completely (in terms of shape) after the
impact and this occurred at a very low force.
Table 2. Test results.
Test Ref. 1 2 3 4 5 6 7 8 10 11 12 13
Impact velocity (kph) 60 60 60 60 60 60 60 60 60 60 80 80
Barrier thickness (m) 1.8 1.84 1.66 2.3 1.65 2.28 1.81 2.39 1.84 1.75 1.74 1.84
Average acc'n thru' barrier (g) 1.8 4 3.7 4.3 6 5.1 8 5.5 5 9 12 12
Change in vel. thru' barrier (m/s) 2 5 4 7 7 9 11 10 6 11 11 12
Peak acceleration (g) 35 28 32 24 23 21 18 20 25 18 27 26
Nosecone damage (m) 0.46 0.36 0.38 0.19 0.25 0.2 0.09 0.13 0.35 0.06 0.35 0.27
Rebound velocity (m/s) 2 3.5 2.5 3 3 4.5 4 4 2.5 7.5 7.5 4
2
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COMPARISON OF BARRIERS highest and, surprisingly, the lowest rebound velocity of
2m/s was achieved by the worst performing barrier. This
The performance of the tyre barriers was compared by result is explained below.
considering three criteria for each barrier: (i) average During all tests, some kinetic energy was absorbed by
deceleration of the trolley as it moves through the barrier, the barrier and some by the nosecone. The nosecone
(ii) peak deceleration of the trolley during the impact, and absorbs energy by gross plastic deformation which is not
(iii) rebound velocity. recoverable. When barrier 1 was tested, the vast majority
The performance of the tyre barriers was found to vary of the kinetic energy was absorbed by the nosecone and
considerably and Figure.1 shows the first two criteria (as this resulted in a low rebound velocity of 2.0m/s. How-
described above) for each barrier. The worst perfor- ever, when barrier 11 was tested, the vast majority of the
mance was achieved by the standard barrier 1 (with tyres kinetic energy was absorbed by the barrier and this
strapped together) and an average deceleration of just resulted in the higher rebound velocity of 7.5m/s.
1.8g was measured as the trolley penetrated through the It should be noted that a rebound velocity of 7.5m/s rep-
barrier. The performance was improved† by over 120% resents only 20% of the pre-impact kinetic energy and
(4.0g for barrier 2) by bolting the tyres together. And the other 80% was dissipated within the barrier. Further-
when the tube inserts were added, the performance was more, when three units of barrier 11 were bolted together
improved† by a further 100% (8.0g for barrier 7). The
(test 13), the rebound velocity was only 4.0m/s, in spite of
addition of conveyor improved performance† still further,
the higher impact velocity of 80km/h. Although a perfect
by between 13% and 60%. The combined effect of these
barrier would absorb 100% of the pre-impact kinetic
modifications (bolted, tube inserts and conveyor) was
energy and induce zero rebound, it may be that 20% is
evaluated during test 11 and an average deceleration
acceptable. And with careful positioning of tyre barriers,
9.0g was measured, which was five times† more effective
the potential for rebounding cars back onto the circuit
than the standard barrier. Three units of barrier 11 were
may be restricted.
fastened together and evaluated during test 13, at an
increased velocity of 80km/h. An improved average It is possible to calculate the energy absorbed (dissi-
deceleration of 12.0g was achieved, see Appendix B. pated) by the barrier, the rebound (stored and released)
energy and the energy absorbed (assumed to be all dissi-
A perfect safety barrier would absorb the kinetic energy
pated) by the nose cone. Figure.2 presents these param-
of an impacting car in a controlled manner whilst ensur-
eters as %Energy (of the total energy) at 60 kph. The 80
ing the car does not rebound back onto the circuit. Barrier
kph tests equate to 178% of the energy at 60 kph:
11 absorbed the kinetic energy in a very controlled man-
ner with an average deceleration of 9.0g and peak of † in terms of average deceleration of the trolley through
18g. However, the rebound velocity of 7.5m/s was the the barrier
Figure 1. Peak and average barrier g-levels.
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Figure 2. Percentage energy dissipated and stored by the barrier, and dissipated by the nose cone.
Because the space to install a critical barrier is often lim- If the energy absorbed by the nose cone is plotted
ited, and the energy absorbed is inevitably a function of against damaged length - Figure.4 - one would expect to
depth for a given barrier configuration, the energy stored see a progressive increase as more of the nose is dam-
(rebound energy) and energy dissipated per unit depth aged, particularly as the cross-section increases as the
are of interest: damaged progresses:
Figure 3. Energy dissipated and stored by the barrier, per metre depth.
4
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Figure 4. Energy absorbed by the nose cone .v. damage length.
The higher energy absorbed in the 80kph tests indicates
a velocity-dependent effect in the way the nosecone
absorbs energy.
CONCLUSIONS
All the barriers tested had the same physical proportions
(excluding those barriers that incorporated a gap
between layers of tyres) and consisted of tyres of similar
sizes. Nevertheless, the performance of the barriers was
found to vary considerably due to the methods of con-
struction, and the best solution was five times better than
the standard barrier. The best solution consisted of tyres
bolted together, with tube inserts fitted and with conveyor
fitted to the face of the barrier. When tested at 60km/h an
average deceleration of 9.0g was achieved, which was a
considerable improvement over the 1.8g for the standard
barrier. And even when tested at a higher velocity of
80km/h, the impact was less severe than the standard
barrier at 60km/h.
The stiffness and profile of the Formula 3000 nosecone
used for this work was considered to be particularly
aggressive. A Formula One nosecone, which is similar to
the Formula 3000 device, is designed to meet with the
requirements of an FIA frontal impact test, which involves
impacting a chassis fitted with the nosecone into a rigid
barrier. By designing the nosecone to be compatible with
a rigid barrier, its compatibility with the safety barrier and
indeed with other vehicles is compromised. However
impacts into both types of barrier, rigid and energy
absorbing, occur and the nosecone must accommodate
both. A variable nosecone stiffness, where the initial part
is much softer and fails in an impact with a tyre barrier,
thus spreading the load, is being explored.
The barrier test used in this programme has become a
new FIA Barrier Test Specification for the evaluation of
barriers to be used on Formula One tracks.
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APPENDIX A
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APPENDIX B
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