Impact Performance Evaluation of a Crash Cushion Design Using Finite Element Simulation and Full-Scale Crash Testing - MDPI
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safety
Article
Impact Performance Evaluation of a Crash Cushion
Design Using Finite Element Simulation and
Full-Scale Crash Testing
Murat Büyük 1 , Ali Osman Atahan 2, * and Kenan Kurucuoğlu 3
1 Department Faculty of Engineering and Natural Sciences, Sabanci University, Main Campus, İstanbul 34956,
Turkey; muratbuyuk@sabanciuniv.edu
2 Department of Civil Engineering, Istanbul Technical University, Ayazaga Campus, İstanbul 34469, Turkey
3 Ulukur Plastic Traffic Products, İstanbul 34870, Turkey; info@ulukur.com
* Correspondence: atahana@itu.edu.tr
Received: 22 August 2018; Accepted: 25 October 2018; Published: 1 November 2018
Abstract: Crash cushions are designed to gradually absorb the kinetic energy of an impacting vehicle
and bring it to a controlled stop within an acceptable distance while maintaining a limited amount of
deceleration on the occupants. These cushions are used to protect errant vehicles from hitting rigid
objects, such as poles and barriers located at exit locations on roads. Impact performance evaluation
of crash cushions are attained according to an EN 1317-3 standard based on various speed limits and
impact angles. Crash cushions can be designed to absorb the energy of an impacting vehicle by using
different material deformation mechanisms, such as metal plasticity supported by airbag folding
or damping. In this study, a new crash cushion system, called the ulukur crash cushion (UCC), is
developed by using linear, low-density polyethylene (LLDPE) containers supported by embedded
plastic energy-absorbing tubes as dampers. Steel cables are used to provide anchorage to the design.
The crashworthiness of the system was evaluated both numerically and experimentally. The finite
element model of the design was developed and solved using LS-DYNA (971, LSTC, Livermore, CA,
USA), in which the impact performance was evaluated considering the EN 1317 standard. Following
the simulations, full-scale crash tests were performed to determine the performance of the design
in containing and redirecting the impacting vehicle. Both the simulations and crash tests showed
acceptable agreement. Further crash tests are planned to fully evaluate the crashworthiness of the
new crash cushion system.
Keywords: crash cushion; crash test; simulation; LS-DYNA; EN 1317; road safety; energy absorption;
linear, low-density polyethylene
1. Introduction
Traffic and road safety is a serious concern worldwide, and multi-phased research has been
undertaken in recent years. The United Nations General Assembly has made an important initiative to
reduce the fatality rate in traffic accidents around the world by 50% and provided funds for research.
In this context, Turkey has prepared a 10-year vision program covering traffic education and training,
safety and enforcement, health and emergency assistance initiatives, and the improvement of traffic
safety with engineering measures [1,2]. This program has been implemented by Ministries of Education,
Interior, Health, and Transportation. Since 2010, serious steps have been taken regarding traffic safety
in Turkey. These advances include speed control using smart detection systems, the enforcement of
traffic rules through cameras, the reduction of arrival times of ambulances in an accident site, and
providing traffic safety culture to students of all ages. These undertakings have resulted in a 10%
Safety 2018, 4, 48; doi:10.3390/safety4040048 www.mdpi.com/journal/safety
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Safety 2018, 4, x FOR PEER REVIEW 2 of 11
decrease
statisticalindata,
fatal the
accidents in Turkey;
level of however,
achievement according
is not to statistical
at the desired level data,
of 15%.the level
Lack ofofachievement
road restraintis
not at the desired level of 15%. Lack of road restraint system
system utilization is one of the areas that needs to be improved [1]. utilization is one of the areas that needs
to beCrash
improved [1]. are widely used in developed countries to protect vehicles against impacts with
cushions
fixed, sharp, narrow,are
Crash cushions andwidely used inlocated
rigid objects developed countries
at road to protect
exit locations, vehicles
tool booths, against impacts
workzones, with
barrier
fixed, sharp, narrow, and rigid objects located at road exit locations, tool booths,
ends, and trees [3,4]. As shown in Figure 1, collision with unprotected objects increases the severity workzones, barrier
ends, and trees
of accidents and[3,4]. As shown
results in Figure
in fatalities. 1, collisiontowith
According unprotected
predictions objects
by the increases
Turkish the severity
statistics of
institute
accidents and results in fatalities. According to predictions by the Turkish statistics
(TUIK), the number of fixed object accidents is on the rise, which creates concern for road-safety institute (TUIK),
the number
targets set byofthe
fixed objectGovernment
Turkish accidents is [5].
on the rise,
Crash which creates
cushions in generalconcern for road-safety
are designed to slow targets
down and set
by the Turkish Government [5]. Crash cushions in general are designed
contain the impacting vehicle in a controlled way by absorbing its kinetic energy. The Istanbulto slow down and contain
the impacting Municipality
Metropolitan vehicle in a controlled way by
(IMM), which absorbing its
is responsible forkinetic
trafficenergy. The Istanbul
safety within the cityMetropolitan
of Istanbul,
Municipality
expressed interest in utilizing low-cost and nationally developed crash cushions in Istanbulinterest
(IMM), which is responsible for traffic safety within the city of Istanbul, expressed due to
in utilizing
budget low-cost[1].
constraints and nationally developed crash cushions in Istanbul due to budget constraints [1].
Figure 1.
Figure 1. Severity
Severity of
of road accidents with
road accidents with narrow
narrow and
and rigid
rigid objects.
objects.
The aim of of this
this project
projectis,
is,therefore,
therefore,totodevelop
develop a new
a newhybrid
hybridcrash cushion
crash system,
cushion called
system, the
called
ulukur crash cushion (UCC), made out of linear, low-density polyethylene (LLDPE)
the ulukur crash cushion (UCC), made out of linear, low-density polyethylene (LLDPE) containers containers and
steelsteel
and plates for the
plates forIMM. In this
the IMM. In respect, the UCC
this respect, will have
the UCC low initial
will have maintenance
low initial and repair
maintenance costs
and repair
with with
costs reusable parts.parts.
reusable The The
crashworthiness
crashworthiness of the system
of the systemis isevaluated
evaluatedboth
both numerically
numerically and
experimentally. The The finite
finite element
element model
model ofof the UCC is developed, and impact performance is
analyzed using LS-DYNA in accordance with TSEN 1317 crash testing standard [6,7]. [6,7]. Following the
simulations, full-scale crash tests were performed to validate validate the
the computer
computer simulation
simulation results.
results. Both
the simulations and crash tests show acceptable agreement. Further crash tests are planned to fully
crashworthiness of
evaluate the crashworthiness of the
the new
new crash
crash cushion
cushion system.
system.
2. Details of Ulukur Crash Cushion Developed
Ulukur crash cushion (UCC) design is composed of linear, low density polyethylene (LLDPE)
containers, energy-absorbing tubes, steel cables, lower plates, and and back
back support
support plate.
plate. Geometrical
Geometrical
details of these materials
materials areare provided
providedin inFigure
Figure2.2.Containers
Containersare areproduced
producedusing usingLLDPE,
LLDPE, since
since it
it is
is a dependableand
a dependable andcost-effective
cost-effectivematerial
materialthatthatcould
couldsustain
sustain large
large deformations,
deformations, endure dynamic dynamic
forces,
forces, and
andabsorb
absorb kinetic energy
kinetic of the
energy of impacting vehiclevehicle
the impacting withoutwithout
crack formation. Detailed technical
crack formation. Detailed
information about LLDPE
technical information aboutcanLLDPE
be foundcaninbea found
study by in aCozzi
studyetbyal.Cozzi
[8]. The measurements
et al. for the LLDPE
[8]. The measurements for
containers
the LLDPEare 500 mmare
containers 500×mm
long 800 long
mm ×wide × 710
800 mm wide 710×
mm×tall mm 8 mmtall thick.
× 8 mmInthick.
addition, 250 mm250
In addition, in
diameter, 460 mm 460
mm in diameter, longmmenergy-absorbing tubes made
long energy-absorbing outmade
tubes of LLDPE areLLDPE
out of utilizedareinside the containers
utilized inside the
to improvetothe
containers crash performance
improve of the design.
the crash performance of the50 mm in
design. 50diameter holes are
mm in diameter provided
holes on tubes
are provided on
to allow controlled air release. The number of tubes varied based on the container
tubes to allow controlled air release. The number of tubes varied based on the container type. In type. In other
words, as shown
other words, in Figure
as shown 2, the lead
in Figure container
2, the with a shield
lead container with aincluded two tubes,
shield included whereas
two tubes, all the other
whereas all
standard
the other containers included four
standard containers tubes.
included This
four is intended
tubes. to provide
This is intended toaprovide
soft nose-section for vehicles
a soft nose-section for
with low-energy
vehicles impacts. Asimpacts.
with low-energy the impactAs energy increases,
the impact so do
energy the energy
increases, so absorption
do the energy capacities of the
absorption
UCC design.
capacities Material
of the properties
UCC design. of LLDPE
Material are provided
properties of LLDPEin Table 1.
are provided in Table 1.
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(a) (b)
(c) (d)
Figure
Figure 2.
2. Details
Details of
of ulukur
ulukur crash
crash cushion
cushion (UCC)
(UCC)(a)
(a) internal
internal view;
view;(b)
(b) energy
energy absorbing
absorbingtube;
tube;(c)
(c) top
top
view; and (d) assembled crash cushion
view; and (d) assembled crash cushion.
1. Material
Table 1.
Table Materialproperties of low-density
properties polyethylene
of low-density (LLDPE)
polyethylene used in
(LLDPE) UCC
used in(ulukur crash cushion)
UCC (ulukur crash
design [9,10].
cushion) design [9,10].
Property Value Test Standard
Property Value Test Standard
Density (kg/m3 ) 3 935 ASTM D 1505
Density (kg/m ) 935 ASTM D 1505
Modulus of Elasticity (MPa) 724 ASTM D 790
Modulus of Elasticity (MPa)
Toughness 724
69 ASTM D 790
ASTM D 2240
Toughness
Yield Strength (MPa) 69
18 ASTM D
ASTM2240
D 638
Yield Strength
Vicat Softening (◦ C)
Temp.(MPa) 18
115 ASTM D 638
ASTM D 1525
Vicat Softening
Brittleness (◦ C) (°C)
Temp.Temp. −75 ASTMASTM
115 D 1525D 746
Brittleness Temp. (°C) −75 ASTM D 746
The UCC design developed in this study is composed of six containers and a frontal shield. The
The UCC design developed in this study is composed of six containers and a frontal shield. The
design is actually intended for 110 kph impacts, so the original design with six containers is not altered
design is actually intended for 110 kph impacts, so the original design with six containers is not
for 50 kph impact. Total length of the design is 3700 mm. The measurements of UCC elements are
altered for 50 kph impact. Total length of the design is 3700 mm. The measurements of UCC
provided in Figure 2. This design is intended to provide safe containment and redirection for 50 kph
elements are provided in Figure 2. This design is intended to provide safe containment and
head-on and side impacts. Since UCC has a modular nature, the design could be easily converted to
redirection for 50 kph head-on and side impacts. Since UCC has a modular nature, the design could
80, 100, or 110 kph impacts by adding more containers, tubes, and steel members. Thus, the length of
be easily converted to 80, 100, or 110 kph impacts by adding more containers, tubes, and steel
the system can change based on target design speed. As shown in Figure 2, UCC used four 19 mm
members. Thus, the length of the system can change based on target design speed. As shown in
diameter steel cables (two on the bottom and two on the side), and cables are anchored to steel plates
Figure 2, UCC used four 19 mm diameter steel cables (two on the bottom and two on the side), and
at both ends. Bottom cables run between two 650 mm wide × 40 mm wide × 25 mm thick steel plates
cables are anchored to steel plates at both ends. Bottom cables run between two 650 mm wide × 40
located under the containers. This allowed controlled deformation of containers during frontal and
mm wide × 25 mm thick steel plates located under the containers. This allowed controlled
side vehicle impacts. Two side cables are used to improve lateral stability of the UCC design.
deformation of containers during frontal and side vehicle impacts. Two side cables are used to
improve
3. TS ENlateral stability
1317 Crash of theStandard
Testing UCC design.
for Crash Cushion Evaluatıon
3. TSToENassess the performance
1317 Crash of crash for
Testing Standard cushions
Crash against
Cushion vehicle impacts, Part 3 of EN 1317 standard,
Evaluatıon
named “road-restraint systems—part 3: performance classes, impact test acceptance criteria and test
To assess
methods thecushions”
for crash performance of crash
is followed [6].cushions
According against
to this vehicle
standard,impacts,
vehiclesPart 3 of EN
weighing 900, 1317
1300,
standard, named “road-restraint systems—part 3: performance classes, impact
or 1500 kg traveling at speeds of 50, 80, 100, or 110 impact crash cushions in five different approaches.test acceptance
criteria
Figure 3and test all
shows methods
possiblefor crash
test cushions”described
combinations is followed [6]. 1317
in EN According
standardto this
Partstandard, vehicles
3 [6]. As shown in
weighing 900, 1300, or 1500 kg traveling at speeds of 50, 80, 100, or 110 impact crash
Table 2, for 50 kph tests there are only two tests, namely, TC 1.1.50 and TC 4.2.50; a 900 kg passenger cushions in five
different approaches.
car at impact positionFigure
1 and 31300
showskg all possiblecar
passenger testatcombinations
impact positon described in EN 1317
2, respectively, are standard
specified.
Part
Both computer simulations and full-scale crash tests on UCC design are performed at 50 and
3 [6]. As shown in Table 2, for 50 kph tests there are only two tests, namely, TC 1.1.50 kph.TC In
4.2.50; a 900 kg passenger car at impact position 1 and 1300 kg passenger car at impact positon 2,
respectively, are specified. Both computer simulations and full-scale crash tests on UCC design are
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other words,atimpact
performed 50 kph.performance of the
In other words, UCC design
impact is evaluated
performance of the using TC 1.1.50
UCC design and TC 4.2.50
is evaluated crash
using TC
tests [6].
1.1.50 and TC 4.2.50 crash tests [6].
Figure 3. Crash cushion test approaches in EN 1317 Standard
Standard Part
Part 33 [6].
[6].
Table 2. Crash testing details for crash cushions in EN 1317 part 3 [6].
Table 2. Crash testing details for crash cushions in EN 1317 part 3 [6].
Test Speed (kph) Acceptance Tests *,,**
Test Speed (kph) Acceptance Tests * **
50 TC 1.1.50 TC 4.2.50
5080 TC 1.1.50
TC 1.1.80 TC 1.2.80 TC 2.1.80 TC 3.2.80 TCTC 4.2.50 TC 5.2.80
4.2.80
80
100 TC 1.1.80
TC 1.1.100 TC 1.2.80
TC 1.2.100 TC 2.1.80
TC 2.1.100 TC 3.2.80
TC 3.2.100 TC 4.2.80 TCTC
TC 4.2.100 5.2.80
5.2.100
100
110 TC 1.1.100
TC 1.1.100 TC 1.2.100
TC 1.3.110 TC 2.1.100
TC 2.1.100 TC 3.2.100
TC 3.3.110 TC 4.2.100
TC 4.3.110 TC 5.2.100
TC 5.3.110
110 TC 1.1.100 TC 1.3.110 TC 2.1.100 TC 3.3.110 TC 4.3.110 TC 5.3.110
* TC 5.3.110 stands for test crash cushion (TC) approach (5), vehicle (3), and speed (110); ** Vehicles 1, 2, and 3 stand
*forTC 5.3.110 stands for test crash cushion
900 kg, 1300 kg, and 1500 kg, respectively. (TC) approach (5), vehicle (3), and speed (110); ** Vehicles 1,
2, and 3 stand for 900 kg, 1300 kg, and 1500 kg, respectively.
4. Computer Simulation of UCC Design
4. Computer Simulation of UCC Design
Before pursuing costly, full-scale crash testing, a detailed finite element simulation study was
Beforeon
performed pursuing costly,Afull-scale
UCC design. crash testing,
highly non-linear a detailed finite element
and large-deformation simulation
finite-element code study
LS-DYNAwas
performed on UCC design. A highly non-linear and large-deformation
developed by the livermore software technology corporation (LSTC) was used to model the barrier finite-element code
LS-DYNA
and simulate developed by the livermore
the vehicle-barrier impactsoftware
event [7].technology corporation
Details of the bridge rail(LSTC) wasvehicle
and both used tomodels
model
the explained
are barrier and simulate the vehicle-barrier impact event [7]. Details of the bridge rail and both
below.
vehicle models are explained below.
4.1. Finite Element Model of UCC Design
4.1. Finite Element Model of UCC Design
A finite element model of the UCC was developed to assess the crash test performance of
A finiteThe
the design. element
model, model of the in
as shown UCC was4,developed
Figure consistedto ofassess
143,063thenodes,
crash 135,389
test performance
shell, andof4264
the
design.
solid The model,
elements. as shown
Shell elements in represented
Figure 4, consisted
the LLDPEof 143,063
members nodes,
and 135,389 shell, and
steel plates 4264
of the solid
model,
elements.
while solidShell elements
elements represented
represented the the
steelLLDPE
cables.members
The shelland steel plates
elements of theofLLDPE
the model, while solid
containers and
elementstubes
internal represented
that arethe steel cables.
expected to get The
in shell
directelements
contact of the vehicles
with LLDPE containers and internalsevere
and thus experience tubes
that are expected
deformations are to get in direct
modeled with contact with vehicles
full integration and thustoexperience
formulation accuratelysevere deformations
represent the complexare
modeled with full integration formulation to accurately represent the
interactions and behavior. All steel elements were modeled with default element formulation for complex interactions and
behavior. All steel
computational elements were modeled with default element formulation for computational
efficiency.
efficiency.
Since containers are expected to sustain large plastic deformations and possible crushing, a
Since linear
piecewise containers
plasticare expected
material to sustain
definition was large
used toplastic
model deformations and possible
the LLDPE elements crushing,
[11,12]. Since noa
piecewise
failure linear plastic
is expected in steelmaterial
members, definition was used
a rigid material to modelwas
modeling theused
LLDPE elementsplates
to represent [11,12].
andSince no
cables.
failure
Steel is expected
cables in steel
were firmly members,
attached to steela rigid
platesmaterial modeling
at both ends, wasplates
and steel used were
to represent
securedplates and
to ground
cables.unfailing
using Steel cables were firmly attached to steel plates at both ends, and steel plates were secured to
connections.
groundIn anusing unfailing
actual connections.
UCC installation, connections between the members, such as lower steel plates and
In an actual UCC installation,
containers, and steel plates to ground, connections between
are established thebolts
using members,
and nuts.suchToas lower steel
accurately plates and
represent the
containers, and steel plates to ground, are established using bolts and nuts. To accurately represent
the behavior of these connections during full-scale crash testing, CONSTRAINED_SPOTWELD
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behavior of these connections during full-scale crash testing, CONSTRAINED_SPOTWELD option
in LS-DYNA
option was used
in LS-DYNA was[7]. By [7].
used definition, this option
By definition, keeps members
this option connected
keeps members until auntil
connected certain force
a certain
criteria is met.isThen,
force criteria met. the connection
Then, fails and
the connection members
fails can move
and members canfreely.
moveTofreely.
determine the required
To determine the
force level that fails a connection, a detailed model is constructed using LS-DYNA.
required force level that fails a connection, a detailed model is constructed using LS-DYNA. The behavior of The
the
connection
behavior ofwas the examined
connection under
was different
examinedloading
under conditions. A reasonable
different loading failure
conditions. A criterion
reasonable obtained
failure
from the component
criterion obtained from simulation was used
the component in the connection
simulation was usedmodel
in the[11].
connection model [11].
(a) (b)
Figure 4. Finite element model of UCC: (a) frontal view and
and (b)
(b) rear
rear view.
view.
4.2.
4.2. Vehicle
Vehicle Model
Model
After
After the
the development
development of of the
the UCC
UCC model,
model, aa small
small passenger
passenger car
car model
model was
was used
used to
to meet
meet the
the EN
EN
1317 standard requirements to impact the barrier. A 2002 Ford Taurus vehicle model obtained
1317 standard requirements to impact the barrier. A 2002 Ford Taurus vehicle model obtained from from the
National Crash
the National Analysis
Crash Center
Analysis (NCAC)
Center was used
(NCAC) was in the in
used study
the [13].
studyThe mass
[13]. Theofmass
the empty
of thevehicle
empty
was adjusted to 900 kg, and it could have been increased to 1300 kg by adding extra mass
vehicle was adjusted to 900 kg, and it could have been increased to 1300 kg by adding extra mass elements.
This particular
elements. This vehicle model
particular was model
vehicle used inwas
many previous
used in many studies with success
previous studies [14].
withAsuccess
picture[14].
of the
A
vehicle
picture is
ofshown in Figure
the vehicle 5. in Figure 5.
is shown
Figure 5. The
Figure 5. The 2002
2002 Ford
Ford Taurus
Taurus vehicle
vehicle model
model used
used in
in LS-DYNA
LS-DYNA Impact
ImpactSimulation.
Simulation.
4.3. TC 1.1.50 Simulation
4.3. TC 1.1.50 Simulation
After the final modifications on the vehicle model, the simulation was setup according to TC 1.1.50
After the final modifications on the vehicle model, the simulation was setup according to TC
conditions specified in EN 1317 part 3 [6]. This head-on crash test with 900 kg vehicle is performed
1.1.50 conditions specified in EN 1317 part 3 [6]. This head-on crash test with 900 kg vehicle is
to evaluate the energy-absorption capability of the UCC design and its effectiveness at reducing the
performed to evaluate the energy-absorption capability of the UCC design and its effectiveness at
velocity of impacting vehicle in a controlled manner, thus reducing occupant injury risks. As shown
reducing the velocity of impacting vehicle in a controlled manner, thus reducing occupant injury
in Figure 6, the vehicle was positioned in front of the cushion at 0 degrees impact angle. The vehicle
risks. As shown in Figure 6, the vehicle was positioned in front of the cushion at 0 degrees impact
speed was 50 kph. In this simulation no dummy was used. Simulation was run about 0.15 s until the
angle. The vehicle speed was 50 kph. In this simulation no dummy was used. Simulation was run
vehicle’s kinetic energy completely dissipated by the crash cushion and vehicle was pushed backwards.
about 0.15 s until the vehicle’s kinetic energy completely dissipated by the crash cushion and vehicle
was pushed backwards. As shown in Figure 7, vehicle hit the barrier; instantly, the front container
began to deform and bent towards the impacting vehicle. 0.06 s after the initial impact, the kinetic
energy of the vehicle was significantly reduced and the velocity of the vehicle was approximately 28
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As shown in Figure 7, vehicle hit the barrier; instantly, the front container began to deform and bent
Safety
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4, xx FOR
2018,the PEER
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impacting
FOR vehicle. 0.06 s after the initial impact, the kinetic energy of the vehicle66 was
REVIEW of
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11
significantly reduced and the velocity of the vehicle was approximately 28 km/h. 0.072 s after the
km/h.
km/h. 0.072
0.072 ss after
after the
the initial
initial contact, the
the second
contact,began second container
container began
began toto deform
deform and absorbed the rest of
initial contact, the second container to deform and absorbed the restand absorbed
of the kinetic the rest of
energy of
the kinetic
the vehicle. energy
kinetic energy of the
of the vehicle.
vehicle. Thus, 0.12
Thus, impact s after
0.12 s after the initial impact with the UCC, vehicle was
the Thus, 0.12 s after the initial with the initial vehicle
the UCC, impact was
withbrought
the UCC, to avehicle was
controlled
brought
brought to
to aa controlled
controlled stop.
stop. Vehicle
Vehicle left
left the
the UCC
UCC in
in aa stable
stable and
and upright
upright position.
position. Energy
Energy
stop. Vehicle left the UCC in a stable and upright position. Energy absorption performance of the UCC
absorption
absorption performance
performance of
of the
the UCC
UCC was acceptable, which resulted in low
low occupant risk values that
was acceptable, which resulted in lowwas acceptable,
occupant which that
risk values resulted
wereinmeasured
occupant
insiderisk
thevalues that
vehicle. A
were
were measured
measured inside
inside the
the vehicle.
vehicle. A
A picture
picture of
of the
the deformed
deformed shape
shape of
of the
the barrier
barrier after
after TC
TC 1.1.50
1.1.50
picture of the deformed shape of the barrier after TC 1.1.50 simulation is shown in Figure 8. Based on
simulation
simulation is
is shown
shown in
in Figure
Figure 8.
8. Based
Based on
on the simulation
thethat
simulation predictions,
predictions, it
it was determined
wascontained
determined that UCC
the simulation predictions, it was determined UCC design successfully andthat UCC
stopped
design
design successfully
successfully contained and
containedinjury stopped
and stopped 900 kg vehicle with minimal injury risk to
900 kg vehicle with minimal injury risk to occupants. occupants.
900 kg vehicle with minimal risk to occupants.
Full-Scale
Full-Scale Crash
Crash Test
Test TC
TC 1.1.50
1.1.50
LS-DYNA
LS-DYNA Simulation
Simulation
Figure
Figure 6.
6. The
The 900
900 kg
kg car
car positioned
positioned in
in front of UCC
front of UCC barrier
barrier before
before TC
TC 1.1.50.
1.1.50.
1.1.50.
Figure 7. Cont.
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Figure
Figure
Figure 7. 7. Sequential
7. Sequential
Sequential picture
picture
picture comparison
comparison
comparison of of
of UCC
UCCUCC after
after
after TCTC
TC 1.1.50
1.1.50
1.1.50 crash
crash
crash testtest
andand simulation.
simulation.
Figure 8. Deformed
Figure shape
8. Deformed comparison
shape of of
comparison UCC after
UCC TC 1.1.50
after crash test and simulation.
Figure 8. Deformed shape comparison of UCC after TCTC 1.1.50
1.1.50 crash
crash testtest
andand simulation.
simulation.
Safety 2018, 4, 48 8 of 11
Safety
Safety 2018,
2018, 4,
4, xx FOR
FOR PEER
PEER REVIEW
REVIEW 88 of
of 11
11
4.4. TC 4.2.50 Simulation
A second
secondsimulation
simulationstudystudywas was also
also performed
performed to evaluate
to evaluate side impact
side impact capacity
capacity of the UCCof thedesign.
UCC
design.
As As described
described by test TC by4.2.50,
test TC 4.2.50,
a 1300 kg acar
1300 kg car
model wasmodel was positioned
positioned so that
so that it would it would
impact impact
the cushion
the cushion 1/3rd of the length (see Figure 9). The vehicle contacted the barrier
1/3rd of the length (see Figure 9). The vehicle contacted the barrier at 15 degrees angle, and the velocityat 15 degrees angle,
and
of thethe velocity
vehicle justofbefore
the vehicle
the impactjust was
before50 the
kph.impact was the
Following 50 kph.
initialFollowing
contact, asthe initialincontact,
shown Figure 10,as
shown
first andinsecond
Figurecontainers
10, first and second
began containers
to deform beganthus
laterally, to deform
absorbing laterally, thus absorbing
the impact energy of the the vehicle.
impact
energy
As of the vehicle.
the vehicle continued As totheslide
vehicle continued
on the to slide
side of the UCC,onit the side ofmore
contacted the UCC, it contacted
containers more
and vehicle
containers and vehicle
speed was further speed
reduced. wass after
At 0.1 furtherthereduced. At 0.1
initial impact, thes first
afterfour
the containers
initial impact, the moderate
received first four
containers
damage and received
vehicle’s moderate
velocity damage
was almost and28vehicle’s
kph. Asvelocity
shown in was almost 28
sequential kph. As
pictures shown 10,
in Figure in
sequential pictures in Figure 10, 0.2 s after the initial impact, cushion was able
0.2 s after the initial impact, cushion was able to contain and redirect impacting vehicle without any to contain and redirect
impacting
breakage ofvehicle withoutDamage
the elements. any breakage
to the UCC of theandelements. Damage
vehicle were to theThe
moderate. UCC and vehicle
vehicle were
left the UCC
moderate. The vehicle left the UCC in a stable and upright position. Energy
in a stable and upright position. Energy absorption performance of the UCC was acceptable, which absorption performance
of the UCC
resulted wasoccupant
in low acceptable, riskwhich
valuesresulted
measured in low occupant
inside risk values
the vehicle. measured
A picture inside theshape
of the deformed vehicle.
of
A
thepicture
barrierof theTC
after deformed shape of the
4.2.50 simulation barrierinafter
is shown FigureTC11.
4.2.50
Based simulation is shownpredictions,
on the simulation in Figure 11. it
Based on the simulation predictions, it was determined that UCC design has
was determined that UCC design has the potential to satisfy 50 kph test requirements described at EN the potential to satisfy
50 kph
1317 test
part 3. requirements described at EN 1317 part 3.
Figure
Figure 9.
9. The
The 1300
1300 kg
kg car
car positioned
positioned in
in front
front of
of UCC
UCC barrier before TC
barrier before TC 4.2.50.
4.2.50.
Figure 10. Cont.
Safety 2018, 4, 48 9 of 11
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Safety 2018, 4, x FOR PEER REVIEW 9 of 11
Figure 10. Sequential pictures comparison of UCC after TC 4.2.50 crash test and simulation.
Sequential pictures
Figure 10. Sequential
Figure pictures comparison
comparison of UCC after TC 4.2.50 crash test and simulation.
Figure 11. Deformed shape comparison of UCC after TC 4.2.50 crash test and simulation.
Figure 11. Deformed shape comparison of UCC after TC 4.2.50 crash test and simulation.
Figure 11. Deformed shape comparison of UCC after TC 4.2.50 crash test and simulation.
5. Full-Scale Crash Testing
5. Full-Scale Crash Testing
After performing
5. Full-Scale two successful simulation studies for tests TC 1.1.50 and TC 4.2.50, same tests
Crash Testing
were performed using two
After performing successful
full scale crashsimulation studies
cushion. Crash forwere
tests testsrun
TC 1.1.50 and TC
in Istanbul 4.2.50,
during thesame tests
summer
After performing two successful simulation studies for tests TC 1.1.50 and TC 4.2.50, same tests
were
of performed
2016. using
These tests werefull scale crash
intended cushion.
to both verifyCrash tests werefindings
the simulation run in Istanbul during theprove
and conclusively summer
the
were performed using full scale crash cushion. Crash tests were run in Istanbul during the summer
of 2016. Theseoftests
acceptability UCCwere intended
design to both
for 50 kph verify the simulation findings and conclusively prove the
conditions.
of 2016. These tests were intended to both verify the simulation findings and conclusively prove the
acceptability of UCC design for 50 kph conditions.
acceptability
5.1. Crash TestofTC
UCC design for 50 kph conditions.
1.1.50
5.1. Crash Test TC
As shown 1.1.50 6 and 7, a full-scale crash test was performed on UCC design according to
in 1.1.50
Figures
5.1. Crash Test TC
EN 1317 part 3 TC
As shown 1.1.50 conditions
in Figures 6 and 7, a[9]. The UCC
full-scale crashdesign wasperformed
test was installed ononconcrete pavement
UCC design and the
according to
impactAs shown in Figures 6 and 7, a full-scale crash test was performed on UCC design according to
EN 1317point,
part 3asTC described in EN 1317
1.1.50 conditions [9].part
The3, wasdesign
UCC a 1991wasmodel Ford Taurus,
installed on concretewhich used as and
pavement the test
the
EN 1317 The
vehicle. parttotal
3 TCmass
1.1.50ofconditions
the tested [9]. The UCC 900
vehicle design was installed on concrete kg pavement and the
impact point, as described in EN 1317 part 3,was
was a 1991 kg when
model empty
Ford and
Taurus,1300which with
usedtheasaddition
the test
impact
of dummy point, as described in EN 1317 part 3, was a 1991 model Ford Taurus, which used as the test
vehicle. Theandtotalmeasurement
mass of the testeddevices. The was
vehicle vehicle
900 positioned
kg when empty in the test1300
and track
kgaccelerated towards
with the addition of
vehicle.
the The total
test article at anmass of the
angle tested
ofdevices.
zero vehicle
degrees was a900
using kg when
cable pullyinempty
mechanismand 1300 kg with the
andaccelerated
impacted theaddition of
barrierthe
at
dummy and measurement The vehicle positioned the test track towards
dummy
51.5 kph.and measurement
Behavior of the devices.
and The vehicleare positioned in the test track accelerated towards the
test article at an angle of UCC
zero degrees the using
vehicle a cable illustrated in Figure
pully mechanism 7. As
and expected,the
impacted vehicle was
barrier at
test
not article at an angle of zero degrees using a cable pully mechanism and impacted the barrier at
51.5able
kph.toBehavior
damage of thethe
cushion
UCC and significantly.
the vehicle Only the first and
are illustrated insecond
Figure containers compressed
7. As expected, vehicle and
was
51.5 kph. Behavior
absorbed ofenergy
the UCC andvehicle.
the vehicle are illustrated in Figurein7.an Asacceptable
expected, manner
vehicle was
not able tothe kinetic
damage the cushion of thesignificantly. The vehicle
Only slowed
the first anddown
second containers compressed and and
not
came able
to ato damage
stop. Data the cushion
collected significantly.
from the Only
accelerometer, the first
which and
was second containers
installed at the compressed
vehicle’s and
center of
absorbed the kinetic energy of the vehicle. The vehicle slowed down in an acceptable manner and
absorbed
gravity, the kinetic energy of the vehicle. The vehicle slowed down in an acceptable manner and
came towere used
a stop. to calculate
Data collectedthe fromoccupant injury risks. which
the accelerometer, Due towas the softened
installednose
at thedesign of the
vehicle’s barrier
center of
came
and to aspeed
low stop. of
Data collected
vehicle occupantfrom injury
the accelerometer,
risk, the valueswhich
were was installed at
determined to the
be vehicle’s center
negligible. Resultsof
gravity, were used to calculate the occupant injury risks. Due to the softened nose design of the
gravity,
of TC 1.1.50werecrash
usedtestto calculatethat the theoccupant injuryisrisks. Due to to thecontain
softened andnose design of the
barrier and low speed showed
of vehicle occupant UCC design
injury risk, soft enough
the values were determined stop annegligible.
to be impacted
barrier
vehicle andanlow speed ofmanner.
vehicle occupant injury risk, the values were determined to be negligible.
Results in of TCacceptable
1.1.50 crash test showed that the UCC design is soft enough to contain and stop an
Results of TC 1.1.50 crash test showed that the UCC design is soft enough to contain and stop an
impacted vehicle in an acceptable manner.
impacted vehicle in an acceptable manner.
Safety 2018, 4, 48 10 of 11
5.2. Crash Test TC 4.2.50
After repairing damaged containers and rotating the cushion 15 degrees, a second crash test
was performed on UCC design according to EN 1317 part 3 test TC 4.2.50 conditions [10]. As shown
in Figure 9, a 1320 kg Ford Taurus impacted the barrier with a speed of 51 kph and at an angle of
15 degrees. The impact point was 1.5 m away from the nose, which is equal to one third of the distance
of the UCC. Following the initial contact, as shown in Figure 10, first two containers that received the
impact force began to deform and absorb the initial impact loads. As the vehicle continued to slide on
the side of the UCC, as in the simulation study, it contacted barriers number three and four, which
reduced the vehicle speed a further 0.1 s; after the initial impact, the first four containers received
moderate damage and the vehicle’s velocity was almost 32 kph. As shown in sequential pictures in
Figure 10, 0.22 s after the initial impact, cushion was able to contain and redirect the impacting vehicle
in an acceptable manner. Damage to the UCC and vehicle were moderate. The vehicle left the UCC
in a stable and upright position. Energy absorption performance of the UCC was acceptable, which
resulted in low occupant risk values measured inside the vehicle. A picture of the deformed shape
of the barrier after TC 4.2.50 crash test is shown in Figure 11. As predicted by LS-DYNA simulation
study, UCC design successfully passed the 50 kph test requirements described in EN 1317 part 3 [6].
6. Summary and Conclusions
This paper deals with designing, analyzing, and testing a new, reusable, low-cost, and simple
crash cushion, UCC, for roads with 50 kph speed limits. UCC design included LLDPE containers
with embedded LLDPE energy-absorbing tubes as dampers. The design was strengthened by steel
cables and steel plates. The crashworthiness of the system was evaluated both numerically and
experimentally. Finite element analysis of the UCC design showed that the design is flexible enough to
contain, and successfully stop, a 900 kg car impacting head-on and rigid enough to successfully redirect
the 15 degree side impact of a 1300 kg vehicle at one third of the location of the design. Following the
promising simulation study, the design was installed at a test facility and two full scale crash tests
were performed on UCC to conclusively determine its performance under 50 kph vehicle impacts.
Both simulation and crash test results agreed well, proving the crashworthiness and acceptability of
the design at 50 kph. Damage to UCC was moderate, and the occupant risk factors were below injury
threshold. Since UCC design is composed of modular elements, the design could be easily repaired
and put back to service. Finally, performing further crash tests at higher speeds, such as 80, 100, and
110 kph, is recommended to fully assess the acceptability of the new crash cushion system developed.
Author Contributions: A.O.A. and M.B. carried out the finite element simulations performed full-scale crash
tests and constructed the manuscript. K.K. provided the crash cushion design, materials and prepared the setup
to perform full-scale crash tests.
Funding: This research received no external funding.
Conflicts of Interest: The authors declare no conflict of interest.
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