Embed Size (px)
Citation preview
www.fka.de
w w w . a u t o s t e e l . o r g
Comparison of Steel and Aluminum Hood with same Design in View of Pedestrian
Head Impact
Dr.-Ing. Dominik Schwarz, fka, Aachen, Germany
CO-AuthorsDipl.-Ing. Harald Bachem, ika, Aachen, Germany
Ed Opbroek, IISI, Detroit, US
www.fka.de
w w w . a u t o s t e e l . o r g
Agenda
Motivation
Structural Stiffness Testing
Pedestrian Safety Testing
Summary
Outlook
Comparison of Steel and Aluminum Hood with same Design in View of Pedestrian Head Impact
www.fka.de
w w w . a u t o s t e e l . o r g
Motivation
Structural Stiffness Testing
Pedestrian Safety Testing
Summary
Outlook
Comparison of Steel and Aluminum Hood with same Design in View of Pedestrian Head Impact
Agenda
www.fka.de
w w w . a u t o s t e e l . o r g
high global stiffness (bending, torsion)
high local denting stiffness and strength (static and dynamic)
dynamic stiffness (vibration behaviour)
controllable deformation behaviour in frontal collision
energy absorption at head impact
minimized weight
low costs
....
Requirements for Automotive Hoods
www.fka.de
w w w . a u t o s t e e l . o r g
application of aluminum hoods because of smaller specific weight
application of steel hoods because of costs and properties
demand for comparing investigation (steel/aluminum)
actual series hood in two different material variants steel and aluminum for North America and Europe
comparison of the two material concepts according toweightstructural behaviorpedestrian head impact
Steel and Aluminum as Hood Material
www.fka.de
w w w . a u t o s t e e l . o r g
aluminum hoodsteel hood
series hoods made of steel (USA) and aluminum (Europe) with nearly the same design of inner hood structure
Structural Design of Analyzed Hoods
www.fka.de
w w w . a u t o s t e e l . o r g
Motivation
Structural Stiffness Testing
Pedestrian Safety Testing
Summary
Outlook
Comparison of Steel and Aluminum Hood with same Design in View of Pedestrian Head Impact
Agenda
www.fka.de
w w w . a u t o s t e e l . o r g
0
20
40
60
80
100
120
0 10 20 30 40 50 60deflection [mm]
forc
e [N
]
original part steeloriginal part aluminumspare part steelspare part aluminum
Stiffness Tests (e.g. Torsion)
www.fka.de
w w w . a u t o s t e e l . o r g
lateral stiffness transversal stiffness
high bending stiffness results in reduced fluttering at high velocities and good accuracy in gap width to the fenders
Further Stiffness Tests
www.fka.de
w w w . a u t o s t e e l . o r g
investigation shows significantly higher stiffness of the steel hood in comparison to the aluminum hood but also significantly higher weight
-29,51,82 N/mm2,58 N/mmtorsional stiffness(absolute value)
-34,763,81 N/mm97,70 N/mmtransversal stiffness(absolute value)
-31,666,42 N/mm97,17 N/mmlateral stiffness(absolute value)
+72,41,00 mm0,58 mmthickness inner panel
+47,11,00 mm0,68 mmthickness outer panel
-46,99,00 kg16,95 kghood mass
comparison [%]aluminum hoodsteel hood
Comparison of Hood Performances
www.fka.de
w w w . a u t o s t e e l . o r g
Motivation
Structural Stiffness Testing
Pedestrian Safety Testing
Summary
Outlook
Comparison of Steel and Aluminum Hood with same Design in View of Pedestrian Head Impact
Agenda
www.fka.de
w w w . a u t o s t e e l . o r g
Animation of Vehicle/Pedestrian-Crash
development of testing procedure which is based on subsystemsfor head, pelvis and leg areas of the pedestrian
experimental testing with full body dummies of pedestrians is too cost-intensive
www.fka.de
w w w . a u t o s t e e l . o r g
Pedestrian Safety Directive of the European Parliament
lower leg impactorphase 1 (2005) phase 2 (2010)
v = 40 km/hm = 13,4 kg
ϕknee = 21°τ knee = 6 mmaknee = 200 g
v = 40 km/hm = 13,4 kg
ϕknee = 15°τ knee = 6 mmaknee = 150 g
upper leg impactor
phase 1 (2005) phase 2 (2010)200 J< E <700 J 200 J< E <700 J
no limit FSum = 5 kNMb = 300 Nm
α = 50°α = 65°
4013,4825
km/hkgJ
vmEkin
===
150156
g°mm
aTibia
ϕKnieτKnie
===
Beinprüfkörper
km/hkgJ
vmEkin
<<<
4017
10004
220kNNm
FMB
==
JEkin < 7005
300kNNm
FMB
==
EEVCWG10
EEVCWG17
Oberschenkel-prüfkörper
vmEkin
===
402,5154
km/hkgJ
1000HIC=
Kinderkopf-prüfkörper
404,8295
km/hkgJ
vmEkin
===
1000HIC=
Erwachsenenkopf-prüfkörper
km/hkgJ
vmEkin
<<<
401710004220
kNNm
FMB
==
JEkin<700
EEVCWG10
EEVC
Oberschenkel-prüfkörper
vmEkin
===
402,5154
km/hkgJ
1000HIC=
Kinderkopf-prüfkörper
km/hkgJ
vmEkin
<<<
4017
10004
220kNNm
FMB
==
JEkin< 700
EEVCWG10
EEVC
Oberschenkel-prüfkörper
vmEkin
===
402,51541000HIC=
Kinderkopprüfkörpe
αcαa
head impactorphase 1 (2005)
m = 3,5 kg
adult headto windscreen
v = 35 km/h v = 35 km/hm = 4,8 kg
no limit
child headto windscreen
2/3: HIC = 1000
1/3: HIC = 2000
phase 2 (2010)child head to bonnet
adult headto bonnet
m = 2,5 kgv = 40 km/h
HIC = 1000m = 4,8 kgv = 40 km/h
HIC = 1000
www.fka.de
w w w . a u t o s t e e l . o r g
Definition of Head Impact Areas (Marking of the Vehicle)
wrap around distance(1.000 mm for child 1.500 mm for adult)
hood rear reference line
sphere
50°
600 mm
hood leading edge reference line
45°
hood side reference line
www.fka.de
w w w . a u t o s t e e l . o r g
Definition of the Impact Areas
child head area
adult head area
determination of the impact areas for adult head and child head and further partitioning in each 3 segments
www.fka.de
w w w . a u t o s t e e l . o r g
Definition of the Impact Points
Ch-R-1
Ch-R-2
Ch-R-3
Ch-M-1
Ch-M-2
Ch-M-3
Ch-L-1
Ch-L-2Ch-L-3
Ah-R-1Ah-R-2 Ah-R-3
Ah-M-1
Ah-M-3
Ah-M-2
Ah-L-2
Ah-L-1 Ah-L-3
reference point
x
y
in each of the 6 segments 3 critical impact points are chosen
critical impact points result from the available package below the hood
the coordinates are measured in relation to the reference point
www.fka.de
w w w . a u t o s t e e l . o r g
Test Parameter
50°65°plunger
hood
impact points
v = 40 km/hm = 2,5 kgdch = 130 mmEkin = 154 J
v = 40 km/hm = 4,8 kgdad = 165 mmEkin = 295 J
9 tests each are executed with the adult and the child head impactor(total 36 tests)
documentation of the results by deceleration pulse, HIC, a3ms, amax, high-speed-videos and digital fotos of plastic hood deformation
www.fka.de
w w w . a u t o s t e e l . o r g
Deformation Behaviour Child Head Impact M2
aluminum (HIC = 785) steel (HIC = 1.278)Ch-M-2
0
50
100
150
200
250
0 5 10 15 20 25
steelaluminium
• bigger window for HIC calculation in aluminum version• adequate deformation travel• higher acceleration peak for steel version• no significant secondary impact takes place • 15-20 % more deformation travel for aluminum version
higher HIC-values for steel version
hood
time [ms]
acce
lera
tion
[g] steel
aluminum
www.fka.de
w w w . a u t o s t e e l . o r g
aluminum (HIC = 1.035) steel (HIC = 869)Ah-L-1
• nearly equal windows for HIC calculation• higher first acceleration peak for steel version• higher secondary acceleration peak for aluminum
version
acce
lera
tion
[g]
time [ms]
higher HIC-values for aluminum version0
50
100
150
200
0 5 10 15 20 25
[g] steel
aluminium
0
50
100
150
200
0 5 10 15 20 25
[g] steel
aluminium
hood underlying structure
Deformation Behaviour Adult Head Impact L1
www.fka.de
w w w . a u t o s t e e l . o r g
Plastic Hood Deformation at Adult Head Impact L3
outer hood view inner hood view
steel
Ah-L-3
aluminum
relatively small deformation because of impact on suspension strut domeslightly bigger local deformation for aluminum hood
www.fka.de
w w w . a u t o s t e e l . o r g
0
2000
4000
6000
8000
10000
12000
14000A
h-R
-1
Ah-
R-2
Ah-
R-3
Ah-
M-1
Ah-
M-2
Ah-
M-3
Ah-L
-1
Ah-L
-2
Ah-L
-3
Ch-
R-1
Ch-
R-2
Ch-
R-3
Ch-
M-1
Ch-
M-2
Ch-
M-3
Ch-
L-1
Ch-
L-2
Ch-
L-3
HIC
aluminium
steelin 13 of 18 cases the steel hood had
a better performance for
the HIC
Test Results - HIC-Value
adult head impact points child head impact points
EEVC-limit HIC 1000
www.fka.de
w w w . a u t o s t e e l . o r g
Agenda
Motivation
Structural Stiffness Testing
Pedestrian Safety Testing
Summary
Outlook
Comparison of Steel and Aluminum Hood with same Design in View of Pedestrian Head Impact
www.fka.de
w w w . a u t o s t e e l . o r g
Summary
analysis of steel and aluminum with nearly identical design under the aspects structural stiffness and pedestrian safety
steel hood shows better stiffness values combined with significantly higher weight
most of the determined HIC values are as expected clearly above the HIC-limit of 1.000, because the vehicle was not constructed explicit for good pedestrian safety
significant influence of the structure below the hood and available free deformation travel, comparatively small material influence
comparison of 18 head impact points (steel vs. aluminum) results in smaller injury severity for the steel hood in 13 points
constructive optimization of the hood for both materials will lead to a reduction of the injury severity
www.fka.de
w w w . a u t o s t e e l . o r g
Agenda
Motivation
Structural Stiffness Testing
Pedestrian Safety Testing
Summary
Outlook
Comparison of Steel and Aluminum Hood with same Design in View of Pedestrian Head Impact
www.fka.de
w w w . a u t o s t e e l . o r g
Development of a Pedestrian-Friendly Hood - Use of Numerical Optimization -
2. draft versions 3. optimised inner panel
1. topography and topology optimization
www.fka.de
w w w . a u t o s t e e l . o r g
Development of a Pedestrian-Friendly Hood - Benchmark of the HIC-Value -
optimised series
>15001000-1500700-1000
< 700HIC
child head area
adult head area
www.fka.de
w w w . a u t o s t e e l . o r g
Development of a Pedestrian-Friendly Hood - Method to Optimize the HIC-Value -
child head impactor
hood inner panel
hood outer panel
glue
rigid wall (e.g. engine block)
60 mm
Δg
Δh toutsidetinside
