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Optimization of an O-EEA-energy absorber for a pedestrian protection loadcase of a vehicle front...
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Transcript of Optimization of an O-EEA-energy absorber for a pedestrian protection loadcase of a vehicle front...
Optimization of an O-EEA-energy absorber for a
pedestrian protection loadcase of a vehicle front
structure with HyperStudy and LS-Dyna
Ihf:
M.Eng. Alexander Froloff,
Prof. Dr.-Ing. Armin Huß,
Dipl.-Ing. Heiko Beck
Novelis Deutschland GmbH:
Dipl.-Ing. Christian Müller
Novelis Deutschland GmbH
Am Eisenwerk 30
58840 - Plettenberg
Ingenieurbüro Huß & Feickert GbR mbH
Im Kohlruß 1-3
65835 Liederbach
5th European HyperWorks Technology Conference
09-11-2011
© 2011 Ingenieurbüro Huß und Feickert GbR mbH
Agenda
• Introduction into the pedestrian safety
• FE-Model
• Definition of Design Variables
• Optimization results
• Summary
09-11-2011
© 2011 Ingenieurbüro Huß und Feickert GbR mbH
Introduction
• EU-Directive 2003/102/EG
- 2 steps phasing-in of safety standards for the protection of vulnerable road
users
• relaxed by EU-Directive 78/2009 und 631/2009
09-11-2011
© 2011 Ingenieurbüro Huß und Feickert GbR mbH
Introduction
• EU-Directive 2003/102/EG
- 2 steps phasing-in of safety standards for the protection of vulnerable road
users
• relaxed by EU-Directive 78/2009 und 631/2009
09-11-2011
© 2011 Ingenieurbüro Huß und Feickert GbR mbH
Introduction
• crash tests for pedestrian safety prescribed by EU-Directive
Upper leg
Child`s head Adult`s head
Lower leg
09-11-2011
© 2011 Ingenieurbüro Huß und Feickert GbR mbH
Introduction
• bio-mechanical limit values according to EU-Directive 78/2009
* limit values according to EU directive 2003/102/EG
Velocity Acceleration Bending angle Shear displacement
40 km/h 170g (150g*) 19° (15°*) 6 mm
Lower leg
09-11-2011
© 2011 Ingenieurbüro Huß und Feickert GbR mbH
FEM - Model
• Ford Taurus from George Washington University
- reduction to the supporting front structure
09-11-2011
© 2011 Ingenieurbüro Huß und Feickert GbR mbH
FEM - Model
• Ford Taurus from George Washington University
- reduction to the supporting front structure
- modifying of the bumper structure
• fitting of the cross beam to absorber-geometry
• lower fascia moved forward and stiffened (with shell elements)
09-11-2011
© 2011 Ingenieurbüro Huß und Feickert GbR mbH
Legform impactor
• Livermore Software Technology Corporation (LSTC)
- detailed simulation model of the real impactor
• different material description (stiff femur- and tibia-cylinder)
09-11-2011
© 2011 Ingenieurbüro Huß und Feickert GbR mbH
Energy absorber
• OHLER(R) -Extruded Energy Absorber (O-EEA)
- developed by Novelis Deutschland GmbH and OTSUKA LTD (Japan)
• Material: Polypropylen, 100% recyclable
• Adaptable to fascia or cross-beam
• Manufacturing:
- extrusion of the square tube
- imprinting of the grooves
Width Height Peak Valley specific weight
50 mm 70 mm 0,9 mm 1,3 mm 0,3 kg/m
Standard parameter of the OHLER(R) OEEA
09-11-2011
© 2011 Ingenieurbüro Huß und Feickert GbR mbH
Energy absorber
• FEM-Model
- Absorber divided into cross stripes
• different wall thickness is assigned to the stripes
- (simulation of the thinning of the wall-thickness)
- fully integrated shell elements
09-11-2011
© 2011 Ingenieurbüro Huß und Feickert GbR mbH
Design Variables
Height
Width
Groove depth
Groove distance Wall thickness
09-11-2011
© 2011 Ingenieurbüro Huß und Feickert GbR mbH
Absorber – Geometry
• reduction of the absorber width changes the distance to the fascia
- side member divided in two pieces
- distance between the side members is parameterized and related to the
variation of absorber width
- load transmission via rigid elements
Side member
09-11-2011
© 2011 Ingenieurbüro Huß und Feickert GbR mbH
wall thickness of the absorber
manufacturing-related exponential thinning of material from
valley to peak
• thinning out depends on
- imprinting distance
• distance between peak and valley
- nominal thickness
• thickness before deep-drawing (groove imprinting)
09-11-2011
© 2011 Ingenieurbüro Huß und Feickert GbR mbH
Wall-thickness of the absorber
five absorber segments
with different wall thickness
09-11-2011
© 2011 Ingenieurbüro Huß und Feickert GbR mbH
Wall-thickness of the absorber
09-11-2011
© 2011 Ingenieurbüro Huß und Feickert GbR mbH
Wall-thickness of the absorber
09-11-2011
© 2011 Ingenieurbüro Huß und Feickert GbR mbH
Wall-thickness of the absorber
09-11-2011
© 2011 Ingenieurbüro Huß und Feickert GbR mbH
Wall-thickness of the absorber
09-11-2011
© 2011 Ingenieurbüro Huß und Feickert GbR mbH
Wall-thickness of the absorber
09-11-2011
© 2011 Ingenieurbüro Huß und Feickert GbR mbH
Wall-thickness of the absorber
• assumption, because of groove-depth variable
12,10
0001,0ln
3,1
3
12,1
v
j evt
02,9
0008,0ln
3,2
3
12,1
v
j evt
15,5
0395,0ln
3,3
3
12,1
v
j evt
65,3
35,0ln
3,4
3
12,1
v
j evt
99,2
176,0ln
3,5
3
12,1
v
j evt
9,59,2 3 v
09-11-2011
© 2011 Ingenieurbüro Huß und Feickert GbR mbH
Overview of the Design Variables
Thickness
[mm]
v3
[-]
Width
[mm]
Height
[mm]
Groove-
Distance
[mm]
Groove-
Depth
[mm]
Nominal Value 0,9* 2,9 40 70* 15,0 4,0
Lower Bound 0,9 2,9 40 70 15,0 4,0
Upper Bound 2,0 5,9 50* 50 16,5* 7,0*
Variable
t1(v3)
v3 B H RA RT
t2(v3)
t3(v3)
t4(v3)
t5(v3)
* nominal value of the absorber before optimization
09-11-2011
© 2011 Ingenieurbüro Huß und Feickert GbR mbH
Optimization
• HyperStudy 10.0
• Constraints • Acceleration
• Bending angle
• Shear displacement
• Objectives • Acceleration
• Bending angle
• Optimization method
- Adaptive Response Surface Method
• solved with LS-Dyna on a 4-node Linux cluster
09-11-2011
© 2011 Ingenieurbüro Huß und Feickert GbR mbH
Optimization results
09-11-2011
© 2011 Ingenieurbüro Huß und Feickert GbR mbH
Before
Optimization Design 1 Design 2
Width 50 mm 50 mm 50 mm
Height 70 mm 50 mm 50 mm
Groove-
Depth 7,0 mm 4,8 mm 5,05 mm
Groove-
Distance 16,5 mm 15,6 mm 15,15 mm
Wall –
Thickness 0,9 mm 0,7 mm 0,7 mm
Acceleration 170 g 132,5 g 132,3 g
Bending angle 22° 15,8° 15,9°
Shear displacement 1.8 mm 1,54 mm 1,58 mm
Acceleration
09-11-2011
© 2011 Ingenieurbüro Huß und Feickert GbR mbH
- 23%
Bending angle
09-11-2011
© 2011 Ingenieurbüro Huß und Feickert GbR mbH
- 28%
Internal Energy
+ 65%
09-11-2011
© 2011 Ingenieurbüro Huß und Feickert GbR mbH
Design comparison – plastic strain
Absorber before
optimization
Design 2
Design 1
09-11-2011
© 2011 Ingenieurbüro Huß und Feickert GbR mbH
Design comparison – plastic strain
Absorber before
optimization
Design 2
Design 1
09-11-2011
© 2011 Ingenieurbüro Huß und Feickert GbR mbH
specific weight
150,0
200,0
250,0
300,0
350,0
before optimizationDesign 1
Design 2
334
164 170
sp
ec
ific
we
igh
t [g
r./m
]
09-11-2011
© 2011 Ingenieurbüro Huß und Feickert GbR mbH
Summary
• Optimization results
- reducing of the biomechanical limit values
- higher rate of the plastic strain
- smaller dimensions
- less weight
09-11-2011
© 2011 Ingenieurbüro Huß und Feickert GbR mbH
09-11-2011
© 2011 Ingenieurbüro Huß und Feickert GbR mbH ingenieurbüro huß & feickert
Thank you for your attention!
09-11-2011
© 2011 Ingenieurbüro Huß und Feickert GbR mbH