innovative vehicle concept for the integration of alternative power trains p. steinle, m. kriescher...
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Innovative Vehicle Concept for the Integration of Alternative Power Trains
P. Steinle, M. Kriescher und Prof. H. E. Friedrich,
17. März 2010 »Stuttgarter Symposium«
Stuttgarter Symposium > P. Steinle und M. Kriescher > 17.03.2010, Folie 2
Sites and employees of the DLR
More than 6000 employees working
in 27 research institutes and facilities
Research Programs:Aeronautics Space Transport Energy
Köln-Porz
Lampoldshausen
Stuttgart
Oberpfaffenhofen
Braunschweig
Göttingen
Berlin-- Adlershof
Bonn
Trauen
Hamburg
Neustrelitz
Weilheim
Berlin-Charlottenburg
Sankt Augustin
Darmstadt
Bremen
Institute of Transportation Systems
Institute of Transport Research
Institute of Vehicle Concepts
Stuttgarter Symposium > P. Steinle und M. Kriescher > 17.03.2010, Folie 3
Motivation
Lightweight design strategies
General Requirements
Two different approaches
Rib and Space-Frame
Hybrid structures
Summary and Conclusion
Table of contents
Stuttgarter Symposium > P. Steinle und M. Kriescher > 17.03.2010, Folie 4
Resources of water and oil run short
Climate change can not be ignored
Increasing population asks for mobility
Reduction of vehicle’s weight for reduced driving resistance
Less fuel consumption and CO2-emissions
Increasing efficiency
Alternative energy and storage
MotivationGlobal trends
Stuttgarter Symposium > P. Steinle und M. Kriescher > 17.03.2010, Folie 5
Shape
Materials ConceptConcept
Requirements
Law
Customer and Market
CO2-Strategy
Package
Integration
Modularisation
TechnologiesShape
Geometry
Materials
Surfaces
Processes
Step 1
Step 2.1
Step 2.3
Step 2.2
Source: Haldenwanger, Beeh, Friedrich
Lightweight design strategies
Stuttgarter Symposium > P. Steinle und M. Kriescher > 17.03.2010, Folie 6
LawStVZO
EG/EWG
ECE
Global (e.g. FMVSS, IIHS)
Customer and MarketImproved modularization
Scalable vehicle and propulsion system
CO2-Restrictions
Alternative Propulsion Systems (e.g. BEV, FC)
e-
H2CH4
Rib and Space-FrameRequirements – general
Stuttgarter Symposium > P. Steinle und M. Kriescher > 17.03.2010, Folie 7
General Requirements
Lightweight Safety
Alternative Propulsion Systems
Cost
Comfort
Customer Acceptance
Rib and Space-FrameRequirements – specific
Stuttgarter Symposium > P. Steinle und M. Kriescher > 17.03.2010, Folie 8
Vehicle ConceptsTwo Different approachesRib-and Space-Frame Higher specific energy absorption
Top-Down-Method Bottom-up-Method
Detail 1 Detail 2 Detail 3
Detail 1Detail 2
Detail 3
Lightweight and safe body structure
Stuttgarter Symposium > P. Steinle und M. Kriescher > 17.03.2010, Folie 9
Alternative propulsion system (e.g. Battery) integrated into the vehicle’s floor
Continuous side members
Continuous rib structure
Crash-Elements between side members and rocker
Fiber Reinforced Plastics
Magnesium
Aluminium
Steel
Rib and Space-FrameConcept
Stuttgarter Symposium > P. Steinle und M. Kriescher > 17.03.2010, Folie 10
Basic idea: rigid B-pillar with flexural joint in the roof pillar and high performance energy absorption below the driver’s seat Minimum deformation in the rib-structure with maximum energy absorption in the crash elements
FCrash
B-Pillar
Side member
Safety-Containment for alternative propulsion systems
Roof Crossbar Joint
Part Requirements: Stiffness, Energy absorption, structural integrity
Rib and Space-Frame Mechanical principle of the rib
Stuttgarter Symposium > P. Steinle und M. Kriescher > 17.03.2010, Folie 11
Topology Optimization with static substitute loads
Benchmark of different materials
Interpretation and realization of the simulation results
Conversion of the generic design to the real design requirements
Omega profile
Inner Skin
Outer Skin
Reinforcement
SupportCrash-cones
Mass per unit of stiffnessShaft in torsion Fixed: length, section shape Free: section area
200 500 1000 2000
Mas
s pe
r un
it of
stiff
ness
Bea
m in b
endin
g
Fix
ed:
length
, w
idth
F
ree:
thic
knes
s
200
500
1000
2000
Rib and Space-FrameDesign of the rib
Stuttgarter Symposium > P. Steinle und M. Kriescher > 17.03.2010, Folie 12
Crash testSimulation side impact
Simulation and Validation of the B-Rip-Design
New design: ca. 29 kg
Reference structure: ca. 45 kg
Rib and Space-FrameSimulation und Crash
Stuttgarter Symposium > P. Steinle und M. Kriescher > 17.03.2010, Folie 13
Rigid structure in the middle of the vehicle
Energy absorption between rocker and side member
Floor Concept: Stiffness, Energy absorption, structural integrity
Rib and Space-FrameMechanical principle of the Crash Compartment
Stuttgarter Symposium > P. Steinle und M. Kriescher > 17.03.2010, Folie 14
Equivalent masses
Crash compartment
Simplified Model Energy Absorber
+
Performed Tests
Side Pole Impact according to:
EuroNCAP
FMVSS 214
Variation along x-axis (real life safety)x-axis
Rib and Space-Frame Boundary Conditions of the Crash compartment
Stuttgarter Symposium > P. Steinle und M. Kriescher > 17.03.2010, Folie 15
Superposition of two different velocities between side member and rocker
Velocity 1: Translation along y-direction
Velocity 2: Translation along x-direction
Rib and Space-FrameGlobal Vehicle Behavior of the Crash compartment
x
y
Stuttgarter Symposium > P. Steinle und M. Kriescher > 17.03.2010, Folie 16
Discrete Energy absorber
Collapse according to shear forces
Continuous energy absorber
Better acceptance of shear forces
Large-scale support of the rocker
Robust against different impact scenarios
Rib and Space-FrameResults of the Crash compartment
Discrete structure Continuous structure
Lower intrusions with the same weight
Stuttgarter Symposium > P. Steinle und M. Kriescher > 17.03.2010, Folie 17
Real life crash represents the worst case
Improved load carrying capacity
Reduced accelerations (compared to the discrete structure)
Rib and Space-FrameResults and further proceedings of the Crash compartment
Further Proceeding
Different types of energy absorbers (Geometry, Material)
Integration of the floor into the energy absorption
Stuttgarter Symposium > P. Steinle und M. Kriescher > 17.03.2010, Folie 18
Table of contents
Motivation
Lightweight design strategies
General Requirements
Two different approaches
Rib and Space-Frame
Hybrid structures
Summary and Conclusion
Stuttgarter Symposium > P. Steinle und M. Kriescher > 17.03.2010, Folie 19
Motivation
collapse of the rocker‘s and side piece‘s cross-section during pole-crash -> energy must be absorbed by various other components
a stabilisation of the cross-section during bending should lead to a much higher weight specific energy-absorption of the rocker -> higher freedom of design and choice of materials for the surrounding structures, like the floor panels -> possibility of an overall weight reduction
the storage of critical components like Li-Ion batteries in the underbody requires a low intrusion
demand for a simple, lightweight concept made of relatively cheap materials, adaptable to different kinds of vehicle concepts
floor structure developed by DLR during SLC-project
Stuttgarter Symposium > P. Steinle und M. Kriescher > 17.03.2010, Folie 20
Basic principle
Absorption of crash energy through elongation of material
Stabilisation of cross section
stabilisation of the beam by a core structure
the core must stay intact, throughout the entire bending process, in order to increase weight specific energy absorption
simplified LS-Dyna-calculations showed an increase in weight specific energy absorption by a factor of about 2,5
Stuttgarter Symposium > P. Steinle und M. Kriescher > 17.03.2010, Folie 21
Testing performed in cooperation with DOWForce-displacement curve
0
5
10
15
20
25
30
35
0 50 100 150 200 250 300 350 400 450 500
Displacement [mm]
Fo
rce
[k
N]
Steel section (hollow)
Steel section (foam-filled)
hollow beam foam filled beam
DC 04 - beam filled with foam bythe DOW chemical company
weight specific energy absorption [J/kg]
0,00
100,00
200,00
300,00
400,00
500,00
600,00
steel section (hollow) steel section (foam- filled)
Stuttgarter Symposium > P. Steinle und M. Kriescher > 17.03.2010, Folie 22
Geometric variations
Force-displacement curve
0
5
10
15
20
25
30
35
40
45
0 50 100 150 200 250 300 350 400 450 500
Displacement [mm]
Forc
e [k
N]
Steel section (hollow)
Steel section (foam-filled)
Steel section (sideways, foam-filled)
deformation mode stays the same for different cross sections
test with a crosssection rotated by 90 ° leads to higher peak force but earlier failure of the material -> steel with a higher max. strain would lead to even better results
Stuttgarter Symposium > P. Steinle und M. Kriescher > 17.03.2010, Folie 23
Integration into the underbody structure, basic principle
conventional rectangular topology:
difficulty in designing an appropriate support structure
a ring-like shaped, filled structure should lead to comparatively low strain values, distributed over a large portion of the structure
Stuttgarter Symposium > P. Steinle und M. Kriescher > 17.03.2010, Folie 24
LS-Dyna-Simulation results with a simplified body structure
modified pole crash:
the modified pole crash was performed to avoid the addition of virtual weights
car body is fixed
weight of pole= 1380 kg
speed of pole = 29 km/hintrusion is slightly more severe compared to a regular pole crash
Stuttgarter Symposium > P. Steinle und M. Kriescher > 17.03.2010, Folie 25
Modified pole crash results with a simplified body structure
results of the new structure:
reduction of intrusion by a factor of 2,7, compared to a full vehicle with interior, even without floor panel, seat structure etc.
proof of the basic principle: the underbody structure is deformed as one „ring“, without any collapse of particular parts
Stuttgarter Symposium > P. Steinle und M. Kriescher > 17.03.2010, Folie 26
Deformation behaviour
Stuttgarter Symposium > P. Steinle und M. Kriescher > 17.03.2010, Folie 27
Summary and conclusions
Two different approaches for lightweight and safe vehicle structures for small/medium and large scale production
DLR Rib and Space-Frame with high intrusion resistance of the B-Rip and Crash compartment
An underbody structure composed of a ring-like filled structure results in a very high intrusion resistance during pole crash. A large portion of the underbody could therefore be used for the storage of critical components like Li-Ion batteries
A more detailed car body structure is needed to make accurate weight predictions
Optimization of the structure by decreasing intrusion resistance in favor of reduced weight seems reasonable
For further questions and to see a model of the car body please visit our exhibition stand
Thank you for your attention
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