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 > , 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 > , 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 > , 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 CO 2 -emissions Increasing efficiency Alternative energy and storage Motivation Global trends

Stuttgarter Symposium > P. Steinle und M. Kriescher > , Folie 5 Shape Materials Concept Requirements Law Customer and Market CO 2 - Strategy Package Integration Modularisation Technologies Shape 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 > , Folie 6 Law StVZO EG/EWG ECE Global (e.g. FMVSS, IIHS) Customer and Market Improved modularization Scalable vehicle and propulsion system CO 2 -Restrictions Alternative Propulsion Systems (e.g. BEV, FC) e-e- H2H2 CH 4 Rib and Space-Frame Requirements – general

Stuttgarter Symposium > P. Steinle und M. Kriescher > , Folie 7 General Requirements LightweightSafetyAlternative Propulsion Systems CostComfortCustomer Acceptance Rib and Space-Frame Requirements – specific

Stuttgarter Symposium > P. Steinle und M. Kriescher > , Folie 8 Vehicle Concepts Two Different approaches Rib-and Space-Frame Higher specific energy absorption Top-Down-MethodBottom-up-Method Detail 1 Detail 2 Detail 3 Detail 1 Detail 2 Detail 3 Lightweight and safe body structure

Stuttgarter Symposium > P. Steinle und M. Kriescher > , 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-Frame Concept

Stuttgarter Symposium > P. Steinle und M. Kriescher > , 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 F Crash B-Pillar Side member Safety-Containment for alternative propulsion systems Roof CrossbarJoint Part Requirements: Stiffness, Energy absorption, structural integrity Rib and Space-Frame Mechanical principle of the rib

Stuttgarter Symposium > P. Steinle und M. Kriescher > , 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 Support Crash-cones Rib and Space-Frame Design of the rib

Stuttgarter Symposium > P. Steinle und M. Kriescher > , Folie 12 Crash test Simulation side impact Simulation and Validation of the B-Rip-Design New design: ca. 29 kg Reference structure: ca. 45 kg Rib and Space-Frame Simulation und Crash

Stuttgarter Symposium > P. Steinle und M. Kriescher > , 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-Frame Mechanical principle of the Crash Compartment

Stuttgarter Symposium > P. Steinle und M. Kriescher > , 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 > , 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-Frame Global Vehicle Behavior of the Crash compartment x y

Stuttgarter Symposium > P. Steinle und M. Kriescher > , 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-Frame Results of the Crash compartment Discrete structureContinuous structure Lower intrusions with the same weight

Stuttgarter Symposium > P. Steinle und M. Kriescher > , Folie 17 Real life crash represents the worst case Improved load carrying capacity Reduced accelerations (compared to the discrete structure) Rib and Space-Frame Results 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 > , 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 > , 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 > , 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 > , Folie 21 Testing performed in cooperation with DOW hollow beamfoam filled beam DC 04 - beam filled with foam by the DOW chemical company

Stuttgarter Symposium > P. Steinle und M. Kriescher > , Folie 22 Geometric variations 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 > , 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 > , 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/h intrusion is slightly more severe compared to a regular pole crash

Stuttgarter Symposium > P. Steinle und M. Kriescher > , 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 > , Folie 26 Deformation behaviour

Stuttgarter Symposium > P. Steinle und M. Kriescher > , 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

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