stuttgarter symposium gesamt

Innovative Vehicle Concept for the Integration of Alternative Power Trains

P. Steinle, M. Kriescher und Prof. H. E. Friedrich,

17. Mrz 2010Stuttgarter Symposium

Stuttgarter Symposium > P. Steinle und M. Kriescher > 17.03.2010, Folie *

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n Kln-Porzn Lampoldshausenn Stuttgartn OberpfaffenhofenBraunschweig nn GttingenBerlin-- nAdlershofn BonnTrauen Hamburg NeustrelitzWeilheim Berlin-Charlottenburg Sankt Augustin DarmstadtBremen nInstitute of Transportation Systems Institute of Transport Research


MotivationLightweight design strategiesGeneral RequirementsTwo different approachesRib and Space-FrameHybrid structuresSummary and ConclusionTable of contents


Resources of water and oil run shortClimate change can not be ignoredIncreasing population asks for mobility

Reduction of vehicles weight for reduced driving resistanceLess fuel consumption and CO2-emissionsIncreasing efficiencyAlternative energy and storageMotivation Global trends


LawCustomer and MarketCO2-Strategy

PackageIntegrationModularisationTechnologiesShapeGeometryMaterialsSurfacesProcessesStep 1Step 2.1Step 2.3Step 2.2Source: Haldenwanger, Beeh, FriedrichLightweight design strategies


LawStVZOEG/EWGECEGlobal (e.g. FMVSS, IIHS)

Customer and MarketImproved modularizationScalable vehicle and propulsion system

CO2-RestrictionsAlternative Propulsion Systems (e.g. BEV, FC)

Rib and Space-Frame Requirements general


General RequirementsRib and Space-Frame Requirements specific


Vehicle Concepts Two Different approachesRib-and Space-FrameHigher specific energy absorptionTop-Down-MethodBottom-up-MethodLightweight and safe body structure


Alternative propulsion system (e.g. Battery) integrated into the vehicles floorContinuous side membersContinuous rib structureCrash-Elements between side members and rocker

Rib and Space-Frame Concept


Basic idea: rigid B-pillar with flexural joint in the roof pillar and high performance energy absorption below the drivers seat Minimum deformation in the rib-structure with maximum energy absorption in the crash elementsFCrashB-PillarPart Requirements: Stiffness, Energy absorption, structural integrity Rib and Space-Frame Mechanical principle of the rib


Topology Optimization with static substitute loadsBenchmark of different materialsInterpretation and realization of the simulation resultsConversion of the generic design to the real design requirementsRib and Space-Frame Design of the rib


Crash testSimulation side impactSimulation and Validation of the B-Rip-DesignRib and Space-Frame Simulation und Crash


Rigid structure in the middle of the vehicleEnergy absorption between rocker and side memberFloor Concept: Stiffness, Energy absorption, structural integrity Rib and Space-Frame Mechanical principle of the Crash Compartment


Equivalent massesCrash compartmentSimplified ModelEnergy Absorber+Performed TestsSide Pole Impact according to:EuroNCAP FMVSS 214Variation along x-axis (real life safety)Rib and Space-Frame Boundary Conditions of the Crash compartment


Superposition of two different velocities between side member and rockerVelocity 1: Translation along y-directionVelocity 2: Translation along x-directionRib and Space-Frame Global Vehicle Behavior of the Crash compartment


Discrete Energy absorberCollapse according to shear forcesContinuous energy absorberBetter acceptance of shear forcesLarge-scale support of the rockerRobust against different impact scenariosRib and Space-Frame Results of the Crash compartmentDiscrete structureContinuous structureLower intrusions with the same weight


Real life crash represents the worst caseImproved load carrying capacityReduced accelerations (compared to the discrete structure)Rib and Space-Frame Results and further proceedings of the Crash compartmentFurther ProceedingDifferent types of energy absorbers (Geometry, Material)Integration of the floor into the energy absorption


Table of contentsMotivationLightweight design strategiesGeneral RequirementsTwo different approachesRib and Space-FrameHybrid structuresSummary and Conclusion


Motivationcollapse of the rockers and side pieces cross-section during pole-crash -> energy must be absorbed by various other componentsa 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 reductionthe storage of critical components like Li-Ion batteries in the underbody requires a low intrusiondemand 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


Basic principleAbsorption of crash energy through elongation of materialStabilisation of cross sectionstabilisation of the beam by a core structurethe core must stay intact, throughout the entire bending process, in order to increase weight specific energy absorptionsimplified LS-Dyna-calculations showed an increase in weight specific energy absorption by a factor of about 2,5


Testing performed in cooperation with DOWhollow beamfoam filled beamDC 04 - beam filled with foam bythe DOW chemical company


Geometric variationsdeformation mode stays the same for different cross sectionstest 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


Integration into the underbody structure, basic principleconventional rectangular topology:difficulty in designing an appropriate support structurea ring-like shaped, filled structure should lead to comparatively low strain values, distributed over a large portion of the structure


LS-Dyna-Simulation results with a simplified body structuremodified pole crash:

the modified pole crash was performed to avoid the addition of virtual weights

car body is fixedweight of pole= 1380 kgspeed of pole = 29 km/hintrusion is slightly more severe compared to a regular pole crash


Modified pole crash results with a simplified body structureresults 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


Deformation behaviour


Summary and conclusionsTwo different approaches for lightweight and safe vehicle structures for small/medium and large scale productionDLR 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 batteriesA more detailed car body structure is needed to make accurate weight predictionsOptimization 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

*Bilder durch Schrittweise neue Elemente ergnzen**Gefhrdung aus Arbeit von W. Chevalier*Bilder nach 50 msUngefhr gleiches Gewicht der beiden Strukturen**ca. 20% werden vom rocker panel absorbiert*max strain 55 % -> nur an einzelnen Stellen -> Optimierung und evtl. Versuch notwendig rot = 20%

stuttgarter symposium gesamt

Documents

steinle und

kriescher und

ribstuttgarter symposium

spaceframe design

maximum energy absorption

generic design

real design requirementsrib

vehicle concepts