PRIVATE/PROPRIETARY Airbag Systems and Occupant Protection Recent Trends in Simulation Kurt Fograscher - Autoliv B.V. & Co. KG LS-DYNA FORUM 2006 Ulm 12.10.2006 AUTOLIV-ASG/KF/ed/061012 - 2 PRIVATE/PROPRIETARY Outline • Passive Safety Market Trends • CAE Process Chains and Process Integration • CAE Methods • Some examples • Trends and outlook
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Airbag Systems and Occupant Protection - DYNAmore GmbH
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PRIVATE/PROPRIETARY
Airbag Systems and Occupant Protection
Recent Trendsin Simulation
Kurt Fograscher - Autoliv B.V. & Co. KGLS-DYNA FORUM 2006
Ulm12.10.2006
AUTOLIV-ASG/KF/ed/061012 - 2 PRIVATE/PROPRIETARY
Outline
• Passive Safety Market Trends • CAE Process Chains and
Process Integration• CAE Methods• Some examples• Trends and outlook
CAE Crash Data Analysis• Velocities• Distances vs. time• Timing
Airbag Chamber Design• Head protection area• Volume and pressure distribution• Loads on fabric and seam
Validation• Acceleration• Bag pressure• Remaining depth
Occupant ProtectionIn-Position
Occupant ProtectionOoP-Position
OEM
Restraint Supplier
OEM
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CAE Process Chains
V‘HI
t‘TTF
SimulationCrash
SimulationHI Test
HorizontalImpact Test
VHI
tTTF
a(t)
p i( t)d(t)
ValidatedAirbag Model
CAE Crash Data Analysis• Velocities• Distances vs. time• Timing
Airbag Chamber Design• Head protection area• Volume and pressure distribution• Loads on fabric and seam
Validation• Acceleration• Bag pressure• Remaining depth
Occupant ProtectionIn-Position
Occupant ProtectionOoP-Position
CAE
Test
Test
Design CAE
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USAAuburn HillsSouthfieldOgden
Great BritainHavant
FranceGournayPont-de-BuisCergy -Pontoise
SwedenVårgårda
Motala/Linköping
GermanyElmshorn
Dachau
JapanTsukuba
AustraliaMelbourne
SpainBarcelona
South KoreaMando
IndiaBanglalore
• Global organisations require global processes
• New CAE processes must be capable for worldwide application• CAE processes must integrate ‘parts & pieces’ from different locations• OEM global standards and diversity must be considered• Cultural aspects, local history and acceptance must be considered
Autoliv -Master-Model (AMM)Master Modell for frontal simulation („Best practice“)
•modular•parametric
•suitable for all In -Position load cases
Methods•Design of Experiments ( DoE)
•Optimization
•Stochastic Methods•Parameter Study
SimulationTest
Shoulder belt force
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Occupant Simulation Frontal Impact
Trends• More details for geometry and deformable structures• More FE content, gap MBS to FE becomes smaller• Angular impacts require combination of front and side impact
methods
Source: Audi AG, M. van den Hoove, Dr. B. Mlekusch, 2005
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Occupant Simulation Side Impact
Occupant ProtectionOoP-Position
Occupant ProtectionIn-Position
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Occupant Simulation Out-of-Position
Tools for Airbag Modeling• joefold: Software for
geometry basedairbag folding
• S-Mesh: Automatic Mesher• joeform: Positioning of the
folded mesh in the package
Important parameters• Vehicle package IP,
windscreen• Module position• Door design• Airbag folding• Inflator characteristics
Load CasesDriver side 5%-Dummy
Passenger side 3yr/6yr child
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Gas Flow Dynamics
Simulation with gas flow Test Simulation without gas flow
Validation is the relevant factor for processlead times and simulation efficiency
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Outline
• Passive Safety Market Trends • CAE Process Chains and
Process Integration• CAE Methods• Some examples• Trends and outlook
AUTOLIV-ASG/KF/ed/061012 - 30 PRIVATE/PROPRIETARY
Simulation Driver Airbag Cover Opening
FE Model
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Simulation Driver Airbag Cover Opening
Basic Design
Improved Design
PRIVATE/PROPRIETARY
Passenger Airbag Integrity Problem
Integrity problem on PAB solved by use of CAE toolsà CAE model could reproduce non-failure / failureà Identification of significant effects for proper functionà Definition of necessary changes in folding processà Physical part verification ok.!
•Prototype Folding
•S
Lower Limità Ok.
Design Stateà Ok.
Upper Limità Problem !
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Pelvis Pusher Airbag
High pressurized airbag in pelvis area
Rib deflection reduced by >20% for IIHS Load Case
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Active Structures
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Outline
• Passive Safety Market Trends • CAE Process Chains and
Process Integration• CAE Methods• Some examples• Trends and outlook
AUTOLIV-ASG/KF/ed/061012 - 36 PRIVATE/PROPRIETARY
Container Influence
Fabric Leakage
Fabric Material Model
Dummy Model Improvement
Autoliv-Master-Models
Vent Modeling
Benefit•less impactor tests for component validation•save validation work•increase quality of simulation predictions•improved mutual model exchange--> reduced system testing--> reduced total development cost--> reduced total time for development
New Methods: Increase Model PredictivityReduce Validation
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Trends and Outlook
Increasing importance of Multi-Physics• CFD / ALE / Particle methods• Material thermo-loading• Material aging
Switch Explicit – Implicit• Use same model
Critical factor: Material data• Dynamic, temperature band• Availability on time
From project engineers strong request for prediction of material failure
• Difficult to handle
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Trends and Outlook
Key success factors
• Process integration of tools and methods• Efficient processes• Process and data management• Stability of new methods• Methods ease of use
(cross-user, cross-site, cross-cultural)• Suitability of tools for standardisation
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Trends and Outlook
• New safety regulations (legal and consumer) drive system complexity
• Optimisation of adaptive systems requires huge number of (quick) simulations
• Accurate / detailed methods required to explore close optimisation margin
• DoE and stochastics• Human body models beyond dummy