generic vehicle models iwg-dpps - unece wiki
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S C I E N C E P A S S I O N T E C H N O L O G Y
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Generic Vehicle ModelsIWG-DPPS
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•Generic vehicle models have been developed by TU Graz within the CoHerent project for the certification of pedestrian models (according to TB024)
•Models are currently maintained by TU Graz and the code houses (dynamore, Altair, esi, Dassault)
• The model owners are TU Graz, ACEA and Euro NCAP
• For a formal agreement, boundary conditions of usage / reference should be further clarified.
•No objection from Euro NCAP and TU Graz for model usage now, but important issue of model maintenance has to be solved
Background
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•Option A: Refer in Mutual Resolution to specific models.
–Where should models be stored? By whom should they be distributed?
–How can we refer to a specific FE model in the mutual resolution? (in terms of formulation and specification)
–Should models be encrypted?
–Who makes sure that models are running in future code versions?
–How should they be revised (update to current fleet every 5 years)?
+ Everyone uses for sure the same models (however: how to proof?)
+ In line with Euro NCAP
- Administrative challenges have to be solved
How to include GV models in regulations?
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• Option B: Detailed specification (description) of the generic vehicle models in the (appendix of) a mutual resolution
– Include mesh as node coordinates into the appendix
– Include description of modelling approach
– Include corridors for the structural behaviour of the model (based on the current Euro NCAP GV models and as tight as possible)
– Applied GV models should be submitted together with certification results
+ Easier from organisational point of view, because theoretically everyone can rebuild the models, but as models are defined in detail, they would still behave very(!) similar (it all depends on a proper specification)
– Not everyone has to use exactly the same model this could affect certification results. (However: If GV models are certified prior to HBM certification, this can be addressed)
– Risk that models that can be used for regulation can’t be used for Euro NCAP
– Higher workload for the certification of the models (as GV models have to be checked)
How to include GV models in regulations?
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• The foam layer features:
–Piecewise-linear behaviour (elasticity, yielding, compaction-initialisation, full-compaction);
–Definable energy absorption;
–Negligible expansion upon compression (i.e. a Poisson’s ratio of 0);
–No strain rate dependency (It is assumed that interface layer’s inertial effects are more important for the impact response behaviour than material induced strain-rate effects.)
Examples for Specification
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Interface Layer Foam Layer Compaction Layer Foam Bottom LayerGeneric Vehicle Interface Layer (elastic-plastic)
Foam (bi-linear)
Bottom Layer (rigid)
Compaction Layer (rigid) Off
set
(de
fau
lt=
98
%) Interface Layer
- Material (mt)- Thickness (th)
Foam- T1, T2, T3, E1, E2- Absorption (ab)
Compaction Layer- Offset (of)
S1
S3
E1 E3=95%
T1
T2
T4=3GPa
Option 2:Piecewise definitionRho=7e-8 kg/mm³
E2
T3
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Corridors for GV responses
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GV Model response in all codes - BMP
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GV Model response in all codes - SPL
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GV Model response in all codes - BNT
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GV Model response in all codes - BLE
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Vehicle Safety Institute
Graz University of Technology
Inffeldgasse 23/1
8010 Graz Austria
www.vsi.tugraz.at
Graz University of Technology | Vehicle Safety Institute
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