Computer simulation is a powerful tool for developing effective airbags for the modern automotive industry. At the present time, almost all airbag calculations are based on the control volume (CV) technique. In the simplest case, for every time step the pressure on the internal surface of the airbag is determined from a given thermodynamic model. Then, pressure is applied as a load to find the airbag shape for the next time step. This approach is quick and gives rather good results for predicting the interaction of the airbag surface with surrounding objects at the later stages of the airbag deployment. However, the pressure constant assumption is not correct in the beginning phase of the airbag motion. To consider this phase more precisely, a more accurate method to describe the interaction between airbag surface, inflow gas and ambient air is needed. One of this formulations based on the Arbitrary Eulerian - Lagrangian (ALE) method is realised in LS-DYNA. The main idea of the ALE airbag application is to model in a precise way the gas generator so that the time consuming process of airbag validation (i.e. calibration of the finite element airbag model against standard test results) can be avoided. However, to produce a precise gas generator model comprehensive information on its geometry, gas properties etc is needed. This is not always available or is rather difficult to model with the use of a present finite element tools of LS-DYNA. In the present paper a basic finite element model of an ALE thorax side airbag with a simplified gas generator will be considered. In particular, it will be discussed how to define boundary conditions and properties of the inflating gas. A possible general approach to ALE airbag validation to fit results of a standard body block test will be described. Finally numerical results for a push-away test for an ALE and corresponding CV airbag will be compared.
On airbag simulation in LS-DYNA with the use of the arbitrary Lagrangian - Eulerian method
Airbagsimulation in LS-DYNA unter Einsatz der willkürlichen Lagrange-Euler-Methode
2003
11 Seiten, 9 Bilder, 4 Quellen
Aufsatz (Konferenz)
Englisch
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