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Finite Element Simulation Study of a Frontal Driver Airbag Deployment for Out-Of-Position Situations
Technical Paper
2003-22-0011
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English
Abstract
As more and more active restraint devices are added by vehicle
manufacturers for occupant protection, the history of driver
frontal airbags illustrates that the design performance of such
devices for in-position (IP) occupants often have to be limited in
order to reduce their aggressiveness for out-of-position (OOP)
situations.
As of today, a limited number of publications dealing with FE
simulation of airbag deployment for OOP are available. The
objective of our study was to evaluate the feasibility of airbag
deployment simulations based on an extensive set of well-defined
physical test matrix.
A driver frontal airbag was chosen (European mid-size car
sample) for this study. It was deployed against a force plate (14
tests in a total of 6 configurations), and used with Hybrid III
50th percentile dummy (HIII) in OOP tests (6 tests, 4
configurations).
Special attention was paid to control the boundary conditions
used in experiments in order to improve the modelling process.
The initial positioning of the dummy (chin against the top of
the steering wheel rim, and back of the torso parallel to the plane
of the rim) for both physical and numerical dummies was maintained
from 23 targets digitized using a 3D Faro arm. Specific test
position/conditions that were deemed important were repeated to
understand the sensitivity and variation.
The software used for the FEM simulations was Radioss, using
uniform pressure method.
The bag was meshed and folded using Excel and Matlab routines.
The inflator characteristics were adapted from data provided by the
inflator manufacturer. The body-block test conducted at 7 mm was
used to tune the different model parameters and the remaining
body-block, 50th%le HIII OOP and plate tests were used for
validation.
The results show comparison of simulation and tests records.
The simulations show a satisfactory matching of the test results
within the first 60 ms and capture the key events of the bag
deployment in a promising manner.
The major study limitation remains the confirmation/validation
aspect of the study as opposed to prediction. Indeed, the model was
developed based on the physical tests. The airbag deployment
pattern too was found to be very sensitive to physical and
numerical input parameters in the test and models respectively. It
is not yet possible to transfer the methodology in order to design
an airbag a priori. However, such a model is very useful for the
understanding of the loading patterns, injury mechanisms and
sensitivity studies.