Airbag Folding Using RADIOSS Pre-simulation
Dr. Dmitri Fokin, Altair
Numerical folding of airbags is a critical step in development
of safety models for automotive crash applications. The folding
quality determines the quality of safety simulation itself,
especially in early airbag deployment stages ("out of
position" occupant simulation, opening of housing cover
etc). A common approach for the folding is based on geometrical
transformations (translation, rotation, scaling) of unfolded
airbag geometry or mesh according to certain folding plan.
The present paper proposes an approach based on direct finite-element
simulation of airbag folding using Radioss 9.0 explicit solver.
The simulation reproduces principal kinematics and dynamics
of real folding process. Unfolded airbag model and associated
folding plan which describes the fold sequence are used as
initial point of the approach. Based on these data, an automatic
script generates and starts Radioss model that simulates the
complete folding process. After simulation, the folded mesh
is exported and used for further airbag deployment calculations.
The folding method is mesh independent and does not require
supplementary fold lines. The final size of the folded airbag
is known before the simulation starts. Application of Radioss "edge
to edge" contacts deliver an intersection-free folded
mesh. In contrast to "geometrical" folding methods,
where the airbag deformations are mainly determined by pure
geometrical consideration, a reliable strain-stress picture
in folded airbag fabrics is provided due to direct finite
element simulation The folded airbag geometry after proper
conversion can be used with any explicit solver. At the present
time the approach is used at Altair internally in current
project work.
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