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Introduction
Airbag as a safety device fitted in
automobiles is fast gaining public acceptance. Improvements in design of
automobile components, often achieved by computer modeling and simulations,
are becoming standards for automobile testing and design. Due to airbags
acceptability for four wheeled vehicles, the concept of airbag in
motorcycles is now being tested by many [references]. Currently passenger
side airbags, which have a larger volume than the driver side airbag, are
considered for airbags to be mounted on motorcycles. Modeling of folding
of passenger side airbag is a complex and time consuming process. In this
work the modeling of folding of passenger side airbag of 160 liter is considered.
This airbag mesh is to be used for exploratory simulations of crashes of
an Indian motorcycle mounted with an airbag. Commercial software tools
used for modeling of airbag folds do not give a realistic inflation
process due to large distortion of airbag mesh elements. In this work we
use simulations for getting the mesh of a folded passenger side airbag.
Unreformed mesh containing six layers of cloth is first generated in
Finite Element software IDEASTM. This mesh is then exported to
PAMCRASHTM. The fold sequence is then modeled using
simulations so as to duplicate the manual folding process. Folds are thus
generated in the airbag mesh using simulations in PAMCRASHTM.
For each simulation of folding, the mesh is held between rigid planes and
these planes are given velocities corresponding to the folding process.
This method of fold simulation is time consuming. But it gives folded
airbag mesh of complex shapes. Inflation process of folded airbag mesh is
in better agreement with unfolded airbag mesh inflation process.
Figure. 1
Figure. 1. Shows arrangement of planes guiding
the airbag mesh to get pressed against the rest of the portion of airbag
mesh supported by fixed rigid vertical plane kept on the other side of
airbag mesh. (A Chawla et al.,2005)
Figure 2 & 3 shows the inflated shape of one such airbag
folded in this manner
Figure.2 Top view of inflated folded
airbag mesh (A Chawla et al.,2005)
Figure. 3. Side view of inflated
folded airbag mesh (A Chawla et
al.,2005)
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