A New Approach for Folding Process Modeling of Passage Airbag

Abstract

A new Passage Airbag (PAB) folding method which integrates simulation folding and manual folding is presented. Determining how to get a multi-layer 2D surface is vital to PAB folding. By means of 3D PAB flattening process simulation, 2D surface with a minimum area loss is created. This method avoids the traditional measurement of real PAB to obtain 2D airbag with inaccurate shape and size. After flattening PAB simulation, the 2D surfaces are meshed with respect to the predefined folding lines. The subsequent folding steps of flat 2D airbag are carried out according to the folding requirements. Finally, the reference geometry meshing and folded airbag are obtained accurately and rapidly. The static PAB deployment test is modeled using particle method for gas flow to validate this folding method. Good correlation between simulation and test results during early deployment phase of airbag is achieved. It has proven the effectiveness and feasibility of this PAB folding method.

Full text

A New Approach for Folding Process Modeling of Passage Airbag
Guoqing Liu
a
, Guohong Xie
b
, Zhenshan Cui
c
NERC for Die & Mold CAD, School of Materials Science and Engineering, Shanghai Jiao Tong
University, Shanghai, 200030, China
aliu_gq@sjtu.edu.cn, bxieguohong@sjtu.edu.cn, ccuizs@sjtu.edu.cn
Keywords: Passage airbag, airbag folding, airbag simulation
Abstract. A new Passage Airbag (PAB) folding method which integrates simulation folding and
manual folding is presented. Determining how to get a multi-layer 2D surface is vital to PAB folding.
By means of 3D PAB flattening process simulation, 2D surface with a minimum area loss is created.
This method avoids the traditional measurement of real PAB to obtain 2D airbag with inaccurate
shape and size. After flattening PAB simulation, the 2D surfaces are meshed with respect to the
predefined folding lines. The subsequent folding steps of flat 2D airbag are carried out according to
the folding requirements. Finally, the reference geometry meshing and folded airbag are obtained
accurately and rapidly. The static PAB deployment test is modeled using particle method for gas flow
to validate this folding method. Good correlation between simulation and test results during early
deployment phase of airbag is achieved. It has proven the effectiveness and feasibility of this PAB
folding method.
Introduction
With the increase in use of different type airbag in vehicle, and simulation becoming time and cost
effective, airbag simulation has been playing vital role in occupant safety. In initial airbag deployment
stage, especially when occupant is sitting closer to the airbag, the folded cushion propelled by the high
momentum jet of gas from the inflator can cause head, thorax and neck injury. This situation where
the occupant deviates from the nominal position is commonly referred to Out Of Position situation or
OOP. For this type of situation, folding airbag is important to evaluate the interaction between
occupant and the deploying airbag.
Currently, there are mainly three types of methods for creating airbag folding:
a) Meshing 2D surfaces and folding the mesh using commercial software. 2D surfaces are meshed
with definite folding lines. The mesh is then folded by geometric transformations about the folding
lines. With this method all types of folds are done like thin fold, thick (smooth) fold, roll fold, tuck
fold and double tuck fold. During this process, small changes in element length take place due to the
geometric transformations.
b) Simply shrunken (scaled) the meshing into housing. Reference mesh is scaled down per
different scale coefficient in different direction to fit it into housing.
c) Folding the cushion using simulation method. The cushion is meshed firstly and then the mesh is
fixed between appropriate rigid planes. Finally, folding process is simulated by giving appropriate
initial velocities to the rigid plane per folding requirement step.
In order to capture the initial stages of inflation of the airbag in OOP simulations, method a) and
method c) can be used to model the airbag deployment. But it is time consuming and maybe introduce
node penetrations and element interactions during folding simulation using method c). So method a)
to model folded airbag mesh is preferred.
But for complex 3D airbag folding, for example PAB folding, the creation of folded meshes of 3D
airbags is very difficult and time consuming. The main problem is the transformation of the 3D shape
to a 2D configuration, the so-called flattening of the 3D shape.
A traditional method for modeling 3D airbag, shown as Fig. 1, was developed by Eriksson and
Faltstom(1998). In this method, a flat foldable mesh was created based on measurements on the
Applied Mechanics and Materials Submitted: 2014-07-14
ISSN: 1662-7482, Vols. 635-637, pp 564-567 Accepted: 2014-07-25
doi:10.4028/www.scientific.net/AMM.635-637.564 Online: 2014-09-19
© 2014 Trans Tech Publications Ltd, All Rights Reserved
All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of Trans
Tech Publications Ltd, www.scientific.net. (Research Gate for subscription journals-27/02/25,03:59:09)