This paper concerns the computer modelling of airbag restraint systems, particularly the aspect of contact interaction between the human body and the airbag. Two approaches can be distinguished for modelling the airbag. The earliest models use a non-deformable elliptical shape or a deformable shape based on line segments and circular arcs for representation of the airbag. Penetration volumes and contact forces are calculated in an empirical manner. A second approach uses the finite element method to simulate the bag material. The finite element bag can deform realistically and bag inertia forces are generated.
In this paper a comparison is made between simulation results obtained with the empirical airbag model in MADYMO 2D and the finite element airbag model in PISCES. Validation for both types of simulation has been carried out using impactor tests on sealed airbags. Parameters varied in these impactor tests include the impact velocity and the shape of the impactor face.
It will be shown that with regard to penetration of average and large sized objects both types of simulation provide reliable results. The predictions of the MADYMO 2D airbag model for relatively small penetrating objects are less adequate. This affects in particular passenger side airbag simulations.
Based on these findings it was decided to develop a three-dimensional airbag model in MADYMO 3D, using a finite element approach rather than an empirical approach as customary up to now in Crash Victim Simulation programs. The airbag in this model will be represented by 3-node membrane elements. A first demonstration of the MADYMO 3D airbag model will be given at the end of this paper.