Analytical modeling of airbag inflation is desirable in automotive design, particularly when the technique encompasses the airbag, occupant and vehicle structure in an integrated system. This paper reviews the development of nonlinear finite element (FE) technology to simulate airbag deployment and its interaction with an articulated occupant model. The technology is being developed in the dynamic large deformation DYNA3D code which has been successfully used in vehicle crashworthiness simulations. During the project evolution, a number of technical issues have become quite clear and dictated specific developments.

A fabric material model which treats wrinkling has been developed. An algorithm to determine the airbag volume during the inflation process was added. A simplified gas model based on assuming uniform thermodynamic properties (pressure, density, temperature and internal energy) throughout the airbag deployment was coupled to the airbag structure. Early in the development, the problem of air bag unfolding was determined to be important, so a new contact algorithm was developed to properly simulate unfolding. This led into identifying a need for generating a folded mesh of an airbag, so this too was developed;​ since no meshing algorithms were available to generate tightly folded fabrics. Finally, work was done to simulate an occupant by a system of jointed ellipsoidal rigid bodies. These new capabilities have been brought together into a framework, MVMA/DYNA3D;​ that can be used in a system’s approach to mathematical simulation of occupant response in a vehicle crash environment.

This paper summarizes these developments with emphasis on validating inflation of an unfolded airbag, predicting its deployment kinematics and identifying its contact and interactions with several spherical and flat surfaces. The predicted bag deformations and contact forces compared favorably with corresponding experimental data. In addition, a preliminary attempt was made to simulate the deployment and interactions of a folded airbag with a hybrid III dummy model.