The progress of computer technology and CAE methodology makes it possible to simulate dummy injury readings in vehicle crash simulations. Dummy neck injuries are generally more difficult to simulate than injuries to other regions such as the head or chest. Accordingly, improving the accuracy of dummy neck injury data is a major concern in frontal occupant safety simulations. This paper describes the use of an advanced airbag modeling methodology to improve the accuracy of dummy neck injury readings.
First, the following items incorporated in the advanced airbag model are explained. (1) The Finite Point Method (FPM) is used to simulate the flow of gas. (2) A folding model is applied to simulate the folded condition. (3) The fabric material properties used in the simulation take into account anisotropy in the fiber directions and the nonlinear, hysteresis characteristics of stiffness. These items make it possible to simulate airbag deployment behavior and reaction force characteristics accurately in impact tests of airbag components.
Full-fledged sled simulations with dummies on board were executed with this advanced airbag model, and the results confirmed the high accuracy of the dummy neck injury data. Useful information for analysis, which cannot be measured in experiments, can be acquired in simulations. This paper also explains the law of causality regarding dummy neck injury data, which was made clear by analyzing the phenomena that occurred in the sled simulations. It is shown that the rebound of the dummy's pelvis is strongly related to the neck bending moment. The results of a case study are presented to verify this causality.