Search Results

The Hybrid III family of dummies is used to estimate the response of an occupant during a crash. One recent area of interest is the response of the neck during air bag loading. The biomechanical response of the Hybrid III dummy's neck was based on inertial loading during crash events, when the dummy is restrained by a seat belt and/or seat back. Contact loading resulting from an air bag was not considered when the Hybrid III dummy was designed. This paper considers the effect of air bag loading on the 5th percentile female Hybrid III dummies. The response of the neck is presented in comparison to currently accepted biomechanical corridors. The Hybrid III dummy neck was designed with primary emphasis on appropriate flexion and extension responses using the corridors proposed by Mertz and Patrick. They formulated the mechanical performance requirements of the neck as the relationship between the moment at the occipital condyles and the rotation of the head relative to the torso.

This paper discusses issues related to the Hybrid III dummy head/neck response due to deploying air bags. The primary issue is the occurrence of large moment at the occypital condyles of the dummy, when the head-rotation with respect to the torso is relatively small. The improbability of such an occurrence in humans is discussed in detail based on the available biomechanical data. A secondary issue is the different anthropometric characteristics of the head/neck region of the Hybrid III dummy when compared to humans. Different modes of interaction between the deploying air bag and the Hybrid III dummy’s neck are discussed. Key features of the dummy’s response in these interaction modes have been described in light of the laxity of the atlanto-occypital joint and the effect of the neck muscle pairs. Issues for improving the biofidelity of the Hybrid III dummy’s neck response due to deploying air bags are discussed.

The responses of the THOR and the Hybrid-III ATDs to head and neck loading due to a deploying air bag were investigated. Matched pair tests were conducted to compare the responses of the two ATDs under similar loading conditions. The two 50th percentile male ATDs, in the driver as well as the passenger positions, were placed close to the air bag systems, in order to enhance the interaction between the deploying air bag and the chin-neck-jaw regions of the ATDs. Although both ATDs nominally meet the same calibration corridors, they differ significantly in their kinematic and dynamic responses to interaction with a deploying air bag. The difference between the structural designs of the Hybrid-III's and the THOR's neck appears to result in significant differences in the manner in which the loads applied on the head are resisted.

While the Hybrid III anthropomorphic test device (ATD) family has experienced a lengthy period of development, and is an essential part of vehicle safety regulation, several issues associated with the ATD's head/neck design and the neck dynamic response due to airbag loading have been identified. As a result, the response of the Hybrid III neck under a number of airbag loading conditions could be an “artifact” of the ATD and not representative of the live human. One area of concern relates to the method of incorporating the human neck muscles into the neck response and how this affects the out-of-position (OOP) tests mandated in the new FMVSS 208. The results of a series of sled and OOP tests are presented in this paper to elaborate on the nature and the magnitude of the ATD's neck response “artifact”. In addition, the complication associated with balancing in-position and OOP requirements as a result of this “artifact” is highlighted.

A hybrid-inflator simulation program, H-ISP, has been developed to facilitate the evaluation of hybrid inflators for airbag systems. Based on fundamental principles of species mass and energy conservation and gas dynamics, this program can simulate the complex thermo-chemical processes of a hybrid inflator, including solid propellant combustion, single-phase or two-phase flow, multiple chemical species with temperature- and composition-dependent thermal properties, and heat transfer phenomena. In this paper, we present the theory, computer program structure and usage of H-ISP with an example.