Method for Developing a Side Impact Upper Neck Injury Criteria Which Compensates for Biomechanical Differences Between ATDs and Humans

OCCUPATIONAL APPLICATIONS

We developed a method to convert between the upper-neck lateral impact accelerative responses obtained from a human and an anthropometric test device (ATD). This conversion allows developers to employ cost-effective methods for applying human-derived neck injury criteria to testing in accelerative environments utilizing ATDs while accurately compensating for biofidelic shortcomings of existing ATDs. This compensation allows accurate risk determinations to be made early in the development cycle for crash systems, including fighter aircraft helmets and ejection seats.

TECHNICAL ABSTRACT

Background: The potential for neck injury in high accelerative environments must be understood to ensure occupant safety during crashes or ejections, such as when operating aircraft or other high-performance vehicles. A human-derived, injury risk criteria has been proposed earlier, which considers five forces or moments to calculate the risk of upper-neck injury in the context of human lateral impacts (Gy). Purpose: Develop a method to transform human Gy upper-neck injury responses to an ATD-equivalent response. The equivalent response is used to identify human-equivalent risk during testing involving ATDs. Methods: Multiple regression was used to evaluate ATD and human upper-neck injury criterion based on a multi-axial neck injury criteria (MANIC(Gy)). The difference in modeled responses at instantaneous peak acceleration defined the transfer function for converting human responses to ATD-equivalent responses. Survival analysis was employed to evaluate human and ATD neck injury risks. Results: Use of the six factor (SF) MANIC(Gy) was found necessary when evaluating Hybrid III ATD neck responses. Human MANIC(Gy) was influenced by Peak G and helmet wear. ATD SF-MANIC(Gy) was influenced by these same factors, as well as peak G³ and a significant intercept. The ATD-equivalent AIS2+ risk curve is steeper and is shifted to the left of the MANIC scale when compared to the human risk curve counterpart. Conclusions: This research bridges the gap between human response functions and the more practical use of ATDs for system evaluation. The method presented here can be applied to generate similar transforms for frontal and vertical force profiles as well as alternate ATD necks.

KEYWORDS:

• Ejection
• neck injury criteria
• risk function
• side impact

DISCLOSURE STATEMENT

The contents of this paper are solely the responsibility of the authors and do not necessarily represent the official views of the United States Air Force.

SUPPLEMENTAL MATERIAL

Supplemental data [material/appendices] for this article can be accessed on the publisher’s website at https://doi.org/10.1080/24725838.2018.1482242.