Combat Helmet-Headform Coupling Characterized From Blunt Impact Events

Observed head injury has historically been mechanically related to headform center of gravity (CG) acceleration. Helmets (motorcycle, sports, military, etc.) are evaluated based on the headform CG peak acceleration for blunt impacts. However, recent interest has shifted to collecting data from the helmet shell itself, as it is an optimal location for mounting sensors due to ease of access, sufficient surface area availability, and limited interference to the wearer. In order to accurately predict head injury from data collected on the helmet shell, the helmet and headform must be rigidly coupled. Headform-helmet fit typically is dependent on the pad fitting system and the person mounting the helmet to the headform because a standard states which headform to use. The objective of this study is to compare the Department of Transportation (DOT) headform (currently used in military blunt impact testing) to the more anthropomorphic International Standard Organization (ISO) half headform. Testing was completed on a monorail drop tower to analyze the effect of helmet/headform coupling on the blunt impact behavior of ACH helmets using FMVSS test methodology. Three headform configurations were used: the DOT headform (standard for military helmet blunt impact testing) with required surrogate chin, the ISO half headform (standard for ASTM helmet testing), and the ISO half headform with a surrogate chin. The two currently field-approved pad types were also used to determine best headform-helmet fit. Results from these series of tests will be presented, including headform peak acceleration and relative motion between the helmet and headform.