Engineering a mechanical surrogate neck-form for impact testing

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Currently, helmet test methods use linear drop assemblies that guide a K1A magnesium headform onto an impact anvil. The magnesium head is constrained to experience only linear acceleration because it is attached to the linear guide via a rigid metal neck. While it was not originally designed to do so, this impact simulation method does not recreate the mechanics of helmeted impact with a human, where the head is supported and kinematically influenced by a neck capable of displacing/rotating along six degrees of freedom (and which allows the head to rotate and experience angular kinematics). Some of the new proposed test methods for helmet certification with angular kinematics have suggested that biofidelic head-neck models should replace the magnesium head and rigid neck methods. Biofidelic head models that are currently available include the NOCSAE and HybridIII headforms, both of which attempt to recreate anthropometry and inertial properties of the human head. Currently available neck models, the most common of which used in helmet testing is the HybridIII neck, are not considered to give realistic response in helmeted impact, and as a result the certification organizations are discussing what, if any, neck model could and should be used for helmet certification. The HybridIII, and other neck models, are accepted to be much too mechanically stiff in axial rotation and axial compression. This is perhaps not surprising given the original purpose of the HybridIII neck, which was to realistically simulate fore-aft rotational response in frontal automotive impacts. The objective of this partnership with Biokinetics and Associates Ltd. (Ottawa ON) is to take the first steps towards prototyping a biofidelic neck model suitable for use in helmet certification.