Quantitative comparison of Hybrid III and National Operating Committee on Standards for Athletic Equipment headform shape characteristics and implications on football helmet fit

Abstract

Laboratory tests in which dummy headforms are used to evaluate helmet performance must be representative of real-world conditions to ensure helmets perform well in the field. The objective of this study was to quantify shape differences that may affect helmet fit between two dummy headforms commonly used for football helmet testing. Point-cloud models of a 50th percentile male Hybrid III headform and a medium NOCSAE headform were generated using a coordinate measuring machine. The headforms were optimally aligned and shape comparisons were made in the mid-sagittal plane, three coronal planes, and 3D. Planar and 3D differences were quantified by comparing maximum (MRD) and root-mean-square (RMSD) radial deviations. Minor differences were observed in the upper skull contours of all planar cross-sections, where MRDs were less than 3.5 mm and RMSDs were less than 1.7 mm. Larger deviations were observed in other regions including the jaw in the anterior coronal plane, where the MRD was 6.6 mm and the RMSD deviation was 4.5 mm. Substantial differences were noted between the Hybrid III and NOCSAE at the base of the skull, cheeks, jaw and chin. The headforms were also compared to a head model based on medical imaging of a human subject, which the NOCSAE matched more closely than the Hybrid III. The data presented in this study show that the Hybrid III and NOCSAE headforms have substantial shape differences in several regions that are important for helmet fit, possibly making the NOCSAE a better option for realistic helmet fit.

Laboratory evaluation of a wearable head impact sensor for use in water polo and land sports

“…The NOCSAE headform has previously been demonstrated to report higher values of PLA and PRA. 28 Cobb et al 29 noted that, unlike the Hybrid III, the back of the NOCSAE headform extends below the lower edge of most headgears and provides a better fit for football helmets. Although the SIM-G was coupled to the rear of the Hybrid III headform in both headgears tested, some material from both the water polo cap and headband protruded over the rear edge of the Hybrid III.…”

Impact Performance Comparison of Advanced Bicycle Helmets with Dedicated Rotation-Damping Systems

“…57 While the headform of the National Operating Committee on Standards for Athletic Equipment (NOC-SAE) is considered to have the most biofidelic headform shape, integration of a neck and instrumentation is more difficult compared to a Hybrid III head. 12 While there is precedent for impact testing using an unconstrained headform without a neck surrogate, 21,33,39,40 the present study simulated quasi-physiologic head constraints with a Hybrid III neck. 7 The Hybrid III neck was validated for flexion and extension, but has been shown to be overly stiff in lateral bending and axial compression.…”

The effect of surface roughness on oblique bicycle helmet impact tests

“…21,22 The NOCSAE headform was selected for its skull deflection properties, improved anthropometry, mass, and moment of inertia, including a glycerin ''brain.'' 23,24,25 The NOCASE headform was attached to a Hybrid III neck assembly in this work, despite known deficiencies in side flexion, 26,27 because of its use in the only extant oblique helmet standard 20 and other oblique impact studies. 6 While headform impact response may be different for tests conducted with a different headform, different neck or without a neck, the aim of this work was to characterize the impact surface friction and its influence on headform impact response.…”