Comparison of surrogate 50th percentile human headforms to an adult male sample using three-dimensional modeling and principal component analysis

Abstract

Ice hockey helmets are required to be impact tested while mounted to a surrogate 50th percentile adult male headform. However, head shape and size can vary substantially from user to user. Furthermore, the contact area between a headform and helmet interior has been identified as an important factor affecting the protective capabilities of a helmet. The objective of this study was to compare quantitative measures of head shapes between three 50th percentile adult male headforms and a sample of adult human subjects who wore a medium-sized helmet. Using three-dimensional models of the human subjects and headforms, head shape was quantified by assessing radial distances in two transverse planes of the head and by using principal component analysis to determine the largest components of fit. Notable differences were found between the headforms and human subjects. The headforms were smaller than the human subjects, demonstrating smaller radial distances for the entire head. The principal components of head shape were overall size and roundness of the head. The results of this study demonstrate the headforms are not representative of the sample median.

Head and neck injury potential during water sports falls: examining the effects of helmets

“…The geometry and stiffness of the Hybrid-III neck are different from a live person and unbiased neckforms [28]. Similarly, 50th percentile Hybrid-III headforms do not represent realistically the geometry and helmet fit for people [29,30]. The larger diameters and irregularities of a live person's head would be expected to increase the effective (total) drag coefficient (C T ) in unhelmeted falls and would reduce the differences between unhelmeted and helmeted tests.…”

Are headforms a poor surrogate for helmet fit?

“…14 This fallacy is highlighted by a recent study, where differences in head shape were observed between a sample of adult males and standard HFs with the anthropometrics of a 50th percentile adult male. 15 It should be noted that the Hybrid III HF was designed using the average cranial measurements of a collection of adult Caucasian male skulls, 16 and the NOCSAE was designed based on the average anthropometrics of 13 cadaver heads within the size range of the most popular football helmet size. 17 With the growing accessibility and continued advancements in three-dimensional (3D) scanning technologies, perhaps updating the shape and dimensions of the HFs with a larger, more biofidelic data set is warranted.…”