Development of a non-destructive method to measure football facemask stiffness

Abstract

Despite heightened awareness of the need for more protective headgear in American football, facemask performance as an individual component of the helmet system has been overlooked. Current methods used to evaluate facemasks are ineffective in separating facemask performance from the performance of the full-helmet system. This article evaluates the use of a non-destructive, quasi-static loading method to measure the structural stiffness of 11 football facemask designs that represent various geometries and materials. The test method determined quantifiable differences in facemask stiffness, while limiting permanent facemask deformation to less than 3.175 mm. The reliability of the structural stiffness measurement process was assessed through a test-retest analysis of three facemask styles. The coefficient of variation for each style of facemask was between 1.1%-3.3%. This novel facemask stiffness test can be used for the nondestructive evaluation of facemasks by reconditioners, as well as facemask manufacturers to differentiate the potential impact performance of novel facemask designs.

Finite element validation of 3D American football faceguard structural stiffness models

“…35,40 Three studies in the literature performed initial work in this area by validating individual components of a football helmet model prior to implementation in a holistic headgear simulation. 35,43,44 The faceguard validation procedures discussed in the studies compressed a faceguard similarly to Bina et al 27 ; however, the validation metric reported was lateral faceguard structural stiffness. The current study has validated the structural stiffness of the faceguard when compressed in the anterior-posterior direction, similar to common, on-field impacts.…”

“…Of the 17 faceguard styles, three common Riddell ® (Des Plaines, IL) Speedflex™ faceguard styles were selected to validate the computational model. The SF-2BD-SW, SF-2BD, and SF-3BD faceguard styles were selected for model validation because the experimental results for each faceguard style were available; they are commonly used at all levels of football; they span a range of stiffness values reported by Bina et al 27 ; and they have a theoretically preferred lower stiffness for impact attenuation. These reasons are important to prove that advancements can be made to already well-performing faceguards currently used in most leagues, and that the modeling methodology is validated across a range of stiffness values to be applied to other faceguards.…”

“…22 The goal of this study is two-fold: to validate the reverse engineering method for developing a library of validated faceguard models; and to validate the finite element simulation of three common American football faceguards subject to a quasi-static structural stiffness test. 27 This study will result in a validated method for model generation and validated models to be used in parametric design analysis and computational optimization. Collectively, these new tools can be used to conduct further work that will assist football athletes, coaches, parents, equipment managers, and headgear manufacturers in the understanding of design variables essential to faceguard performance.…”

“…Recently, a novel testing procedure was developed to analyze the structural stiffness of faceguards independent of the helmet system. 27 This testing methodology has demonstrated the ability to statistically differentiate performance-relevant stiffness measures between faceguard designs. Faceguard stiffness is a result of its material and geometry; however, little is known about which specific design parameters most influence faceguard structural stiffness.…”