Date of Award

5-2026

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Bioengineering

Committee Chair/Advisor

Dr. John DesJardins

Committee Member

Dr. Gregory Batt

Committee Member

Dr. Reed Gurchiek

Committee Member

Dr. Jeremy Mercuri

Abstract

Anthropometric test devices (ATDs) are human surrogate models used to represent the human body response in the context of compliance and safety testing. These devices are used in multiple industries, including automotive and aerospace, and have recently been incorporated into impact testing for the evaluation of helmet performance in American football. The Hybrid III 50th percentile male ATD head and neck assembly is the most commonly used surrogate for these tests, although it was developed for automotive frontal crash scenarios that induce an inertial force on the body, leading to head and neck motion primarily in the sagittal plane. In contrast, football impacts are not isolated to one direction and in many cases occur directly to the head, eliciting a much different response. Despite this, little work has been done to characterize Hybrid III behavior during sports-specific impacts, leading to an increased potential for inaccurate laboratory testing data. This research addresses this concern by investigating the mechanical response of the Hybrid III neckform under loading scenarios relevant to American football. Experimental studies were performed to characterize both the quasi-static and dynamic response of the neckform across multiple planes of motion. Static bending experiments were used to quantify stiffness and range of motion. Dynamic testing was performed using a pneumatic linear impactor to obtain a kinematic impact response recorded using a 6a3w accelerometer array fixed within the Hybrid III headform. A validated computational head and neck model (HYOID OpenSim model) was used to estimate the muscular stiffness required to reproduce the mechanical behavior of the Hybrid III neckform as a physiological reference. Muscle parameters were optimized to match experimentally measured stiffnesses across multiple bending directions. Finally, Forward Dynamics simulations were performed in OpenSim using the HYOID model to evaluate how variations in muscular strength influence the head and neck response to impacts. This analysis identified the equivalent muscular capacity required for a human neck model to reproduce the kinematic behavior of the Hybrid III. This study provides a comprehensive evaluation of the Hybrid III neckform and highlights limitations in current surrogate models. The findings from this work support the development of sports-specific, biofidelic surrogate devices for the evaluation of head protective equipment.

Author ORCID Identifier

0000-0003-4244-5414

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