Aaron Brice

Topic

A Laboratory Study on the Influence of Guided Drop Tower Carriage Mass and Kinematic Differences to Full-Surrogate Free Falls Toward Enhanced Helmet Certification Methods

Department of Mechanical Engineering

Date & location

• Thursday, March 24, 2024

• 10:00 A.M.

• Virtual Defence

Reviewers

Supervisory Committee

• Dr. Christopher Dennison, Department of Mechanical Engineering, University of Victoria (Supervisor)

• Dr. Joshua Giles, Department of Mechanical Engineering, UVic (Unit Member)

• Dr. Peter Wild, Department of Mechanical Engineering, UVic (Unit Member)

External Examiner

• Dr. Jeremy Wulff, Department of Chemistry, University of Victoria 

Chair of Oral Examination

• Dr. Sudhakar Ganti, Department of Computer Science, UVic

   

Abstract

Falling from height presents a significant risk for military personnel due to the frequency at which they perform high exposure maneuvers, such as walking along unstable structures, repelling from buildings or aircrafts, and low altitude egressing. Traumatic brain injury (TBI) resulting from falls from height (FFH) account for approximately 20% of TBIs with a reported cause in the military, despite the presence of protective head gear. This is likely because current certification testing performed on military helmets emphasize protection against ballistic threats over blunt impacts, such as falls. Military personnel have identified the need for the next generation of helmets to provide better protection against blunt impacts. To develop such helmets, a method for helmet evaluation in scenarios that are representative of real-life falls must be established as the new standard for helmet impact testing.

Guided vertical drop towers are a test device commonly utilized to evaluate the impact attenuating properties of protective headgear in headfirst falls during certification testing. These devices provide a simple, low cost, repeatable means for conducting certification tests over utilizing full-body surrogates to replicate a person experiencing a headfirst fall. However, there are some limitations to the guided drop tower that may limit their ability to properly replicate a fall from height. The most notable limitations are that guided drop towers are constrained to only a single degree of freedom and the impact mass of a drop tower assembly typically only includes the mass of a human head and neck rather than the mass of a full-body. At present there is little work on how these limitations may yield a differing kinematic response between a guided drop tower and that of an actual fall. The objectives of this thesis was to determine if kinematic differences exist between a guided drop tower and a free-falling person, in unhelmeted and helmeted scenarios. The outcomes of this thesis will contribute toward the development of enhanced test standards that evaluate protective headgear in scenarios that are more representative of real-life falls.