Establishing Boundary Conditions for Optimized Reconstruction of Head Impacts

Stark, Nicole Elizabeth

Establishing Boundary Conditions for Optimized Reconstruction of Head Impacts

dc.contributor.author	Stark, Nicole Elizabeth	en
dc.contributor.committeechair	Rowson, Steven	en
dc.contributor.committeemember	Urban, Jillian	en
dc.contributor.committeemember	Kuehl, Damon R.	en
dc.contributor.committeemember	Duma, Stefan M.	en
dc.contributor.committeemember	Madigan, Michael L.	en
dc.contributor.department	Department of Biomedical Engineering and Mechanics	en
dc.date.accessioned	2024-06-04T08:02:54Z	en
dc.date.available	2024-06-04T08:02:54Z	en
dc.date.issued	2024-06-03	en
dc.description.abstract	Traumatic brain injuries (TBIs) encompass an array of head trauma caused by diverse mechanisms, including falls, vehicular accidents, and sports-related incidents. These injuries vary from concussions to diffuse axonal injuries. TBIs are characterized by the linear and rotational accelerations of the head during an impact, which are influenced by various factors such as the velocity and location of the impact and the contact surface. Consequently, the accuracy of laboratory tests designed to evaluate protective technologies must closely mirror real-world conditions. This dissertation explores the boundary conditions essential for accurately replicating head impacts in laboratory settings. The research aims to improve the reconstruction of head impacts, concentrating on two main areas: 1) examining various aspects of friction during head impacts and 2) biomechanically characterizing the head impacts sustained by older adults during falls. This study provides insights into the overall influence of friction during head impacts. It investigates the friction coefficients between the helmet's shell and the impact surface, as well as between human heads, headforms, and helmets. Additionally, it assesses how these frictional interactions influence oblique impact kinematics. Defining static and dynamic friction coefficients of the human head and headforms is needed to develop more realistic head impact testing methods, define helmet-head boundary conditions for computer-aided simulations, and provide a framework for cross-comparative analysis between studies that use different headforms and headform alterations. This research also introduces and evaluates the accuracy of a model-based image mapping method to measure head impact speeds from single-view videos in un-calibrated environments. This measurement technique advances our comprehension of head impact kinematics derived from uncalibrated video data. By applying this method, videos of falls involving older adults were analyzed to determine head impact speeds and boundary conditions. The resulting data was used to construct headform impacts, capturing linear and rotational head impact kinematics. These reconstructions can inform the development of biomechanical testing protocols tailored to assess protective gear for older adults, with the goal of reducing fall-related head injuries.	en
dc.description.abstractgeneral	Traumatic brain injuries (TBIs) are head injuries that can happen in many ways, such as from falling, car accidents, or playing sports. These injuries can range from mild concussions to more severe cases, brain bleeds, or skull fractures. They happen when the head moves quickly or spins because of a hit, which can be affected by the speed of the impact, where on the head the impact happens, or what the head impacts against. Therefore, the accuracy of laboratory reconstruction head impact tests must closely mirror real-world conditions. This dissertation explores the boundary conditions essential for accurately replicating head impacts in laboratory settings. The research aims to improve the reconstruction of head impacts, concentrating on two main areas: 1) examining various aspects of friction during head impacts and 2) biomechanically characterizing the head impacts sustained by older adults during falls. This study provides insights into the overall influence of friction during head impacts. It investigates the friction coefficients between the helmet's shell and the impact surface, as well as between human heads, headforms, and helmets. Additionally, it assesses how these frictional interactions affect head impacts. Understanding how friction influences head impacts is crucial for improving helmet testing methods and allows for more consistent comparisons across various research studies that use different headform models or modifications. This research also introduces and evaluates a method to calculate head impact speeds by analyzing video footage, even if the video was not taken with special equipment or setup. This approach improves our understanding of head movements during accidents by using video clips of falls, particularly those involving older adults, to determine the head speeds and conditions of the impact. The information gathered from these analyses helps to reconstruct these impacts using a headform to measure injury metrics. These reconstructions are crucial for designing tests that can evaluate safety equipment meant to protect older adults from head injuries during falls.	en
dc.description.degree	Doctor of Philosophy	en
dc.format.medium	ETD	en
dc.identifier.other	vt_gsexam:40418	en
dc.identifier.uri	https://hdl.handle.net/10919/119242	en
dc.language.iso	en	en
dc.publisher	Virginia Tech	en
dc.rights	In Copyright	en
dc.rights.uri	http://rightsstatements.org/vocab/InC/1.0/	en
dc.subject	Keywords: Headforms	en
dc.subject	Friction	en
dc.subject	Biomechanics	en
dc.subject	Falls	en
dc.subject	Older Adults	en
dc.subject	Head Impacts	en
dc.title	Establishing Boundary Conditions for Optimized Reconstruction of Head Impacts	en
dc.type	Dissertation	en
thesis.degree.discipline	Biomedical Engineering	en
thesis.degree.grantor	Virginia Polytechnic Institute and State University	en
thesis.degree.level	doctoral	en
thesis.degree.name	Doctor of Philosophy	en