Browsing by Author "Rowson, Bethany M."
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- Assessing the Efficacy of Bicycle Helmets in Reducing Risk of Head InjuryBland, Megan Lindsay (Virginia Tech, 2019-05-09)Although cycling offers many health and environmental benefits, it is not an activity free of injury risk. Increases in cycling popularity in the United States over the past 15 years have been paralleled by a 120% growth in cycling-related hospital admissions, with injuries to the head among the most common and debilitating injuries. Bicycle helmets can reduce head injury risk and are presently required to meet safety standard certification criteria specifying a minimal level of acceptable impact protection. However, the conditions surrounding cyclist head impacts are thought to be much more complex than the test conditions prescribed in standards and have important implications related to mechanisms of injury. The overarching aim of this dissertation was thus to investigate the protective capabilities of bicycle helmets in the context of real-world impact conditions and relevant head injury mechanisms. This aim was achieved through a series of studies, the objectives of which were to: compare helmet impact performance across standards impact testing and more realistic, oblique impact testing; to probe how changing boundary conditions of oblique impact testing may influence helmet test outcomes; to use this knowledge to inform the development of an objective helmet evaluation protocol reflective of realistic impact conditions and related head injury risks; and finally, to enhance the body of knowledge pertaining to cyclist head impact conditions via advanced helmet damage reconstruction techniques. The compilation of results across these studies serves to enhance cyclist safety by stimulating improved helmet evaluation and design while simultaneously providing objective, biomechanical data to consumers, enabling them to make safety-based purchasing decisions.
- Evaluation and Application of Brain Injury Criteria to Improve Protective Headgear DesignRowson, Bethany M. (Virginia Tech, 2016-09-01)As many as 3.8 million sports-related traumatic brain injuries (TBIs) occur each year, nearly all of which are mild or concussive. These injuries are especially concerning given recent evidence that repeated concussions can lead to long-term neurodegenerative processes. One way of reducing the number of injuries is through improvements in protective equipment design. Safety standards and relative performance ratings have led to advancements in helmet design that have reduced severe injuries and fatalities in sports as well as concussive injuries. These standards and evaluation methods frequently use laboratory methods and brain injury criteria that have been developed through decades of research dedicated to determining the human tolerance to brain injury. It is necessary to determine which methods are the most appropriate for evaluating the performance of helmets and other protective equipment. Therefore, the aims of this research were to evaluate the use of different brain injury criteria and apply them to laboratory evaluation of helmets. These aims were achieved through evaluating the predictive capability of different brain injury criteria and comparing laboratory impact systems commonly used to evaluate helmet performance. Laboratory methods were developed to evaluate the relative performance of hockey helmets given the high rate of concussions associated with the sport. The implementation of these methods provided previously unavailable data on the relative risk of concussion associated with different hockey helmet models.
- Hockey STAR MethodologyBegonia, Mark T.; Tyson, Abigail M.; Rowson, Bethany M.; Rowson, Steven (Virginia Tech, 2022-02-08)This document details the protocol used by the Virginia Tech Helmet Ratings to rate hockey helmets based on concussion risk.
- Laboratory evaluation of climbing helmets: assessment of linear accelerationBegonia, Mark T.; Rowson, Bethany M.; Scicli, Blake; Goff, John Eric (IOP Publishing, 2023-03-01)This study utilized a guided free-fall drop tower and standard test headform to measure the peak linear acceleration (PLA) generated by different climbing helmet models that were impacted at various speeds (2-6 m s(-1)) and locations (top, front, rear, side). Wide-ranging impact performance was observed for the climbing helmet models selected. Helmets that produced lower PLAs were composed of protective materials, such as expanded polystyrene (EPS) or expanded polypropylene, which were integrated throughout multiple helmet regions including the front, rear and side. Climbing helmets that produced the highest PLAs consisted of a chinstrap, a suspension system, an acrylontrile butadiene styrene (ABS) outer shell, and an EPS inner layer, which was applied only to the top location. Variation in impact protection was attributed not only to helmet model but also impact location. Although head acceleration measurements were fairly similar between helmet models at the top location, impacts to the front, rear, and side led to larger changes in PLA. A 300 g cutoff for PLA was chosen due to its use as a pass/fail threshold in other helmet safety standards, and because it represents a high risk of severe head injury. All seven helmet models had the lowest acceleration values at the top location with PLAs below 300 g at speeds as high as 6 m s(-1). Impact performance varied more substantially at the front, rear, and side locations, with some models generating PLAs above 300 g at speeds as low as 3 m s(-1). These differences in impact performance represent opportunities for improved helmet design to better protect climbers across a broader range of impact scenarios in the event of a fall or other collision. An understanding of how current climbing helmets attenuate head acceleration could allow manufacturers to enhance next-generation models with innovative and more robust safety features including smart materials.
- Ranges of Injury Risk Associated with Impact from Unmanned Aircraft SystemsCampolettano, Eamon T.; Bland, Megan L.; Gellner, Ryan A.; Sproule, David W.; Rowson, Bethany M.; Tyson, Abigail M.; Duma, Stefan M.; Rowson, Steven (2017-12)Regulations have allowed for increased unmanned aircraft systems (UAS) operations over the last decade, yet operations over people are still not permitted. The objective of this study was to estimate the range of injury risks to humans due to UAS impact. Three commercially-available UAS models that varied in mass (1.2-11 kg) were evaluated to estimate the range of risk associated with UAS-human interaction. Live flight and falling impact tests were conducted using an instrumented Hybrid III test dummy. On average, live flight tests were observed to be less severe than falling impact tests. The maximum risk of AIS 3+ injury associated with live flight tests was 11.6%, while several falling impact tests estimated risks exceeding 50%. Risk of injury was observed to increase with increasing UAS mass, and the larger models tested are not safe for operations over people in their current form. However, there is likely a subset of smaller UAS models that are safe to operate over people. Further, designs which redirect the UAS away from the head or deform upon impact transfer less energy and generate lower risk. These data represent a necessary impact testing foundation for future UAS regulations on operations over people.
- Virginia Tech Hockey Helmet Ratings MemorandumRowson, Steven; Begonia, Mark T.; Rowson, Bethany M.; Duma, Stefan M. (Virginia Tech, 2022-01-25)This memorandum serves to reiterate the goals of the Virginia Tech Helmet Ratings, discuss the hockey helmet ratings, and announce an update to the exposure weightings and star thresholds used to rate hockey helmets.