Design of a Neck-Support-Incorporated Helmet for Reducing the Risk of Concussion in Ice Hockey

The goal of this project was to reduce the likelihood of concussions for ice hockey players by designing a neck support utilizing shear-thickening fluids. A testing mechanism was created to simulate concussion causing impacts while measuring accelerations. It was found that the use of a shear-thickening non-Newtonian fluid reduced the likelihood of a concussion. To support our findings, we computed and compared standard injury indices to evaluate if our goal was met

Effects of Expected Service Life Exposures on the Functional Properties and Impact Performance of an American Football Helmet Outer Shell Material

The purpose of this dissertation is to gain a greater scientific understanding of the changes in functional material properties and impact performance of an American football helmet outer shell material under expected service life exposures. The research goals are to (i) quantify chemical, physical, thermal, and mechanical degradation of an American football outer shell material under expected environmental conditions and (ii) develop a linear drop test impact protocol to employ expected on-field impact conditions to American football helmet components and a plaque-foam (i.e., shell-liner) surrogate. Overall, a step-wise progression of analysis was demonstrated to concurrently quantify and understand changes in material properties at the molecular, microscopic, and macroscopic levels. Changes across chemical, physical, thermal, and mechanical properties were evaluated following laboratory exposures to 480 hours of accelerated weathering, increasing intensities of n-Butyl acetate solvent, and 12 repetitive linear plaque-foam impacts. In Chapter II, an instrumented drop test setup was substantiated to investigate linear impact attenuation performance. In Chapter III, laboratory exposure to UV light, oxygen, moisture, and elevated temperatures induced molecular degradative bi-products and physical aging up to ~1% into the plaque thickness which led to altered aesthetic properties, chemi-crystallization, and an increased resistance to surface indentation and tensile deformation. In Chapter IV, solvent-induced plasticization, crystallization, and stress-cracking of up to ~3% into the plaque thickness led to an increase in surface porosity which scattered light and decreased tensile properties. In Chapter V, impact exposure induced rubber-toughener (RT) cavitation that generated voids via delamination at the RT-matrix interface at which led to rings of stress-whitening, strain-induced crystallization, increased butadiene RT density, and shifts surface modulus and tensile properties. This dissertation preliminarily substantiated (i) a drop test setup attempting to accurately replicate on-field impact conditions to investigate linear impact attenuation performance, and (ii) polymer techniques and protocols that could elucidate the rates and degrees of material degradation

Design of an American Football Helmet Liner for Concussion Mitigation

The objective of this research was to develop an optimal design for a polymeric American football helmet liner for concussion prevention utilizing experiments and high performance. Along with well-established injury criteria (HIC, SI, and Peak acceleration), localized brain injury mechanisms were explored by employing Finite Element simulations and experimental validation. Varying strain rate experiments (monotonic and hysteresis) were conducted on modern football helmet (Rush, Rawlings, Riddell, Schutt, and Xenith) liners and new possible polymeric foam liner materials. These experiments were used to characterize each material at low strain rates (0.1/sec; Instron), intermediate strain rates (100-120/sec; NOCSAE drop tower) and high strain rates (600-1000/sec; Split Hopkinson Pressure Bar). Experimental design optimization was performed on a football helmet liner by utilizing an exploratory Design of Experiments by National Operating Committee on Standards for Athletic Equipment (NOCSAE) drop tests. FEA simulations of drop impact tests were conducted on a helmeted NOCSAE headform model and a helmeted human head model. Correlations were made between both models to relate localized brain response to the global acceleration and the dynamic-based injury criteria HIC, SI, and Peak acceleration). FEA simulations were experimentally validated by twin-wire drop tests of the NOCSAE headform using correlations for validation of the human head model. The helmeted human head simulations were used to explore a Mild Traumatic Brain Injury (MTBI) limits based localized brain response (e.g. pressure and impulse). Based on these limits, future FEA simulations will be used to explore these limits as helmet liner design criteria

Material Characterization and Finite Element simulation of Ice Hockey Helmets under rotational impact conditions

Il presente lavoro tratta la caratterizzazione della schiuma EPP presente in un casco da Hockey e modellazione tramite codice algi Elementi Finiti (LS-Dyna) di tre situazioni di impatto obliquo. La caratterizzazione del materiale avviene in compressione e taglio per mezzo di un sistema appositamente progettato. Il modello FE del materiale viene validato in compressione e taglio includendo l'effetto della velocità di deformazione

Design of an American Football Helmet Liner for Concussion Mitigation

The objective of this research was to develop an optimal design for a polymeric American football helmet liner for concussion prevention utilizing experiments and high performance. Along with well-established injury criteria (HIC, SI, and Peak acceleration), localized brain injury mechanisms were explored by employing Finite Element simulations and experimental validation. Varying strain rate experiments (monotonic and hysteresis) were conducted on modern football helmet (Rush, Rawlings, Riddell, Schutt, and Xenith) liners and new possible polymeric foam liner materials. These experiments were used to characterize each material at low strain rates (0.1/sec; Instron), intermediate strain rates (100-120/sec; NOCSAE drop tower) and high strain rates (600-1000/sec; Split Hopkinson Pressure Bar). Experimental design optimization was performed on a football helmet liner by utilizing an exploratory Design of Experiments by National Operating Committee on Standards for Athletic Equipment (NOCSAE) drop tests. FEA simulations of drop impact tests were conducted on a helmeted NOCSAE headform model and a helmeted human head model. Correlations were made between both models to relate localized brain response to the global acceleration and the dynamic-based injury criteria HIC, SI, and Peak acceleration). FEA simulations were experimentally validated by twin-wire drop tests of the NOCSAE headform using correlations for validation of the human head model. The helmeted human head simulations were used to explore a Mild Traumatic Brain Injury (MTBI) limits based localized brain response (e.g. pressure and impulse). Based on these limits, future FEA simulations will be used to explore these limits as helmet liner design criteria

Mechanisms Of Head Injuries In Road Traffic Accidents; A Potential Solution For Data Collection

Despite advances in road safety, head injuries still account for many of the most serious and fatal injuries in road traffic accidents. This PhD thesis provides a summary of knowledge regarding the current position in head injury research with regard to: Previous assertions as to head injury mechanisms Existing head injury criteria The availability of data to explore potential confounding factors in predicting head injury risk and to propose or validate a new injury criterion or criteria. On the basis of the existing information the question was posed, whether it is possible to validate advanced head injury criteria and head models using additional (new) head injury case data so as to make their application more robust in efforts to mitigate future injuries. In order to answer this question, priority was given to the pursuit of new data, offering six degree of freedom time-series data with detailed information on the exact injuries sustained. A working in-ear sensor system was deemed to offer a potential solution in obtaining elusive data regarding the kind of impact events that could cause head injuries for road users. An in-ear accelerometer system used by the FIA Institute was evaluated through experimentation. Then a low-cost solution was developed with the aim to give similar sensor performance for a wider market of potential wearers. The prototype low-cost sensor system was evaluated in a small series of drop tests and also in a very small real-world data collection trial. This evaluation identified a series of issues that need to be resolved before the system can be used to generate valuable data. A viable system is not ready immediately, but could be following modifications to the prototype system evaluated. Taking this revised system, the next step would be to initiate a larger trial to start the collection of high fidelity data and impact event details; in order to address the need for such information and confirm that even the low-cost system would be fit for that purpose

Effectiveness of a football over helmet padding system in reducing peak acceleration of the head and severity index.

The purpose of this study was to determine if: (a) a football helmet equipped with the Guardian Cap meets the National Operating Committee on Standards for Athletic Equipment (NOCSAE) football helmet standards and (b) if the Severity Indexes and peak accelerations produced during the NOCSAE impact tests were smaller for a football helmet equipped with the Guardian Cap over-helmet padding system than for the same helmet without the Guardian Cap. A total of 54 drop impact tests were completed, 27 on the football helmet alone and 27 on the football helmet equipped with the Guardian Cap. Tests were completed on seven different locations on the helmet at four different velocities and two different temperatures as per NOCSAE test standards. When the helmet was outfitted with the Guardian Cap, the highest Severity Index (SI) recorded was 751 at the rear impact location as compared to an SI of 842 at the same impact location on the helmet alone. Overall, the average SI when the Guardian Cap was attached was 324 ± 195 as compared to an overall average of 368 ± 219 for the helmet alone. The average peak acceleration (gmax) for the helmet with the Guardian Cap was 85 g’s ± 23 as compared to 91 g’s ± 26 for the helmet alone. These data for the Guardian Cap covered football helmet were below the maximum SI allowed by NOCSAE to be a certified football helmet. The SI and peak accelerations for the Guardian Cap covered football helmet were smaller than the SI and peak accelerations for the helmet alone on the NOCSAE impact tests. Medical professionals, coaches, players and parents can use this information to make informed decisions on the role of the Guardian Cap in possibly preventing or limiting the risk of concussions in football

Hydrolastic Damping: A Change to the Modern Helmet

High rates of concussion in the NFL suggest that helmet technology is not satisfactory for the athletes, and soft foam padding has dominated the helmet industry since its inception. The team proposed that implementing a fluid-based hydrolastic suspension system in the helmet would reduce the risk of concussions at all levels of competition. After using COMSOL to successfully model fluid flow through the dampers and after physical testing on dampers filled with air and water lead to increased time to stop of an average of 240% when compared to traditional foam padding, the team concluded that the dampers showed promise and the potential to benefit the padding potential of football helmets and decrease the risk of concussion for football athletes

Prevention of Head and Neck Injuries at the High School Level of Football: Implementation Levels and Perceived Importance of Established Recommendations

The occurrence of head and neck injury in football has prompted various authorities to outline recommendations which can be used as a guideline for the prevention of such injuries. The seven recommendations included for study in this research were classroom education of athletes, correct technique emphasis, enforcement of established rules, conditioning of neck musculature, medical coverage of events, athletic training services, and the proper fit of helmets. The primary purpose of this study was to determine whether coaches of high school football programs were implementing the commonly cited recommendations for preventing head and neck injuries. In addition to levels of implementation, both ratings of importance and the relationship between perceived importance and implementation were measured for each recommendation. One hundred and two coaches (54% of the sample) across the state of Illinois responded to mailed questionnaires which elicited data on whether they implemented each recommendation into their football program and how important they felt each recommendation was in preventing head and neck injuries. Frequency counts were used to describe levels of implementation and ratings of importance for each recommendation. Chi square analysis was used to determine whether perceived importance affected the implementation of each recommendation. Findings revealed very high levels (near 100%) of implementation for correct technique emphasis, rule enforcement, and neck strengthening. Levels of implementation for classroom education and athletic training services were somewhat lower, yet still around 80%. Levels of implementation for medical coverage of events and proper helmet fit were significantly lower, 28% and 61 % respectively. The highest levels of rated importance were among those recommendations with the highest level of implementation, those being technique emphasis, rule enforcement, and neck strengthening. However, proper fit of helmets was also perceived as very important. Perceived importance was considerably lower for classroom education, athletic training services, and medical coverage of events. When the relationship between implementation and importance was studied for each individual recommendation, classroom education, rule enforcement, and neck strengthening showed a strong significant difference in levels of implementation between those who rated importance differently. This finding suggests that perceived importance by the coach may have been a strong determinant in whether these recommendations were implemented. Chi square analysis could not be performed for technique emphasis due to the lack of varied responses for both implementation and perceived importance. There was no statistically significant difference in levels of implementation of athletic training services, proper fitting of helmets, and medical coverage between those who rated their importance differently. These findings suggest that there may be stronger determinants than importance of whether the latter recommendations were implemented

FE-Modelling and Material Characterization of Ice-Hockey Helmet

A finite element model of an ice-hockey helmet has been developed from CAD geometry. The mechanical properties of the EPP liner were tested in the laboratory; these properties and those of the shell and the anvil were implemented into the model and simulations were run in order to validate the modelope