Helmet Design Research Articles

Hydrodynamic Design of New Type of Artificial Reefs

The purpose of this research work is to study the hydrodynamic characteristics of a new type of artificial reef structure, in order to provide a structure with low flow resistance, which will be a more suitable shelter for fishes and marine organisms. The idea of the new artificial reef is based on the streamlined bicycle helmet design concept. The hydrodynamic characteristics of the helmet and hollow cube artificial reefs (ARs) of the same volume have been studied at different water depths and wave frequencies of Malaysia seas using Computational Fluid Dynamics (CFD) method. The finite volume RANSE (Reynolds-Averaged Navier-Stokes Eqs.) code Ansys CFX was used for calculating the reefs drag force (FD) and flow characteristics, while the potential flow code Ansys Aqwa was used for calculating the reefs inertia force (FI). The Shear Stress Transport (SST) turbulence model was used in the RANSE code. The results of the two ARs were then compared for studying the hydrodynamic improvement due to the use of streamlined helmet artificial reef on the flow pattern around it. The streamlined body of the helmet artificial reef enhances the flow pattern at the aft region of the reef and provides flow zones with moderate flow speed at this area, which can help fishes and marine organisms from finding good shelter. The special shape of the different openings in the body of the helmet artificial reef improves the condition of the flow velocity distribution inside the unit than that of the hollow cube unit, which can increase the amount of the nutrient to the living fishes and organisms inside the reef.

Testing of Energy Absorption Capability of Sandwich Structures Based on Metal Foams for Design of Protective Helmets

Purpose of this study is investigation of energy absorption capability of the sandwich structures composed of combination of polystyrene and metal foam element and their suitability as new structure for design of protective helmets. Two types of the metal foams were experimentally tested and evaluated: Alporas (Shinko Wire Ltd., Japan) and Aluhab (Aluinvent Plc., Hungary). Samples of the sandwich structure are composed of two layers: bottom expanded polystyrene (EPS 200S) layer and upper metal foam layer which are glued together. Prepared samples are tested using a drop tower experiment to measure sample response (acceleration, reaction force) at different strain rates and energies. From acceleration/time history the Head Injury Criterion (HIC) is calculated as significant parameters in terms of protective helmets. Moreover, measured and derived characteristics are compared with pure EPS samples to obtain comparison of deformation behaviour between conventional structure for protective helmets and designed sandwich structures.

Towards Safer Helmets: Characterisation, Modelling and Monitoring

Bike and ski helmets are mainly made up of two layers: the external shell and the foam liner. The foam liner, typically made of expanded polystyrene (EPS) or polypropylene (EPP), is asked to provide energy absorption in case of impacts. Standard helmet design requires the foam to maximize this energy absorption, thus achieving large deformations (up to 25% in compression) while maintaining the stress level below a threshold value. To optimize the helmet construction in terms of foam composition, structure and density, reliable numerical models are required, which in turn need to be fed with accurate experimental data.A characterisation of several foams was performed, including EPS and EPP having varying densities, under tensile and compressive stress states at varying strain rates. Typical mechanical parameters (elastic moduli and plateau stress in compression, Poisson's ratio) were compared with literature data and applicability of existing models to experimental results was discussed. A marked strain rate dependence – very important for impact applications – was accurately described using the Nagy phenomenological model. The foam microstructure was investigated using scanning electron microscopy (SEM) to assess structural changes before and after compression. The aforementioned mechanical features were then adopted in a rate-dependent constitutive law for crushable foams, to model the shock attenuation properties of helmets and validate the approach against available data.Finally, a microelectromechanical system based in-helmet wireless micro monitoring system was developed and inserted in a helmet prototype. The system is capable of acquiring impact load spectra, providing valuable information to investigate generic impacts with varying angles and energy. In particular, it can monitor the effect of repeated micro-impacts on the residual energy absorption characteristics of the foam.

A Study in Developing a Charger Helmet as Power Bank of Mobile Phone for Motorcyclists

<p>Wearing a helmet is one of the obligations to be adhered to motorcyclists. Yet, the existence of helmets is not only as protective gear head but also as a lifestyle even leading to advanced technologies, such as 1) color changing helmet, 2) folding helmets, 3) glowing helmets, and so on. Therefore, the innovation has given a touch on the idea of helmet concepts that is more useful than before and a prototype that has never existed before. This paper describes how the concept of helmet charger is. In fact, the innovation is conceptualized to generate electricity from the helmet, which is a photovoltaic solar cell. The electricity generated can be used for various purposes, like charging a cell phone. Furthermore, the things underlying helmets as a means of placing solar cells is that the body heat of the sun which is quite broad and equitable helmet that will help the solar cells to have an ideal position by facing the sun directly. At the end, the helmet covered by solar cells will have been ready to store electrical energy in batteries as much as 12 VDC. This paper describes a helmet design for the solar power charger and a solar-powered helmet design that can generate voltage as needed. </p><p><strong>Keywords:</strong> charger, electric energy, helm, photovoltaic cells</p>

Simulating bio-composite cycling helmet performance through FEA and CFD approaches

<p>Finite Element Analysis (FEA) and Computational Fluid Dynamics (CFD) analysis were performed in this work in order to obtain the best design for safety and aerodynamic performance of the bicycle cycling helmet. FEA analysis was computed on two different helmet designs to determine the critical area subjected to impact. A pressure load was applied on the helmets’ outer surface to simulate oblique loading. The critical areas of the helmets were then highlighted and identified, enabling design improvements to be made on both designs. CFD analysis was then executed in order to obtain the lowest drag coefficient number in reducing the air resistance induced by both of the helmet designs, inherently increasing cyclist performance and ensuring competition success.</p>

Hockey STAR: A Methodology for Assessing the Biomechanical Performance of Hockey Helmets.

Optimizing the protective capabilities of helmets is one of several methods of reducing brain injury risk in sports. This paper presents the experimental and analytical development of a hockey helmet evaluation methodology. The Summation of Tests for the Analysis of Risk (STAR) formula combines head impact exposure with brain injury probability over the broad range of 227 head impacts that a hockey player is likely to experience during one season. These impact exposure data are mapped to laboratory testing parameters using a series of 12 impact conditions comprised of three energy levels and four head impact locations, which include centric and non-centric directions of force. Injury risk is determined using a multivariate injury risk function that incorporates both linear and rotational head acceleration measurements. All testing parameters are presented along with exemplar helmet test data. The Hockey STAR methodology provides a scientific framework for manufacturers to optimize hockey helmet design for injury risk reduction, as well as providing consumers with a meaningful metric to assess the relative performance of hockey helmets.

Correlates and Barriers Associated with Motorcycle Helmet Use in Wa, Ghana

Objective: This study was conducted to investigate the correlates and barriers to helmet use among motorcycle riders in Wa, a motorcycle-predominant town in Ghana. An additional objective was to determine the association between helmet use and riders' knowledge, attitudes, and beliefs toward helmets.Methods: Cross-sectional surveys including both observation of helmet use and interviews were conducted among motorcycle riders at 6 randomly selected fuel stations and 4 motorcycle service centers within and outside the Central Business District of Wa. Questions covered riders' sociodemographic and riding characteristics, helmet use, reasons for use or nonuse of helmets, and knowledge, attitudes, and beliefs about helmets. Analyses were based on frequencies and testing of strength of association using adjusted odds ratios (with 95% confidence intervals) in binary logistic regression.Results: The prevalence of helmet use among the 271 sampled riders was 46% (95% confidence interval [CI], 40.2–52.0). Gender, age, marital status, and occupation were significant sociodemographic correlates of helmet use in Wa. Compared to currently married riders, unmarried riders were 5 times less likely to use a helmet. No significant association existed between riders' educational attainment and helmet use. Helmet use was also positively correlated with helmet ownership and license holding. The leading reasons stated for helmet nonuse among nonusers were not traveling a long distance and helmets block vision and hearing. Protection from injury, legal requirement, and coping with the police for fear of being accosted for helmet nonuse were identified as common reasons for helmet use. Positive attitudes and beliefs were also significantly correlated with helmet use.Conclusions: Despite the existence of a legislation mandating the use of helmets on all roads as well as the high level of awareness among riders on this legislation and the benefits of helmets, the incidence of helmet use among motorists continue to be low in Wa, Ghana. This means that efforts to identify strategies to increase helmet use need to continue. The evidence provided by this study suggests that stakeholders in road safety need to put in interventions to ensure a rigorous enforcement of the helmet use legislation and improvement in helmet design. These should be combined with the development of targeted educational programs with the aim of changing unfavorable attitudes and beliefs toward helmet use.

Feasibility of optimising bicycle helmet design safety through the use of additive manufactured TPE cellular structures

Bicycle helmets are designed to attenuate forces and accelerations experienced by the head during cycling accidents. An essential element of bicycle helmet design is, therefore, the appropriate manufacturing of energy-dissipating components. The focus of this study was to evaluate the feasibility of using thermoplastic elastomer (TPE) cellular structures (Duraform® Flex), manufactured via a laser sintering (LS) process, as the energy-dissipating inner liner of the bicycle helmet. This study is presented in two sections; the optimisation of the LS process capabilities for the manufacture of cellular structures and an evaluation of the effects of cellular structure density on helmet impact kinematics. Through the fabrication and testing of tensile and compressive specimens, each process parameter (laser power, scanning exposure, build temperature and part orientation) was optimised to maximise compressive strength. The energy-dissipating characteristics of helmet cellular structures, made from this optimised material, were evaluated during simulated helmeted headform impact tests. Reduced accelerations and increased pulse durations were reported for decreased structural densities, demonstrating improved energy-dissipating characteristics for this novel technique. This study demonstrates that cellular structure-based inner liners, manufactured via additive manufacturing processes, have exciting potential towards improving bicycle helmet safety.

Skanowanie 3D jako narzędzie do projektowania kasków korekcyjnych

Skanowanie 3D jako narzędzie do projektowania kasków korekcyjnych

Effects of Helmet Surface Geometry on Head Acceleration in High Velocity Water Sports

This paper explores the effects of helmet surface geometry on head acceleration in high-velocity water sports in an effort to help reduce the probability of concussion. An instrumented Hybrid III anthropomorphic head was fitted with a football helmet covered in a smooth control shell and with one covered in a shell with a designed geometry involving dimples and fin/channels. The head was dropped from a height of 73 inches (185.42cm) into a tank of water at varying impact angles and the peak accelerations were recorded and compared at each impact angle. High speed camera images were also taken to observe dynamic behavior of the water during the impact. The results showed an average reduction in acceleration over all angles of around 17% and a peak reduction in acceleration of 37% for impacts on the crown of the head. High speed camera analysis and acceleration analysis also revealed that fins were the dominant factor in acceleration reduction, but dimples did have a moderate effect. It was also determined that the reduction in acceleration created by the geometry could result in around a 30% reduction in the probability of concussion at the optimal impact angle. Overall, these results showed that helmet geometry can significantly reduce the linear acceleration a head undergoes in high velocity water sports. Further investigation is needed to see how geometry influences rotational acceleration and how to implement this geometry into a helmet design.

Impact Attenuation of Customized User-centered Bicycle Helmet Design

Bicycle helmets are currently available to cater to general head sizes, ranging from S/M and L/XL, but there is also a universal model that can fit all sizes through adjustable helmet strap. Numerous surveys addressed that wearing helmet is not comfortable and the current sizing did not accommodate various range of users, because the human head shapes and dimensions are different according to ethnic groups, age and gender. This paper describes impact attenuation of user-centred design approach, i.e by modifying the shape of the liner to improve fit of bicycle helmet in accordance to AS/NZS 2063:2008. Head scans of 15 participants from a selected control group were captured using Artec3D portable scanner, while bicycle helmets and J headform were scanned using Flexscan 3D scanning equipment. These participants were selected based on a grouping method referring to selected 37 landmarks on human head shape. A new headform for the control group was developed by aligning and combining all the involved head scans in Geomagic Studio 12. Several new helmets with different liner thickness were designed based on the new headform. A validated drop impact simulation model, developed using Abaqus FEA software, was used to conduct drop impact simulation of each customized helmet design. Thickness of each user-centred helmet models at 37 landmarks was also recorded and the peak linear acceleration (PLA) of the helmet at impact locations such as top, side and front area were measured. Results revealed that the PLA increases as the thickness of helmet liner decreases. The rate of increase of PLA as the helmet liner thickness decreases is different at each impact location; it was greater at front and side location compared to top impact location.

3D Anthropometric Investigation of Head and Face Characteristics of Australian Cyclists

Designspecialists have acknowledged the need for more accurate measurements of human anthropometry through the use of 3D data, especially for the design of head and facial equipment. However, 3D anthropometric surveys of the human head are sparse in the literature and practically non-existent for Australia. Research published to date has not proposed concrete methods that can accurately address the hair thickness responsible for inaccurate representation of the head's shape. This study used a state-of-the-art handheld white light scanner to digitize 3D anthropometric data of 222 participants in the Melbourne Metropolitan Area. The participants volunteered for the study consisted of 46 females and 176 males (age: 34.6 ± 12.5). The participants’ head scans were aligned to a standard axis system, whereby a Hair Thickness Offset (HTO) method was introduced to more accurately describe the true shape of the head. It is envisaged that the database constructed through this research can be used as a reference for the design and testing of helmets in Australia.

Modelling and impact analysis of football player head with helmet toward mitigating brain concussion

In recent years, increasing concussions among American football players have drawn attention and concerns regarding safety of today's football helmets. This study investigates the effects of concussive impact forces on the brain of football players and the shock absorbing performance of actual football helmets. Initially, the mechanical properties of typical helmet materials were obtained through compression tests and hysteresis loop experiments. Next, a lumped-mass model was developed to physically describe both the head and helmet together against an impact load, and the brain response was obtained from the semi-analytical analysis. To extract more information such as strains and wave propagations within the brain, a detailed continuum model was constructed and the response of the brain was analysed by using the finite element method. A realistic impact load was obtained from a case study of actual football play. Our experimental data along with biomechanical data of the head and brain from the available literature were incorporated into our modelling and analyses. The results indicated that the accelerations and strains in the brain were both above the concussion thresholds and that current football helmet designs may not protect players against concussion.

Temporal bone fractures: sequelae and their impact on quality of life

PurposeTo present a prospective temporal bone fracture database, and study facial and cochleovestibular sequelae and their impact on quality of life. Materials and methodsProspective study of consecutive cases of 39 patients with 45 temporal bone fractures over 11-month period in a university tertiary referral center. Based on epidemiological data, clinical and imaging findings, treatment modalities and outcome of patients with follow-up of one year, the present study focused on facial and cochleovestibular sequelae and their impact on quality of life after one-year period. ResultsAfter 12months, 44% of patients present with balance problems, 56% with hypoacusis, 56% with tinnitus, and 15% with facial paralysis. In 75%–80% of patients, the cochleovestibular sequelae are described as disabling. Post-trauma quality of life was significantly impaired compared with pre-trauma quality of life, even after 12months. Long-term cochleovestibular sequelae were significantly associated with poor long-term quality of life. ConclusionsThe study demonstrates the need to focus on prevention of temporal bone fractures, notably by promoting the use of helmets and improvements in helmet design. The rapid diagnosis of temporal bone fracture is crucial as it enables effective initial management aimed at avoiding sequelae. The frequency of cochleovestibular sequelae after temporal bone fracture and their impact on quality of life demonstrate the importance of, and need for, ongoing follow-up by a local medical team who can diagnose and manage these long-term sequelae.

ANTHROPOMETRIC FACE IN BASRAH

ANTHROPOMETRIC FACE IN BASRAH Nada H Al-jassim , Zuhair F Fathallah & Nawal M Abdullah MB,ChB, DGO. Anatomy. Abstract Anthropometry is the systematic quantitative representation of the human body, it is used to measure the absolute and relative variability in size and shape of the human body. Over the centuries, there have been remarkable changes in anthropometric measurements due to geographical, cultural, genetic and environmental factors. The studying of human face and the assessment of facial dimensions attract the attention of the artists, poets and scientists and takes a prime importance in medical and dental fields in both diagnosis and treatment planning. Anthropometry also used for the design of clothing and equipment, e.g. Gas masks, oxygen masks, dust masks and respirators as well as design of military and industrial helmets. There had been no studies done on facial measurement in Basrah therefore, this study is to be considered as the first in this field and the baseline for further studies. This study had attempted to quantitatively measure the human face in different ethnic groups of the local population and to identify the differences between individuals of different races and sexes, also to identify the differences between the people of Basrah and other people worldwide. These differences which are responsible for the special facial features in different ethnic groups should be maintained during reconstructive or aesthetic surgery otherwise the patients will lose their ethnic features. The people of Basrah have different racial and ethnic background, there are Semites which are the Arabs and Syrian (Assyrian & Chaldean), Arian, who are the Armenian, Kurdish and Persian, and then there is the mixed group result from interracial marriages. This study is a cross sectional study with a comparative component conducted in Basrah governorate. The data was randomly collected from volunteers, for the period from February to July 2013. Raw data used in this study was originated from a total number of 1000 Iraqi adults (526 females and 474 males) living throughout Basrah governorate and were used to create a database for statistical analysis. The result of this study shows that there are differences between the races and between the local people and the surrounding countries and indeed there is a great difference from the standard measurement advocated by western researchers. Introduction he human face is a living mirror held Tout to the world, it has the power to common expression is “I may forget a name, but I’d never forget a face’ Anthropometry quantitative representation of the human individual understanding human physical variations . Over remarkable measurements cultural, Bas J Surg, December, 20, 2014 Original Article MEASUREMENTS OF HUMAN MB,ChB, MSc, Assist. Prof. Plastic Surgeon. MB,ChB, MSc, Assist.Prof. o

An animal-to-human scaling law for blast-induced traumatic brain injury risk assessment

Despite recent efforts to understand blast effects on the human brain, there are still no widely accepted injury criteria for humans. Recent animal studies have resulted in important advances in the understanding of brain injury due to intense dynamic loads. However, the applicability of animal brain injury results to humans remains uncertain. Here, we use advanced computational models to derive a scaling law relating blast wave intensity to the mechanical response of brain tissue across species. Detailed simulations of blast effects on the brain are conducted for different mammals using image-based biofidelic models. The intensity of the stress waves computed for different external blast conditions is compared across species. It is found that mass scaling, which successfully estimates blast tolerance of the thorax, fails to capture the brain mechanical response to blast across mammals. Instead, we show that an appropriate scaling variable must account for the mass of protective tissues relative to the brain, as well as their acoustic impedance. Peak stresses transmitted to the brain tissue by the blast are then shown to be a power function of the scaling parameter for a range of blast conditions relevant to TBI. In particular, it is found that human brain vulnerability to blast is higher than for any other mammalian species, which is in distinct contrast to previously proposed scaling laws based on body or brain mass. An application of the scaling law to recent experiments on rabbits furnishes the first physics-based injury estimate for blast-induced TBI in humans.

Head Impact Exposure in Youth Football

To provide data describing the head impact exposure of 7- to 8-year-old football players. Head impact data were collected from 19 players over the course of 2 seasons using helmet-mounted accelerometer arrays. Data were collected from 2 youth football teams in Blacksburg, VA, spanning 2 seasons. A total of 19 youth football players aged 7-8 years. Type of session (practice or game) and the player's experience. Head impact frequency, acceleration magnitude, and impact location for games, practices, and the season as a whole were measured. The average instrumented player sustained 9 ± 6 impacts per practice, 11 ± 11 impacts per game, and 161 ± 111 impacts per season. The average instrumented player had a median impact of 16 ± 2 g and 686 ± 169 rad/s and a 95th percentile impact of 38 ± 13 g and 2052 ± 664 rad/s throughout a season. Impacts of 40 g or greater tended to occur more frequently in practices than in games, and practices had a significantly higher 95th percentile impact magnitude than games (P = 0.023). Returning players had significantly more impacts than first time players (P = 0.007). These data are a further step toward developing effective strategies to reduce the incidence of concussion in youth football and have applications toward youth-specific football helmet designs.

Simulation, fabrication and impact testing of a novel football helmet padding system that decreases rotational acceleration

Recent studies suggest that concussion may be associated with long-term neurological sequelae. Both linear impact and rotational acceleration have been identified as contributors to concussion and traumatic brain injury (TBI). Modern football helmets are designed according to the National Operating Committee on Standards for Athletic Equipment (NOCSAE) standard for protection from linear impact, without consideration of protection from rotational injury. A multidisciplinary team was assembled with expertise in brain injury, computational modeling, and materials engineering to design, fabricate and impact test a novel helmet padding system. A rotational fixture with magnesium headform and linear impactor was constructed using a rotary encoder to enable measurement of z axis rotational angle, velocity and acceleration. Helmet padding material designs were evaluated using finite element (FE) computational modeling, fabricated to specification and then impact tested. Models from two different manufacturers were retrofit with prototype pads and then compared with unmodified versions for attenuation of rotational acceleration. The helmets were then tested using a standard NOCSAE drop apparatus and headform for linear acceleration performance. Large-size Riddell Revolution and Schutt ION4D helmets retrofit with prototype padding demonstrated 21.6 and 33.6 % decreased peak z axis rotational acceleration following a 3.2 m/s side impact compared with their respective unmodified commercial models (717.7 vs. 914.0 rad/s2 and 768.4 vs. 1,158.6 rad/s2, p < 0.0001, respectively). The improved performance effect appeared consistent over at least 50 impacts without evidence of early material degradation or helmet damage. Compared with unmodified versions, drop test performance for hybridized helmets, measured by Peak G and severity index (SI), were comparable for most, but were worse for rear (Riddell Revolution) and side (Schutt ION4D) impact conditions. Rotational acceleration from side impacts may be attenuated by directed helmet design while maintaining acceptable linear impact performance. Future work will focus on optimization and durability testing of prototype padding for larger impacts.

Head impact exposure in youth football: middle school ages 12-14 years.

The head impact exposure experienced by football players at the college and high school levels has been well documented; however, there are limited data regarding youth football despite its dramatically larger population. The objective of this study was to investigate head impact exposure in middle school football. Impacts were monitored using a commercially available accelerometer array installed inside the helmets of 17 players aged 12-14 years. A total of 4678 impacts were measured, with an average (±standard deviation) of 275 ± 190 impacts per player. The average of impact distributions for each player had a median impact of 22 ± 2 g and 954 ± 122 rad/s², and a 95th percentile impact of 54 ± 9 g and 2525 ± 450 rad/s². Similar to the head impact exposure experienced by high school and collegiate players, these data show that middle school football players experience a greater number of head impacts during games than practices. There were no significant differences between median and 95th percentile head acceleration magnitudes experienced during games and practices; however, a larger number of impacts greater than 80 g occurred during games than during practices. Impacts to the front and back of the helmet were most common. Overall, these data are similar to high school and college data that have been collected using similar methods. These data have applications toward youth football helmet design, the development of strategies designed to limit head impact exposure, and child-specific brain injury criteria.

Dynamic simulation and finite element analysis of the human mandible injury protected by polyvinyl alcohol sponge

There have been intensive efforts to find a suitable kinetic energy absorbing material for helmet and bulletproof vest design. Polyvinyl alcohol (PVA) sponge is currently in extensive use as scaffolding material for tissue engineering applications. PVA can also be employed instead of commonly use kinetic energy absorbing materials to increase the kinetic energy absorption capacity of current helmet and bulletproof vest materials owing to its excellent mechanical properties. In this study, a combined hexahedral finite element (FE) model is established to determine the potential protection ability of PVA sponge in controlling the level of injury for gunshot wounds to the human mandible. Digital computed tomography data for the human mandible are used to establish a three-dimensional FE model of the human mandible. The mechanism by which a gunshot injures the protected mandible by PVA sponge is dynamically simulated using the LS-DYNA code under two different shot angles. The stress distributions in different parts of the mandible and sponge after injury are also simulated. The modeling results regardless of shot angle reveal that the substantial amount of kinetic energy of the steel ball (67%) is absorbed by the PVA sponge and, consequently, injury severity of the mandible is significantly decreased. The highest energy loss (170J) is observed for the impact at entry angle of 70°. The results suggest the application of the PVA sponge as an alternative reinforcement material in helmet and bulletproof vest design to absorb most of the impact energy and reduce the transmitted load.