scholarly journals An Overview of the Effectiveness of Bicycle Helmet Designs in Impact Testing

2021 ◽  
Vol 9 ◽  
Author(s):  
Javid Abderezaei ◽  
Fargol Rezayaraghi ◽  
Brigit Kain ◽  
Andrea Menichetti ◽  
Mehmet Kurt
Keyword(s):  
Angular Momentum ◽  
Brain Injury ◽  
Impact Velocity ◽  
New Technologies ◽  
Expanded Polystyrene ◽  
Impact Testing ◽  
Superior Performance ◽  
Bicycle Helmet ◽  
Bicycle Helmets ◽  
The Impact

Cycling accidents are the leading cause of sports-related head injuries in the US. Conventional bicycle helmets typically consist of polycarbonate shell over Expanded Polystyrene (EPS) foam and are tested with drop tests to evaluate a helmet’s ability to reduce head kinematics. Within the last decade, novel helmet technologies have been proposed to mitigate brain injuries during bicycle accidents, which necessitates the evaluation of their effectiveness in impact testing as compared to conventional helmets. In this paper, we reviewed the literature to collect and analyze the kinematic data of drop test experiments carried out on helmets with different technologies. In order to provide a fair comparison across different types of tests, we clustered the datasets with respect to their normal impact velocities, impact angular momentum, and the type of neck apparatus. When we analyzed the data based on impact velocity and angular momentum clusters, we found that the bicycle helmets that used rotation damping based technology, namely MIPS, had significantly lower peak rotational acceleration (PRA) and Generalized Acceleration Model for Brain Injury Threshold (GAMBIT) as compared to the conventional EPS liner helmets (p < 0.01). SPIN helmets had a superior performance in PRA compared to conventional helmets (p < 0.05) in the impact angular momentum clustered group, but not in the impact-velocity clustered comparisons. We also analyzed other recently developed helmets that primarily use collapsible structures in their liners, such as WaveCel and Koroyd. In both of the impact velocity and angular momentum groups, helmets based on the WaveCel technology had significantly lower peak linear acceleration (PLA), PRA, and GAMBIT at low impact velocities as compared to the conventional helmets, respectively (p < 0.05). The protective gear with the airbag technology, namely Hövding, also performed significantly better compared to the conventional helmets in the analyzed kinematic-based injury metrics (p < 0.001), possibly due to its advantage in helmet size and stiffness. We also observed that the differences in the kinematic datasets strongly depend on the type of neck apparatus. Our findings highlight the importance and benefits of developing new technologies and impact testing standards for bicycle helmet designs for better prevention of traumatic brain injury (TBI).

Impact performance of innovative corrugated polystyrene foam for bicycle helmets

2020 ◽  
pp. 0021955X2096521
Author(s):  
Somen K Bhudolia ◽  
Goram Gohel ◽  
Kah Fai Leong
Keyword(s):  
Energy Absorption ◽  
High Speed ◽  
Head Injuries ◽  
Expanded Polystyrene ◽  
The Novel ◽  
Comparison Study ◽  
Impact Performance ◽  
Bicycle Helmets ◽  
Weight Property ◽  
The Impact

Expanded Polystyrene (EPS) is a common material used to manufacture the inner foam liner of a bicycle helmet due to its outstanding energy absorption characteristics and light-weight property. The current research presents a novel corrugated expanded polystyrene (EPS) foam design concept which is used to enhance the impact dissipation of bicycle helmets from the safety standpoint to reduce head injuries and make them lighter. The baseline comparison study under impact for different foam configurations is compared with a conventional EPS foam sample without corrugation. Corrugated foam designs under current investigation are 12.5–20% lighter and provide up to 10% higher energy absorption. The details of the novel manufacturing concept, CPSC 1203 helmet impact tests, high-speed camera study to understand the differences in the failure mechanisms are deliberated in this paper.

scholarly journals A Biomechanical Evaluation of a Novel Airbag Bicycle Helmet Concept for Traumatic Brain Injury Mitigation

2021 ◽  
Vol 8 (11) ◽  
pp. 173
Author(s):  
Kwong Ming Tse ◽  
Daniel Holder
Keyword(s):  
Traumatic Brain Injury ◽  
Brain Injury ◽  
Injury Risk ◽  
Synergetic Effect ◽  
Human Head ◽  
Head Model ◽  
Bicycle Helmet ◽  
Impact Simulations ◽  
The Impact ◽  
Helmet Design

In this study, a novel expandable bicycle helmet, which integrates an airbag system into the conventional helmet design, was proposed to explore the potential synergetic effect of an expandable airbag and a standard commuter-type EPS helmet. The traumatic brain injury mitigation performance of the proposed expandable helmet was evaluated against that of a typical traditional bicycle helmet. A series of dynamic impact simulations on both a helmeted headform and a representative human head with different configurations were carried out in accordance with the widely recognised international bicycle helmet test standards. The impact simulations were initially performed on a ballast headform for validation and benchmarking purposes, while the subsequent ones on a biofidelic human head model were used for assessing any potential intracranial injury. It was found that the proposed expandable helmet performed admirably better when compared to a conventional helmet design—showing improvements in impact energy attenuation, as well as kinematic and biometric injury risk reduction. More importantly, this expandable helmet concept, integrating the airbag system in the conventional design, offers adequate protection to the cyclist in the unlikely case of airbag deployment failure.

scholarly journals Experimental and Numerical Simulation Studies of RC Beams under the Actions of Equal Energy Impact Loads

2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
Xiwu Zhou ◽  
Xiangyu Wang ◽  
Runcheng Zhang ◽  
Wen Zhang
Keyword(s):  
Impact Velocity ◽  
Impact Force ◽  
Impact Testing ◽  
Rc Beams ◽  
Finite Element Software ◽  
Equal Energy ◽  
Drop Weight ◽  
Weight Impact ◽  
The Impact ◽  
Peak Value

In this study, two groups of RC beams were subjected to low-speed drop weight impact test by using the domestic advanced ultrahigh heavy-duty drop weight impact testing machine system. The main aspects studied are the influence of the combination of different impact velocity and mass on the dynamic response and local and global damage change of RC beam under the same impact energy. Next, the numerical model considering material strain rate is established using ABAQUS finite element software to verify and expand the experimental results. The results show the following: (1) under the condition of equal energy, the peak value of impact force measured in this experiment increases with the increase of impact velocity, yet the mid span displacement and rebar strain first increase and then decrease. In addition, when the impact velocity is 2.25 m/s and the impact mass is 400 kg, the beam has the most serious damage; (2) compared with the mass, the impact velocity has more obvious effects on the peak value of cumulative impact force, mid span displacement, and rebar strain; (3) with the decrease of the impact velocity (the increase of the mass), the local damage of the beam is gradually weakened and the overall damage is gradually exacerbated. The failure mode of the beam is transformed from local punching shear failure to overall static failure type.

scholarly journals The impact of bicycle helmet legislation on cycling fatalities in Australia

2019 ◽  
Vol 48 (4) ◽  
pp. 1197-1203 ◽  
Author(s):  
Jake Olivier ◽  
Sofiane Boufous ◽  
Raphael Grzebieta
Keyword(s):  
Head Injury ◽  
Interrupted Time Series ◽  
Bicycle Helmet ◽  
Australian Capital Territory ◽  
Helmet Use ◽  
Bicycle Helmets ◽  
Time Series Approach ◽  
Helmet Laws ◽  
The Impact ◽  
Robust Evidence

Abstract Background Australian bicycle helmet laws were first introduced in Victoria in July 1990 and the remaining Australian states, Australian Capital Territory and Northern Territory by July 1992. Previous research on helmet legislation has focused on changes in helmet wearing and bicycle-related head injury. Although it is generally accepted that bicycle helmets can reduce the risk of fatality due to head injury, there has been little research assessing the impact of helmet legislation on cycling fatalities. Methods An interrupted time series approach was used to assess the impact of bicycle helmet legislation on yearly-aggregated rates of bicycle-related fatalities per population from 1971 to 2016. Results Immediately following bicycle helmet legislation, the rate of bicycle fatalities per 1 000 000 population reduced by 46% relative to the pre-legislation trend [95% confidence interval (CI): 31, 58]. For the period 1990–2016, we estimate 1332 fewer cycling fatalities (95% CI: 1201, 1463) or an average of 49.4 per year (95% CI: 44.5, 54.2). Reductions were also observed for pedestrian fatalities; however, bicycle fatalities declined by 36% relative to pedestrian fatalities (95% CI: 12, 54). Conclusions In the absence of robust evidence showing a decline in cycling exposure following helmet legislation or other confounding factors, the reduction in Australian bicycle-related fatality appears to be primarily due to increased helmet use and not other factors.

EFFECTS OF IMPACT VELOCITY AND SLENDERNESS RATIO ON DYNAMIC BUCKLING LOAD FOR LONG COLUMNS

2008 ◽  
Vol 22 (31n32) ◽  
pp. 5596-5602 ◽  
Author(s):  
K. MIMURA ◽  
T. UMEDA ◽  
M. YU ◽  
Y. UCHIDA ◽  
H. YAKA
Keyword(s):  
Impact Velocity ◽  
Dynamic Load ◽  
Slenderness Ratio ◽  
Testing Machine ◽  
Dynamic Buckling ◽  
Impact Testing ◽  
Buckling Load ◽  
Square Function ◽  
Buckling Loads ◽  
The Impact

In this research, the buckling behavior of long columns under dynamic load was investigated both experimentally and numerically, and an effective buckling criterion for dynamic load was derived from the results in terms of the impact velocity and the slenderness ratio. In the experiments, a free fall drop-weight type impact testing machine was employed. The dynamic buckling loads were measured by the load sensing block, and the displacements were measured by a high speed magnetic-resistance device. In the numerical analyses, dynamic FEM code 'MSC-Dytran' was used to simulate the typical experimental results, and the validity and the accuracy of the simulations were checked. The dynamic buckling loads at various impact velocities were then systematically investigated. From both experimental and simulated results, it was found that the dynamic to static buckling load ratios can be successfully described as a square function of the slenderness ratio of the columns, while they can be also described by a power law of the applied impact velocity.

A Computational Study of Liquid Shock Absorption for Prevention of Traumatic Brain Injury

2020 ◽  
Author(s):  
Hossein Vahid Alizadeh ◽  
Michael G. Fanton ◽  
August G. Domel ◽  
Gerald Grant ◽  
David Camarillo
Keyword(s):  
Traumatic Brain Injury ◽  
Brain Injury ◽  
New Technologies ◽  
Computational Study ◽  
Impact Testing ◽  
American Football ◽  
Constant Force ◽  
Shock Absorption ◽  
Future Design ◽  
Football Helmets

Abstract Mild traumatic brain injury (mTBI), more colloquially known as concussion, is common in contact sports such as American football, leading to increased scrutiny of head protective gear. Standardized laboratory impact testing, such as the yearly NFL helmet test, is used to rank the protective performance of football helmets, motivating new technologies to improve the safety of helmets relative to existing equipment. In this work, we hypothesized that a helmet which transmits a nearly constant minimum force will result in a reduced risk of mTBI. To evaluate the plausibility of this hypothesis, we first show that the optimal force transmitted to the head, in a reduced order model of the brain, is in fact a constant force profile. To simulate the effects of a constant force within a helmet, we conceptualize a fluid-based shock absorber system for use within a football helmet. We integrate this system within a computational helmet model and simulate its performance on the standard NFL helmet test impact conditions. The simulated helmet is compared with other helmet designs with different technologies. Computer simulations of head impacts with liquid shock absorption predict that, at the highest impact speed (9.3 m/s), the average brain tissue strain is reduced by 27.6% ± 9.3 compared to existing helmet padding when tested on the NFL helmet protocol. This simulation-based study puts forth a target benchmark for the future design of physical manifestations of this technology.

scholarly journals A New Assessment of Bicycle Helmets: The Brain Injury Mitigation Effects of New Technologies in Oblique Impacts

2021 ◽  
Author(s):  
Fady Abayazid ◽  
Ke Ding ◽  
Karl Zimmerman ◽  
Helena Stigson ◽  
Mazdak Ghajari
Keyword(s):  
Brain Injury ◽  
Corpus Callosum ◽  
Brain Injuries ◽  
New Technologies ◽  
Rotational Velocity ◽  
Head Rotation ◽  
Oblique Impact ◽  
Bicycle Helmets ◽  
Oblique Impacts ◽  
The Brain

AbstractNew helmet technologies have been developed to improve the mitigation of traumatic brain injury (TBI) in bicycle accidents. However, their effectiveness under oblique impacts, which produce more strains in the brain in comparison with vertical impacts adopted by helmet standards, is still unclear. Here we used a new method to assess the brain injury prevention effects of 27 bicycle helmets in oblique impacts, including helmets fitted with a friction-reducing layer (MIPS), a shearing pad (SPIN), a wavy cellular liner (WaveCel), an airbag helmet (Hövding) and a number of conventional helmets. We tested whether helmets fitted with the new technologies can provide better brain protection than conventional helmets. Each helmeted headform was dropped onto a 45° inclined anvil at 6.3 m/s at three locations, with each impact location producing a dominant head rotation about one anatomical axes of the head. A detailed computational model of TBI was used to determine strain distribution across the brain and in key anatomical regions, the corpus callosum and sulci. Our results show that, in comparison with conventional helmets, the majority of helmets incorporating new technologies significantly reduced peak rotational acceleration and velocity and maximal strain in corpus callosum and sulci. Only one helmet with MIPS significantly increased strain in the corpus collosum. The helmets fitted with MIPS and WaveCel were more effective in reducing strain in impacts producing sagittal rotations and a helmet fitted with SPIN in coronal rotations. The airbag helmet was effective in reducing brain strain in all impacts, however, peak rotational velocity and brain strain heavily depended on the analysis time. These results suggest that incorporating different impact locations in future oblique impact test methods and designing helmet technologies for the mitigation of head rotation in different planes are key to reducing brain injuries in bicycle accidents.

scholarly journals Exploring the Relationship Between Mandatory Helmet Use Regulations and Adult Cyclists’ Behavior in California Using Hybrid Machine Learning Models

2021 ◽  
Author(s):  
Fatemeh Davoudi Kakhki ◽  
Maria Chierichetti
Keyword(s):  
Machine Learning ◽  
Sociodemographic Characteristics ◽  
Bicycle Helmet ◽  
Learning Models ◽  
Helmet Use ◽  
Bicycle Helmets ◽  
Hybrid Machine ◽  
The Impact ◽  
The Relationship ◽  
Machine Learning Models

In California, bike fatalities increased by 8.1% from 2015 to 2016. Even though the benefits of wearing helmets in protecting cyclists against trauma in cycling crash has been determined, the use of helmets is still limited, and there is opposition against mandatory helmet use, particularly for adults. Therefore, exploring perceptions of adult cyclists regarding mandatory helmet use is a key element in understanding cyclists’ behavior, and determining the impact of mandatory helmet use on their cycling rate. The goal of this research is to identify sociodemographic characteristics and cycling behaviors that are associated with the use and non-use of bicycle helmets among adults, and to assess if the enforcement of a bicycle helmet law will result in a change in cycling rates. This research develops hybrid machine learning models to pinpoint the driving factors that explain adult cyclists’ behavior regarding helmet use laws.

Age Does Not Affect the Material Properties of Expanded Polystyrene Liners in Field-Used Bicycle Helmets

2016 ◽  
Vol 138 (4) ◽  
Author(s):  
Shannon G. Kroeker ◽  
Stephanie J. Bonin ◽  
Alyssa L. DeMarco ◽  
Craig A. Good ◽  
Gunter P. Siegmund
Keyword(s):  
Strain Curve ◽  
Expanded Polystyrene ◽  
Stress Strain Curve ◽  
Yield Strain ◽  
Stress Strain ◽  
Bicycle Helmets ◽  
Dependent Variables ◽  
Impact Attenuation ◽  
Age Range ◽  
The Impact

Bicycle helmet foam liners absorb energy during impacts. Our goal was to determine if the impact attenuation properties of expanded polystyrene (EPS) foam used in bicycle helmets change with age. Foam cores were extracted from 63 used and unused bicycle helmets from ten different models spanning an age range of 2–20 yrs. All cores were impact tested at a bulk strain rate of 195 s−1. Six dependent variables were determined from the stress–strain curve derived from each impact (yield strain, yield stress, elastic modulus, plateau slope, energy at 65% compression, and stress at 65% compression), and a general linear model was used to assess the effect of age on each dependent variable with density as a covariate. Age did not affect any of the dependent variables; however, greater foam density, which varied from 58 to 100 kg/m3, generated significant increases in all of the dependent variables except for yield strain. Higher density foam cores also exhibited lower strains at which densification began to occur, tended to stay within the plateau region of the stress–strain curve, and were not compressed as much compared with the lower density cores. Based on these data, the impact attenuation properties of EPS foam in field-used bicycle helmets do not degrade with the age.

Study on Impact Protection Properties of Titanium Alloy Using Modified SHPB

2013 ◽  
Vol 302 ◽  
pp. 14-19 ◽  
Author(s):  
Jie Liu ◽  
Jin Xu Liu ◽  
Hong Sheng Ding ◽  
Shu Kui Li ◽  
Yu Meng Luo
Keyword(s):  
Impact Velocity ◽  
Loading Condition ◽  
Hopkinson Bar ◽  
Impact Testing ◽  
Direct Impact ◽  
Protective Properties ◽  
Impact Protection ◽  
Protective Performance ◽  
The Impact ◽  
Modified Hopkinson Bar

In order to evaluate the impact protection capacity of armor material quantitatively, direct impact testing loaded by modified Hopkinson bar was used to simulate the impaction between penetrator and armor. Protection coefficient k was defined to describe the protective performance. Using the direct impact testing, Ti-6Al-4V specimens with different microstructure and thickness were tested. Results show that k decreases with increased impact velocity and increases with increased thickness of specimen. Under a given loading condition, binary microstructure exhibits the highest k, indicating the best protective performance. Moreover, its k shows the most sensitivity to thickness (mt) and the least sensitivity to impact energy (me), which means that its protective performance can be improved most efficiently by increasing its thickness and it will exhibit good protective performance in a wider impact velocity range. This new method can evaluate the impact protective properties of armor materials efficiently, which may have a broad application prospect.

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