The Effects of Helmet Weight on Hybrid III Head and Neck Responses by Comparing Unhelmeted and Helmeted Impacts

Most studies on football helmet performance focus on lowering head acceleration-related parameters to reduce concussions. This has resulted in an increase in helmet size and mass. The objective of this paper was to study the effect of helmet mass on head and upper neck responses. Two independent test series were conducted. In test series one, 90 pendulum impact tests were conducted with four different headform and helmet conditions: unhelmeted Hybrid III headform, Hybrid III headform with a football helmet shell, Hybrid III headform with helmet shell and facemask, and Hybrid III headform with the helmet and facemask with mass added to the shell (n = 90). The Hybrid III neck was used for all the conditions. For all the configurations combined, the shell only, shell and facemask, and weighted helmet conditions resulted in 36%, 43%, and 44% lower resultant head accelerations (p < 0.0001), respectively, when compared to the unhelmeted condition. Head delta-V reductions were 1.1%, 4.5%, and 4.4%, respectively. In contrast, the helmeted conditions resulted in 26%, 41%, and 49% higher resultant neck forces (p < 0.0001), respectively. The increased neck forces were dominated by neck tension. In test series two, testing was conducted with a pneumatic linear impactor (n = 178). Fourteen different helmet makes and models illustrate the same trend. The increased neck forces provide a possible explanation as to why there has not been a corresponding reduction in concussion rates despite improvements in helmets ability to reduce head accelerations.

Download Full-text

Crash-test dummy and pendulum impact tests of ice hockey boards: greater displacement does not reduce impact

British Journal of Sports Medicine ◽

10.1136/bjsports-2017-097735 ◽

2017 ◽

Vol 52 (1) ◽

pp. 41-46 ◽

Cited By ~ 2

Author(s):

Kai-Uwe Schmitt ◽

Markus H Muser ◽

Hansjuerg Thueler ◽

Othmar Bruegger

Keyword(s):

Injury Risk ◽

Ice Hockey ◽

Crash Test ◽

Head Acceleration ◽

Impact Tests ◽

Body Regions ◽

Biomechanical Loading ◽

Risk Of Injury ◽

Crash Test Dummy ◽

Pendulum Impact

BackgroundOne injury mechanism in ice hockey is impact with the boards. We investigated whether more flexible hockey boards would provide less biomechanical loading on impact than did existing (reference) boards.MethodsWe conducted impact tests with a dynamic pendulum (mass 60 kg) and with crash test dummies (ES-2 dummy, 4.76 m/s impact speed). Outcomes were biomechanical loading experienced by a player in terms of head acceleration, impact force to the shoulder, spine, abdomen and pelvis as well as compression of the thorax.ResultsThe more flexible board designs featured substantial displacement at impact. Some so-called flexible boards were displaced four times more than the reference board. The new boards possessed less stiffness and up to 90 kg less effective mass, reducing the portion of the board mass a player experienced on impact, compared with boards with a conventional design. Flexible boards resulted in a similar or reduced loading for all body regions, apart from the shoulder. The displacement of a board system did not correlate directly with the biomechanical loading.ConclusionsFlexible board systems can reduce the loading of a player on impact. However, we found no correlation between the displacement and the biomechanical loading; accordingly, displacement alone was insufficient to characterise the overall loading of a player and thus the risk of injury associated with board impact. Ideally, the performance of boards is assessed on the basis of parameters that show a good correlation to injury risk.

Download Full-text

A Six Degree of Freedom Head Acceleration Measurement Device for Use in Football

Journal of Applied Biomechanics ◽

10.1123/jab.27.1.8 ◽

2011 ◽

Vol 27 (1) ◽

pp. 8-14 ◽

Cited By ~ 91

Author(s):

Steven Rowson ◽

Jonathan G. Beckwith ◽

Jeffrey J. Chu ◽

Daniel S. Leonard ◽

Richard M. Greenwald ◽

...

Keyword(s):

Degree Of Freedom ◽

Head Acceleration ◽

Wireless Data ◽

Measurement Device ◽

Football Helmet ◽

Wireless Data Transmission ◽

Hybrid Iii ◽

Football Helmets ◽

High Incidence Rate ◽

Six Degree Of Freedom

The high incidence rate of concussions in football provides a unique opportunity to collect biomechanical data to characterize mild traumatic brain injury. The goal of this study was to validate a six degree of freedom (6DOF) measurement device with 12 single-axis accelerometers that uses a novel algorithm to compute linear and angular head accelerations for each axis of the head. The 6DOF device can be integrated into existing football helmets and is capable of wireless data transmission. A football helmet equipped with the 6DOF device was fitted to a Hybrid III head instrumented with a 9 accelerometer array. The helmet was impacted using a pneumatic linear impactor. Hybrid III head accelerations were compared with that of the 6DOF device. For all impacts, peak Hybrid III head accelerations ranged from 24 g to 176 g and 1,506 rad/s2to 14,431 rad/s2. Average errors for peak linear and angular head acceleration were 1% ± 18% and 3% ± 24%, respectively. The average RMS error of the temporal response for each impact was 12.5 g and 907 rad/s2.

Download Full-text

Finite Element Model Validation of the Hybrid-III Rail Safety (H3-RS) Anthropomorphic Test Device (ATD)

Volume 13: Design, Reliability, Safety, and Risk ◽

10.1115/imece2018-87736 ◽

2018 ◽

Author(s):

Shaun Eshraghi ◽

Kristine Severson ◽

David Hynd ◽

A. Benjamin Perlman

Keyword(s):

Finite Element ◽

Public Transportation ◽

Crash Test ◽

Fe Model ◽

Test Device ◽

Sled Test ◽

Impact Tests ◽

Hybrid Iii ◽

Pendulum Impact ◽

Vertical Impact

The Hybrid-III Rail Safety (H3-RS) anthropomorphic test device (ATD), also known as a crash test dummy, was developed by the Rail Safety and Standards Board (RSSB), DeltaRail (now Resonate Group Ltd.), and the Transport Research Laboratory (TRL) in the United Kingdom between 2002 and 2005 for passenger rail safety applications [1]. The H3-RS is a modification of the standard Hybrid-III 50th percentile male (H3-50M) ATD with additional features in the chest and abdomen to increase its biofidelity and eight sensors to measure deflection. The H3-RS features bilateral (left and right) deflection sensors in the upper and lower chest and in the upper and lower abdomen; whereas, the standard H3-50M only features a single unilateral (center) deflection sensor in the chest with no deflection sensors located in the abdomen. Additional H3-RS research was performed by the Volpe National Transportation Systems Center (Volpe Center) under the direction of the U.S. Department of Transportation, Federal Railroad Administration (FRA) Office of Research, Development, and Technology. The Volpe Center contracted with TRL to conduct a series of dynamic pendulum impact tests [2]. The goal of testing the abdomen response of the H3-RS ATD was to develop data to refine an abdomen design that produces biofidelic and repeatable results under various impact conditions with respect to impactor geometry, vertical impact height, and velocity. In this study, the abdominal response of the H3-RS finite element (FE) model that TRL developed is validated using the results from pendulum impact tests [2]. Results from the pendulum impact tests and corresponding H3-RS FE simulations are compared using the longitudinal relative deflection measurements from the internal sensors in the chest and abdomen as well as the longitudinal accelerometer readings from the impactor. The abdominal response of the H3-RS FE model correlated well with the physical ATD as the impactor geometry, vertical impact height, and velocity were changed. There were limitations with lumbar positioning of the H3-RS FE model as well as the material definition for the relaxation rate of the foam in the abdomen that can be improved in future work. The main goal of validating the abdominal response of the dummy model is to enable its use in assessing injury potential in dynamic sled testing of crashworthy workstation tables, the results of which are presented in a companion paper [3]. The authors used the model of the H3-RS ATD to study the 8G sled test specified in the American Public Transportation Association (APTA) workstation table safety standard [4]. The 8G sled test is intended to simulate the longitudinal crash accleration in a severe train-to-train collision involving U.S. passenger equipment. Analyses of the dynamic sled test are useful for studying the sensitivity of the sled test to factors such as table height, table force-crush behavior, seat pitch, etc., which help to inform discussions on revisions to the test requirements eventually leading to safer seating environments for passengers.

Download Full-text

Head acceleration measurement techniques: Reliability of angular rate sensor data in helmeted impact testing

Proceedings of the Institution of Mechanical Engineers Part P Journal of Sports Engineering and Technology ◽

10.1177/1754337117708092 ◽

2017 ◽

Vol 232 (2) ◽

pp. 176-181 ◽

Cited By ~ 5

Author(s):

Bryan R Cobb ◽

Abigail M Tyson ◽

Steven Rowson

Keyword(s):

Root Mean Square ◽

Angular Rate ◽

Angular Acceleration ◽

Impact Testing ◽

Sensor Data ◽

Mean Square ◽

Head Acceleration ◽

Angular Rate Sensor ◽

Impact Tests ◽

Rate Sensor

This study sought to evaluate the suitability of angular rate sensors for quantifying angular acceleration in helmeted headform impacts. A helmeted Hybrid III headform, instrumented with a 3-2-2-2 nine accelerometer array and angular rate sensors, was impacted (n = 90) at six locations and three velocities (3.1, 4.9, and 6.4 m/s). Data were low-pass filtered using Butterworth four-pole phaseless digital filters which conform to the specifications described in the Society of Automotive Engineers J211 standard on instrumentation for impact tests. Nine accelerometer array data were filtered using channel frequency class 180, which corresponds to a −3 db cutoff frequency of 300 Hz. Angular rate sensor data were filtered using channel frequency class values ranging from 5 to 1000 Hz in increments of 5 Hz, which correspond to −3 db cutoff frequencies of 8 to 1650 Hz. Root-mean-square differences in peak angular acceleration between the two instrumentation schemes were assessed for each channel frequency class value. Filtering angular rate sensor data with channel frequency class values between 120 and 205 all produced mean differences within ±5%. The minimum root-mean-square difference of 297 rad/s2 was found when the angular rate sensor data were filtered using channel frequency class 175. This filter specification resulted in a mean difference of 28 ± 297 rad/s2 (1.8% ± 8.6%). Condition-specific differences (α=0.05) were observed for 11 of 18 test conditions. A total of 4 of those 11 conditions were within ±5%, and 10 were within ±10%. Furthermore, the nine accelerometer array and angular rate sensor methods demonstrated similar levels of repeatability. These data suggest that angular rate sensor may be an appropriate alternative to the nine accelerometer array for measuring angular head acceleration in helmeted head impact tests with impactor velocities of 3.1–6.4 m/s and impact durations of approximately 10 ms.

Download Full-text

Development of an Improved Dummy Head for Use in Helmet Certification Tests

10.1115/imece2000-2479 ◽

2000 ◽

Author(s):

Eric H. L. A. van den Bosch ◽

Martijn W. B. M. Leensen ◽

Nancy H. M. Klomp ◽

Fons A. A. H. J. Sauren ◽

Jac S. H. M. Wismans

Keyword(s):

Brain Structure ◽

Evaluation Process ◽

Drop Test ◽

Head Acceleration ◽

First Order ◽

Certification Tests ◽

Hybrid Iii

Abstract First order improvements to the rigid headform, used in current helmet certification tests, are made by introducing a skull and brain structure. In developing the new headform certain requirements were taken into consideration. The new headform appears to meet all requirements but one. The 200 mm drop test with Hybrid-III skin padding on the anvil resulted in too low resultant linear head accelerations. Using a stiffer, more realistic padding on the anvil resulted in a resultant linear head acceleration which satisfies the requirements (100 – 150 g). The padding plays an important role in the evaluation process. Because of the deformable skull, a fairly stiff padding has to be used in order to let the resultant linear head acceleration satisfy the requirements. In contrast to the 200 mm drop test experiments, the padding properties of the skin are of no importance when an EPS padding is placed between the skin and the anvil.

Download Full-text

The Influence of Hard Hat Design Features on Head Acceleration Attenuation

Journal of Applied Biomechanics ◽

10.1123/jab.2020-0182 ◽

2020 ◽

pp. 1-7

Author(s):

Arthur Alves Dos Santos ◽

James Sorce ◽

Alexandra Schonning ◽

Grant Bevill

Keyword(s):

Lead Shot ◽

Construction Site ◽

Head Acceleration ◽

Protective Capacity ◽

Design Features ◽

Shell Design ◽

Hybrid Iii ◽

Hard Hat ◽

Head Neck

This study evaluated the performance of 6 commercially available hard hat designs—differentiated by shell design, number of suspension points, and suspension tightening system—in regard to their ability to attenuate accelerations during vertical impacts to the head. Tests were conducted with impactor materials of steel, wood, and lead shot (resembling commonly seen materials in a construction site), weighing 1.8 and 3.6 kg and dropped from 1.83 m onto a Hybrid III head/neck assembly. All hard hats appreciably reduced head acceleration to the unprotected condition. However, neither the addition of extra suspension points nor variations in suspension tightening mechanism appreciably influenced performance. Therefore, these results indicate that additional features available in current hard hat designs do not improve protective capacity as related to head acceleration metrics.

Download Full-text

The Effects of Curtain Airbag on Occupant Kinematics and Injury Index in Rollover Crash

Applied Bionics and Biomechanics ◽

10.1155/2018/4980413 ◽

2018 ◽

Vol 2018 ◽

pp. 1-12

Author(s):

Hongyun Li ◽

Chengyue Jiang ◽

Dong Cui ◽

Shuang Lu

Keyword(s):

Restraint System ◽

Head Acceleration ◽

Physical Test ◽

Injury Index ◽

Hybrid Iii ◽

Protection Area ◽

Occupant Injuries ◽

Occupant Kinematics ◽

Head And Neck Injury ◽

Rollover Crash

Background. Occupant injuries in rollover crashes are associated with vehicle structural performance, as well as the restraint system design. For a better understanding of the occupant kinematics and injury index in certain rollover crash, it is essential to carry out dynamic vehicle rollover simulation with dummy included. Objective. This study focused on effects of curtain airbag (CAB) parameters on occupant kinematics and injury indexes in a rollover crash. Besides, optimized parameters of the CAB were proposed for the purpose of decreasing the occupant injuries in such rollover scenario. Method and Material. The vehicle motion from the physical test was introduced as the input for the numerical simulation, and the 50% Hybrid III dummy model from the MADYMO database was imported into a simulation model. The restraint system, including a validated CAB module, was introduced for occupant kinematics simulation and injury evaluation. TTF setting, maximum inflator pressure, and protection area of the CAB were analysed. Results. After introducing the curtain airbag, the maximum head acceleration was reduced from 91.60 g to 49.52 g, and the neck Mx and neck Fz were reduced significantly. Among these CAB parameters, the TTF setting had the largest effect on the head acceleration which could reduce 8.6 g furthermore after optimization. The neck Fz was decreased from 3766.48 N to 2571.77 N after optimization of CAB protection area. Conclusions. Avoiding hard contact is critical for the occupant protection in the rollover crashes. The simulation results indicated that occupant kinematics and certain injury indexes were improved with the help of CAB in such rollover scenario. Appropriate TTF setting and inflator selection could benefit occupant kinematics and injury indexes. Besides, it was advised to optimize the curtain airbag thickness around the head contact area to improve head and neck injury indexes.

Download Full-text