The influence of deflection and neck compliance on the impact dynamics of a Hybrid III headform

2009 ◽  
Vol 223 (3) ◽  
pp. 89-97 ◽  
Author(s):  
P Rousseau ◽  
T B Hoshizaki
Keyword(s):  
Angular Acceleration ◽  
Linear Acceleration ◽  
Severity Index ◽  
Impact Dynamics ◽  
Risk Of Injury ◽  
Lateral Translation ◽  
Hybrid Iii ◽  
Front Impact ◽  
The Impact

The objective of this study was to determine the influence of impact deflection and neck compliance on the Gadd severity index (GSI), peak linear acceleration, and peak angular acceleration during a front impact to a Hybrid III head using a pneumatic linear impactor. Impact deflection was performed by translating the headform laterally and was shown to be effective at reducing the linear and angular accelerations as well as the GSI. Neck compliance was altered using one Hybrid III 50th percentile neck and two modified Hybrid III necks. A less compliant neck increased linear acceleration but decreased angular acceleration and GSI. When compared with estimated injury thresholds, the results demonstrated that an increase in the lateral translation or a decrease in the neck compliance resulted in a significant decrease in the risk of injury as reflected by peak linear and angular accelerations and the GSI.

scholarly journals Impact test comparisons of 20th and 21st century American football helmets

2012 ◽  
Vol 116 (1) ◽  
pp. 222-233 ◽  
Author(s):  
Adam Bartsch ◽  
Edward Benzel ◽  
Vincent Miele ◽  
Vikas Prakash
Keyword(s):  
Head Injury ◽  
21St Century ◽  
Injury Risk ◽  
Diffuse Axonal Injury ◽  
Angular Acceleration ◽  
Linear Acceleration ◽  
Severity Index ◽  
Head Impact ◽  
American Football ◽  
Acute Subdural Hematoma

Object Concussion is the signature American football injury of the 21st century. Modern varsity helmets, as compared with vintage leather helmets, or “leatherheads,” are widely believed to universally improve protection by reducing head impact doses and head injury risk for the 3 million young football players in the US. The object of this study was to compare the head impact doses and injury risks with 11 widely used 21st century varsity helmets and 2 early 20th century leatherheads and to hypothesize what the results might mean for children wearing similar varsity helmets. Methods In an injury biomechanics laboratory, the authors conducted front, oblique front, lateral, oblique rear, and rear head impact tests at 5.0 m/second using helmeted headforms, inducing near- and subconcussive head impact doses on par with approximately the 95th percentile of on-field collision severity. They also calculated impact dose injury risk parameters common to laboratory and on-field traumatic neuromechanics: linear acceleration, angular acceleration, angular velocity, Gadd Severity Index, diffuse axonal injury, acute subdural hematoma, and brain contusion. Results In many instances the head impact doses and head injury risks while wearing vintage leatherheads were comparable to or better than those while wearing several widely used 21st century varsity helmets. Conclusions The authors do not advocate reverting to leather headgear, but they do strongly recommend, especially for young players, instituting helmet safety designs and testing standards, which encourage the minimization of linear and angular impact doses and injury risks in near- and subconcussive head impacts.

Head Kinematics in Mini-Sled Tests of Foam Padding: Relevance of Linear Responses From Free Motion Headform (FMH) Testing to Head Angular Responses

2003 ◽  
Vol 125 (4) ◽  
pp. 523-532 ◽  
Author(s):  
J. Ivarsson ◽  
D. C. Viano ◽  
P. Lo¨vsund ◽  
Y. Parnaik
Keyword(s):  
Angular Velocity ◽  
Brain Injuries ◽  
Motor Vehicle ◽  
Sagittal Plane ◽  
Angular Acceleration ◽  
Linear Acceleration ◽  
Free Motion ◽  
Constant Thickness ◽  
Head Impacts ◽  
Hybrid Iii

The revised Federal Motor Vehicle Safety Standard (FMVSS) No. 201 specifies that the safety performance of vehicle upper interiors is determined from the resultant linear acceleration response of a free motion headform (FMH) impacting the interior at 6.7 m/s. This study addresses whether linear output data from the FMH test can be used to select an upper interior padding that decreases the likelihood of rotationally induced brain injuries. Using an experimental setup consisting of a Hybrid III head-neck structure mounted on a mini-sled platform, sagittal plane linear and angular head accelerations were measured in frontal head impacts into foam samples of various stiffness and density with a constant thickness (51 mm) at low (∼5.0 m/s), intermediate (∼7.0 m/s), and high (∼9.6 m/s) impact speeds. Provided that the foam samples did not bottom out, recorded peak values of angular acceleration and change in angular velocity increased approximately linearly with increasing peak resultant linear acceleration and value of the Head Injury Criterion HIC36. The results indicate that the padding that produces the lowest possible peak angular acceleration and peak change in angular velocity without causing high peak forces is the one that produces the lowest possible HIC36 without bottoming out in the FMH test.

Design of Dual Layer Liner with Deformable Semi-Spherical Convex for Bicycle Helmet

2013 ◽  
Vol 284-287 ◽  
pp. 681-686
Author(s):  
Tso Liang Teng ◽  
Cho Chung Liang ◽  
Van Hai Nguyen
Keyword(s):  
Finite Element ◽  
Heat Dissipation ◽  
Linear Acceleration ◽  
Liner Material ◽  
Bicycle Helmets ◽  
Risk Of Injury ◽  
Standard Finite Element Method ◽  
Energy Absorbing ◽  
The Impact ◽  
Impact Absorption

Bicycle helmets aim to reduce the risk of injury due to impacts on the head. Generally, a bike helmet consists of the outer shell, liner, vents and straps. The liner helps absorb the effects of the impact to keep that force away from your head. To satisfy the functions of helmet liner, several criteria should be considered. The ideal liner would be stiffer in hard impacts, softer in lighter impacts, light, cheap, reliable to manufacture and easy to ventilate. Currently, there are many different design trends and concepts in the design of helmet liner. Researchers have tended to focus on the liner material. The Expended Polystyrene (EPS) foam is the most popular choice for liner material of helmet. The EPS foam is commonly used in helmets as an energy absorbing liner. However, EPS has some disadvantages, such as the difficulty to optimize energy absorbing in different areas of head and inferior effect of heat dissipation. Moreover, EPS is generally too brittle. In order to overcome its drawback, to search a better alternative is necessary. In this study, a dual layer liner is proposed to yield enhanced impact absorption, that is to say, the liner is constructed by two layers of polycarbonate with deformable semi-spherical convex. The energy absorbed by deformation of convexes which is described by a combination of folding and collapsing. The main advantages of this liner design not only show the energy absorbing capabilities like EPS foam but also gain a better optimization of energy absorbing for different sites. This study focuses on assessment of a helmet with dual layer liner based on the shock absorbing test of CPSC’s standard. Finite element method (FEM) is available contribution greatly to helmet test modeling. This study performs finite element analyses of helmet impact tests using LS-DYNA software. The simulation of helmeted headform drop test is implemented for the four kinds of liner thickness. To confirm the energy absorbing capabilities of dual layer liner, the resultant CG linear acceleration of the headform is measured from the helmet test simulation. According to the CPSC’s standard specification, the acceleration of headform should be less than 300 g's during the impact.

Risk assessment in different Judo techniques for children and adolescent athletes

2020 ◽  
Vol 234 (7) ◽  
pp. 686-696
Author(s):  
Luca Vacca ◽  
Valeria Rosso ◽  
Laura Gastaldi
Keyword(s):  
Head Injury ◽  
Injury Risk ◽  
Inertial Sensors ◽  
Angular Acceleration ◽  
Linear Acceleration ◽  
Severity Index ◽  
Time Duration ◽  
Neck Extension ◽  
Children And Adolescent ◽  
Experience Levels

Judo is a combat sport that involves throwing the opponent onto the back. When being thrown, head biomechanics may be related to head injury risk. This study aimed to assess head injury risks associated with four Judo techniques in children and adolescents with different experience levels. Twenty children (<12 years) and 20 adolescents (≥ 12 years) judoka were recruited. Each group was divided into non-expert and expert. Two inertial sensors were fixed on fallers’ head and torso. Two backward ( o-soto-gari and o-uchi-gari) and two forward ( ippon-seoi-nage and tai-otoshi) techniques were performed. Peak of linear and angular head acceleration magnitude, impact time duration, neck angle, and the Gadd Severity Index were assessed. Children did not show differences between techniques or experience levels. In contrast, adolescents showed greater linear acceleration peak in o-soto-gari than tai-otoshi (p = 0.03), greater angular acceleration peak in o-soto-gari and o-uchi-gari than ippon-seoi-nage (p < 0.05), and greater neck flexion in o-uchi-gari than ippon-seoi-nage (p = 0.004). Compared to expert adolescents, non-expert adolescents showed greater angular acceleration peak, impact duration, and the Gadd Severity Index in o-soto-gari (p < 0.05) and greater neck extension in o-uchi-gari (p = 0.02). Current results pointed out higher risks for adolescents judoka while being thrown with backward techniques, especially for non-expert participants. This study highlights the need of training athletes in controlling head and neck during back falls from a young age to become expert judoka in adulthood.

scholarly journals Concussion and the severity of head impacts in mixed martial arts

2020 ◽  
Vol 234 (12) ◽  
pp. 1472-1483 ◽  
Author(s):  
Stephen Tiernan ◽  
Aidan Meagher ◽  
David O’Sullivan ◽  
Eoin O’Keeffe ◽  
Eoin Kelly ◽  
...  
Keyword(s):  
Martial Arts ◽  
Angular Acceleration ◽  
Linear Acceleration ◽  
Head Impact ◽  
Sensor Technology ◽  
Mixed Martial Arts ◽  
Head Impacts ◽  
Impact Power ◽  
Average Maximum ◽  
The Impact

Concern about the consequences of head impacts in US football has motivated researchers to investigate and develop instrumentation to measure the severity of these impacts. However, the severity of head impacts in unhelmeted sports is largely unknown as miniaturised sensor technology has only recently made it possible to measure these impacts in vivo. The objective of this study was to measure the linear and angular head accelerations in impacts in mixed martial arts, and correlate these with concussive injuries. Thirteen mixed martial arts fighters were fitted with the Stanford instrumented mouthguard (MiG2.0) participated in this study. The mouthguard recorded linear acceleration and angular velocity in 6 degrees of freedom. Angular acceleration was calculated by differentiation. All events were video recorded, time stamped and reported impacts confirmed. A total of 451 verified head impacts above 10g were recorded during 19 sparring events (n = 298) and 11 competitive events (n = 153). The average resultant linear acceleration was 38.0624.3g while the average resultant angular acceleration was 256761739 rad/s2. The competitive bouts resulted in five concussions being diagnosed by a medical doctor. The average resultant acceleration (of the impact with the highest angular acceleration) in these bouts was 86.7618.7g and 756163438 rad/s2. The average maximum Head Impact Power was 20.6kW in the case of concussion and 7.15kW for the uninjured athletes. In conclusion, the study recorded novel data for sub-concussive and concussive impacts. Events that resulted in a concussion had an average maximum angular acceleration that was 24.7% higher and an average maximum Head Impact Power that was 189% higher than events where there was no injury. The findings are significant in understanding the human tolerance to short-duration, high linear and angular accelerations.

scholarly journals A Rational Numerical Method for Simulation of Drop-Impact Dynamics of Oleo-Pneumatic Landing Gear

2021 ◽  
Vol 11 (9) ◽  
pp. 4136
Author(s):  
Rosario Pecora
Keyword(s):  
Numerical Method ◽  
Initial Conditions ◽  
Impact Load ◽  
Numerical Models ◽  
Landing Gear ◽  
Design Stage ◽  
Impact Dynamics ◽  
State Variables ◽  
Adopted Model ◽  
The Impact

Oleo-pneumatic landing gear is a complex mechanical system conceived to efficiently absorb and dissipate an aircraft’s kinetic energy at touchdown, thus reducing the impact load and acceleration transmitted to the airframe. Due to its significant influence on ground loads, this system is generally designed in parallel with the main structural components of the aircraft, such as the fuselage and wings. Robust numerical models for simulating landing gear impact dynamics are essential from the preliminary design stage in order to properly assess aircraft configuration and structural arrangements. Finite element (FE) analysis is a viable solution for supporting the design. However, regarding the oleo-pneumatic struts, FE-based simulation may become unpractical, since detailed models are required to obtain reliable results. Moreover, FE models could not be very versatile for accommodating the many design updates that usually occur at the beginning of the landing gear project or during the layout optimization process. In this work, a numerical method for simulating oleo-pneumatic landing gear drop dynamics is presented. To effectively support both the preliminary and advanced design of landing gear units, the proposed simulation approach rationally balances the level of sophistication of the adopted model with the need for accurate results. Although based on a formulation assuming only four state variables for the description of landing gear dynamics, the approach successfully accounts for all the relevant forces that arise during the drop and their influence on landing gear motion. A set of intercommunicating routines was implemented in MATLAB® environment to integrate the dynamic impact equations, starting from user-defined initial conditions and general parameters related to the geometric and structural configuration of the landing gear. The tool was then used to simulate a drop test of a reference landing gear, and the obtained results were successfully validated against available experimental data.

Will We Lose If We Lose You? Players’ Absence, Teams’ Performance and the Overlapping of Competitions

2021 ◽  
pp. 152700252110084
Author(s):  
Levi Pérez
Keyword(s):  
Negative Impact ◽  
Potential Cost ◽  
Psychological Momentum ◽  
Risk Of Injury ◽  
European Football ◽  
The Impact

It is common for elite players to represent their respective countries in international competitions. However, there is a potential cost to the club team derived from that situation (risk of injury, fatigue, psychological momentum, etc.). This paper evaluates the impact of players’ absence on European football teams’ performance by focusing on the Africa Cup of Nations as the case study. The results indicate that the sending of players to the African tournament has a relatively small negative impact on teams’ performance. But this cannot be generalized to all the leagues and loses significance when corrected by players’ abilities.

Tinnitus Impact: Three Different Measurement Tools

2003 ◽  
Vol 14 (04) ◽  
pp. 181-187 ◽  
Author(s):  
Christopher D. Bauch ◽  
Susan G. Lynn ◽  
Donald E. Williams ◽  
Michael W. Mellon ◽  
Amy L. Weaver
Keyword(s):  
Quality Of Life ◽  
Severity Index ◽  
Assessment Tools ◽  
Symptom Checklist ◽  
Tinnitus Handicap Inventory ◽  
Measurement Tools ◽  
Medical Population ◽  
High Level ◽  
The Impact

The impact of tinnitus and overall levels of distress were measured with three assessment tools for patients with tinnitus. The Tinnitus Handicap Inventory (THI), the Symptom Checklist-90-Revised (SCL-90-R) and an activities limitations questionnaire were administered to 53 audiology patients reporting tinnitus. Forty-three percent of these patients experienced either quality of life reductions associated with tinnitus, substantial perceived handicap, and/or a high level of distress. Results from the General Severity Index (GSI) of the SCL-90-R indicated that 25% of these patients displayed distress greater than that of the general medical population. The SCL-90-R can be a useful tool for audiologists working with tinnitus patients in assessing needs for referral for psychological or psychiatric counseling.

scholarly journals Sex differences in self-report anxiety and sleep quality during COVID-19 stay-at-home orders

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Jeremy A. Bigalke ◽  
Ian M. Greenlund ◽  
Jason R. Carter
Keyword(s):  
Sex Differences ◽  
Sleep Quality ◽  
State Anxiety ◽  
Severity Index ◽  
Self Report ◽  
Analysis Of Covariance ◽  
Chi Square ◽  
Perceived Impact ◽  
The Impact ◽  
At Home

Abstract Background COVID-19 and home isolation has impacted quality of life, but the perceived impact on anxiety and sleep remains equivocal. The purpose of this study was to assess the impact of COVID-19 and stay-at-home orders on self-report anxiety and sleep quality, with a focus on sex differences. We hypothesized that the COVID-19 pandemic would be associated with increased anxiety and decreased sleep quality, with stronger associations in women. Methods One hundred three participants (61 female, 38 ± 1 years) reported perceived changes in anxiety and sleep quality due to stay-at-home orders during the COVID-19 pandemic and were administered the Spielberger State-Trait Anxiety Inventory (STAI), Pittsburgh Sleep Quality Index (PSQI), and Insomnia Severity Index (ISI). Chi-square and T test analyses were utilized to assess sex differences in reported anxiety and sleep. Analysis of covariance was used to compare the associations between reported impact of COVID-19 and anxiety/sleep parameters. Results Women (80.3%) reported higher prevalence of increased general anxiety due to COVID-19 when compared to men (50%; p = 0.001) and elevated STAI state anxiety compared to men (43 ± 1 vs. 38 ± 1 a.u., p = 0.007). Despite these differences in anxiety, the perceived impact of COVID-19 on PSQI was not different between sexes. However, when stratified by perceived changes in anxiety due to COVID-19, participants with higher anxiety responses to COVID-19 had higher ISI compared to those with no perceived changes in anxiety (9 ± 1 vs. 5 ± 1 a.u., p = 0.003). Additionally, participants who reported reduced sleep quality due to COVID-19 reported higher state anxiety (45 ± 1 a.u.) compared to those that perceived no change (36 ± 2 a.u., p = 0.002) or increased (36 ± 2 a.u., p < 0.001) sleep quality. Conclusion COVID-19 and state-ordered home isolation was associated with higher anxiety and reduced sleep quality, with a stronger association in women with respect to anxiety.

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