The Effect of Padding Layers Arrangement on Mitigating Head Impacts

2016 ◽  
Author(s):  
Shahab Mansoor-Baghaei ◽  
Ali M. Sadegh
Keyword(s):  
Head Injury ◽  
Corpus Callosum ◽  
Spherical Model ◽  
Viscoelastic Materials ◽  
Head Impacts ◽  
Head Injury Criterion ◽  
First Case ◽  
Preliminary Study ◽  
The Impact ◽  
The Brain

In this study the effect of the stiffness sequence of the padding materials of sports equipment, and in particular helmets, on absorbing the impact to the head has been investigated. Specifically, for each arrangement of the padding materials, the strain in the brain has been calculated. In addition, for each impact, the acceleration of the centroid of the head and the Head Injury Criterion (HIC) has also been obtained. As the first preliminary study a simple spherical model of head/brain, including the skull and the brain and three layers of the padding have been generated. The materials of the three layers of padding vary from viscoelastic, soft elastic to a hard elastic material. Then the head was impacted to the padding with the speed of 2 m/s. Finally the sequence of the padding layers was rearranged and the head was impacted to the padding with the same speed. For each case, the HIC value of the impact was determined. The results revealed that when the viscoelastic materials was in the middle (the first case) the HIC was 143.5 and the strain in the brain at the center corresponding to corpus callosum was 0.192%. Also for, the second case, where the viscoelastic materials was directly the contacting layer with the head, the HIC value was 46.8 and the brain strain was 0.15%. The reason that the strain in corpus callosum has been determined in this analysis is due to the fact that the literature reflects that the strain in corpus callosum is a good predictor for the onset of concussion due to an impact. It was concluded that when the viscoelastic padding is located on the outer surface of the protective padding device, the HIC value and the strain in the brain are lower, i.e. it is safer. This study can be employed to analyze head impacts with different layered barriers, i.e., composite materials, sandwich panels, glass, and also the interior trim of a car and as well as many other protective paddings.

scholarly journals Limiting Performance of Helmets for the Prevention of Head Injury

1999 ◽  
Vol 6 (5-6) ◽  
pp. 299-320 ◽  
Author(s):  
Z.Q. Cheng ◽  
W.D. Pilkey ◽  
J.R. Crandall ◽  
C.R. Bass ◽  
K. Darvish
Keyword(s):  
Head Injury ◽  
Skull Fracture ◽  
Head Acceleration ◽  
Head Injury Criterion ◽  
Bicycle Helmets ◽  
Injury Criteria ◽  
Injury Model ◽  
Head Injury Criteria ◽  
The Impact ◽  
The Brain

This is a study of the theoretical optimal (limiting) performance of helmets for the prevention of head injury. A rigid head injury model and a two-mass translational head injury model are employed. Several head injury criteria are utilized, including head acceleration, the head injury criterion (HIC), the energy imparted to the brain which is related to brain injury, and the power developed in the skull that is associated with skull fracture. A helmeted head hitting a rigid surface and a helmeted head hit by a moving object such as a ball are considered. The optimal characteristics of helmets and the impact responses of the helmeted head are investigated computationally. An experiment is conducted on an ensemble of bicycle helmets. Computational results are compared with the experimental results.

Dependence of the Head Injury Criterion and Maximum Acceleration on Headform Mass and Initial Velocity in Tests Simulating Pedestrian Impacts With Vehicles

2013 ◽  
Vol 135 (11) ◽  
Author(s):  
T. P. Hutchinson
Keyword(s):  
Head Injury ◽  
Initial Velocity ◽  
Impact Testing ◽  
Nonlinearity Parameter ◽  
Power Functions ◽  
Maximum Displacement ◽  
Maximum Acceleration ◽  
Head Injury Criterion ◽  
Specific Assumption ◽  
The Impact

Impact testing of pedestrian headforms is usually conducted at one velocity and with one mass of headform, but real impacts occur at a range of velocities and masses. A method is proposed to predict the Head Injury Criterion (HIC) and similar quantities at other velocities from their values observed under test conditions. A specific assumption is made about acceleration during the impact as related to displacement, its differential (instantaneous velocity), mass of headform, and initial velocity: namely, that it is the product of a power function of displacement (representing a possibly nonlinear spring) and a term that includes a type of damping. This equation is not solved, but some properties of the solution are obtained: HIC, maximum acceleration, and maximum displacement are found to be power functions of mass of headform and initial velocity. Expressions for the exponents are obtained in terms of the nonlinearity parameter of the spring. Simple formulae are obtained for the dependence of HIC, maximum acceleration, and maximum displacement on velocity and mass. These are relevant to many types of impact.

An Analytical Viscoelastic Model of the Head in Blunt Impacts

2008 ◽  
Author(s):  
Shahab Baghaei ◽  
Ali Sadegh ◽  
Mohamad Rajaai
Keyword(s):  
Mathematical Model ◽  
Finite Element ◽  
Spherical Shell ◽  
Head Injuries ◽  
Head Impacts ◽  
Closed Head Injuries ◽  
Brain Motion ◽  
Closed Head ◽  
The Impact ◽  
The Brain

The relative motion between the brain and skull and an increase in contact and shear stresses in the meningeal region could cause traumatic closed head injuries due to vehicular collisions, sport accidents and falls. There are many finite element studies of the brain/head models, but limited analytical models. The goal of this paper is to mathematically model subarachnoid space and the meningeal layers and to investigate the motion of the brain relative to the skull during blunt head impacts. The model consists of an elastic spherical shell representing the skull containing a visco-elastic solid material as the brain and a visco-elastic interface, which models the meningeal layers between the brain and the skull. In this study, the shell (the head) is moved toward a barrier and comes in contact with the barrier. Consequently, the skull deforms elastically and the brain is excited to come in contact with the skull. The viscoelastic characteristics of the interface (consisting of springs and dampers) are determined using experimental results of Hardy et al. [5]. Hertzian contact theory and Newtonian method are employed to acquire time dependant equations for the problem. The governing nonlinear integro-differential equations are formed and are solved using 4th order Runge Kutta method and elastic deformation of spherical shell, brain motion during the impact, and contact conditions between the brain and the skull are evaluated. Furthermore, some important mechanical parameters such as acceleration, impact force, and the impact time duration are also specified. The results of the analytical method are validated by performing an explicit finite element analysis. Acceptable agreement between these two methods is observed. The results of the analytical investigation give the contact threshold of the skull/brain, and represent the relevant velocity of this event. Furthermore, the impact analysis in different velocities is performed in order to compare the transmitted forces and the impact durations in different cases. It is concluded that the proposed mathematical model can predict head impacts in accidents and is capable in determining the relative brain motion of the skull and the brain. The mathematical model could be employed by other investigators to parametrically study the traumatic closed head injuries and hence to propose new head injury criteria.

scholarly journals EXPERIMENTAL EVALUATION OF THE IMPACTABSORPTION PROPERTIES OF RUBBER TILES FOR THE PLAYGROUND

2004 ◽  
Vol 16 (05) ◽  
pp. 244-250 ◽  
Author(s):  
LI-TUNG CHANG ◽  
KUEN-HORNG TSAI ◽  
JIN-SHAN SHIAU
Keyword(s):  
Head Injury ◽  
Head Injuries ◽  
Peak Acceleration ◽  
Critical Height ◽  
Shock Absorption ◽  
Absorption Properties ◽  
Head Injury Criterion ◽  
The Impact ◽  
Impact Absorption ◽  
Base Structure

Rubber tiles are popular in playgrounds as protective surfacing to reduce the incidence of head injuries caused by children falling from equipment. However, Taiwan has not yet established a test code for assessment of the shock-absorption properties of such surfacing. For this study, an experimental model was established to evaluate the behavior of various rubber tiles. A hemispherical headform was dropped from a set height to strike the center of the specimen tile. The peak acceleration and Head Injury Criterion (HIC) were measured to assess the impact absorption of and critical height for a given rubber tile. The results show that utilization of the HIC index provides a more conservative assessment of the shock absorption and, ultimately, protection from head injuries than peak acceleration. The maximum critical heights of the rubber tiles used in this study for tile thicknesses of 45, 60 and 80 mm were 1.6, 2.0 and 2.2 m, respectively. Two-part rubber tiles with a base structure consisting of a box-like core offer superior protection from head injuries relative to analogous cylindrical, square pillar and solid structures. The maximum differences in peakacceleration and HIC values comparing the box-like core and solid structures at a thickness of 45 mm were 21% and 44%, respectively. The results of this study suggest a minimum of rubber thickness of 60 mm, based on probable maximum fall heights of more than 1.6 m. Moreover, incorporation of an appropriate cushioning structure in the base of the rubber tile could further improve protection.

scholarly journals Unusual case of Marchiafava-Bignami disease presenting as axial hypotonia

2019 ◽  
Vol 76 (6) ◽  
pp. 645-647
Author(s):  
Svetlana Miletic-Drakulic ◽  
Jasna Jevdjic ◽  
Dejan Aleksic ◽  
Gordana Toncev
Keyword(s):  
Alcohol Consumption ◽  
Corpus Callosum ◽  
Motor Coordination ◽  
Early Recognition ◽  
Medical Emergency ◽  
First Case ◽  
Heavy Alcohol Consumption ◽  
History Of ◽  
Acute Form ◽  
The Brain

Introduction. Marchiafava-Bignami disease is a rare disorder mostly associated with chronic heavy alcohol consumption that results in progressive demyelination and necrosis of the corpus callosum. Case report. We reported a 35-year-old woman with a history of alcohol consumption and malnutrition. Neurological examination revealed axial hypotonia, dysarthric speech and lack of motor coordination. The brain multislice computed tomography imaging demonstrated hypodense lesion of the corpus callosum. On the basis of her history, clinical features and imaging studies, the diagnosis of an acute form of Marchiava-Bignami disease was made. Definite diagnosis was confirmed at autopsy. Conclusion. Marchiafava-Bignami disease is of a medical emergency and early recognition and early aggressive treatment are critical for a good clinical outcome. To our knowledge, this is the first case of Marchiafava-Bignami disease presented with axial hypotonia.

scholarly journals A NEW BIOMECHANICAL HEAD INJURY CRITERION

2006 ◽  
Vol 06 (04) ◽  
pp. 349-371 ◽  
Author(s):  
CHARLES F. BABBS
Keyword(s):  
Head Injury ◽  
High Speed ◽  
Compressive Strain ◽  
Experimental Studies ◽  
Closed Head Injury ◽  
Lumped Parameter Model ◽  
Viscoelastic Deformation ◽  
Head Injury Criterion ◽  
Closed Head ◽  
The Brain

This paper presents a new analysis of the physics of closed head injury caused by intense acceleration of the head. At rest a 1 cm gap filled with cerebrospinal fluid (CSF) separates the adult human brain from the skull. During impact, whole head acceleration induces artificial gravity within the skull. Because its density differs slightly from that of CSF, the brain accelerates, strikes the inner aspect of the rigid skull, and undergoes viscoelastic deformation. Analytical methods for a lumped parameter model of the brain predict internal brain motions that correlate well with published high-speed photographic studies. The same methods predict a truncated hyperbolic strength-duration curve for impacts that produce a given critical compressive strain. A family of such curves exists for different critical strains. Each truncated hyperbolic curve defines a head injury criterion (HIC) or threshold for injury, which is little changed by small offsetting corrections for curvature of the brain and for viscous damping. Such curves predict results of experimental studies of closed head injury, known limits for safe versus dangerous falls, and the relative resistance of smaller versus larger animals to acceleration of the head. The underlying theory provides improved understanding of closed head injury and better guidance to designers of protective equipment and to those extrapolating research results from animals to man.

scholarly journals Effect of Football Size and Mass in Youth Football Head Impacts

Proceedings ◽  
2020 ◽  
Vol 49 (1) ◽  
pp. 29
Author(s):  
Marcus Dunn ◽  
Dyfan Davies ◽  
John Hart
Keyword(s):  
Head Injury ◽  
Three Dimensional ◽  
Head Impacts ◽  
Association Football ◽  
Safety Concerns ◽  
Head Injury Criterion ◽  
Injury Criteria ◽  
Youth Football ◽  
Head Injury Criteria

In youth association football, the use of different size and/or mass footballs might represent a feasible intervention for addressing heading impact severity and player safety concerns. This study assessed the effects of football size and mass on head impacts based on defensive heading in youth football. Three-dimensional trajectories of U16 youth academy free kicks were modelled to derive three impact trajectories, representing defensive heading in youth football. Three football models (standard: S5, standard-light: S5L, and small: S4) impacted an instrumented headform; Head Injury Criterion (HIC15) and Rotational Injury Criterion (RIC15) were calculated. For headform impacts, S4 and S5L footballs yielded lower HIC15 magnitudes than S5 footballs. Further, S4 footballs yielded lower HIC15 and lower RIC15 magnitudes than S5 and S5L footballs. Initial findings indicated that smaller, S4 footballs reduced linear and rotational head injury criteria for impacts representative of defensive heading in youth football.

scholarly journals Case Report: Two cases of rare head injuries from Nepal

F1000Research ◽  
2021 ◽  
Vol 7 ◽  
pp. 1483
Author(s):  
Joe M. Das ◽  
Apar Pokharel ◽  
Rashmi Sapkota ◽  
Manish Mishra ◽  
Ashish Babu Aryal
Keyword(s):  
Head Injury ◽  
Case Reports ◽  
Head Injuries ◽  
Neurological Deficits ◽  
Accidental Injury ◽  
First Case ◽  
Aged Woman ◽  
The Face ◽  
Middle Aged Woman ◽  
The Impact

Background: There are a number of ways in which one can sustain a head injury. Even if you are doing simple household activities or going out for a morning walk, you cannot be sure of what type of injury awaits you. The source of injury may be a pressure cooker whistle acting as a projectile or a hailstone falling from the sky. Such injuries are common in Nepal, considering the socio-demographic and geographic conditions. In this article, we present two such very rare cases of head injury. Case Reports: The first case is a middle-aged woman who sustained an accidental injury to the face associated with fracture of frontal sinus and frontal contusion, following the impact from a high momentum projectile in the form of the pressure regulator of a pressure cooker. She underwent craniotomy and removal of the foreign body. In the second case, an elderly man sustained minor injury to the head following the fall of hail. The abrasions and contusions produced by the hail were managed conservatively. Since he did not have any clinical evidence of head injury, other than multiple abrasions with contusions in the scalp, he did not undergo any imaging studies. He did not have any neurological deficits. The postoperative period was uneventful for the first patient and she was followed up for one month. The second patient was lost to follow-up. Conclusion: Successful management of two very rare cases of head injuries from Nepal are reported. Proper care and maintenance of the house-hold utensils that are constantly used may protect people from head injuries.  Though natural calamities cannot always be avoided, simple measures like using an umbrella while going outdoors may protect individuals from head injuries due to hailstones.

Computer Simulation of Head Impact: Estimation of Head-Injury Risk during Soccer Heading

1988 ◽  
Vol 4 (4) ◽  
pp. 358-371 ◽  
Author(s):  
Klaus Schneider ◽  
Ronald F. Zernicke
Keyword(s):  
Head Injury ◽  
Injury Risk ◽  
Cervical Vertebrae ◽  
Rigid Bodies ◽  
Head Impacts ◽  
Frontal Impacts ◽  
Medium Range ◽  
The Impact ◽  
Head Neck ◽  
Soccer Heading

With a validated mathematical model of the head-neck consisting of nine rigid bodies (skull, seven cervical vertebrae, and torso), we simulated head impacts to estimate the injury risk associated with soccer heading. Experimental data from head-linear accelerations during soccer heading were used to validate the nine-body head-neck model for short duration impact loading of the head. In the computer simulations, the mass ratios between head mass and impacting body mass, the velocity of the impacting body, and the impact elasticity were varied. Head-linear and angular accelerations were compared to standard head-injury tolerance levels, and the injury risk specifically related to soccer heading was estimated. Based on our choice of tolerance levels in general, our simulations showed that injury risk from angular head accelerations was greater than from linear head accelerations, and compared to frontal impacts, lateral impacts had greater angular and less linear head accelerations. During soccer heading, our simulations indicated an unacceptable injury risk caused by angular head accelerations for frontal and lateral impacts at relatively low impact velocities for children, and at medium range impact velocities for adults. For linear head accelerations, injury risk existed for frontal and lateral impacts at medium range to relatively larger impact velocities for children, while no injury risk was shown for adults throughout the entire velocity range. For injury prevention, we suggest that head-injury risk can be reduced most substantially by increasing the mass ratio between head and impacting body. In soccer with children, the mass of the impacting body has to be adjusted to the reduced head mass of a child, that is, it must be clearly communicated to parents, coaches, and youngsters to only use smaller soccer balls.

scholarly journals Measured Impact

2018 ◽  
Vol 140 (01) ◽  
pp. 42-45
Author(s):  
James G. Skakoon
Keyword(s):  
Finite Element ◽  
Corpus Callosum ◽  
Degrees Of Freedom ◽  
Head Injuries ◽  
Analysis Model ◽  
Element Analysis ◽  
Falx Cerebri ◽  
Institute Of Technology ◽  
The Impact ◽  
The Brain

This article focuses on an innovative methodology developed by researchers at Stanford University. The new way of measuring the forces that cause head injuries aim to change how engineers protect professional and weekend athletes. By embedding both accelerometers and gyroscopes within the mouth guards, the laboratory tracked all six degrees of freedom and slashed data errors to 10 percent or less. According to one of the developer, since the upper teeth are firmly coupled to the bones of the cranium, the mouthguards can provide data accurate enough for the lab to use in finite element models to describe what is happening inside the brain. The team input the incident’s kinematics data into a finite element analysis model of the brain developed by the KTH Royal Institute of Technology in Sweden. This enabled them to simulate how different structures within the brain responded to the impact. The computer simulation showed that the falx cerebri appears to be the culprit. It is a rigid vertical sheet that separates the brain’s two lobes. It lies right above the corpus callosum and extends upward, attaching to the skull at the very top. It conducts impact energy from the skull deep into the brain, where it oscillates and induces strain in the corpus callosum.

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