scholarly journals Protective Headgear Attenuates Forces on the Inner Table and Pressure in the Brain Parenchyma During Blast and Impact: An Experimental Study Using a Simulant-Based Surrogate Model of the Human Head

2019 ◽  
Vol 142 (4) ◽  
Author(s):  
Austin Azar ◽  
Kapil Bharadwaj Bhagavathula ◽  
James Hogan ◽  
Simon Ouellet ◽  
Sikhanda Satapathy ◽  
...  
Keyword(s):  
Surrogate Model ◽  
Brain Injuries ◽  
Human Head ◽  
Brain Parenchyma ◽  
Blast Energy ◽  
Elevated Pressures ◽  
Blunt Impact ◽  
Head Protection ◽  
Impact Events ◽  
The Brain

Abstract Military personnel sustain head and brain injuries as a result of ballistic, blast, and blunt impact threats. Combat helmets are meant to protect the heads of these personnel during injury events. Studies show peak kinematics and kinetics are attenuated using protective headgear during impacts; however, there is limited experimental biomechanical literature that examines whether or not helmets mitigate peak mechanics delivered to the head and brain during blast. While the mechanical links between blast and brain injury are not universally agreed upon, one hypothesis is that blast energy can be transmitted through the head and into the brain. These transmissions can lead to rapid skull flexure and elevated pressures in the cranial vault, and, therefore, may be relevant in determining injury likelihood. Therefore, it could be argued that assessing a helmet for the ability to mitigate mechanics may be an appropriate paradigm for assessing the potential protective benefits of helmets against blast. In this work, we use a surrogate model of the head and brain to assess whether or not helmets and eye protection can alter mechanical measures during both head-level face-on blast and high forehead blunt impact events. Measurements near the forehead suggest head protection can attenuate brain parenchyma pressures by as much as 49% during blast and 52% during impact, and forces on the inner table of the skull by as much as 80% during blast and 84% during impact, relative to an unprotected head.

The Strain Rates of the Brain and Skull Under Dynamic Loading

2018 ◽  
Author(s):  
Mohammad Hosseini Farid ◽  
Ashkan Eslaminejad ◽  
Mohammadreza Ramzanpour ◽  
Mariusz Ziejewski ◽  
Ghodrat Karami
Keyword(s):  
Material Properties ◽  
Brain Injuries ◽  
Human Head ◽  
Element Model ◽  
Blast Waves ◽  
Cranial Bone ◽  
Strain Rates ◽  
Head Acceleration ◽  
Blunt Impact ◽  
The Brain

Accurate material properties of the brain and skull are needed to examine the biomechanics of head injury during highly dynamic loads such as blunt impact or blast. In this paper, a validated Finite Element Model (FEM) of a human head is used to study the biomechanics of the head in impact and blast leading to traumatic brain injuries (TBI). We simulate the head under various direction and velocity of impacts, as well as helmeted and un-helmeted head under blast waves. It is shown that the strain rates for the brain at impacts and blast scenarios are usually in the range of 36 to 241 s−1. The skull was found to experience a rate in the range of 14 to 182 s−1 under typical impact and blast cases. Results show for impact incidents the strain rates of brain and skull are approximately 1.9 and 0.7 times of the head acceleration. Also, this ratio of strain rate to head acceleration for the brain and skull was found to be 0.86 and 0.43 under blast loadings. These findings provide a good insight into measuring the brain tissue and cranial bone, and selecting material properties in advance for FEM of TBI.

scholarly journals Evaluation of Combat Helmet Behavior under Blunt Impact

2020 ◽  
Vol 10 (23) ◽  
pp. 8470
Author(s):  
Carlos Moure-Guardiola ◽  
Ignacio Rubio ◽  
Jacobo Antona-Makoshi ◽  
Álvaro Olmedo ◽  
José Antonio Loya ◽  
...  
Keyword(s):  
Brain Injuries ◽  
Linear Acceleration ◽  
Human Head ◽  
Critical Parameters ◽  
Head Model ◽  
Ballistic Impacts ◽  
Impact Surface ◽  
Blunt Impact ◽  
Wide Range ◽  
Design And Manufacture

New threats are a challenge for the design and manufacture of modern combat helmets. These helmets must satisfy a wide range of impact velocities from ballistic impacts to blunt impacts. In this paper, we analyze European Regulation ECE R22.05 using a standard surrogate head and a human head model to evaluate combat helmet performance. Two critical parameters on traumatic brain analysis are studied for different impact locations, i.e., peak linear acceleration value and head injury criterion (HIC). The results obtained are compared with different injury criteria to determine the severity level of damage induced. Furthermore, based on different impact scenarios, analyses of the influence of impact velocity and the geometry impact surface are performed. The results show that the risks associated with a blunt impact can lead to a mild traumatic brain injury at high impact velocities and some impact locations, despite satisfying the different criteria established by the ECE R22.05 standard. The results reveal that the use of a human head for the estimation of brain injuries differs slightly from the results obtained using a surrogate head. Therefore, the current combat helmet configuration must be improved for blunt impacts. Further standards should take this into account and, consequently, combat helmet manufacturers on their design process.

Mechanical Response of the Brain Under Blast: The Effect of Blast Direction and the Head Protection

2016 ◽  
Author(s):  
Hesam Sarvghad-Moghaddam ◽  
Asghar Rezaei ◽  
Ashkan Eslaminejad ◽  
Mariusz Ziejewski ◽  
Ghodrat Karami
Keyword(s):  
Brain Injury ◽  
Mechanical Response ◽  
Experimental Studies ◽  
Human Head ◽  
Blast Waves ◽  
Arbitrary Lagrangian Eulerian ◽  
Explosion Pressure ◽  
Head Protection ◽  
Coupling Algorithm ◽  
The Brain

Blast-induced traumatic brain injury (bTBI), is defined as a type of acquired brain injury that occurs upon the interaction of the human head with blast-generated high-pressure shockwaves. Lack of experimental studies due to moral issues, have motivated the researchers to employ computational methods to study the bTBI mechanisms. Accordingly, a nonlinear finite element (FE) analysis was employed to study the interaction of both unprotected and protected head models with explosion pressure waves. The head was exposed to the incoming shockwaves from front, back, and side directions. The main goal was to examine the effects of head protection tools and the direction of blast waves on the tissue and kinematical responses of the brain. Generation, propagation, and interactions of blast waves with the head were modeled using an arbitrary Lagrangian-Eulerian (ALE) method and a fluid-structure interaction (FSI) coupling algorithm. The FE simulations were performed using Ls-Dyna, a transient, nonlinear FE code. Side blast predicted the highest mechanical responses for the brain. Moreover, the protection assemblies showed to significantly alter the blast flow mechanics. Use of faceshield was also observed to be highly effective in the front blast due to hindering of shockwaves.

scholarly journals Development of a Finite Element Head Model for the Study of Impact Head Injury

2014 ◽  
Vol 2014 ◽  
pp. 1-14 ◽  
Author(s):  
Bin Yang ◽  
Kwong-Ming Tse ◽  
Ning Chen ◽  
Long-Bin Tan ◽  
Qing-Qian Zheng ◽  
...  
Keyword(s):  
Finite Element ◽  
Brain Injuries ◽  
Current Knowledge ◽  
Human Head ◽  
Von Mises Stress ◽  
Head Model ◽  
Fe Model ◽  
Prediction And Prevention ◽  
Von Mises ◽  
The Brain

This study is aimed at developing a high quality, validated finite element (FE) human head model for traumatic brain injuries (TBI) prediction and prevention during vehicle collisions. The geometry of the FE model was based on computed tomography (CT) and magnetic resonance imaging (MRI) scans of a volunteer close to the anthropometry of a 50th percentile male. The material and structural properties were selected based on a synthesis of current knowledge of the constitutive models for each tissue. The cerebrospinal fluid (CSF) was simulated explicitly as a hydrostatic fluid by using a surface-based fluid modeling method. The model was validated in the loading condition observed in frontal impact vehicle collision. These validations include the intracranial pressure (ICP), brain motion, impact force and intracranial acceleration response, maximum von Mises stress in the brain, and maximum principal stress in the skull. Overall results obtained in the validation indicated improved biofidelity relative to previous FE models, and the change in the maximum von Mises in the brain is mainly caused by the improvement of the CSF simulation. The model may be used for improving the current injury criteria of the brain and anthropometric test devices.

scholarly journals Development Of A Hyperspectral NIRS System For Functional Imaging Of The Brain And For Cerebral Status Monitoring During Cardiac Surgery

2021 ◽  
Author(s):  
Ermias Woldemichael
Keyword(s):  
Optical Fiber ◽  
Near Infrared ◽  
Brain Injuries ◽  
Imaging Modality ◽  
Optical Power ◽  
Human Head ◽  
Biological Tissues ◽  
Fiber Bundles ◽  
Set Up ◽  
The Brain

Hyperspectral near infrared spectroscopy (hNIRS) is a noninvasive, real-time imaging modality with an improved quantitative accuracy and increased number of detectable chromophores. It uses the broadband spectrum of light wavelengths in the range of 700 – 1100 nm and is based on the unique absorbance property of molecules and the fact that all biological tissues are relatively transparent to these wavelengths which allow for measuring concentrations of light absorbing molecules such as the Oxy- and Deoxy- hemoglobin and Cytochrome C Oxidase. As opposed to fMRI, PET and SPECT, hNIRS is inexpensive and portable. The purpose of this thesis project was to employ advantages of hNIRS by developing the multichannel hNIRS set-up for the simultaneous assessment of multiple areas of the brain and to test the system in clinical applications. To achieve these goals, I developed a new optical fiber bundle design providing improvement of the optical power throughput into the hNIRS light detectors. I also developed a novel probe for measurements on hairy areas of the human head. To validate the hNIRS system I used it simultaneously with fMRI, which revealed a good correlation of hNIRS and fMRI BOLD signals from the brain. The multichannel hNIRS set up with the increased signals due to the novel optical fiber bundles was then used during various brain activation protocols, which in the future can allow for the assessment of patients with mild traumatic brain injuries (mTBI). Finally, the hNIRS system with the new fiber bundles was compared with a commercial NIRS system in clinical setting for brain monitoring of patients during the transcatheter aortic valve implantation operation (TAVI).

Skull Deformation Has No Impact on the Variation of Brain Intracranial Pressure

2016 ◽  
Author(s):  
Asghar Rezaei ◽  
Hesam Sarvghad-Moghaddam ◽  
Ashkan Eslaminejad ◽  
Mariusz Ziejewski ◽  
Ghodrat Karami
Keyword(s):  
Intracranial Pressure ◽  
Brain Injuries ◽  
Computational Study ◽  
Human Head ◽  
Body Motion ◽  
Stress Wave Propagation ◽  
Head Model ◽  
The Impact ◽  
The Brain ◽  
Skull Deformation

Skull deformation and vibration has been hypothesized to be an injury mechanism when the human head undergoes an impact scenario. The extent that skull deformation may increase the risk of traumatic brain injury, however, is not well understood. This computational study explains whether skull deformation has any impact on the variation of intracranial pressure (ICP). To this end, a finite element head model including major anatomical components of the human head was employed. The head model has been validated against ICP variations on the brain. The impact simulations were carried out using a rigid cylindrical impactor. The scenarios were frontal impacts with the impactor hitting the forehead of the head model at two impact severity levels. In order to examine the effect of skull elasticity on the stress wave propagation inside the cranium under an external applied force, the skull was also taken as a rigid body with the same density as the elastic one, and the result were compared with those obtained with the deformable skull. For the two cases, the variation of ICPs at the coup and countercoup sites were recorded and compared. The results of the study showed that, for the case studies presented here, the deformation of skull didn’t increase the level of ICP inside the brain. It was concluded that the skull rapid body motion might be responsible for brain injuries.

Biomechanics of Head/Brain Due to Angular Head Acceleration

2004 ◽  
Author(s):  
M. Zoghi-Moghadam ◽  
Ali M. Sadegh
Keyword(s):  
Cerebrospinal Fluid ◽  
Brain Injuries ◽  
Angular Acceleration ◽  
Shear Stresses ◽  
Head Acceleration ◽  
Global Models ◽  
Contact Sports ◽  
Blunt Impact ◽  
The Brain

In vehicular collisions, contact sports or falls, in addition to blunt impacts, head is subjected to high angular accelerations. This causes relative motion between the brain and skull and an increase in contact and shear stresses in meningeal region which leads to brain injuries. In our previous study Zoghi et al (14), the mechanical role of the fibrous trabeculae and the Cerebrospinal Fluid (CSF) in Subarachnoid space (SAS) were investigated. This is a continuation study of (14) where the attention is focused on the angular acceleration of head rather than blunt impacts. Improved 2-D solid and fluid global models of the head and a local model of the SAS trabeculae were developed. The CSF pressure distribution and the trabeculae deformations were determined. It is expected that in angular acceleration of head, similar to blunt impact, the arachnoid trabeculae reduce the pressure in the CSF and both play a major role in damping the acceleration.

scholarly journals The Strain Rates in the Brain, Brainstem, Dura, and Skull under Dynamic Loadings

2020 ◽  
Vol 25 (2) ◽  
pp. 21 ◽  
Author(s):  
Mohammad Hosseini-Farid ◽  
MaryamSadat Amiri-Tehrani-Zadeh ◽  
Mohammadreza Ramzanpour ◽  
Mariusz Ziejewski ◽  
Ghodrat Karami
Keyword(s):  
Dura Mater ◽  
Material Properties ◽  
Brain Injuries ◽  
Human Head ◽  
Biological Tissues ◽  
Cranial Bone ◽  
Head Model ◽  
Strain Rates ◽  
Head Acceleration ◽  
The Brain

Knowing the precise material properties of intracranial head organs is crucial for studying the biomechanics of head injury. It has been shown that these biological tissues are significantly rate-dependent; hence, their material properties should be determined with respect to the range of deformation rate they experience. In this paper, a validated finite element human head model is used to investigate the biomechanics of the head in impact and blast, leading to traumatic brain injuries (TBI). We simulate the head under various directions and velocities of impacts, as well as helmeted and unhelmeted head under blast shock waves. It is demonstrated that the strain rates for the brain are in the range of 36 to 241 s−1, approximately 1.9 and 0.86 times the resulting head acceleration under impacts and blast scenarios, respectively. The skull was found to experience a rate in the range of 14 to 182 s−1, approximately 0.7 and 0.43 times the head acceleration corresponding to impact and blast cases. The results of these incident simulations indicate that the strain rates for brainstem and dura mater are respectively in the range of 15 to 338 and 8 to 149 s−1. These findings provide a good insight into characterizing the brain tissue, cranial bone, brainstem and dura mater, and also selecting material properties in advance for computational dynamical studies of the human head.

The Effect of the Sulcus Morphology on the Transduction of Impacts to the Brain

2012 ◽  
Author(s):  
Parisa Saboori ◽  
Ali Sadegh
Keyword(s):  
Human Brain ◽  
Brain Injuries ◽  
Fundamental Problem ◽  
Human Head ◽  
Traumatic Brain Injuries ◽  
The Body ◽  
Brain Morphology ◽  
Body Region ◽  
Pia Mater ◽  
The Brain

The human head, being a vulnerable body region, is most frequently involved in traumatic brain injuries (TBI) and life threatening injuries. Accurate modeling of the variability of the brain morphology is a fundamental problem in investigating TBI. Improved computational/mathematical structural models of the brain are needed to help investigators to have a better understanding of the phenomena of different traumatic brain injuries such as concussion. The human brain is the most complex region of the body. There is a very thin membrane known as a pia mater that covers all the surface of the brain. The pia mater follows all the fissure of the brain and covers all the surface of the sulci and gyri. Sulcus is referred to any furrow in the brain. Statistically there are about 72 main sulci in the human brain. Previous FE studies of TBI have ignored sulcus morphology in their modeling and thus, their results could be unreliable. In this paper, the effect of the brain sulcus structure on mechanotransduction of impacts to the brain has been investigated. This was accomplished by using series of parametric studies and comparing the results with the model without sulci. The results of this study reveal that the brain’s strain is reduced in the present of sulcus and gyrus structures. We have hypothesized that the presence of sulcus increases the surface area of the brain thereby decreases the normal and shear strain in the brain. That is, the presence of sulcus and gyrus reduce the transduction of the external load and impacts to the white and gray matters of the brain and thereby reduces the risk of TBI. Ignoring sulci in any FE modeling and analysis of the brain may lead to unreliable results.

scholarly journals Development Of A Hyperspectral NIRS System For Functional Imaging Of The Brain And For Cerebral Status Monitoring During Cardiac Surgery

2021 ◽  
Author(s):  
Ermias Woldemichael
Keyword(s):  
Optical Fiber ◽  
Near Infrared ◽  
Brain Injuries ◽  
Imaging Modality ◽  
Optical Power ◽  
Human Head ◽  
Biological Tissues ◽  
Fiber Bundles ◽  
Set Up ◽  
The Brain

Hyperspectral near infrared spectroscopy (hNIRS) is a noninvasive, real-time imaging modality with an improved quantitative accuracy and increased number of detectable chromophores. It uses the broadband spectrum of light wavelengths in the range of 700 – 1100 nm and is based on the unique absorbance property of molecules and the fact that all biological tissues are relatively transparent to these wavelengths which allow for measuring concentrations of light absorbing molecules such as the Oxy- and Deoxy- hemoglobin and Cytochrome C Oxidase. As opposed to fMRI, PET and SPECT, hNIRS is inexpensive and portable. The purpose of this thesis project was to employ advantages of hNIRS by developing the multichannel hNIRS set-up for the simultaneous assessment of multiple areas of the brain and to test the system in clinical applications. To achieve these goals, I developed a new optical fiber bundle design providing improvement of the optical power throughput into the hNIRS light detectors. I also developed a novel probe for measurements on hairy areas of the human head. To validate the hNIRS system I used it simultaneously with fMRI, which revealed a good correlation of hNIRS and fMRI BOLD signals from the brain. The multichannel hNIRS set up with the increased signals due to the novel optical fiber bundles was then used during various brain activation protocols, which in the future can allow for the assessment of patients with mild traumatic brain injuries (mTBI). Finally, the hNIRS system with the new fiber bundles was compared with a commercial NIRS system in clinical setting for brain monitoring of patients during the transcatheter aortic valve implantation operation (TAVI).

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