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 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 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.

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).

Addressing Uncertainty in Constitutive Model Forms and Parameters for FE Models of the Human Head Subjected to Blast Loading

2017 ◽  
Author(s):  
Patrick Brewick ◽  
Kirubel Teferra
Keyword(s):  
Experimental Data ◽  
Constitutive Model ◽  
Material Properties ◽  
Mechanical Response ◽  
Blast Loading ◽  
Human Head ◽  
Biological Tissues ◽  
Threshold Values ◽  
Injury Response ◽  
The Brain

This work lies within an overall effort to improve, as well as quantify, the uncertainty of traumatic brain injury (TBI) prediction for blast loading. Detailed finite element (FE) modeling of the human head currently provides the only viable means to quantify the mechanical response within the brain during a blast loading event. Unfortunately, the exact linkages between loading patterns, tissue mechanical response, and injury/physiological effects are still quite unknown; however, the exceedance of specified threshold values based on direct and derived measures of stress, strain, pressure, and acceleration within the brain have been shown to be useful injury criteria. The utility of these threshold values is somewhat mitigated by the fact that preliminary parametric studies focusing on varying head morphology and the material properties of FE head model components have shown significant variation in the predicted injury response, indicating that the exact relationship between model geometry, material properties, and mechanics-based injury response metrics has not yet been established. Identifying an appropriate constitutive model form and optimal parameter values for biological tissues is an enormous challenge hindered by large epistemic uncertainties. Available experimental data sets frequently offer valuable but limited information due to the many vagaries associated with the testing of biomaterials, such as testing on different species, e.g., porcine and bovine specimens, testing with inapplicable strain rates, and having too little data. The parameters of hyperelastic, hyper-viscoelastic, and viscoelastic constitutive models, which are commonly utilized for modeling these biological tissues, can be fit to an aggregation of experimental data through a constrained optimization formulation. Specifically, this study considers fitting data from biomaterials to Ogden’s model of hyperelasticity. The goodness of fit of the optimization is limited by the appropriateness of the model forms as well as limited, and at times contradictory, data. In order to properly account for these uncertainties, a Bayesian approach is adopted for model calibration and posterior distributions are therefore produced for each model parameter.

Experimental Study on Non-Exit Ballistic Induced Traumatic Brain Injury

2007 ◽  
Author(s):  
Jiangyue Zhang ◽  
Narayan Yoganandan ◽  
Frank A. Pintar ◽  
Yabo Guan ◽  
Thomas A. Gennarelli
Keyword(s):  
Traumatic Brain Injury ◽  
Brain Injury ◽  
Brain Injuries ◽  
Gunshot Wounds ◽  
Pressure Change ◽  
Frame Rate ◽  
Cranial Bone ◽  
Head Model ◽  
Injury Biomechanics ◽  
The Brain

Ballistic-induced traumatic brain injury remains the most severe type of injury with the highest rate of fatality. Yet, its injury biomechanics remains the least understood. Ballistic injury biomechanics studies have been mostly focused on the trunk and extremities using large gelatin blocks with unconstrained boundaries [1, 2]. Results from these investigations are not directly applicable to brain injuries studies because the human head is smaller and the soft brain is enclosed in a relatively rigid cranium. Thali et al. developed a “skin-skull-brain” model to reproduce gunshot wounds to the head for forensic purposes [3]. These studies focused on wound morphology to the skull rather than brain injury. Watkins et al. used human dry skulls filled with gelatin and investigated temporary cavities and pressure change [4]. However, the frame rate of the cine X-ray was too slow to describe the cavity dynamics, and pressures were only quantified at the center of skull. In addition, the ordnance gelatin used in these studies is not the most suitable simulant to model brain material because of differences in dynamic moduli [5]. Sylgard gel (Dow Corning Co., Midland, MI) demonstrates similar behavior as the brain and has been used as a brain surrogate to determine brain deformations under blunt impact loading [6, 7]. Zhang et al. used the simulant for ballistic brain injury and investigated the correlation between temporary cavity pulsation and pressure change [8, 9]. However, the skulls used in these models were not as rigid as the human cranium. The presence of a stronger cranial bone may significantly decrease the projectile velocity and change the kinematics of cavity and pressure distribution in the cranium. In addition, projectiles perforated through the models in these studies. Patients with through-and-through perforating gunshot wounds to the head have a greater fatality rate than patients with non-exit penetrating wounds [10]. Therefore, it is more clinically relevant to investigate non-exit ballistic traumatic brain injuries. Consequently, the current study is designed to investigate the brain injury biomechanics from non-exit penetrating projectile using an appropriately sized and shaped physical head model.

Biomechanical Analysis of the Sensitivity of Brain Tissue Responses to FE Head Models in the Study of Impact-Induced TBI

2020 ◽  
Author(s):  
Hesam S. Moghaddam ◽  
Asghar Rezaei ◽  
Mariusz Ziejewski ◽  
Ghodrat Karami
Keyword(s):  
Shear Stress ◽  
Mesh Size ◽  
Human Head ◽  
Biomechanical Analysis ◽  
Head Model ◽  
Tissue Responses ◽  
Stress Prediction ◽  
Brain Material ◽  
The Brain

Abstract A numerical investigation is conducted on the injury-related biomechanical parameters of the human head under blunt impacts. The objective of this research is twofold; first to understand the role of the employed finite element (FE) head model — with its specific components, shape, size, material properties, and mesh size — in predicting tissue responses of the brain, and second to investigate the fidelity of pressure response in validating FE head models. Accordingly, two independently established and validated FE head models are impacted in two directions under two impact severities and their predicted responses in terms of intracranial pressure (ICP) and shear stress are compared. The coup-counter ICP peak values are less sensitive to head model, mesh size, and the brain material. In all cases, maximum ICPs occur on the outer surface, vanishing linearly toward the center of the brain. Hence, it is concluded that different head models may simply reproduce the results of ICP variations due to impact. Shear stress prediction, however, is mainly affected by the head model, direction and severity of impact, and the brain material.

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.

Relaxation Time Effect on the Human Head Using the Thermal Wave Model

2012 ◽  
Author(s):  
Toni K. Tullius ◽  
Yildiz Bayazitoglu
Keyword(s):  
Relaxation Time ◽  
Wave Model ◽  
Human Head ◽  
The Body ◽  
Bioheat Transfer ◽  
Time Dependent ◽  
Head Model ◽  
Transfer Model ◽  
The Waves ◽  
The Brain

The most common electronics used by the vast majority of the world’s population emit low radio frequencies and they may be harmful to both skin and brain tissue. The bio-heat transfer model is numerically solved to predict the time dependent temperature distribution of micro waves as it emits to the brain caused by everyday electronics in order to understand the effects the waves have on our organs. A time dependent finite difference technique is used to model a multilayer system depicting this external heat source passing through skin, bone, and into the brain. This model accounts for the extra heat generated within the body from the chemical reactions of the tissue, whereas pervious work took this heat sources to be negligible. A relaxation time is also included in the bioheat transfer model in order to account for the response time the tissue takes caused by the perturbation. Most studies neglect this parameter. Parameters for the adult and child head model are compared. The manuscript is aimed to understand the potential threats on the human body caused by everyday use of the technologies such as Ipods, cellular phones, bluetooth’s, etc.

Sign in / Sign up

Export Citation Format

Share Document