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 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.

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.

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 Mechanical Strength Study of a Cranial Implant Using Computational Tools

2022 ◽  
Vol 12 (2) ◽  
pp. 878
Author(s):  
Pedro O. Santos ◽  
Gustavo P. Carmo ◽  
Ricardo J. Alves de Sousa ◽  
Fábio A. O. Fernandes ◽  
Mariusz Ptak
Keyword(s):  
Structural Integrity ◽  
Mechanical Performance ◽  
Skull Fracture ◽  
Human Head ◽  
Element Model ◽  
Von Mises Stress ◽  
Cranial Implant ◽  
Von Mises ◽  
Two Parameters ◽  
The Brain

The human head is sometimes subjected to impact loads that lead to skull fracture or other injuries that require the removal of part of the skull, which is called craniectomy. Consequently, the removed portion is replaced using autologous bone or alloplastic material. The aim of this work is to develop a cranial implant to fulfil a defect created on the skull and then study its mechanical performance by integrating it on a human head finite element model. The material chosen for the implant was PEEK, a thermoplastic polymer that has been recently used in cranioplasty. A6 numerical model head coupled with an implant was subjected to analysis to evaluate two parameters: the number of fixation screws that enhance the performance and ensure the structural integrity of the implant, and the implant’s capacity to protect the brain compared to the integral skull. The main findings point to the fact that, among all tested configurations of screws, the model with eight screws presents better performance when considering the von Mises stress field and the displacement field on the interface between the implant and the skull. Additionally, under the specific analyzed conditions, it is observable that the model with the implant offers more efficient brain protection when compared with the model with the integral skull.

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.

Chest Deflection vs. Chest Acceleration as Injury Indicator in Front Impact Simulations Using Full Human Body Finite Element Model

2009 ◽  
Author(s):  
Raed E. El-Jawahri ◽  
Jesse S. Ruan ◽  
Stephen W. Rouhana ◽  
Saeed D. Barbat
Keyword(s):  
Finite Element ◽  
Plastic Strain ◽  
Finite Element Model ◽  
Human Body ◽  
Element Model ◽  
Von Mises Stress ◽  
Head Acceleration ◽  
Blunt Impact ◽  
Von Mises ◽  
Impact Simulations

The Ford Motor Company Human Body Finite Element Model (FHBM) was validated against rib dynamic tension and 3-point bending tests. The stress-strain and moment-strain data from the tension and bending simulations respectively were compared with human rib specimen test data. The model used represented a 50th percentile adult male. It was used to compare chest deflection and chest acceleration as thoracic injury indicator in blunt impact and belted occupants in front sled impact simulations. A 150 mm diameter of 23.4 kg impactor was used in the blunt impact simulations with impact speeds of 2, 4, and 8 m/s. In the Front sled impact simulations, single-step acceleration pulses with peaks of 10, 20, and 30 g were used. The occupants were restrained by 3-point belt system, however neither pretensioner nor shoulder belt force limiter were used. The external force, head acceleration, chest deflection, chest acceleration, and the maximum values of Von Mises stress and plastic strain were the model outputs. The results showed that the external contact force, head acceleration, chest deflection, and chest acceleration in the blunt impact simulations varied between 1.5–7 kN, 5–28 g, 18–80 mm, and 8–40 g respectively. The same responses varied between 7–24 kN, 13–40 g, 15–50 mm, and 16–46 g respectively in the front sled impact simulations. The maximum Von Mises stress and plastic strain were 50–127 MPa, and 0.04–2% respectively in the blunt impact simulations and 72–134 MPa, and 0.13–3% respectively in the sled impact simulations.

scholarly journals Modelling the Ability of Rheoencephalography to Measure Cerebral Blood Flow

2019 ◽  
Vol 5 (1) ◽  
pp. 110-113 ◽  
Author(s):  
Konstantin S. Brazovskii ◽  
Jacov S. Pekker ◽  
Oleg S. Umanskii
Keyword(s):  
Blood Flow ◽  
Cerebrospinal Fluid ◽  
Electrical Resistivity ◽  
Cerebral Blood Flow ◽  
Potential Benefit ◽  
Human Head ◽  
Element Model ◽  
History Of ◽  
Electrode Method ◽  
The Brain

Abstract Despite the long history of rheoencephalography (REG), some important aspects of the method are still debatable. Bioimpedance measurements offer great potential benefit for study of the human brain, but the traditional four or six electrode method suffers from potential misinterpretations and lack of accuracy. The objective of this paper is to study the possible mechanism of REG formation by means of numerical modelling using a realistic finite element model of the human head. It is shown that the cardiac related variations in electrical resistivity of the scalp contributes more than 60% to the REG amplitude, whereas the brain and cerebrospinal fluid are mutually compensated by each over.

Wavelet Analysis of Head Acceleration Response Under Dirac Excitation for Early Oedema Detection

2008 ◽  
Vol 130 (2) ◽  
Author(s):  
V. Kostopoulos ◽  
T. H. Loutas ◽  
C. Derdas ◽  
E. Douzinas
Keyword(s):  
Brain Volume ◽  
Energy Content ◽  
Human Head ◽  
Complex Model ◽  
Head Acceleration ◽  
Acceleration Response ◽  
Volume Increase ◽  
Early Oedema ◽  
The Brain ◽  
Brain Density

The present work deals with the application of an innovative in-house developed wavelet-based methodology for the analysis of the acceleration responses of a human head complex model as a simulated diffused oedema progresses. The human head complex has been modeled as a structure consisting of three confocal prolate spheroids, whereas the three defined regions by the system of spheroids, from the outside to the inside, represent the scull, the region of cerebrospinal fluid, and the brain tissue. A Dirac-like pulse has been used to excite the human head complex model and the acceleration response of the system has been calculated and analyzed via the wavelet-based methodology. For the purpose of the present analysis, a wave propagation commercial finite element code, LS-DYNA 3D, has been used. The progressive diffused oedema was modeled via consecutive increases in brain volume accompanied by a decrease in brain density. It was shown that even a small increase in brain volume (at the level of 0.5%) can be identified by the effect it has on the vibration characteristics of the human head complex. More precisely, it was found that for some of the wavelet decomposition levels, the energy content changes monotonically as the brain volume increases, thus providing a useful index of monitoring an oncoming brain oedema before any brain damage appears due to uncontrolled intracranial hypertension. For the purpose of the present work and for the levels of brain volume increase considered in the present analysis, no pressure increase was assumed into the cranial vault and, associatively, no brain compliance variation.

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.

Computational model of an infant brain subjected to periodic motion simplified modelling and bayesian sensitivity analysis

2011 ◽  
Vol 225 (11) ◽  
pp. 1036-1049 ◽  
Author(s):  
D C Batterbee ◽  
N D Sims ◽  
W Becker ◽  
K Worden ◽  
J Rowson
Keyword(s):  
Sensitivity Analysis ◽  
Finite Element ◽  
Shaken Baby Syndrome ◽  
Human Head ◽  
Element Model ◽  
Model Parameters ◽  
Lack Of Information ◽  
Eulerian Mesh ◽  
Model Geometry ◽  
The Brain

Non-accidental head injury in infants, or shaken baby syndrome, is a highly controversial and disputed topic. Biomechanical studies often suggest that shaking alone cannot cause the classical symptoms, yet many medical experts believe the contrary. Researchers have turned to finite element modelling for a more detailed understanding of the interactions between the brain, skull, cerebrospinal fluid (CSF), and surrounding tissues. However, the uncertainties in such models are significant; these can arise from theoretical approximations, lack of information, and inherent variability. Consequently, this study presents an uncertainty analysis of a finite element model of a human head subject to shaking. Although the model geometry was greatly simplified, fluid-structure-interaction techniques were used to model the brain, skull, and CSF using a Eulerian mesh formulation with penalty-based coupling. Uncertainty and sensitivity measurements were obtained using Bayesian sensitivity analysis, which is a technique that is relatively new to the engineering community. Uncertainty in nine different model parameters was investigated for two different shaking excitations: sinusoidal translation only, and sinusoidal translation plus rotation about the base of the head. The level and type of sensitivity in the results was found to be highly dependent on the excitation type.

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