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.

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.

Traumatic Brain Injury Caused by +Gz Acceleration

2016 ◽  
Author(s):  
Abbas Shafiee ◽  
Mohammad Taghi Ahmadian ◽  
Maryam Hoviattalab
Keyword(s):  
Traumatic Brain Injury ◽  
Brain Injury ◽  
Damage Threshold ◽  
Human Head ◽  
Loss Of Consciousness ◽  
Time Duration ◽  
University Of Technology ◽  
Trauma Model ◽  
The Brain ◽  
Brain Pressure

Traumatic brain injury (TBI) has long been known as one of the most anonymous reasons for death around the world. This phenomenon has been under study for many years and yet it remains a question due to physiological, geometrical and computational complexity. Although the modeling facilities for soft tissue have improved, the precise CT-imaging of human head has revealed novel details of the brain, skull and meninges. In this study a 3D human head including the brain, skull, and meninges is modeled using CT-scan and MRI data of a 30-year old human. This model is named “Sharif University of Technology Head Trauma Model (SUTHTM)”. By validating SUTHTM, the model is then used to study the effect of +Gz acceleration on the human brain. Damage threshold based on loss of consciousness in terms of acceleration and time duration is developed using Maximum Brain Pressure criteria. Results revealed that the Max. Brain Pressure ≥3.1 are representation of loss of consciousness. 3D domains for the loss of consciousness are based on Max. Brain Pressure is developed.

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.

Blast Wave Loading Pathways in Heterogeneous Material Systems–Experimental and Numerical Approaches

2013 ◽  
Vol 135 (6) ◽  
Author(s):  
Veera Selvan ◽  
Shailesh Ganpule ◽  
Nick Kleinschmit ◽  
Namas Chandra
Keyword(s):  
Brain Injury ◽  
Blast Wave ◽  
Injury Severity ◽  
Flexural Rigidity ◽  
Temporal Variations ◽  
Blast Waves ◽  
Cylinder Surface ◽  
Mechanical Pressure ◽  
Pressure Pulses ◽  
The Brain

Blast waves generated in the field explosions impinge on the head-brain complex and induce mechanical pressure pulses in the brain resulting in traumatic brain injury. Severity of the brain injury (mild to moderate to severe) is dependent upon the magnitude and duration of the pressure pulse, which in turn depends on the intensity and duration of the oncoming blast wave. A fluid-filled cylinder is idealized to represent the head-brain complex in its simplest form; the cylinder is experimentally subjected to an air blast of Friedlander type, and the temporal variations of cylinder surface pressures and strains and fluid pressures are measured. Based on these measured data and results from computational simulations, the mechanical loading pathways from the external blast to the pressure field in the fluid are identified; it is hypothesized that the net loading at a given material point in the fluid comprises direct transmissive loads and deflection-induced indirect loads. Parametric studies show that the acoustic impedance mismatches between the cylinder and the contained fluid as well as the flexural rigidity of the cylinder determine the shape/intensity of pressure pulses in the fluid.

Development and validation of a biofidelic head form model to assess blast-induced traumatic brain injury

2017 ◽  
Vol 15 (3) ◽  
pp. 257-267
Author(s):  
Devon Downes ◽  
Amal Bouamoul ◽  
Simon Ouellet ◽  
Manouchehr Nejad Ensan
Keyword(s):  
Finite Element ◽  
Brain Injury ◽  
Blast Wave ◽  
Skull Fracture ◽  
Free Field ◽  
Blast Loading ◽  
Human Head ◽  
Arbitrary Lagrangian Eulerian ◽  
Element Analysis ◽  
Head Form

Traumatic Blast Injury (TBI) associated with the human head is caused by exposure to a blast loading, resulting in decreased level of consciousness, skull fracture, lesions, or death. This paper presents the simulation of blast loading of a human head form from a free-field blast with the end goal of providing insight into how TBI develops in the human head. The developed numerical model contains all the major components of the human head, the skull, and brain, including the tentorium, cerebral falx, and gray and white matter. A nonlinear finite element analysis was employed to perform the simulation using the Arbitrary Lagrangian–Eulerian finite element method. The simulation captures the propagation of the blast wave through the air, its interaction with the skull, and its transition into the brain matter. The model quantifies the pressure histories of the blast wave from the explosive source to the overpressure on the skull and the intracranial pressure. This paper discusses the technical approach used to model the head, the outcome from the analysis, and the implication of the results on brain injury.

Simulation of Blast Induced Traumatic Brain Injury using Finite Element Method

2021 ◽  
Vol 13 (2) ◽  
Author(s):  
G. Krishnaveni ◽  
D. Dominic Xavier ◽  
R. Sarathkumar ◽  
G. Kavitha ◽  
M. Senbagan
Keyword(s):  
Traumatic Brain Injury ◽  
Finite Element ◽  
Brain Injury ◽  
Blast Wave ◽  
Ambient Pressure ◽  
Memory Loss ◽  
Human Head ◽  
Head Model ◽  
Stress Concentrations ◽  
The Brain

Because of increase in threat from militant groups and during war exposure to blast wave from improvised explosive devices, Traumatic Brain Injury (TBI), a signature injury is on rise worldwide. During blast, the biological system is exposed to a sudden blast over pressure which is several times higher than the ambient pressure causing the damage in the brain. The severity of TBI due to air blast may vary from brief change in mental status or consciousness (termed as mild) to extended period of unconsciousness or memory loss after injuries (termed as severe). The blast wave induced impact on head propagates as shock wave with the broad spectrum of frequencies and stress concentrations in the brain. The primary blast TBI is directly induced by pressure differentials across the skull/fluid/soft tissue interfaces and is further reinforced by the reflected stress waves within the cranial cavity, leading to stress concentrations in certain regions of the brain. In this paper, an attempt has been made to study the behaviour of a human brain model subjected to blast wave based on finite element model using LSDYNA code. The parts of a typical human head such as skull, scalp, CSF, brain are modelled using finite element with properties assumed based on available literature. The model is subjected to blast from frontal lobe, occipital lobe, temporal lobe of the brain. The interaction of the blast wave with the head and subsequent transformation of various forms of shock energy internally have been demonstrated in the human head model. The brain internal pressure levels and the shear stress distribution in the various lobes of the brain such as frontal, parietal, temporal and occipital are determined and presented.

Comparison of Mechanical Variable Identifiers of Brain Injury

2013 ◽  
Author(s):  
Siddiq M. Qidwai ◽  
Nithyanand Kota ◽  
Alan C. Leung ◽  
Amit Bagchi
Keyword(s):  
Brain Injury ◽  
Ex Vivo ◽  
Computational Simulation ◽  
Region Of Interest ◽  
Human Head ◽  
Critical Value ◽  
Loading Test ◽  
Mechanical Variable ◽  
Location Type ◽  
The Brain

Multiple mechanical variables have been used to describe the occurrence of brain injury in impact modeling of the human head [1, 2]. The validity of these variables for this purpose is usually established separately through the following process. First, a loading test is performed on an animal. Location, type and spatial extent of injury on the brain are measured upon or after loading. Subsequently, computational simulation is performed based on a particular constitutive model of the brain. Mechanical variables such as pressure or effective stress are plotted for the region of interest. The magnitude of the mechanical variable that results in a contour of the same size as the observed extent of experimental injury is declared as the critical value for that type of injury. The choice of mechanical variable itself could be based on conventional wisdom, precedence, or experience of the researcher. Another, much simpler variable-injury correlation process, which does not rely upon simulations, uses the ex vivo failure response of brain tissue as the criterion. For example, the uniaxial failure strain of the tissue may be taken as the critical value for injury.

scholarly journals Brain Injury Differences in Frontal Impact Crash Using Different Simulation Strategies

2015 ◽  
Vol 2015 ◽  
pp. 1-8
Author(s):  
Dao Li ◽  
Chunsheng Ma ◽  
Ming Shen ◽  
Peiyu Li ◽  
Jinhuan Zhang
Keyword(s):  
Brain Injury ◽  
Human Body ◽  
Human Head ◽  
Von Mises Stress ◽  
Head Model ◽  
Fe Model ◽  
Human Body Model ◽  
Body Model ◽  
Cumulative Strain ◽  
The Brain

In the real world crashes, brain injury is one of the leading causes of deaths. Using isolated human head finite element (FE) model to study the brain injury patterns and metrics has been a simplified methodology widely adopted, since it costs significantly lower computation resources than a whole human body model does. However, the degree of precision of this simplification remains questionable. This study compared these two kinds of methods: (1) using a whole human body model carried on the sled model and (2) using an isolated head model with prescribed head motions, to study the brain injury. The distribution of the von Mises stress (VMS), maximum principal strain (MPS), and cumulative strain damage measure (CSDM) was used to compare the two methods. The results showed that the VMS of brain mainly concentrated at the lower cerebrum and occipitotemporal region close to the cerebellum. The isolated head modelling strategy predicted higher levels of MPS and CSDM 5%, while the difference is small in CSDM 10% comparison. It suggests that isolated head model may not equivalently reflect the strain levels below the 10% compared to the whole human body model.

Experimental and Computational Analysis of Brain Deformations in Linear Head Impact

2008 ◽  
Author(s):  
Kurosh Darvish ◽  
Mehdi Shafieian ◽  
Kaveh Laksari ◽  
Banafsheh Barabadi ◽  
Cristina Parenti
Keyword(s):  
Viscoelastic Properties ◽  
Computational Models ◽  
Computational Analysis ◽  
Axonal Injury ◽  
Human Head ◽  
Finite Element Models ◽  
Arbitrary Lagrangian Eulerian ◽  
Strain Stress ◽  
The Brain ◽  
Experimental Strains

In this study two-dimensional physical and finite element models of human head under linear deceleration were developed. 5% gelatin was used as the brain substitute material with similar viscoelastic properties. The experimental strains and pressure during 55G impacts were measured to validate the element formulations used in the computational models. The Lagrangian and Arbitrary Lagrangian Eulerian (ALE) formulations were used in the FE models. It was shown that without Cerebrospinal Fluid (CSF), the Lagrangian strains passed the 10% threshold of axonal injury. At the presence of CSF, no significant strain was observed while 6 to 8 times increase in the intracranial pressure was recorded. The FE models showed similar trends for strain, stress, and pressure but were generally more aggressive than the experimental results. The ALE model was more stable and its effective damping was more consistent with the experimental data.

Quantification of Shockwave Transmission Through the Cranium Using an Experimental Model

2013 ◽  
Author(s):  
Alok S. Shah ◽  
Brian D. Stemper ◽  
Narayan Yoganandan ◽  
Barry S. Shender
Keyword(s):  
Brain Injury ◽  
Brain Tissue ◽  
Human Subjects ◽  
Fluid Pressure ◽  
Diffuse Axonal Injury ◽  
Mechanical Damage ◽  
Human Head ◽  
Blast Injury ◽  
Blast Waves ◽  
High Rate

Studies have hypothesized mechanisms for brain injury resulting from exposure to blast waves. Theories include shockwaves increasing fluid pressure within brain tissue by transmitting through bones and blood vessels 1, indirect brain tissue damage due to ischemia from pulmonary blast injury 2, and formation of mechanical stresses that can result in tissue distortion 3. Mechanical damage to brain tissue can occur due to skull flexure resulting in loads typically seen in impact-induced injury 4 or axonal shearing/stretching, due to linear or rotational accelerations resulting in Diffuse Axonal Injury (DAI) 5. Despite several investigations it remains unclear whether direct propagation of the shockwave through the cranium can deform brain tissue and result in mechanically-induced injury 6. Finite element 7, 8 and animal 9, 10 models provide information on mechanisms and outcomes of blast-induced mTBI (mild traumatic brain injury). However, validations of FEM studies were limited due to the paucity of high rate material properties. Animal tests were designed to understand mechanisms of shockwave transmission but most did not report intracranial pressures. Understanding blast injury mechanisms requires a better delineation of shockwave energy transfer through the head and the influence of factors including region-specific differences, and mechanical properties of brain simulant. A Post Mortem Human Subjects (PMHS) model was used in this study to examine these factors and provide an understanding of shockwave transmission through the tissues of the human head.

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