The Influence of Neck Kinematics on Brain Pressures and Strains Under Blast Loading

2013 ◽  
Author(s):  
J. C. Roberts ◽  
T. P. Harrigan ◽  
E. E. Ward ◽  
D. Nicolella ◽  
L. Francis ◽  
...  
Keyword(s):  
Shock Tube ◽  
Blast Loading ◽  
Human Head ◽  
Pressure Response ◽  
System Level ◽  
Hybrid Iii ◽  
Head Rotations ◽  
The Brain ◽  
Head Neck

Strains and pressures in the brain are known to be influenced by rotation of the head in response to loading. This brain rotation is governed by the motion of the head, as permitted by the neck, due to loading conditions. In order to better understand the effect neck characteristics have on pressures and strains in the brain, a human head finite element model (HHFEM) was attached to two neck FEMs: a standard, well characterized Hybrid III Anthropometric Test Device neck FEM; and a high fidelity parametric probabilistic human FEM neck that has been hierarchically validated. The Hybrid III neck is well-established in automotive injury prevention studies, but is known to be much stiffer than in vivo human necks. The parametric FEM is based on CT scans and anatomic data, and the components of the model are validated against biomechanical tests at the component and system level. Both integrated head-neck models were loaded using pressure histories based on shock tube exposures. The shock tube loading applied to these head models were obtained using a computational fluid dynamics (CFD) model of the HHFEM surface in front of a 6 inch diameter shock tube. The calculated pressure-time histories were then applied to the head-neck models. The global head rotations, pressures, brain displacements, and brain strains of both head-neck models were compared for shock tube driver pressures from 517 to 862 kPa. The intracranial pressure response occurred in the first 1 to 5 msec, after blast impact, prior to a significant kinematic response, and was very similar between the two models. The global head rotations and the strains in the brain occurred at 20 to 100 msec after blast impact, and both were approximately two times higher in the model using the head parametric probabilistic neck FEM (H2PN), as compared to the model using the head Hybrid III neck FEM (H3N). It was also discovered that the H2PN exhibited an initial backward and small downward motion in the first 10 ms not seen in the H3N. The increased displacements and strains were the primary difference between the two combined models, indicating that neck constraints are a significant factor in the strains induced by blast loading to the head. Therefore neck constraints should be carefully controlled in studies of brain strain due to blast, but neck constraints are less important if pressure response is the only response parameter of primary interest.

Development of a Human Head Physical Surrogate Model for Investigating Blast Injury

2009 ◽  
Author(s):  
A. C. Merkle ◽  
I. D. Wing ◽  
R. A. Armiger ◽  
B. G. Carkhuff ◽  
J. C. Roberts
Keyword(s):  
Blast Loading ◽  
Human Head ◽  
Head Model ◽  
Loading Conditions ◽  
Pressure Loading ◽  
Spatial Response ◽  
Displacement Sensors ◽  
Hybrid Iii ◽  
Intracranial Pressures ◽  
The Brain

The objective of this effort was to develop a Human Surrogate Head Model (HSHM) and measure its response to pressure loading conditions representative of a blast environment. The HSHM consists of skin, face, skull, and brain fabricated using biosimulant materials and mounted to the neck of a Hybrid III Anthropomorphic Test Device to allow head motion during loading. The HSHM instrumentation includes pressure and displacement sensors embedded in the anterior and posterior areas of the brain along the saggital plane. The displacement sensors are a custom solution developed for this particular application. A series of shock tube tests at three varying load levels were conducted with the HSHM to simulate blast loading conditions. As pressure loading levels increased, the intracranial pressures and brain displacements increased as well. However, the spatial response of the displacement sensors varied with location in the brain. The results of this test series provide the first instance of intracranial pressure and directly measured brain displacements recorded from an anatomically correct head surrogate exposed to conditions representative of blast loading.

Effects of CSF Properties on Brain Response Under Impact Loading

2009 ◽  
Author(s):  
M. S. Chafi ◽  
V. Dirisala ◽  
G. Karami ◽  
M. Ziejewski
Keyword(s):  
Human Head ◽  
Brain Response ◽  
Pia Mater ◽  
Mechanical Shocks ◽  
The Central Nervous System ◽  
Simultaneous Loading ◽  
The Impact ◽  
Impact Experiments ◽  
The Brain

In the central nervous system, the subarachnoid space is the interval between the arachnoid membrane and the pia mater. It is filled with a clear, watery liquid called cerebrospinal fluid (CSF). The CSF buffers the brain against mechanical shocks and creates buoyancy to protect it from the forces of gravity. The relative motion of the brain due to a simultaneous loading is caused because the skull and brain have different densities and the CSF surrounds the brain. The impact experiments are usually carried out on cadavers with no CSF included because of the autolysis. Even in the cadaveric head impact experiments by Hardy et al. [1], where the specimens are repressurized using artificial CSF, this is not known how far this can replicate the real functionality of CSF. With such motivation, a special interest lies on how to model this feature in a finite element (FE) modeling of the human head because it is questionable if one uses in vivo CSF properties (i.e. bulk modulus of 2.19 GPa) to validate a FE human head against cadaveric experimental data.

An Experimental Study of Package Cushioning for the Human Head

1976 ◽  
Vol 43 (3) ◽  
pp. 469-474
Author(s):  
Y. King Liu ◽  
K. B. Chandran
Keyword(s):  
Mathematical Model ◽  
Animal Experiments ◽  
Human Head ◽  
Head Impacts ◽  
Closed Head ◽  
The Mathematical Model ◽  
Experimental Pressure ◽  
The Brain ◽  
Good Agreement

An experiment was performed to determine the container acceleration and pressure distribution in a Plexiglass cylinder, filled either with water or 3 percent set-gelatin, and impacted against a wall. This experiment serves to quantitatively validate a theoretical model simulating an one-dimensional closed-head impact given earlier. The experiments showed important differences between the theoretical and experimental pressure measurements. When the medium contained within the cylinder was water the coup pressure as found by experiment, was higher than the mathematical model prediction while the contrecoup pressure was in good agreement. When the container was filled with a set gel, the coup pressure was in agreement with the mathematical model but the contrecoup pressure is considerably lower than the calculated result. Since the brain is neither water nor gel, in vivo animal experiments are needed to obtain meaningful tolerance limits for injury due to cavitation at the contrecoup region in closed-head impacts.

scholarly journals A simplified human head finite element model for brain injury assessment of blunt impacts

2020 ◽  
Vol 14 (2) ◽  
pp. 6538-6547 ◽  
Author(s):  
M.H.A. Hassan ◽  
Z. Taha ◽  
I. Hasanuddin ◽  
A.P.P.A. Majeed ◽  
H. Mustafa ◽  
...  
Keyword(s):  
Finite Element ◽  
Three Dimensional ◽  
Human Head ◽  
Brain Trauma ◽  
Head Model ◽  
Human Cadaver ◽  
Brain Responses ◽  
Dimensional Models ◽  
The Brain ◽  
Head Neck

Blunt impacts contribute more than 95% of brain trauma injuries in Malaysia. Modelling and simulation of these impacts are essential in understanding the mechanics of the injuries to develop a protective equipment that might prevent brain trauma. Various finite element models of human head have been developed, ranging from two-dimensional models to very complex three-dimensional models. The aim of this study is to develop a simplified three-dimensional human head model with low computational cost, yet capable of producing reliable brain responses. The influence of different head-neck boundary conditions on the brain responses were also examined. Our model was validated against an experimental work on human cadaver. The model with free head-neck boundary condition was found to be in good agreement with experimental results. The head-neck joint was found to have a significant influence on the brain responses upon impact. Further investigations on the head-neck joint modelling are needed. Our simplified model was successfully validated against experimental data on human cadaver and could be used in simulating blunt impact scenarios.

Response of Post-Mortem Human Head Under Primary Blast Loading Conditions: Effect of Blast Overpressures

2013 ◽  
Author(s):  
Shailesh Ganpule ◽  
Robert Salzar ◽  
Namas Chandra
Keyword(s):  
Brain Injury ◽  
Blast Loading ◽  
Human Head ◽  
Severe Injury ◽  
Post Mortem ◽  
Loading Conditions ◽  
Primary Blast ◽  
Blast Overpressure ◽  
Moderate Traumatic Brain Injury ◽  
The Brain

Blast induced neurotrauma (BINT), and posttraumatic stress disorder (PTSD) are identified as the “signature injuries” of recent conflicts in Iraq and Afghanistan. The occurrence of mild to moderate traumatic brain injury (TBI) in blasts is controversial in the medical and scientific communities because the manifesting symptoms occur without visible injuries. Whether the primary blast waves alone can cause TBI is still an open question, and this work is aimed to address this issue. We hypothesize that if a significant level of intracranial pressure (ICP) pulse occurs within the brain parenchyma when the head is subjected to pure primary blast, then blast induced TBI is likely to occur. In order to test this hypothesis, three post mortem human heads are subjected to simulated primary blast loading conditions of varying intensities (70 kPa, 140 kPa and 200 kPa) at the Trauma Mechanics Research Facility (TMRF), University of Nebraska-Lincoln. The specimens are placed inside the 711 mm × 711 mm square shock tube at a section where known profiles of incident primary blast (Friedlander waveform in this case) are obtained. These profiles correspond to specific field conditions (explosive strength and stand-off distance). The specimen is filled with a brain simulant prior to experiments. ICPs, surface pressures, and surface strains are measured at 11 different locations on each post mortem human head. A total of 27 experiments are included in the analysis. Experimental results show that significant levels of ICP occur throughout the brain simulant. The maximum peak ICP is measured at the coup site (nearest to the blast) and gradually decreases towards the countercoup site. When the incident blast intensity is increased, there is a statistically significant increase in the peak ICP and total impulse (p<0.05). Even after five decades of research, the brain injury threshold values for blunt impact cases are based on limited experiments and extensive numerical simulations; these are still evolving for sports-related concussion injuries. Ward in 1980 suggested that no brain injury will occur when the ICP<173 kPa, moderate to severe injury will occur when 173 kPa<ICP<235 kPa and severe injury will occur when ICP>235 kPa for blunt impacts. Based on these criteria, no injury will occur at incident blast overpressure level of 70 kPa, moderate to severe injuries will occur at 140 kPa and severe head injury will occur at the incident blast overpressure intensity of 200 kPa. However, more work is needed to confirm this finding since peak ICP alone may not be sufficient to predict the injury outcome.

scholarly journals Afferent Responses During Experimentally Induced Semicircular Canalithiasis

2007 ◽  
Vol 97 (3) ◽  
pp. 2355-2363 ◽  
Author(s):  
Suhrud M. Rajguru ◽  
Richard D. Rabbitt
Keyword(s):  
Semicircular Canal ◽  
Time Course ◽  
Discharge Rate ◽  
Initial Increase ◽  
Vestibular Disorder ◽  
Afferent Discharge ◽  
Oyster Toadfish ◽  
Head Rotations ◽  
The Brain

Benign paroxysmal positional vertigo (BPPV) is a common vestibular disorder that results in brief periods of vertigo and nystagmus, when the head is tipped relative to gravity. Symptoms are commonly attributed to the pathological presence of heavy calcium carbonate particles within the lumen of the semicircular canal(s)—a condition termed canalithiasis. In the present work, we induced canalithiasis in an animal model (oyster toadfish, Opsanus tau) by introducing heavy glass microbeads into the lumen of the lateral semicircular canal. Bead movement under the action of gravity and canal afferent nerve discharge were recorded in vivo. When the head was oriented nose-down, beads moved toward the nose and the lateral canal afferent discharge rate increased. Afferents that normally encoded angular velocity during oscillatory head rotations responded with tonic increases in the discharge rate during gravity-dependent bead movement. Other afferents, such as the units that rapidly adapt to a step increase in angular head velocity, responded with an initial increase in discharge rate followed by a period of adaptation. Afferent responses occurred in the complete absence of head movement and quantify the pathological inputs to the brain that arise from canalithiasis. The magnitude and time course of the responses reported here are sufficient to explain the symptoms of BPPV.

Development of a Human Head-Neck Computational Model for Assessing Blast Injury

2009 ◽  
Author(s):  
J. C. Roberts ◽  
E. E. Ward ◽  
T. P. Harrigan ◽  
T. M. Taylor ◽  
M. A. Annett ◽  
...  
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Experimental Testing ◽  
Grid Point ◽  
Blast Loading ◽  
Human Head ◽  
Material Model ◽  
Element Model ◽  
Head Model ◽  
The Brain

A finite element model (FEM) of the human head attached to a Hybrid III FEM neck was developed to study the effects of blast loading on the brain. Simulations of blast loading to this Human Head Finite Element Model (HHFEM) were generated by creating a computational fluid dynamics (CFD) model of the HHFEM headform in a shock tube. Three different driver pressure loading conditions from experimental testing of the Human Surrogate Head Model (HSHM) were simulated by this model. The pressure time histories at each grid point of the CFD headform were used as inputs to the HHFEM. Brain/cerebral spinal fluid (CSF) and CSF/skull boundary conditions along with different brain material models were considered. The Kelvin-Maxwell material model and a low friction surface-to-surface interface were found to best replicate conditions seen in experimental testing of the HSHM. Deformations in the anterior and posterior locations of the brain varied from 0.5–0.9 mm and intracranial pressures at those locations were between 32 and 55 kPa.

Biomechanical Evaluation of the Axial Compressive Responses of the Human Cadaveric and Manikin Necks

1989 ◽  
Vol 111 (3) ◽  
pp. 250-255 ◽  
Author(s):  
N. Yoganandan ◽  
A. Sances ◽  
F. Pintar
Keyword(s):  
Human Head ◽  
Axial Stiffness ◽  
Axial Loads ◽  
Anatomic Structure ◽  
Clinical Prognosis ◽  
Cervical Spine Injuries ◽  
Compressive Response ◽  
Hybrid Iii ◽  
Human Cadavers ◽  
Head Neck

Cervical spine injuries such as wedge, burst, and tear drop fractures are often associated with compressive axial loads delivered to the human head-neck complex. Understanding the injury mechanisms, the kinematics of the anatomic structure, and the tissue tolerances can improve clinical prognosis and facilitate a better design for anthropomorphic devices. The axial compressive response of human cadaveric preparations was compared with the 50th percentile anthropomorphic Hybrid III manikin under various loading rates. Ten fresh human cadavers were used in the study. Intact cadaver torsos, head-cervical spines, and ligamentous cervical columns were tested. The head-neck structure and the neck (without head) of the Hybrid III manikin were also tested. Responses of the human cadaveric preparations and manikin structures were nonlinear at all rates of loading. However, axial stiffness, a measure of the ability of the structure to withstand external force, was higher under all rates of loading for manikin preparations when compared with the human cadaveric tissues.

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.

scholarly journals Cerebral Vasculature Influences Blast-Induced Biomechanical Responses of Human Brain Tissue

2021 ◽  
Vol 9 ◽  
Author(s):  
Dhananjay Radhakrishnan Subramaniam ◽  
Ginu Unnikrishnan ◽  
Aravind Sundaramurthy ◽  
Jose E. Rubio ◽  
Vivek Bhaskar Kote ◽  
...  
Keyword(s):  
Human Brain ◽  
Shock Tube ◽  
Brain Tissue ◽  
Human Head ◽  
Cerebral Veins ◽  
Fe Model ◽  
Cerebral Vasculature ◽  
Tissue Properties ◽  
Biomechanical Responses ◽  
The Brain

Multiple finite-element (FE) models to predict the biomechanical responses in the human brain resulting from the interaction with blast waves have established the importance of including the brain-surface convolutions, the major cerebral veins, and using non-linear brain-tissue properties to improve model accuracy. We hypothesize that inclusion of a more detailed network of cerebral veins and arteries can further enhance the model-predicted biomechanical responses and help identify correlates of blast-induced brain injury. To more comprehensively capture the biomechanical responses of human brain tissues to blast-wave exposure, we coupled a three-dimensional (3-D) detailed-vasculature human-head FE model, previously validated for blunt impact, with a 3-D shock-tube FE model. Using the coupled model, we computed the biomechanical responses of a human head facing an incoming blast wave for blast overpressures (BOPs) equivalent to 68, 83, and 104 kPa. We validated our FE model, which includes the detailed network of cerebral veins and arteries, the gyri and the sulci, and hyper-viscoelastic brain-tissue properties, by comparing the model-predicted intracranial pressure (ICP) values with previously collected data from shock-tube experiments performed on cadaver heads. In addition, to quantify the influence of including a more comprehensive network of brain vessels, we compared the biomechanical responses of our detailed-vasculature model with those of a reduced-vasculature model and a no-vasculature model for the same blast-loading conditions. For the three BOPs, the predicted ICP values matched well with the experimental results in the frontal lobe, with peak-pressure differences of 4–11% and phase-shift differences of 9–13%. As expected, incorporating the detailed cerebral vasculature did not influence the ICP, however, it redistributed the peak brain-tissue strains by as much as 30% and yielded peak strain differences of up to 7%. When compared to existing reduced-vasculature FE models that only include the major cerebral veins, our high-fidelity model redistributed the brain-tissue strains in most of the brain, highlighting the importance of including a detailed cerebral vessel network in human-head FE models to more comprehensively account for the biomechanical responses induced by blast exposure.

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