Experimental Studies of Side Impact to the Human Head

1980 ◽  
Author(s):  
A. Nahum ◽  
C. Ward ◽  
E. Raasch ◽  
S. Adams ◽  
D. Schneider
2004 ◽  
Vol 97 (6) ◽  
pp. 2051-2055 ◽  
Author(s):  
Christopher M. Collins ◽  
Michael B. Smith ◽  
Robert Turner

Experimental results for changes in brain temperature during functional activation show large variations. It is, therefore, desirable to develop a careful numerical model for such changes. Here, a three-dimensional model of temperature in the human head using the bioheat equation, which includes effects of metabolism, perfusion, and thermal conduction, is employed to examine potential temperature changes due to functional activation in brain. It is found that, depending on location in brain and corresponding baseline temperature relative to blood temperature, temperature may increase or decrease on activation and concomitant increases in perfusion and rate of metabolism. Changes in perfusion are generally seen to have a greater effect on temperature than are changes in metabolism, and hence active brain is predicted to approach blood temperature from its initial temperature. All calculated changes in temperature for reasonable physiological parameters have magnitudes <0.12°C and are well within the range reported in recent experimental studies involving human subjects.


2015 ◽  
Vol 9 (1) ◽  
pp. 138-145 ◽  
Author(s):  
Irene Karanasiou

Aims:Modeling of ionic distribution fluctuations of excitable tissues based on data elicited using focused microwave radiometry.Methodology:Focused Microwave Radiometry implemented to carry out measurements of in depth body temperature distributions, may provide the capability of sensing local electrical conductivity fluctuations during the cycle of actions potentials in the case of brain excitable cell clusters. An analog beamformer consisting of a conductive inner-surface ellipsoidal cavity is used to focus the chaotic-black body radiation emerging from human tissues by providing convergence of the electromagnetic energy from one focus area where the phantom or subject is placed, to the other where the antennas of sensitive radiometric receivers are positioned. During the past 10 years numerous phantom, animal and human volunteer experiments have been performed with the focused radiometry imaging system. The results show that the detected changes of the output radiometric voltage are attributed to temperature and/or conductivity changes that occur locally concentrated at the areas of interest under measurement. Theoretical and experimental studies are continuously carried out at various frequency bands in conjunction with the use of matching materials placed around the human head or phantom to improve focusing and detection depth. It seems that the manipulation of the focusing area in the tissue in terms of detection depth and spatial resolution is feasible depending on the suitable combination of operation frequencies and matching material. In this paper, theoretical analysis of ion charge diffusion during the cycle of action potentials, propagating along the axons in case of measurements of specific cortical regions is presented. The ion charge diffusion modeling is based on electromagnetic diffusion analogies in the effort to explain the observed experimental results obtained under various psychophysiological conditions in the case of human volunteer measurements.Results:By implementing an analysis based on the continuity equations of ionic charges it is concluded that the microwave radiometry output voltage is not affected by the temporal and spatial average fluctuations of Na+, K+, and Cl-ions of neural cell axons.Conclusion:The analysis of conductivity fluctuations in the central neural system in conjunction with the electromagnetic analysis of the system, leads to the interpretation of the previously acquired experimental data. The application of this technique with other brain functional mapping methods, may provide complementary knowledge to the understanding of the functional organization of psychophysiological processes.


Author(s):  
Hesam Sarvghad-Moghaddam ◽  
Asghar Rezaei ◽  
Ashkan Eslaminejad ◽  
Mariusz Ziejewski ◽  
Ghodrat Karami

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.


2014 ◽  
Vol 07 (06) ◽  
pp. 1450073 ◽  
Author(s):  
Mir Aijaz ◽  
M. A. Khanday ◽  
Aasma Rafiq

The human head is one of the most sensitive parts of human body due to the fact that it contains brain. Any abnormality in the functioning of brain may disturb the entire system. One of the disturbing factors of brain is thermal stress. Thus, it is imperative to study the effects of thermal stress on human head at various environmental conditions. For the thermoregulation process, the human head is considered to be a structure of four layers viz.; brain, cerebrospinal fluid (CSF), skull and scalp. A mathematical model has been formulated to estimate the variation of temperature at these layers. The model is based on radial form of bio-heat equation with the appropriate boundary conditions and has been solved by variational finite element method. The rate of metabolic heat generation and thermal conductivity in this study have been assumed to be heterogeneous. The results were compared with the experimental studies for their coincidence and it has been observed theoretically and experimentally that the human head has greater resistance to compete with the thermal stress up to large extent.


2014 ◽  
Vol 14 (06) ◽  
pp. 1440002 ◽  
Author(s):  
XINGQIAO DENG ◽  
SHOU AN CHEN ◽  
R. PRABHU ◽  
YUANYUAN JIANG ◽  
Y. MAO ◽  
...  

Mechanical response of the human head under a side car crash impact is crucial for modeling traumatic brain injuries (TBI) or concussions. The current advances in computational methods and the finite element models of the human head provide a significant opportunity for biomechanical study of brain injuries; however, limited experimental data is available for delineating the injury relationship between the head injury criteria (HIC) and the tensile pressure or von Mises stress. In this research, we assess human head injuries in a side impact car crash using finite element (FE) simulations that quantify the tensile pressures and maximum strain profiles. In doing so, five FE analyses for the human head have been carried out to investigate the correlations between the HIC measured in the dummy model at different moving deformable barrier (MDB) velocities increasing from 10 mph to 30 mph in 5 mph increments and the pressure and von Mises stress of the skull, the skin, the cerebral spinal fluid (CSF) and the brain. The computational simulation results for the tensile pressures and von Mises stresses correlated well with the HIC15 and peak accelerations. Also a second-order polynomial seemed to fit the stress levels to the impact speeds and as such the presented method for using FE human head analysis could be used for reconstruction of head impacts in different side car crash conditions; furthermore, the head model would provide a tool for investigation of the cause and mechanisms of head injuries once the type and locations of injuries are quantified.


1991 ◽  
Vol 113 (3) ◽  
pp. 276-283 ◽  
Author(s):  
J. S. Ruan ◽  
T. Khalil ◽  
A. I. King

The dynamic response of the human head to side impact was studied by 2-dimensional finite element modeling. Three models were formulated in this study. Model I is an axisymmetric model. It simulated closed shell impact of the human head, and consisted of a single-layered spherical shell filled with an inviscid fluid. The other two models (Model II and III) are plane strain models of a coronal section of the human head. Model II approximated a 50th percentile male head by an outer layer to simulate cranial bone and an inviscid interior core to simulate the intracranial contents. The configuration of Model III is the same as Model II but more detailed anatomical features of the head interior were added, such as, cerebral spinal fluid (CSF); falx cerebri, dura, and tentorium. Linear elastic material properties were assigned to all three models. All three models were loaded by a triangular pulse with a peak pressure of 40 kPa, effectively producing apeak force of 1954 N (440 lb). The purpose of this study was to determine the effects of the membranes and that of the mechanical properties of the skull, brain, and membrane on the dynamic response of the brain during side impact, and to compare the pressure distributions from the plane strain model with the axisymmetric model. A parametric study was conducted on Model II to characterize fully its response to impact under various conditions. It was found that: (a) The membranes affected the dynamic response of the brain significantly, the fundamental frequency of the brain was 72 Hz with membranes and 49 Hz without them: (b) Significant variations in the pressure distribution were obtained as a result of assigning different material properties to the skull and brain; (c) The normal variation of pressure from compression at the pole (impact side) to tension at the antipole (opposite to the impact side) was disrupted by the membrane and a complex distribution of pressure was found.


Author(s):  
Siavash Hashemi ◽  
Sharlin Anwar ◽  
Shahab Mansoorbaghaei ◽  
Ali M. Sadegh

Traumatic brain injury (TBI) is an intracranial injury caused by impacts or angular accelerations of the head such as a violent blow, a bump, a projectile, or even a blast. TBI is a major problem that accounts for over 1.4 million emergency room visits in US. Thus, it is important to understand and predict the occurrence of TBI. Previous studies have shown that the interaction between the subarachnoid space (SAS) trabeculae and the cerebrospinal fluid (CSF) plays an important role in damping the effect of impacts and reducing the brain injuries. However, the influence of sulci parameters and sulci trabeculae in impact induced TBI is still unexplored. A few studies have shown that inclusion of sulci in brain models alters the brain injuries conclusions, even though those models do not take into account the trabecular tissue present in the sulci. In this study, to obtain a perspective of the morphology and architecture of the sulci trabeculae at the frontal lobe of the brain, Human cadaver brain of an 87 year old male was used. For the first experiment, several sulci from the frontal lobe were sectioned and measured to find the average sulci depth, using the image processing software called ‘ImageJ’. This experiment was followed by the Scanning Electron Microscopy (SEM) study on the samples prepared from the frontal lobe. Indeed, numerous images were taken at various magnifications to find different trabecular morphology and architecture in the sulci. The results from the experimental studies were used in our numerical analyses. To do so, the validated global 3D FE model of the human head and neck, created at The City College of New York, were impacted by a rigid barrier on the forehead. The pressure time history, beneath the skull, was calculated during and after the impact. Moreover, a local 3D FE model has been created, having the meninges and the brain with sulci, including the trabeculae and the CSF. The depth of the sulci and the architecture of the trabeculae have been inspired by the imaging and SEM studies. Indeed, the top surface of the local model was subjected to the pressure loading condition obtained from the global model. The results of the finite element simulations reveal that the interaction between the trabeculae and the CSF inside the sulci, would affect and reduce the movement and displacement of gyri and sulci’s walls when the forehead of the head is impacted by an elastic barrier.


Author(s):  
Seth C. Taylor ◽  
Benjamin Ondruschka ◽  
David C. Kieser ◽  
Niels Hammer ◽  
Matthew Lee ◽  
...  

AbstractRifles are often involved in violent deaths such as homicide and suicide. Consequently, expert knowledge and experimental forensic investigations are important to clarify the nature of ballistic trauma when applied to the human head and neurocranium. This study investigated differences in entrance wound morphology with Synbone® spheres which are described as being comparable to human flat bones. A series of ballistic experiments were conducted using two different rifle calibers (5.56 × 45 mm and 7.62 × 39 mm Full Metal Jacket (FMJ)). Synbone® spheres were used for close-range 0.3 m simulated executions as well as at 25 m and 35 m to simulate urban and military engagements. Results were compared with previously published experimental studies using similar military ammunition. In our study, entry wound morphology closely resembles real forensic cases compared to exit wound and overall shape morphology independently of the distance and the caliber. Circumferential delamination was clearly visible with full metal jacket (FMJ) rounds, yielding similar damage pattern morphology to the human crania. This study documented the presence of hydraulic burst or shock in all ten rounds from all three distances. Krönlein shots were also observed in some cases. Synbone® spheres constitute an acceptable synthetic surrogate for ballistic experiments. The present study offers new initial data on the behavior of Synbone® proxies in ballistic testing of military ammunitions; FMJ gunshot injuries to the human head, for distances that have not previously been published, suggesting that efficient tests can take place under these conditions. Further research on experimental ballistics with a larger number of controlled factors and multiple repetitions is recommended to verify the results of this pilot study before applied in forensic simulations.


Author(s):  
Kent McDonald ◽  
David Mastronarde ◽  
Rubai Ding ◽  
Eileen O'Toole ◽  
J. Richard McIntosh

Mammalian spindles are generally large and may contain over a thousand microtubules (MTs). For this reason they are difficult to reconstruct in three dimensions and many researchers have chosen to study the smaller and simpler spindles of lower eukaryotes. Nevertheless, the mammalian spindle is used for many experimental studies and it would be useful to know its detailed structure.We have been using serial cross sections and computer reconstruction methods to analyze MT distributions in mitotic spindles of PtK cells, a mammalian tissue culture line. Images from EM negatives are digtized on a light box by a Dage MTI video camera containing a black and white Saticon tube. The signal is digitized by a Parallax 1280 graphics device in a MicroVax III computer. Microtubules are digitized at a magnification such that each is 10-12 pixels in diameter.


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