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Author: Timothy Darling
Publisher:
ISBN:
Category : Brain
Languages : en
Pages : 63
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Book Description
The football helmet is a device used to help mitigate the occurrence of impact-related traumatic (TBI) and minor traumatic brain injuries (mTBI) in the game of American football. The current design methodology of using a hard shell with an energy absorbing liner may be adequate for minimizing TBI, however it has had less effect in minimizing mTBI. The latest research in brain injury mechanisms has established that the current design methodology has produced a helmet to reduce linear acceleration of the head. However, angular accelerations also have an adverse effect on the brain response, and must be investigated as a contributor of brain injury. To help better understand how the football helmet design features effect the brain response during impact, this research develops a validated football helmet model and couples it with a full LS-DYNA human body model developed by the Global Human Body Modeling Consortium (v4.1.1). The human body model is a conglomeration of several validated models of different sections of the body. Of particular interest for this research is the Wayne State University Head Injury Model for modeling the brain. These human body models were validated using a combination of cadaveric and animal studies. In this study, the football helmet was validated by laboratory testing using drop tests on the crown of the helmet. By coupling the two models into one finite element model, the brain response to impact loads caused by helmet design features can be investigated. In the present research, LS-DYNA is used to study a helmet crown impact with a rigid steel plate so as to obtain the strain-rate, strain, and stress experienced in the corpus callosum, midbrain, and brain stem as these anatomical regions are areas of concern with respect to mTBI.
Author: Timothy Darling
Publisher:
ISBN:
Category : Brain
Languages : en
Pages : 63
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Book Description
The football helmet is a device used to help mitigate the occurrence of impact-related traumatic (TBI) and minor traumatic brain injuries (mTBI) in the game of American football. The current design methodology of using a hard shell with an energy absorbing liner may be adequate for minimizing TBI, however it has had less effect in minimizing mTBI. The latest research in brain injury mechanisms has established that the current design methodology has produced a helmet to reduce linear acceleration of the head. However, angular accelerations also have an adverse effect on the brain response, and must be investigated as a contributor of brain injury. To help better understand how the football helmet design features effect the brain response during impact, this research develops a validated football helmet model and couples it with a full LS-DYNA human body model developed by the Global Human Body Modeling Consortium (v4.1.1). The human body model is a conglomeration of several validated models of different sections of the body. Of particular interest for this research is the Wayne State University Head Injury Model for modeling the brain. These human body models were validated using a combination of cadaveric and animal studies. In this study, the football helmet was validated by laboratory testing using drop tests on the crown of the helmet. By coupling the two models into one finite element model, the brain response to impact loads caused by helmet design features can be investigated. In the present research, LS-DYNA is used to study a helmet crown impact with a rigid steel plate so as to obtain the strain-rate, strain, and stress experienced in the corpus callosum, midbrain, and brain stem as these anatomical regions are areas of concern with respect to mTBI.
Author: David Bruneau
Publisher:
ISBN:
Category : Biomechanics
Languages : en
Pages : 159
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Book Description
Among high school and college athletes, ~50% of American football players report a concussion each year, and at least 30% of players sustain more than one concussion per year, which may be reduced in part through improvements in head protection. Football helmets are commonly assessed experimentally using a linear impactor test, where a helmet is donned on a Hybrid III Anthropometric Testing Device (ATD) head and neck affixed to a sliding carriage, and is struck by a deformable impactor. The biofidelity of the Hybrid III ATD is known to have some limitations: the ATD was developed to predict anterior-posterior response while the current test includes multi-directional loading, and the passive neck structure does not simulate active muscle. Additionally, the linear impactor test does not include the body of the player, which may influence the head response. The current study used an advanced Human Body Model (HBM) combined with a validated finite element model of a modern football helmet to assess the importance of the aforementioned limitations, and was then extended to investigate the response of the brain to impact scenarios. A virtual evaluation tool provides the advantage of assessing changes to current helmet designs, and new helmet designs prior to the construction of a physical prototype. An existing ATD head and neck model validated in the linear impact configuration, and a validated football helmet model previously assessed with 60 impact cases, were used as a baseline for the assessment of head response in football impact scenarios. The Global Human Body Models Consortium (GHBMC) head and neck model (HNM) and Full Human Body Model (FBM) were integrated with the helmet and linear impactor, and assessed using the same boundary conditions as the ATD. The HNM allowed for the investigation of muscle activation, using a muscle activation scheme representing a player braced for impact, and a baseline case with no activation. The models were used in three studies to assess: (1) the kinematic response of the ATD and HNM, (2) the effect of ATD and HNM boundary conditions on brain response, and (3) the role of the whole body mass and inertia on head and brain response. The first study compared the head kinematics of the HNM to those of the ATD simulation using the boundary conditions of the linear impactor test. It was found that the HNM and ATD had similar head acceleration and angular velocity in the primary direction of impact, and exhibited similar responses regardless of muscle activation. Differences between the ATD and HNM were identified in the axial head acceleration, attributed to axial neck stiffness, and longer term metrics measured at the base of the neck differed but did not have a large effect on the short-term head response assessed using existing head response metrics (HIC, BrIC, HIP). In the second study, two boundary conditions were investigated for a head FE model: (1) a commonly-used simplified boundary condition where head model kinematics are prescribed from experimentally measured ATD kinematics and (2) a full simulation of the HNM, helmet and linear impactor. The second approach enables the opportunity to assess the effect of modifications to the helmet. While the lateral and rear impacts exhibited similar levels of Maximum Principal Strain (MPS) in the brain tissue using both the prescribed kinematics and simulated HNM boundary condition, differences were noted in the frontal orientation (MPS varied by
Author: Derek Wallin
Publisher:
ISBN:
Category :
Languages : en
Pages : 63
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Book Description
Football helmets worn today are primarily designed to prevent skull fracture and irreversible brain injury. In that limited respect, today’s helmets are a success with the frequency of reported football-related skull fracture a rare occurrence. In recent decades, however, concussion, mild traumatic brain injury (mTBI), and chronic traumatic encephalopathy (CTE) are being reported with increasing incidence. Helmet manufacturing companies are limited in their performance analysis of helmets, with no standard helmet testing procedures incorporating anatomical data or physiological weaknesses of the brain. Finite Element Modeling of the brain has allowed for analysis of the mechanics of brain injury and can provide injury metrics based on simulated brain injury. In this study the background on current helmet testing procedures is provided as well as a finite element study of brain injury to determine helmet performance. In addition, this modeling will be used to identify what types of impacts are most dangerous.
Author: Mark F. Horstemeyer
Publisher: Elsevier
ISBN: 0128181443
Category : Technology & Engineering
Languages : en
Pages : 276
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Book Description
Multiscale Biomechanical Modeling of the Brain discusses the constitutive modeling of the brain at various length scales (nanoscale, microscale, mesoscale, macroscale and structural scale). In each scale, the book describes the state-of-the- experimental and computational tools used to quantify critical deformational information at each length scale. Then, at the structural scale, several user-based constitutive material models are presented, along with real-world boundary value problems. Lastly, design and optimization concepts are presented for use in occupant-centric design frameworks. This book is useful for both academia and industry applications that cover basic science aspects or applied research in head and brain protection. The multiscale approach to this topic is unique, and not found in other books. It includes meticulously selected materials that aim to connect the mechanistic analysis of the brain tissue at size scales ranging from subcellular to organ levels. Presents concepts in a theoretical and thermodynamic framework for each length scale Teaches readers not only how to use an existing multiscale model for each brain but also how to develop a new multiscale model Takes an integrated experimental-computational approach and gives structured multiscale coverage of the problems
Author: Society of Automotive Engineers
Publisher: SAE International
ISBN:
Category : Science
Languages : en
Pages : 158
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Book Description
Thirteen papers from the biomechanics technical sessions of the 2002 SAE congress use laboratory experiments, computer models, and field data to evaluate the human body's kinematics, kinetics, and injury potential in response to impact loads caused by automobile accidents. Topics include finite elem
Author: Anna Marie Dulaney
Publisher:
ISBN:
Category :
Languages : en
Pages : 89
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Book Description
A finite element model was developed for a range of human head-sUAS impacts to provide multiple case scenarios of impact severity at two response regions of interest: global and local. The hypothesis was that for certain impact scenarios, local response injuries of the brain (frontal, parietal, occipital, temporal lobes, and cerebellum) have a higher severity level compared to global response injury, the response at the Center of Gravity (CG) of the head. This study is the first one to predict and quantify the influence of impact parameters such as impact velocity, location, offset, and angle of impact to severity of injury. The findings show that an sUAS has the potential of causing minimal harm under certain impact scenarios, while other scenarios cause fatal injuries. Additionally, results indicate that the human head’s global response as a less viable response region of interest when measuring injury severity for clinical diagnosis. It is hoped that the results from this research can be useful to assist decision making for treatments and may offer different perspectives in sUAS designs or operation environments.
Author: Tate Russell Fonville
Publisher:
ISBN:
Category : Brain
Languages : en
Pages : 0
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Book Description
The objective of this research was to present a model for brain damage to investigate the head’s response to mechanical loadings. A Finite Element (FE) head and brain mesh used throughout this dissertation was constructed from Magnetic Resonance Imaging (MRI) scan data of one of the authors and validated in previous research. A computational modal analysis was first conducted on the whole head and an isolated brain to identify the resonant frequencies, mode shapes, and locations. A physics-based Internal State Variable (ISV) constitutive model for polymers was modified to include damage in the form of pore growth. The brain damage model was developed to capture pore growth influenced by both tensile pressure and shear strains. The damage model constants were calibrated to match intermediate strain rate (50 s-1) compression tests done on fresh porcine brain samples. The calibrated brain damage model was then used to evaluate the relationship between impact, brain pressure, brain strain, and damage using a 2D model of a helmeted head. The same boundary conditions were then applied to a 3D model of a helmeted head to study the differences in responses between 2D and 3D. Finally, a sensitivity analysis was conducted to study the influence of impact location, impact velocity, helmet shell material, helmet facemask material, helmet foam liner classification, and helmet foam liner general stiffness level. Both impact studies were carried out at low and high velocities intending to replicate a range of common impact magnitudes experienced by both linemen and skill positions. Based on the findings presented in this dissertation, a deeper understanding of brain damage resulting from head impacts is useful to help designers engineer safer helmet equipment.
Author: João Manuel R. S. Tavares
Publisher: Springer
ISBN: 3030230732
Category : Medical
Languages : en
Pages : 160
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Book Description
This book gathers selected, extended and revised contributions to the 15th International Symposium on Computer Methods in Biomechanics and Biomedical Engineering (CMBBE2018), and the 3rd Conference on Imaging and Visualization, which took place on 26-29 March, 2018, in Lisbon, Portugal. The respective chapters highlight cutting-edge methods, e.g. new algorithms, image analysis techniques, and multibody modeling methods; and new findings obtained by applying them in biological and/or medical contexts. Original numerical studies, Monte Carlo simulations, FEM analyses and reaction-diffusion models are described in detail, together with intriguing new applications. The book offers a timely source of information for biologists, engineers, applied mathematicians and clinical researchers working on multidisciplinary projects, and is also intended to foster closer collaboration between these groups.
Author: Sahil Kulkarni
Publisher:
ISBN:
Category :
Languages : en
Pages : 224
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Book Description
The use of body armor and combat helmets has reduced fatalities from explosions and ballistic attacks. However, frequent use of improvised explosive devices and continuing efforts to reduce the weight of each combat helmet have increased the risk of ballistic-impact and blast-induced traumatic brain injuries among soldiers. The objective of this dissertation research project is to develop predictive constitutive and computational models to be used in head injury diagnosis and to aid in the development of new combat helmets that can mitigate non-penetrating head injuries. A transversely isotropic visco-hyperelastic constitutive model is provided for soft tissues, which accounts for large deformations, high strain rates, and short-memory effects. The presented model is tested for a range of strain rates and for multiple loading scenarios based on available experimental data for porcine and human brain tissues. Using this constitutive relation, a finite element model of a helmet/head assembly is developed to study non-penetrating TBI. The effects of constitutive models and blast directions on finite elements simulations of blast induced TBI are investigated. Further, the effectiveness of combat helmets against non-penetrating TBI induced by blast and ballistic impacts is studied. Two types of combat helmets are considered: the advanced combat helmet (ACH) and the enhanced combat helmet (ECH). Spatial distributions and temporal variations of the intracranial pressure and stress components obtained in the simulations reveal significant differences in brain tissue responses to different constitutive models and blast directions. It is found that these combat helmets provide some level of protection against non-penetrating TBI and that the level of protection is higher for the ECH than the ACH. The electronic version of this dissertation is accessible from http://hdl.handle.net/1969.1/151836
Author: Ramachandra B. Balasubramanian
Publisher:
ISBN:
Category :
Languages : en
Pages : 162
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Book Description
