Techniques in Finite Element Modeling of Helmeted-Head Biomechanics

2009 ◽  
Author(s):  
Andrzej Przekwas ◽  
X. G. Tan ◽  
Z. J. Chen ◽  
Xianlian Zhou ◽  
Debbie Reeves ◽  
...  
Keyword(s):  
Finite Element ◽  
Brain Injury ◽  
Injury Risk ◽  
High Energy ◽  
Dense Layer ◽  
Hard Material ◽  
Absorption Mechanism ◽  
Military Applications ◽  
Main Components ◽  
The Impact

Generally a helmet comprises two main components: the shell and the fitting system. Despite the variations in designs due to the different usage requirements, typically helmets are intended to protect the user’s head through an energy absorption mechanism. The weight and volume are important factors in helmet design since both may alter the injury risk to the head and neck. The helmet outer shell is usually made of hard material that will deform when it is hit by hard objects. This action disperses energy from the impact to lessen the force before it reaches the head. The fitting system frequently includes a dense layer that cushions and absorbs the energy as a result of relative motion between the helmet and the head. A balance needs to be achieved on how strong and how stiff a helmet should be to provide the best possible protection. If a helmet is too stiff it can be less able to prevent brain injury in the kinds of impacts that may occur. If it is too flexible or soft, it might not protect the user in a violent, high-energy crash. For military applications, the requirements for helmet performance may be even more demanding. Not only do helmets have to protect a Soldier’s head from blunt impacts, but helmets also are expected to provide mounting platforms for ancillary devices and to function in ballistic and blast events as well.

Investigation of Stress Wave Propagation in Brain Tissues Through the Use of Finite Element Method

2010 ◽  
Author(s):  
Biaobiao Zhang ◽  
W. Steve Shepard ◽  
Candace L. Floyd
Keyword(s):  
Finite Element ◽  
Wave Propagation ◽  
Brain Injury ◽  
Stress Wave ◽  
Brain Research ◽  
Complex Structure ◽  
Stress Wave Propagation ◽  
Wave Loads ◽  
The Impact ◽  
The Brain

Because axons serve as the conduit for signal transmission within the brain, research related to axon damage during brain injury has received much attention in recent years. Although myelinated axons appear as a uniform white matter, the complex structure of axons has not been thoroughly considered in the study of fundamental structural injury mechanisms. Most axons are surrounded by an insulating sheath of myelin. Furthermore, hollow tube-like microtubules provide a form of structural support as well as a means for transport within the axon. In this work, the effects of microtubule and its surrounding protein mediums inside the axon structure are considered in order to obtain a better understanding of wave propagation within the axon in an attempt to make progress in this area of brain injury modeling. By examining axial wave propagation using a simplified finite element model to represent microtubule and its surrounding proteins assembly, the impact caused by stress wave loads within the brain axon structure can be better understood. Through conducting a transient analysis as the wave propagates, some important characteristics relative to brain tissue injuries are studied.

scholarly journals A Biomechanical Evaluation of a Novel Airbag Bicycle Helmet Concept for Traumatic Brain Injury Mitigation

2021 ◽  
Vol 8 (11) ◽  
pp. 173
Author(s):  
Kwong Ming Tse ◽  
Daniel Holder
Keyword(s):  
Traumatic Brain Injury ◽  
Brain Injury ◽  
Injury Risk ◽  
Synergetic Effect ◽  
Human Head ◽  
Head Model ◽  
Bicycle Helmet ◽  
Impact Simulations ◽  
The Impact ◽  
Helmet Design

In this study, a novel expandable bicycle helmet, which integrates an airbag system into the conventional helmet design, was proposed to explore the potential synergetic effect of an expandable airbag and a standard commuter-type EPS helmet. The traumatic brain injury mitigation performance of the proposed expandable helmet was evaluated against that of a typical traditional bicycle helmet. A series of dynamic impact simulations on both a helmeted headform and a representative human head with different configurations were carried out in accordance with the widely recognised international bicycle helmet test standards. The impact simulations were initially performed on a ballast headform for validation and benchmarking purposes, while the subsequent ones on a biofidelic human head model were used for assessing any potential intracranial injury. It was found that the proposed expandable helmet performed admirably better when compared to a conventional helmet design—showing improvements in impact energy attenuation, as well as kinematic and biometric injury risk reduction. More importantly, this expandable helmet concept, integrating the airbag system in the conventional design, offers adequate protection to the cyclist in the unlikely case of airbag deployment failure.

Measurement of the Strain Distribution in Notch Tip Hydrides With High Energy X-Ray Diffraction and the Impact on Overload Modeling

2010 ◽  
Author(s):  
Matthew Kerr ◽  
Stephanie Tracy ◽  
Mark R. Daymond ◽  
Richard A. Holt ◽  
Jonathon D. Almer
Keyword(s):  
Finite Element ◽  
Strain Distribution ◽  
Process Zone ◽  
High Energy ◽  
X Ray Diffraction ◽  
Strain Fields ◽  
X Ray ◽  
Pressure Tubes ◽  
Notch Tip ◽  
The Impact

The formation of notch-tip hydrides in CANDU® Zr-2.5Nb pressure tubes can significantly reduce their resistance to fracture, particularly during overload conditions. This paper outlines recent high energy X-ray diffraction measurements of notch tip strain fields in Zr-2.5Nb specimens, during both hydride growth and overload. The use of this data to validate continuum Finite Element (FE) and possible inclusion in ‘Process Zone’ models of hydride fracture are also discussed.

scholarly journals A Computational Biomechanics Human Body Model Coupling Finite Element and Multibody Segments for Assessment of Head/Brain Injuries in Car-To-Pedestrian Collisions

2020 ◽  
Vol 17 (2) ◽  
pp. 492 ◽  
Author(s):  
Chao Yu ◽  
Fang Wang ◽  
Bingyu Wang ◽  
Guibing Li ◽  
Fan Li
Keyword(s):  
Finite Element ◽  
Brain Injury ◽  
The Netherlands ◽  
Finite Element Model ◽  
Element Model ◽  
The Body ◽  
Human Model ◽  
Computational Biomechanics ◽  
Head Kinematics ◽  
The Impact

It has been challenging to efficiently and accurately reproduce pedestrian head/brain injury, which is one of the most important causes of pedestrian deaths in road traffic accidents, due to the limitations of existing pedestrian computational models, and the complexity of accidents. In this paper, a new coupled pedestrian computational biomechanics model (CPCBM) for head safety study is established via coupling two existing commercial pedestrian models. The head–neck complex of the CPCBM is from the Total Human Model for Safety (THUMS, Toyota Central R&D Laboratories, Nagakute, Japan) (Version 4.01) finite element model and the rest of the parts of the body are from the Netherlands Organisation for Applied Scientific Research (TNO, The Hague, The Netherlands) (Version 7.5) multibody model. The CPCBM was validated in terms of head kinematics and injury by reproducing three cadaveric tests published in the literature, and a correlation and analysis (CORA) objective rating tool was applied to evaluate the correlation of the related signals between the predictions using the CPCBM and the test results. The results show that the CPCBM head center of gravity (COG) trajectories in the impact direction (YOZ plane) strongly agree with the experimental results (CORA ratings: Y = 0.99 ± 0.01; Z = 0.98 ± 0.01); the head COG velocity with respect to the test vehicle correlates well with the test data (CORA ratings: 0.85 ± 0.05); however, the correlation of the acceleration is less strong (CORA ratings: 0.77 ± 0.06). No significant differences in the behavior in predicting the head kinematics and injuries of the tested subjects were observed between the TNO model and CPCBM. Furthermore, the application of the CPCBM leads to substantial reduction of the computation time cost in reproducing the pedestrian head tissue level injuries, compared to the full-scale finite element model, which suggests that the CPCBM could present an efficient tool for pedestrian brain-injury research.

Towards a Failure Criterion for Microtubules Based on Matching Strength Analysis in Finite Element Models to AFM Loads

2011 ◽  
Author(s):  
William Taylor ◽  
W. Steve Shepard ◽  
Candace L. Floyd
Keyword(s):  
Finite Element ◽  
Wave Propagation ◽  
Brain Injury ◽  
Failure Criterion ◽  
Point Load ◽  
Strength Analysis ◽  
Finite Element Models ◽  
Loading Conditions ◽  
Starting Point ◽  
The Impact

In previous research studies, the geometric and elastic properties for a critical component of axon health, the microtubule (MT), have been determined using lateral indentation with the tip of an atomic force microscope (AFM). Although the response due to the indentations caused by the AFM was observed to be linear for most of the tests, forces greater than 300pN would result in a permanent irreversible collapse of the MT’s structure. While the intent of those researchers was not to evaluate microtubule strength properties, that load can be used as a starting point to evaluate internal stress failure criterion for such structures. To that end, the current research is investigating MT strength by replicating the loading and boundary conditions in a finite element model. This work is an extension of previous work aimed at using this 300 pN point load to develop failure criteria for MTs under more realistic loading conditions. In the present work, modeling has been used to correlate the AFM point load response with the more realistic distributed loading conditions that would result during a brain injury event. Furthermore, the impact of nearby MTs on the stresses that occur under similar loading conditions is also examined. These results are being used to analytically determine a stress threshold related to MT structural failure. Correspondingly, models that include dynamic wave propagation through the microtubule will be studied. The failure criterion determined in both cases would aid in evaluating brain injury studies that involve pressure wave propagation in whole-head finite element models, even when such models represent the white matter using homogeneous properties.

scholarly journals Low-intensity blast-induced mild traumatic brain injury : linking blast physics to biological outcomes

2019 ◽  
Author(s):  
◽  
Hailong Song
Keyword(s):  
Traumatic Brain Injury ◽  
Brain Injury ◽  
Open Field ◽  
Mild Traumatic Brain Injury ◽  
Military Training ◽  
High Energy ◽  
Behavioral Changes ◽  
Synaptic Proteins ◽  
Low Intensity ◽  
The Impact

Blast-induced mild traumatic brain injury (mTBI) is of particular concern among military personnel due to exposure to blast energy during military training and combat. The impact of primary low-intensity blast (LIB) mediated pathophysiology upon later neurobehavioral disorders has been controversial. Our prior considerations of blast physics predicted ultrastructural injuries at nanoscale levels. Here, we provide quantitative data using a LIB injury murine model exposed to open-field detonation of 350 g of high-energy explosive C4. The use of an open-field experimental blast generated a primary blast wave with a peak overpressure of 6.76 pounds per square inch (PSI) (46.6 kPa) at a 3-meter (m) distance from the center of the explosion, with no apparent impact / acceleration in exposed animals. We first characterized neuropathological and behavioral changes. Using transmission electron microscopy (TEM), we further identified multifocal neuronal damages, myelin sheath defects, mitochondrial abnormalities, and synaptic dysregulation after LIB injury. Next, we used quantitative proteomics, bioinformatics analysis, biochemical investigations to seek insights into the molecular mechanisms underlying the ultrastructural pathology. Results illustrated the alterations of mitochondrial, axonal, synaptic proteins in related signaling pathways. These observations uncover unique ultrastructural brain abnormalities, biochemical correlates, and associated behavioral changes due to LIB injury. Insights on the early pathogenesis of LIB-induced brain damages provide a template for further characterization of its chronic effects, identification of potential biomarkers and targets for intervention.

scholarly journals The Impact Behaviour of Carbon Fiber-Epoxy Composite Leading Edge using Finite Element Method

2019 ◽  
Vol 8 (2) ◽  
pp. 2617-2622
Keyword(s):  
Finite Element ◽  
Weight Ratio ◽  
Leading Edge ◽  
High Strength ◽  
Failure Criteria ◽  
High Energy ◽  
Rigid Sphere ◽  
Impact Behaviour ◽  
Finite Element Software ◽  
The Impact

Composite material has been widely used in aircrafts due to its high strength to weight ratio that leads to weight saving of the aircrafts. Equally important, aircraft material should be tough i.e. it should have the ability to absorb high energy and thus resist fracture. The aircraft’s wing design requires the material to have high toughness as parts of the wing especially its leading edge is subjected to impact loadings. Using finite element software of LS-DYNA, this research focuses on studying the impact behaviour of composite panels that represent the leading edges of wings when the panels are subjected to rigid sphere projectile. Three shapes of panels are used: flat, semi-circular and semi ellipse while panels can be of 2, 4 and 8 layers to vary its thickness. The panels are made of laminated composites with woven carbon fibres and the angle of orientations are [0/90] n, [0/45]n and [45/-45]n where n will give the number of layer for the composite. The Mat-58 material type suitable for woven type fibre is used where failure criteria of Hashin is applied. It was found that the simulation results are in a very close agreement with the finding from experiments conducted earlier. Furthermore, the optimum stacking sequence was found to be the [0/45]2 stacking sequences

scholarly journals Injury Biomechanics of a Child’s Head: Problems, Challenges and Possibilities with a New aHEAD Finite Element Model

2020 ◽  
Vol 10 (13) ◽  
pp. 4467
Author(s):  
Johannes Wilhelm ◽  
Mariusz Ptak ◽  
Fábio A. O. Fernandes ◽  
Konrad Kubicki ◽  
Artur Kwiatkowski ◽  
...  
Keyword(s):  
Finite Element ◽  
Brain Injury ◽  
White Matter ◽  
Numerical Models ◽  
Material Models ◽  
Detailed Model ◽  
Hexahedral Elements ◽  
The Impact ◽  
The Brain ◽  
Brain Tissues

Traumatic brain injury (TBI) is a major public health problem among children. The predominant causes of TBI in young children are motor vehicle accidents, firearm incidents, falls, and child abuse. The limitation of in vivo studies on the human brain has made the finite element modelling an important tool to study brain injury. Numerical models based on the finite element approach can provide valuable data on biomechanics of brain tissues and help explain many pathological conditions. This work reviews the existing numerical models of a child’s head. However, the existing literature is very limited in reporting proper geometric representation of a small child’s head. Therefore, an advanced 2-year-old child’s head model, named aHEAD 2yo (aHEAD: advanced Head models for safety Enhancement And medical Development), has been developed, which advances the state-of-the-art. The model is one of the first published in the literature, which entirely consists of hexahedral elements for three-dimensional (3D) structures of the head, such as the cerebellum, skull, and cerebrum with detailed geometry of gyri and sulci. It includes cerebrospinal fluid as Smoothed Particle Hydrodynamics (SPH) and a detailed model of pressurized bringing veins. Moreover, the presented review of the literature showed that material models for children are now one of the major limitations. There is also no unambiguous opinion as to the use of separate materials for gray and white matter. Thus, this work examines the impact of various material models for the brain on the biomechanical response of the brain tissues during the mechanical loading described by Hardy et al. The study compares the inhomogeneous models with the separation of gray and white matter against the homogeneous models, i.e., without the gray/white matter separation. The developed model along with its verification aims to establish a further benchmark in finite element head modelling for children and can potentially provide new insights into injury mechanisms.

BIOMECHANICAL ANALYSIS OF OCCUPANT’S BRAIN RESPONSE AND INJURY IN VEHICLE INTERIOR SECOND IMPACT UTILIZING A REFINED HEAD FINITE ELEMENT MODEL

2017 ◽  
Vol 17 (07) ◽  
pp. 1740018
Author(s):  
ZHENGWEI MA ◽  
LELE JING ◽  
JINLUN WANG ◽  
JIQING CHEN ◽  
FENGCHONG LAN
Keyword(s):  
Finite Element ◽  
Brain Injury ◽  
Side Impact ◽  
Positive Pressure ◽  
Head Model ◽  
Vertical Angle ◽  
Extreme Stress ◽  
Horizontal Angle ◽  
The Impact ◽  
The Brain

In vehicle side collisions, traumatic brain injury caused by the impact between occupant’s head and the interior parts of A or B pillar is a major reason of death and disability. In order to analyze the biomechanical response and injury mechanism of occupant’s brain in side collisions, a refined finite element head model representing the 50th percentile Chinese male was developed. Its improvements of biofidelity comparing to the original head model were illustrated through model simulation against the same post mortem human subjects test. Based on the refined head model, the brain biomechanical responses and injuries in the side impact with interior parts of A pillar and B pillar were analyzed according to FMVSS 201U, and the influences of different impact locations and directions were investigated. The results showed that the brain tissues on impact side sustained positive pressure and those on the opposite side experienced negative pressure. The transmission of pressure wave was easy to cause brain concussion and other diffuse brain injuries. The intracranial pressure distribution exhibited a typical pattern of contrecoup injury. The extreme stress concentration in the junction area of the cerebrum, cerebellum and brain stem could lead to focal injury such as brain contusion and laceration. Moreover, the impact injury of A pillar was more serious than that of B pillar, which was consistent with the traffic injury statistics that the head injury in oblique side collisions was more serious than that of vertical side collisions. Therefore, the interior parts of A pillar should be designed to absorb more energy than those of B pillar under the same conditions. In addition, the severity of brain injury is more sensitive to the variation of the horizontal angle than that of the vertical angle. Both the peak values of the occipital fossa pressure in effect simulations of the horizontal and vertical angles were three to four times of the peak values of the forehead pressure. When the impact horizontal angle was up to 255[Formula: see text], or the vertical angle was up to 45[Formula: see text], the head HIC(d) values would be up to 1320.45 and 1101.06, respectively, which indicated a AIS 3[Formula: see text] injury risk of the head.

Restraint Systems in Tactical Vehicles: Uncertainty Study Involving Airbags, Seatbelts and Military Gear

2017 ◽  
Author(s):  
Dorin Drignei ◽  
Zissimos P. Mourelatos ◽  
Ervisa Zhamo ◽  
Jingwen Hu ◽  
Cong Chen ◽  
...  
Keyword(s):  
Experimental Data ◽  
Finite Element ◽  
Body Size ◽  
Injury Risk ◽  
Finite Element Models ◽  
Risk Distribution ◽  
Frontal Crashes ◽  
Safety Features ◽  
The Impact

Adding advanced safety features (e.g. airbags) to restraint systems in tactical vehicles could decrease the injury risk of their occupants. The impact of frontal crashes on the occupants has been assessed recently through experimental data and finite element models. However, the number of such experiments is relatively small due to high cost. In this paper, we conduct an uncertainty study to infer the advantage of including advanced safety features, if a larger number of experiments were possible. We introduce the concept of group injury risk distribution that allows us to quantify under uncertainty the injury risk associated with advanced safety features, while averaging out the effect of uncontrollable factors such as body size. Statistically, the group injury risk distribution is a mixture of individual injury risk distributions of design conditions in the group. We infer that advanced safety features reduce the injury risk by at least two thirds in frontal crashes.

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