scholarly journals Evaluation of Combat Helmet Behavior under Blunt Impact

2020 ◽  
Vol 10 (23) ◽  
pp. 8470
Author(s):  
Carlos Moure-Guardiola ◽  
Ignacio Rubio ◽  
Jacobo Antona-Makoshi ◽  
Álvaro Olmedo ◽  
José Antonio Loya ◽  
...  
Keyword(s):  
Brain Injuries ◽  
Linear Acceleration ◽  
Human Head ◽  
Critical Parameters ◽  
Head Model ◽  
Ballistic Impacts ◽  
Impact Surface ◽  
Blunt Impact ◽  
Wide Range ◽  
Design And Manufacture

New threats are a challenge for the design and manufacture of modern combat helmets. These helmets must satisfy a wide range of impact velocities from ballistic impacts to blunt impacts. In this paper, we analyze European Regulation ECE R22.05 using a standard surrogate head and a human head model to evaluate combat helmet performance. Two critical parameters on traumatic brain analysis are studied for different impact locations, i.e., peak linear acceleration value and head injury criterion (HIC). The results obtained are compared with different injury criteria to determine the severity level of damage induced. Furthermore, based on different impact scenarios, analyses of the influence of impact velocity and the geometry impact surface are performed. The results show that the risks associated with a blunt impact can lead to a mild traumatic brain injury at high impact velocities and some impact locations, despite satisfying the different criteria established by the ECE R22.05 standard. The results reveal that the use of a human head for the estimation of brain injuries differs slightly from the results obtained using a surrogate head. Therefore, the current combat helmet configuration must be improved for blunt impacts. Further standards should take this into account and, consequently, combat helmet manufacturers on their design process.

Computational Modeling of Combat Helmet Performance Analysis Integrating Blunt and Blast Loadings

2020 ◽  
Author(s):  
X. Gary Tan ◽  
Amit Bagchi
Keyword(s):  
System Analysis ◽  
Plastic Material ◽  
Human Head ◽  
Material Model ◽  
Head Model ◽  
Ballistic Impacts ◽  
Rate Dependent ◽  
Brain Responses ◽  
Suspension Geometry ◽  
System Configurations

Abstract Combat helmets have gone through many changes, from shells made of metal to advanced composites using Kevlar and Dyneema, along with introduction of pad suspensions to provide comfort and protection. Helmets have been designed to perform against ballistic and blunt impact threats. But, in today’s warfare, combat helmets are expected to protect against all three threats, blunt, ballistic impacts and blast effects to minimize traumatic brain injury (TBI) and provide a better thermal comfort. We are developing a helmet system analysis methodology integrating the effect of multiple threats, i.e., blast and blunt impacts, to achieve an optimal helmet system design, by utilizing multi-physics computational tools. We used a validated human head model to represent the warfighter’s head. The helmet composite shell was represented by an orthotropic elasto-plastic material model. A strain rate dependent model was employed for pad suspension material. Available dynamic loading data was used to calibrate the material parameters. Multiple helmet system configurations subjected to blast and blunt loadings were considered to quantify their influence on brain biomechanical response. Parametric studies were carried out to assess energy absorption for different suspension geometry and material morphology for different loadings. The resulting brain responses were used with published injury criteria to characterize the helmet system performance through a single metric for each threat type. Approaches to combine single-threat metrics to allow aggregating performance against multiple threats were discussed.

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.

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.

Intracranial pressure–based validation and analysis of traumatic brain injury using a new three-dimensional finite element human head model

2019 ◽  
Vol 234 (1) ◽  
pp. 3-15 ◽  
Author(s):  
Tanu Khanuja ◽  
Harikrishnan Narayanan Unni
Keyword(s):  
Finite Element ◽  
Brain Injury ◽  
Intracranial Pressure ◽  
Brain Injuries ◽  
Three Dimensional ◽  
Human Head ◽  
Von Mises Stress ◽  
Head Model ◽  
Injury Mechanisms ◽  
Von Mises

Traumatic brain injuries are life-threatening injuries that can lead to long-term incapacitation and death. Over the years, numerous finite element human head models have been developed to understand the injury mechanisms of traumatic brain injuries. Many of these models are erroneous and used ellipsoidal or spherical geometries to represent brain. This work is focused on the development of high-quality, comprehensive three-dimensional finite element human head model with accurate representation of cerebral sulci and gyri structures in order to study traumatic brain injury mechanisms. Present geometry, predicated on magnetic resonance imaging data consist of three rudimentary components, that is, skull, cerebrospinal fluid with the ventricular system, and the soft tissues comprising the cerebrum, cerebellum, and brain stem. The brain is modeled as a hyperviscoelastic material. Meshed model with 10 nodes modified tetrahedral type element (C3D10M) is validated against two cadaver-based impact experiments by comparing the intracranial pressures at different locations of the head. Our results indicate a better agreement with cadaver results, specifically for the case of frontal and parietal intracranial pressure values. Existing literature focuses mostly on intracranial pressure validation, while the effects of von Mises stress on brain injury are not analyzed in detail. In this work, a detailed interpretation of neurological damage resulting from impact injury is performed by analyzing von Mises stress and intracranial pressure distribution across numerous segments of the brain. A reasonably good correlation with experimental data signifies the robustness of the model for predicting injury mechanisms based on clinical predictions of injury tolerance criteria.

Evaluation of the Kinematic Biofidelity and Inter-Test Repeatability of Global Accelerations and Brain Parenchyma Pressure for a Head-Brain Physical Model

2021 ◽  
Author(s):  
Yizhao Li ◽  
Simon Ouellet ◽  
Albert Vette ◽  
Don W. Raboud ◽  
Ashton Martin ◽  
...  
Keyword(s):  
Linear Acceleration ◽  
Brain Parenchyma ◽  
Head Model ◽  
Civilian Life ◽  
Head Kinematics ◽  
Blunt Impact ◽  
Hybrid Iii ◽  
Drop Tests ◽  
Multiple Impact ◽  
Injury Protection

Abstract Head surrogates are used in biomechanical research and headgear assessment. They are designed to approximate the properties of the head and are instrumented to measure global head kinematics. Due to the recent interest in studying disruption to the brain, some head models include internal fluid layers and brain tissue, and instrumentation to measure head intracranial biomechanics. However, it is unknown whether such models exhibit realistic human responses. Therefore, this study aims to assess the biofidelity and repeatability of a head model, the Blast Injury Protection Evaluation Device (BIPED), that can measure both global head kinematics and intraparenchymal pressure (IPP) for application in blunt impact, a common loading scenario in civilian life. Drop tests were conducted with the BIPED and the widely used Hybrid III headform. BIPED measures were compared to the Hybrid III data and published cadaveric data, and the biofidelity level of the global linear acceleration was quantified using CORrelation and Analysis (CORA) ratings. The repeatability of the acceleration and IPP measurements in multiple impact scenarios was evaluated via the coefficient of variation (COV) of the magnitudes and pulse durations. BIPED acceleration peaks were generally not significantly different from cadaver and Hybrid III data. The CORA ratings for the BIPED and Hybrid III accelerations ranged from 0.50 to 0.61 and 0.51 to 0.77, respectively. The COVs of acceleration and IPP were generally below 10%. This study is an important step toward a biofidelic head surrogate measuring both global kinematics and IPP in blunt impact.

Experimental Determination of Pressure Wave Transmission to the Brain During Head-Neck Blast Tests

2013 ◽  
Author(s):  
Kyle Ott ◽  
Liming Voo ◽  
Andrew Merkle ◽  
Alexander Iwaskiw ◽  
Alexis Wickwire ◽  
...  
Keyword(s):  
Brain Injury ◽  
Brain Injuries ◽  
Head Injuries ◽  
Strong Association ◽  
Skull Fracture ◽  
Linear Acceleration ◽  
Military Operations ◽  
Blunt Impact ◽  
Injury Mechanisms ◽  
Inertial Loading

Traumatic Brain Injury (TBI) has been the termed the “signature injury” in wounded soldiers in recent military operations [1]. Evidence has shown a strong association between TBI and blast loading to the head due to exposure to explosive events [2, 3]. Head injury mechanisms in a primary blast environment remain elusive and are the subject of much speculation and hypotheses. However, brain injury mechanisms have traditionally been attributed to either a direct impact or a rapid head acceleration or deceleration. Extensive research has been performed regarding the effects of blunt trauma and inertial loading on head injuries [4, 5]. Direct impacts to the head can largely be described based on linear acceleration measurements that correlate to skull fracture and focal brain injuries [6]. Computational head modeling of blunt impact events has shown that the linear acceleration response correlates well with increases in brain pressure [7]. Intracranial pressure, therefore, has been one of the major quantities investigated for correlation to blast induced TBI injury mechanisms [8–14].

scholarly journals Development of a Finite Element Head Model for the Study of Impact Head Injury

2014 ◽  
Vol 2014 ◽  
pp. 1-14 ◽  
Author(s):  
Bin Yang ◽  
Kwong-Ming Tse ◽  
Ning Chen ◽  
Long-Bin Tan ◽  
Qing-Qian Zheng ◽  
...  
Keyword(s):  
Finite Element ◽  
Brain Injuries ◽  
Current Knowledge ◽  
Human Head ◽  
Von Mises Stress ◽  
Head Model ◽  
Fe Model ◽  
Prediction And Prevention ◽  
Von Mises ◽  
The Brain

This study is aimed at developing a high quality, validated finite element (FE) human head model for traumatic brain injuries (TBI) prediction and prevention during vehicle collisions. The geometry of the FE model was based on computed tomography (CT) and magnetic resonance imaging (MRI) scans of a volunteer close to the anthropometry of a 50th percentile male. The material and structural properties were selected based on a synthesis of current knowledge of the constitutive models for each tissue. The cerebrospinal fluid (CSF) was simulated explicitly as a hydrostatic fluid by using a surface-based fluid modeling method. The model was validated in the loading condition observed in frontal impact vehicle collision. These validations include the intracranial pressure (ICP), brain motion, impact force and intracranial acceleration response, maximum von Mises stress in the brain, and maximum principal stress in the skull. Overall results obtained in the validation indicated improved biofidelity relative to previous FE models, and the change in the maximum von Mises in the brain is mainly caused by the improvement of the CSF simulation. The model may be used for improving the current injury criteria of the brain and anthropometric test devices.

Skull Deformation Has No Impact on the Variation of Brain Intracranial Pressure

2016 ◽  
Author(s):  
Asghar Rezaei ◽  
Hesam Sarvghad-Moghaddam ◽  
Ashkan Eslaminejad ◽  
Mariusz Ziejewski ◽  
Ghodrat Karami
Keyword(s):  
Intracranial Pressure ◽  
Brain Injuries ◽  
Computational Study ◽  
Human Head ◽  
Body Motion ◽  
Stress Wave Propagation ◽  
Head Model ◽  
The Impact ◽  
The Brain ◽  
Skull Deformation

Skull deformation and vibration has been hypothesized to be an injury mechanism when the human head undergoes an impact scenario. The extent that skull deformation may increase the risk of traumatic brain injury, however, is not well understood. This computational study explains whether skull deformation has any impact on the variation of intracranial pressure (ICP). To this end, a finite element head model including major anatomical components of the human head was employed. The head model has been validated against ICP variations on the brain. The impact simulations were carried out using a rigid cylindrical impactor. The scenarios were frontal impacts with the impactor hitting the forehead of the head model at two impact severity levels. In order to examine the effect of skull elasticity on the stress wave propagation inside the cranium under an external applied force, the skull was also taken as a rigid body with the same density as the elastic one, and the result were compared with those obtained with the deformable skull. For the two cases, the variation of ICPs at the coup and countercoup sites were recorded and compared. The results of the study showed that, for the case studies presented here, the deformation of skull didn’t increase the level of ICP inside the brain. It was concluded that the skull rapid body motion might be responsible for brain injuries.

A Proposed New Brain Injury Tolerance for Minor Traumatic Brain Injury

2001 ◽  
Author(s):  
Liying Zhang ◽  
King H. Yang ◽  
Albert I. King
Keyword(s):  
Brain Injury ◽  
Brain Injuries ◽  
Injury Severity ◽  
Human Head ◽  
Head Model ◽  
Tolerance Level ◽  
Social And Emotional ◽  
Accident Data ◽  
Actual Field ◽  
Injury Tolerance

Abstract Traumatic brain injuries constitute a significant portion of injury resulting from automotive collisions, motorcycle crashes, and sports collisions. Brain injuries not only represent a serious trauma for those involved but also place an enormous burden on society, often exacting a heavy economical, social, and emotional price. Development of intervention strategies to prevent or minimize these injuries requires a complete understanding of injury mechanism, response and tolerance level. In this study, an attempt is made to delineate actual injury causation and establish a meaningful injury criterion through the use of the actual field accident data. Twenty-four actual field head-to-head collisions that occurred in professional football games were duplicated using a validated finite element human head model. The injury predictors and injury levels were analyzed based on resulting brain tissue responses and were correlated with the site and occurrence of MTBI. Prediction indicated that the shear deformation around the brainstem region could be an injury predictor for concussion. Statistical analyses were performed to establish the new brain injury tolerance level and to further reduce brain injury severity.

FINITE ELEMENT ANALYSIS OF THE HUMAN HEAD UNDER SIDE CAR CRASH IMPACTS AT DIFFERENT SPEEDS

2014 ◽  
Vol 14 (06) ◽  
pp. 1440002 ◽  
Author(s):  
XINGQIAO DENG ◽  
SHOU AN CHEN ◽  
R. PRABHU ◽  
YUANYUAN JIANG ◽  
Y. MAO ◽  
...  
Keyword(s):  
Finite Element ◽  
Brain Injuries ◽  
Head Injuries ◽  
Human Head ◽  
Side Impact ◽  
Von Mises Stress ◽  
Head Model ◽  
Car Crash ◽  
Von Mises ◽  
The Impact

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.

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