Examination of the protective roles of helmet/faceshield and directionality for human head under blast waves

Sarvghad-Moghaddam, Hesam; Jazi, Mehdi Salimi; Rezaei, Asghar; Karami, G.; Ziejewski, Mariusz

doi:10.1080/10255842.2014.977878

Cited by 29 publications

(31 citation statements)

References 14 publications

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“…All the head components, except for the brain, were modeled as isotropic linear elastic materials , where the material properties for these tissues can be found in detail elsewhere . This assumption is in accordance with many other published data which state that the elastic behavior can predict the mechanical behavior of these tissues and is able to capture the propagation of the stress waves in the cranial space .…”

Section: Numerical Methods and Materials Modelingmentioning

confidence: 64%

“…Moreover, the pads were removed from the helmet to observe the fluid flow and wave propagation around the head and between head and helmet. The details for the FE discretization of head, protection, and media components can be found in .…”

Section: Numerical Methods and Materials Modelingmentioning

confidence: 99%

“…Because of the moral issues and experimental limitations on the bTBI studies, many researchers have been employing computational methods to investigate the mechanisms leading to blast‐induced brain injuries . While significantly effective against ballistic impacts, helmet and faceshield protection efficiency against blast shockwaves has been under investigation because of the complicated nature of explosion mechanism and have been the subject of few studies . In order to improve the protection efficiency of current protective tools against blast waves, the interaction of blast waves with these tools as well as the alteration of blast flow mechanics should be further studied.…”

Section: Introductionmentioning

confidence: 99%

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Evaluation of brain tissue responses because of the underwash overpressure of helmet and faceshield under blast loading

Sarvghad-Moghaddam

Rezaei

Ziejewski

et al. 2016

Numer Methods Biomed Eng

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Head protective tools such as helmets and faceshields can induce a localized high pressure region on the skull because of the underwash of the blast waves. Whether this underwash overpressure can affect the brain tissue response is still unknown. Accordingly, a computational approach was taken to confirm the incidence of underwash with regards to blast direction, as well as examine the influence of this effect on the mechanical responses of the brain. The variation of intracranial pressure (ICP) as one of the major injury predictors, as well as the maximum shear stress were mainly addressed in this study. Using a nonlinear finite element (FE) approach, generation and interaction of blast waves with the unprotected, helmeted, and fully protected (helmet and faceshield protected) FE head models were modeled using a multi-material arbitrary Lagrangian-Eulerian (ALE) method and a fluid-structure interaction (FSI) coupling algorithm. The underwash incidence overpressure was found to greatly change with the blast direction. Moreover, while underwash induced ICP (U-ICP) did not exceed the peak ICP of the unprotected head, it was comparable and even more than the peak ICP imposed on the protected heads by the primary shockwaves (Coup-ICP). It was concluded that while both helmet and faceshield protected the head against blast waves, the underwash overpressure affected the brain tissue response and altered the dynamic load experienced by the brain as it led to increased ICP levels at the countercoup site, imparted elevated skull flexure, and induced high negative pressure regions. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

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Section: Numerical Methods and Materials Modelingmentioning

confidence: 64%

Section: Numerical Methods and Materials Modelingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Evaluation of brain tissue responses because of the underwash overpressure of helmet and faceshield under blast loading

Sarvghad-Moghaddam

Rezaei

Ziejewski

et al. 2016

Numer Methods Biomed Eng

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“…The application of the film reduced the surface tension of the water, and therefore discouraged air contamination at the water-acrylic interfaces, which could act as cavitation seeds. Petroleum jelly was used as a coupling agent between the incident bar and chamber to ensure full contact and relieve friction forces [9,80]. When filling the chamber, care was taken to ensure that the there was no entrapped air in the chamber and the cap covered the venting channel without compressing the fluid inside, thus preserving atmospheric pressure.…”

Section: Test Protocolmentioning

confidence: 99%

Polymeric Hopkinson Bar-Confinement Chamber Apparatus to Evaluate Fluid Cavitation

2017

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Mild traumatic brain injury associated with blast exposure is an important issue, and cavitation of the cerebrospinal fluid (CSF) has been suggested as a potential injury mechanism; however, physical measurements are required to evaluate cavitation thresholds. Modifications to a Split Hopkinson Pressure Bar (SHPB) apparatus were investigated with the aim to generate localized fluid cavitation and measure the cavitation threshold of fluids. The proposed design incorporated a novel closed cavitation chamber to generate localized cavitation resulting from a reflected compression pulse, which was generated by a spherical steel striker and Polymethyl methacrylate (PMMA) incident bar. A numerical model of the incident bar was developed and validated with 24 independent tests (cross-correlation: 0.970-0.997), and this was extended to a numerical model of the apparatus including the chamber, validated with 27 independent tests (cross-correlation: 0.921) to predict the tensile fluid pressure in the chamber. Tests on distilled water were performed with comparable numerical results for the chamber strain (R 2 : 0.875) and chamber end-wall velocity (R 2 : 0.992). The pressure in the chamber was determined from the model to avoid introducing a nucleation site via a pressure gauge, and was verified with a firstorder approximation showing good agreement (R 2 : 0.892). The 50% probability of cavitation for distilled water was −3.32 MPa ±3%, comparable to values in the literature. This novel apparatus, including a closed confinement chamber integrated with a polymeric SHPB apparatus was able to create localized fluid cavitation with loading comparable to blast exposure. Future studies will include the measurement of CSF cavitation pressure.

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“…Such studies have helped to e ciently develop TBI prediction tools based 1 on the current injury threshold criteria of kinematics, intracranial pressure (ICP), tissue strain, and tissue shear stress [11]. Mechanical responses of human head brain and skull have been studied using multi-material FE simulations [5,12]. Representative FE head models, which include major components of the head such as brain, skull bones, and cerebrospinal uid (CSF), have been employed to study the response of the head under di erent loadings.…”

Section: Introductionmentioning

confidence: 99%

Brain Tissue Constitutive Material Models and the Finite Element Analysis of Blast-Induced Traumatic Brain Injury

et al. 2018

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Abstract. Traumatic Brain Injury (TBI) often occurs due to assaulting loads such as blast on the human head. Finite Elements (FEs) can approximately simulate blast interactions with the human head. An important parameter in the FE modelling procedures is the accuracy of constitutive formulation of the brain tissue. This paper focuses on implementation of three brain tissue constitutive relations to measure and compare the dynamic behaviour of the brain under identical blast loads. For the geometry, a simple spherical head model is employed to monitor the brain tissue response and examine the uncertainties in FE brain tissue constitutive modelling. The brain tissue is constitutively modelled as hyperelastic, viscoelastic, and hyperviscoelastic material types. Intracranial Pressures (ICP), strains, and shear stresses as the dynamic parameters are measured with time. These biomechanical parameters can be compared against the injury thresholds. Our analyses show that although the results of ICPs and strains are close for the three models, shear stresses are considerably di erent. The study will further provide a new insight into selecting a proper constitutive model of the brain tissue under dynamic conditions.

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Examination of the protective roles of helmet/faceshield and directionality for human head under blast waves

Cited by 29 publications

References 14 publications

Evaluation of brain tissue responses because of the underwash overpressure of helmet and faceshield under blast loading

Evaluation of brain tissue responses because of the underwash overpressure of helmet and faceshield under blast loading

Polymeric Hopkinson Bar-Confinement Chamber Apparatus to Evaluate Fluid Cavitation

Brain Tissue Constitutive Material Models and the Finite Element Analysis of Blast-Induced Traumatic Brain Injury

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