Computational Biomechanics of Blast-Induced Traumatic Brain Injury: Role of Loading Directionality, Head Protection, and Blast Flow Mechanics

In this dissertation, blast-induced traumatic brain injury (bTBI) is studied with respect to the blast wave directionality, mitigation capability of helmet/faceshield, and blast flow mechanics using finite element (FE) and computational fluid dynamics (CFD) schemes. For the FE study, simulations...

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Main Author: Sarvghad-Moghaddam, Hesam
Format: Others
Published: North Dakota State University 2015
Online Access:http://hdl.handle.net/10365/25381
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spelling ndltd-ndsu.edu-oai-library.ndsu.edu-10365-253812021-09-28T17:11:28Z Computational Biomechanics of Blast-Induced Traumatic Brain Injury: Role of Loading Directionality, Head Protection, and Blast Flow Mechanics Sarvghad-Moghaddam, Hesam In this dissertation, blast-induced traumatic brain injury (bTBI) is studied with respect to the blast wave directionality, mitigation capability of helmet/faceshield, and blast flow mechanics using finite element (FE) and computational fluid dynamics (CFD) schemes. For the FE study, simulations are performed on a detailed FE head model using LS-DYNA, and CFD simulations are carried out using the ANSYS-CFX to examine the underwash development by analyzing the behavior of blast flow from different directions. The following tasks are conducted. First, the effects of the loading direction on the mechanical response of the head and brain is investigated through impact and blast induced loading on the head. Due to the differences in the shape, function, and tolerance of brain components, the response of the head/brain varies with the direction of the impact and blast waves. In identical situations, the head shows to have lower tolerance to side loading. Second, the inclusion of the faceshield as a potential head protective tool against blast threats is evaluated with respect to blast direction. The helmet-faceshield and helmeted assemblies are shown to be most efficient when the head is exposed to blast from the front and top sides, respectively. Faceshield is observed to be effective only in front blast as it might impose either adverse or no effects in other directions. The shockwaves are seen to form a high pressure region in head-helmet-faceshield gap (underwash effect) which induces elevated pressures on the skull. Third, the underwash effect’s mechanism is investigated through CFD simulations of supersonic shockwave flow around the helmeted head assemblies. CFD results reveals that the backpressure is produced due to the creation of a backflow in the exterior flow on the outgoing interior flow. The bottom and side shockwave directions predict the highest underwash overpressures, respectively. Finally, the ICP and shear stress of the brain is evaluated in case of underwash incidence. FEA results show that underwash overpressure greatly changes with the blast direction. It is concluded that underwash clearly altered the tissue response of the brain as it increases ICP levels at the countercoup site and imparts elevated skull flexure. 2015-11-16T20:45:17Z 2015-11-16T20:45:17Z 2015 text/dissertation movingimage/video http://hdl.handle.net/10365/25381 NDSU Policy 190.6.2 https://www.ndsu.edu/fileadmin/policy/190.pdf video/quicktime application/pdf North Dakota State University
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description In this dissertation, blast-induced traumatic brain injury (bTBI) is studied with respect to the blast wave directionality, mitigation capability of helmet/faceshield, and blast flow mechanics using finite element (FE) and computational fluid dynamics (CFD) schemes. For the FE study, simulations are performed on a detailed FE head model using LS-DYNA, and CFD simulations are carried out using the ANSYS-CFX to examine the underwash development by analyzing the behavior of blast flow from different directions. The following tasks are conducted. First, the effects of the loading direction on the mechanical response of the head and brain is investigated through impact and blast induced loading on the head. Due to the differences in the shape, function, and tolerance of brain components, the response of the head/brain varies with the direction of the impact and blast waves. In identical situations, the head shows to have lower tolerance to side loading. Second, the inclusion of the faceshield as a potential head protective tool against blast threats is evaluated with respect to blast direction. The helmet-faceshield and helmeted assemblies are shown to be most efficient when the head is exposed to blast from the front and top sides, respectively. Faceshield is observed to be effective only in front blast as it might impose either adverse or no effects in other directions. The shockwaves are seen to form a high pressure region in head-helmet-faceshield gap (underwash effect) which induces elevated pressures on the skull. Third, the underwash effect’s mechanism is investigated through CFD simulations of supersonic shockwave flow around the helmeted head assemblies. CFD results reveals that the backpressure is produced due to the creation of a backflow in the exterior flow on the outgoing interior flow. The bottom and side shockwave directions predict the highest underwash overpressures, respectively. Finally, the ICP and shear stress of the brain is evaluated in case of underwash incidence. FEA results show that underwash overpressure greatly changes with the blast direction. It is concluded that underwash clearly altered the tissue response of the brain as it increases ICP levels at the countercoup site and imparts elevated skull flexure.
author Sarvghad-Moghaddam, Hesam
spellingShingle Sarvghad-Moghaddam, Hesam
Computational Biomechanics of Blast-Induced Traumatic Brain Injury: Role of Loading Directionality, Head Protection, and Blast Flow Mechanics
author_facet Sarvghad-Moghaddam, Hesam
author_sort Sarvghad-Moghaddam, Hesam
title Computational Biomechanics of Blast-Induced Traumatic Brain Injury: Role of Loading Directionality, Head Protection, and Blast Flow Mechanics
title_short Computational Biomechanics of Blast-Induced Traumatic Brain Injury: Role of Loading Directionality, Head Protection, and Blast Flow Mechanics
title_full Computational Biomechanics of Blast-Induced Traumatic Brain Injury: Role of Loading Directionality, Head Protection, and Blast Flow Mechanics
title_fullStr Computational Biomechanics of Blast-Induced Traumatic Brain Injury: Role of Loading Directionality, Head Protection, and Blast Flow Mechanics
title_full_unstemmed Computational Biomechanics of Blast-Induced Traumatic Brain Injury: Role of Loading Directionality, Head Protection, and Blast Flow Mechanics
title_sort computational biomechanics of blast-induced traumatic brain injury: role of loading directionality, head protection, and blast flow mechanics
publisher North Dakota State University
publishDate 2015
url http://hdl.handle.net/10365/25381
work_keys_str_mv AT sarvghadmoghaddamhesam computationalbiomechanicsofblastinducedtraumaticbraininjuryroleofloadingdirectionalityheadprotectionandblastflowmechanics
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