Transverse Compression Response of a Multi-Ply Kevlar Vest

Raftenberg, Martin N.; Scheidler, Michael J.; Moy, Paul

doi:10.21236/ada430190

Cited by 8 publications

(8 citation statements)

References 1 publication

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“…69,86 Early studies suggested that ballistic protective vests might increase pulmonary injury risk by acting as pressure amplifiers, 33,80 a result that makes the current clinical evidence for blast TBI harder to explain. This previous work only examined low areal density fiberbased vests and did not look at the use of hard ceramic plates.…”

Section: Effect Of Thoracic Protectionmentioning

confidence: 99%

Brain Injuries from Blast

et al. 2011

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Traumatic brain injury (TBI) from blast produces a number of conundrums. This review focuses on five fundamental questions including: (1) What are the physical correlates for blast TBI in humans? (2) Why is there limited evidence of traditional pulmonary injury from blast in current military field epidemiology? (3) What are the primary blast brain injury mechanisms in humans? (4) If TBI can present with clinical symptoms similar to those of Post-Traumatic Stress Disorder (PTSD), how do we clinically differentiate blast TBI from PTSD and other psychiatric conditions? (5) How do we scale experimental animal models to human response? The preponderance of the evidence from a combination of clinical practice and experimental models suggests that blast TBI from direct blast exposure occurs on the modern battlefield. Progress has been made in establishing injury risk functions in terms of blast overpressure time histories, and there is strong experimental evidence in animal models that mild brain injuries occur at blast intensities that are similar to the pulmonary injury threshold. Enhanced thoracic protection from ballistic protective body armor likely plays a role in the occurrence of blast TBI by preventing lung injuries at blast intensities that could cause TBI. Principal areas of uncertainty include the need for a more comprehensive injury assessment for mild blast injuries in humans, an improved understanding of blast TBI pathophysiology of blast TBI in animal models and humans, the relationship between clinical manifestations of PTSD and mild TBI from blunt or blast trauma including possible synergistic effects, and scaling between animals models and human exposure to blasts in wartime and terrorist attacks. Experimental methodologies, including location of the animal model relative to the shock or blast source, should be carefully designed to provide a realistic blast experiment with conditions comparable to blasts on humans. If traditional blast scaling is appropriate between species, many reported rodent blast TBI experiments using air shock tubes have blast overpressure conditions that are similar to human long-duration nuclear blasts, not high explosive blasts.

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Section: Effect Of Thoracic Protectionmentioning

confidence: 99%

Brain Injuries from Blast

et al. 2011

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“…Figure 8, reproduced from Raftenberg, et al (in review), presents stress-strain data from a single ply of plainwoven, 600-denier Kevlar KM2 pulled in quasi-static, uniaxial tension along its warp yarns. Figure 9, reproduced from Raftenberg, Scheidler, and Moy (2004), presents stress-strain data from the multi-ply Kevlar vest subjected to quasi-static, uniaxial, transverse compression. Figures 8 and 9 make clear that the vest's stress-strain response is nonlinear as well as anisotropic.…”

Section: Progress In Modeling the Kevlar Vestmentioning

confidence: 99%

“…13 we show four such slidelines, and the vest is correspondingly modeled with five 8-node brick elements through its thickness. In order to benchmark the FE fabric model prior to placing it on a thorax, we applied the model in an LS-DYNA simulation of a ballistic test involving the vest impacted by a M882 at 370 m/s (Raftenberg, Scheidler, and Moynihan, 2004).…”

Section: Progress In Modeling the Kevlar Vestmentioning

confidence: 99%

Modeling Thoracic Blunt Trauma: Towards a Finite-Element-Based Design Methodology for Body Armor

Raftenberg

2006

Transformational Science and Technology for the Current and Future Force

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“…Phoenix and Skelton (1974) argued that fibers which are directly underneath the projectile and at yarn cross over points are expected to have substantial transverse compressive stresses. Raftenburg et al (2004) conducted transverse compression tests on 28 plies of Kevlar KM2 and indicated transverse compressive stresses may be amplified depending on specific boundary conditions like multi-layer impact scenarios with surrogate backing, which constrain out-of-plane displacements of the yarns. The dominant role and contribution of principal yarns (yarns directly in contact with the projectile) to energy absorption and projectile deceleration is reported by several researchers (Cheeseman and Bogetti, 2003;Ha-Minh et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

Dynamic modeling of Kevlar KM2 single fiber subjected to transverse impact

Sockalingam

Gillespie

Keefe

2015

International Journal of Solids and Structures

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a b s t r a c tIn this paper, the transverse impact onto a Kevlar KM2 single fiber is studied using analytical and numerical models. The impact response of fibers with reduced longitudinal shear moduli ('string' model) is studied with a 3D finite element model and the wave propagation results converge to the classic 1D analytic solution that supports only axial loads. A dispersive flexural wave mode is predicted numerically for the single fiber during transverse impact due to its finite longitudinal shear modulus. The numerical results are confirmed with an analytical solution derived for the response of an infinitely long EulerBernoulli beam subjected to a constant velocity impact. Fiber bounce is predicted for impact with a cylindrical projectile with fiber velocity exceeding impact velocity by 60-80%. At short time scales significant transverse compressive stresses and strains develop in the fiber and the magnitude depends on the impact velocity. The breaking speed predicted by the 3D model based on maximum principal stress criterion for a single fiber is between 26% (membrane failure) and 76% (combined membrane and flexure failure) less than the 1D analytical solution. The flexural wave and projectile fiber interactions induce curvatures in the fiber significant enough to induce compressive fiber failure and fibrillation.

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Transverse Compression Response of a Multi-Ply Kevlar Vest

Cited by 8 publications

References 1 publication

Brain Injuries from Blast

Brain Injuries from Blast

Modeling Thoracic Blunt Trauma: Towards a Finite-Element-Based Design Methodology for Body Armor

Dynamic modeling of Kevlar KM2 single fiber subjected to transverse impact

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