Role of Inelastic Transverse Compressive Behavior and Multiaxial Loading on the Transverse Impact of Kevlar KM2 Single Fiber

Sockalingam, Subramani; Gillespie, John W.; Keefe, Michael

doi:10.3390/fib5010009

Cited by 14 publications

(8 citation statements)

References 29 publications

(68 reference statements)

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“…These exact same result and findings were further simulated by Sockalingam et al to show the effects of multiaxial stress states numerically. 7 Hudspeth et al later transversely impacted high-performance polymer yarns with the same round, FSP, and razor blade projectiles in order to demonstrate the same detrimental effects of localized stress concentrations. 8 In the same manner as the fibers under quasistatic indentation, the razor blade projectiles initiated stress states that reduced the overall ballistic performance of the yarn compared to a round indenter, which tends to initiate axial tensile failure in the yarns.…”

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confidence: 99%

Localized impact stress concentrations in soft armors due to microscale projectile edge geometries

Guo

Chen²,

Zheng

2018

Textile Research Journal

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Although extensive focus has been placed on the ballistic performance of projectiles with certain macroscale geometries and dimensions, the microscale geometries are not as rigorously standardized. The localized stress concentrations arising from microscale geometries introduce multiaxial and locally concentrated stress states within the constituent material of the soft-armor target, which can result in premature failure that is not predicted with existing models. In this study, the microscale edge/corner geometries of right circular cylinder (RCC) projectiles are varied, and their respective ballistic performance was determined via experiments to examine the effects of the localized stress concentrations. Target panels were examined post-mortem and the effects of these localized stress concentrations on the failure modes were quantified. Experiments results indicate that stress concentrations drastically reduce the ballistic performance of the soft armor targets, and the fabric targets appear to fail without significant strain energy absorption.

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confidence: 99%

Localized impact stress concentrations in soft armors due to microscale projectile edge geometries

Guo

Chen²,

Zheng

2018

Textile Research Journal

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“…It should be noted that the dynamic SCF during transverse impact are higher than their static counterparts by two-fold as shown by the single fiber impact models. 7 The average SCF over all the angles of quasi-static FSP loading is 2.2 (see Figure 8(c)). Dynamic SCF is taken to be twice this quasi-static average.…”

Section: Discussionmentioning

confidence: 97%

“…Ballistic impact onto these fiber-based armor systems induces complex high strain rate (HSR) deformation mechanisms. [5][6][7] The deformation modes includes axial tension, axial compression, transverse compression and transverse shear. Predicting ballistic impact performance of these armor systems requires an understanding of the failure of the fibers under complex multiaxial loading conditions.…”

Section: Introductionmentioning

confidence: 99%

Failure of Dyneema® SK76 single fiber under multiaxial transverse loading

Sockalingam

Thomas

Casem

et al. 2018

Textile Research Journal

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This article investigates the failure of ultra-high molecular weight polyethylene Dyneema Õ SK76 single fibers widely used in protective armor applications. Indenter geometry and the associated stress concentration are known to have a significant effect on the average axial tensile failure strain of Dyneema Õ SK76 fibers subjected to quasi-static transverse loading experiments by three indenter geometries. In this study, a 3D finite element model is developed to predict the degree of multiaxial loading at the location of fiber failure in these experiments. A failure criterion based on maximum axial tensile strain considering the statistical strength distribution and multiaxial loading (transverse compression and transverse shear) induced degradation effects is applied to predict the fiber failure. The influence of transverse compression on the tensile strength of single fibers is experimentally determined. The average failure strains predicted by the model are found to agree well with the experimental results indicating fiber failure may be initiated based on a gage length dependent maximum axial tensile strain in the fiber.

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“…This causes a significant increase in the axial strain concentration in the fiber cross-section at the location of failure. They have also shown via single fiber impact models [30] that the dynamic strain concentration factors are approximately twice that of their static counterparts for Kevlar ® KM2. Besides, for UHMWPE Dyneema ® SK-76 fibers tensile failure strains decrease with increasing strain rates, as reported by Sanborn et al [31] and Thomas [32].…”

Section: Effect Of Multi-axial Stress States On Yarn Breaking Speedsmentioning

confidence: 95%

Experimental Investigation of Transverse Loading Behavior of Ultra-High Molecular Weight Polyethylene Yarns

Shah

Sockalingam

2020

Fibers

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Ultra-high molecular weight polyethylene (UHMWPE) Dyneema® SK-76 fibers are widely used in personnel protection systems. Transverse ballistic impact onto these fibers results in complex multiaxial deformation modes such as axial tension, axial compression, transverse compression, and transverse shear. Previous experimental studies on single fibers have shown a degradation of tensile failure strain due to the presence of such multi-axial deformation modes. In this work, we study the presence and effects of such multi-axial stress-states on Dyneema® SK-76 yarns via transverse loading experiments. Quasi-static transverse loading experiments are conducted on Dyneema® SK-76 single yarn at different starting angles (5°, 10°, 15°, and 25°) and via four different indenter geometries: round (radius of curvature (ROC) = 3.8 mm), 200-micron, 20-micron, and razor blade (ROC ~2 micron). Additionally, transverse loading experiments were also conducted for a 0.30 cal. fragment simulating projectile (FSP) and compared to other indenters. Experimental results show that for the round, 200-micron indenter, and FSP geometry the yarn fails in tension with no degradation in axial failure strain compared to the uniaxial tensile failure strain of SK-76 yarn (2.58%). Whereas for the 20-micron indenter and razor blade, fibers fail progressively in transverse shear followed by progressive strength degradation of the yarn. Strength degradation of yarn occurs at relatively low strains of 0.6–0.7% with eventual failure of the yarn at approximately ~1.8% and ~1.5% strain for the 20-micron indenter and razor blade, respectively. Breaking angles (range of 10°–30°) are observed to have little effect on the failure strain for all indenter geometries.

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Role of Inelastic Transverse Compressive Behavior and Multiaxial Loading on the Transverse Impact of Kevlar KM2 Single Fiber

Cited by 14 publications

References 29 publications

Localized impact stress concentrations in soft armors due to microscale projectile edge geometries

Localized impact stress concentrations in soft armors due to microscale projectile edge geometries

Failure of Dyneema® SK76 single fiber under multiaxial transverse loading

Experimental Investigation of Transverse Loading Behavior of Ultra-High Molecular Weight Polyethylene Yarns

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