High-performance ballistic fibers

Werff, H. van der; Heisserer, Ulrich

doi:10.1016/b978-1-78242-461-1.00003-0

Cited by 67 publications

(28 citation statements)

References 37 publications

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“…Coincidentally, a yarn strength of σ max = 3.38 GPa, and Young's modulus, E = 130 GPa, under Hookean assumptions, does result in V C = 801m/s, using his Equation (4). Nonetheless significant discrepancies remain unexplained.…”

Section: Yarn Failure Stress and Strain At Critical Velocity Versus Tmentioning

confidence: 97%

“…The normalizing quantity in Equation (1), was viewed by Cunniff [5] as a characteristic velocity, V C , and using Equation (2) and the relationship, ε max = σ max /E, this velocity can be written in the form (4) where, V crit , defined in the square parenthesis is a critical impact velocity for failure arising later.…”

Section: Fundamental Parameters Governing the Ballistic Resistance Ofmentioning

confidence: 99%

“…Since the helical length of one turn of twist is about 2.5 cm, there will initially be a significant interference effect between the fibers. Fibers contacted first are at a higher deflection angle, γ, and thus, have more strained than others beneath at lower deflection angles, particularly since the induced tensile strain varies roughly as γ 4 . Consequently, fibers underneath are simply in the way, in some respects acting as added mass to the fibers above, thus slowing down the transverse and tensile waves.…”

Section: Strain Concentration From Impact and Shock Wave Distortion Omentioning

confidence: 99%

“…Thus, during transverse compression of a yarn, void space between fibers can be squeezed out so that the transverse stiffness and resisting compressive stress becomes governed by bulk modulus properties of the fiber material. These unique features, not shared by brittle carbon or E-glass fibers, make such polymeric fibers very forgiving of large transverse loads, and thus, well suited to ballistic protection applications, as discussed by van der Werff and Heisserer [4].…”

Section: Introductionmentioning

confidence: 99%

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Modeling and Experiments on Ballistic Impact into UHMWPE Yarns Using Flat and Saddle-Nosed Projectiles

Phoenix

Heisserer

Werff

et al. 2017

Fibers

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Abstract:Yarn shooting experiments were conducted to determine the ballistically-relevant, Young's modulus and tensile strength of ultra-high molecular weight polyethylene (UHMWPE) fiber. Target specimens were Dyneema ® SK76 yarns (1760 dtex), twisted to 40 turns/m, and initially tensioned to stresses ranging from 29 to 2200 MPa. Yarns were impacted, transversely, by two types of cylindrical steel projectiles at velocities ranging from 150 to 555 m/s: (i) a reverse-fired, fragment simulating projectile (FSP) where the flat rear face impacted the yarn rather than the beveled nose; and (ii) a 'saddle-nosed projectile' having a specially contoured nose imparting circular curvature in the region of impact, but opposite curvature transversely to prevent yarn slippage off the nose. Experimental data consisted of sequential photographic images of the progress of the triangular transverse wave, as well as tensile wave speed measured using spaced, piezo-electric sensors. Yarn Young's modulus, calculated from the tensile wave-speed, varied from 133 GPa at minimal initial tension to 208 GPa at the highest initial tensions. However, varying projectile impact velocity, and thus, the strain jump on impact, had negligible effect on the modulus. Contrary to predictions from the classical Cole-Smith model for 1D yarn impact, the critical velocity for yarn failure differed significantly for the two projectile types, being 18% lower for the flat-faced, reversed FSP projectile compared to the saddle-nosed projectile, which converts to an apparent 25% difference in yarn strength. To explain this difference, a wave-propagation model was developed that incorporates tension wave collision under blunt impact by a flat-faced projectile, in contrast to outward wave propagation in the classical model. Agreement between experiment and model predictions was outstanding across a wide range of initial yarn tensions. However, plots of calculated failure stress versus yarn pre-tension stress resulted in apparent yarn strengths much lower than 3.4 GPa from quasi-static tension tests, although a plot of critical velocity versus initial tension did project to 3.4 GPa at zero velocity. This strength reduction (occurring also in aramid fibers) suggested that transverse fiber distortion and yarn compaction from a compressive shock wave under the projectile results in fiber-on-fiber interference in the emerging transverse wave front, causing a gradient in fiber tensile strains with depth, and strain concentration in fibers nearest the projectile face. A model was developed to illustrate the phenomenon.

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Section: Yarn Failure Stress and Strain At Critical Velocity Versus Tmentioning

confidence: 97%

Section: Fundamental Parameters Governing the Ballistic Resistance Ofmentioning

confidence: 99%

Section: Strain Concentration From Impact and Shock Wave Distortion Omentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Modeling and Experiments on Ballistic Impact into UHMWPE Yarns Using Flat and Saddle-Nosed Projectiles

Phoenix

Heisserer

Werff

et al. 2017

Fibers

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“…Together with the higher molecular weight with respect to LLDPE, these features explain the elevated mechanical properties of these fibers. 51…”

Section: Resultsmentioning

confidence: 99%

Polyethylene-based single polymer laminates: Synergistic effects of nanosilica and metal hydroxides

Dorigato

Fredi

Fambri

et al. 2018

Journal of Reinforced Plastics and Composites

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This work aims to investigate the fire performance of novel polyethylene-based single polymer composites. Fumed silica nanoparticles and magnesium hydroxide microfiller were added at an optimized concentration to a linear low-density polyethylene matrix, which was then reinforced with ultra-high molecular weight polyethylene fibers. Through the optimization of the production process, it was possible to limit the porosity inside the single polymer composites, thus retaining the pristine mechanical properties of the fibers. The addition of SiO2 and magnesium hydroxide determined an increase in the elastic modulus in both the longitudinal and transversal direction, but it concurrently led to a reduction in ductility, especially in the transversal direction. The fillers were proved to bring interesting improvements of the thermal degradation resistance and of the flame behaviour. Thermogravimetric analysis tests highlighted an increase in the onset degradation temperature and in the temperature associated to the maximum degradation rate. Moreover, both the oxidation onset temperature and limiting oxygen index were considerably improved. Cone calorimetry tests evidenced that filled single polymer composites were characterized by lower peak heat release rate and total heat released with respect to neat single polymer composites.

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Flow‐Induced Crystallization of Semicrystalline Polymer

Chen

Sheng

et al. 2022

Macromolecular Engineering

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This article summarizes our recent efforts to understand the fundamental mechanism of flow‐induced crystallization of semicrystalline polymers in the melt state. Three general experimental phenomena for polymer crystallization underflow are presented first, which are related to crystal morphology, polymorphism, and crystallization kinetics. Then, theoretical efforts to clarify the above phenomena are briefly summarized. The validation of coil‐stretch transition proposed by de Gennes and the stretched network model in flow‐induced crystallization of polymers is discussed. We proposed a new thermodynamics scenario to quantify the nucleation barrier through decoupling the contribution of conformational entropy and segmental orientation order of initial deformed melt. We also incorporated the crystal morphology and polymorphism into calculating the free energy of nuclei. The proposed model can well agree with the experimental observations. Finally, we present some recent synchrotron radiation X‐ray scattering and molecular dynamics simulation results, which challenge the classical one‐step nucleation model. These results suggest a multistep ordering of flow‐induced nucleation, which is discussed in detail.

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High-performance ballistic fibers

Cited by 67 publications

References 37 publications

Modeling and Experiments on Ballistic Impact into UHMWPE Yarns Using Flat and Saddle-Nosed Projectiles

Modeling and Experiments on Ballistic Impact into UHMWPE Yarns Using Flat and Saddle-Nosed Projectiles

Polyethylene-based single polymer laminates: Synergistic effects of nanosilica and metal hydroxides

Flow‐Induced Crystallization of Semicrystalline Polymer

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