Kevlar 29 parachute fabrics

“…Although a rather uncommon experiment, transverse impact into single yarns has been historically used to determine baseline yarn mechanical properties, specifically to determine yarn stiffness in the longitudinal direction and the yarn critical velocity, wherein the material fails "instantly" upon projectile-yarn contact [1][2][3][4][5][6][7][8][9][10]. Such an understanding of stiffness and critical velocity is used to assess the efficacy of implementing a specific yarn material into a full body armor system; an efficacy analysis is most reasonably performed by determining the Cunniff parameter (Ω 1/3 ) [11], which is described in Equation (1),…”

Section: Introductionmentioning

confidence: 99%

Exploration of Wave Development during Yarn Transverse Impact

Hudspeth

Jewell

Horner³

et al. 2017

Fibers

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Abstract:Single yarns have been impacted in a transverse fashion so as to probe the characteristics of resulting wave development. Longitudinal wave speeds were tracked in efforts to directly measure the yarn tensile stiffness, resulting in a slight increase in the modulus of Kevlar R KM2 and Dyneema R SK76. Additionally, the load developed in AuTx R and Kevlar R KM2 yarns behind the longitudinal wave front has been recorded, providing additional verification for the Smith relations. Further effort to bolster the Smith equations has been successfully performed via tracking transverse wave speeds in AuTx R yarns over a range of impacting velocities. Additional emphasis has been placed at understanding the transverse wave development around the yarn critical velocity, demonstrating that there is a velocity zone where partial yarn failure is detected. Above the critical velocity, measurement of early time transverse wave speeds also agrees with the Smith solution, though the wave speed quickly reduces in value due to the drop in tensile stresses resulting from filament rupture. Finally, the Smith equations have been simplified and are compared to the Cunniff equation, which bear a striking resemblance. Due to such a resemblance, it is suggested that yarn critical velocity experiments can be performed on trial yarn material, and the effect of modifying yarn mechanical properties is discussed.

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“…Simple calculatioizs indicate that replacement of nylon 66 by Kevlar 29 on an. equal strength basis result in a 67% reduction in weight and a 75% reducti n in bulk [4]. Nylon 66 is a relatively efficient parachute mlterial, so the degree .to which the theoretical potential of Kevlar can be achieved depends upon how well Kevlar ca be processed into equivalent end-use structures, m Most hevlar 9 parachute materials available at the initiation of this work were developed by the Air Force <at rR~, Division Albany International.2 The main hbjective of this work 4-as to develop a series of Kevlar textiles corresponding to width-strength combinations available in standard MIL specification nylon textiles.…”

Section: Introductionmentioning

confidence: 98%

“…High-rate testing was carried out using a 'cold-gas-gun ballistic-' pendulum apparatus: The basic test system and . 4)rocedtire has been described in detail previously ~3~.…”

Section: Introductionmentioning

confidence: 99%

“…The manual method of determining curvature and torsion is not only tedious and prone to error but also impractical. To overcome this difficult, Brand el aL [3,4] developed the Automatic Crimp Measuring Instruments (ACMI) in the , duPont laboratories, which not only determines the , distribution statistics of the crimp form in terms of geometric curvature and-torsion, but also provides data in terms of 'classical . imp parameters such as -crimp frequency a~d-.tota crimp.…”

mentioning

confidence: 99%

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The Effect of Warp and Filling Variables on the Tensile Failure and Joint Strength of Kevlar® 29 Parachute .Webbing

Ericksen¹,

Abbott

Donovan

et al. 1979

Textile Research Journal

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The effect of filling and warp yarn variables on the strength of a nominally designated 60 kN, 2.9 cm Kevlar® 29 parachute webbing was investigated. The goal was to increase webbing and jointed webbing strength without in creasing the weight of the structure. Webbing of varying pick spacing, filling yarn strength, and amount of warp yarn twist was fabricated and tested at quasi-static and high strain rates. Improved strength was obtained when: a the filling was reduced from two to single-ply yarn, b) pick spacing was increased to 6.3 picks per cm, and c twist was removed from the warp. Kevlar® webbing strength was not reduced at high strain rates of 3000% s compared with quasi-static values. The strength of jointed samples at high strain rate loading was higher than that obtained in quasi static tests. ,

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Kevlar 29 parachute fabrics

Cited by 10 publications

References 0 publications

Penetration Mechanics of Textile Structures

Penetration Mechanics of Textile Structures

Exploration of Wave Development during Yarn Transverse Impact

The Effect of Warp and Filling Variables on the Tensile Failure and Joint Strength of Kevlar® 29 Parachute .Webbing

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