Yarn Pull-Out as a Mechanism for Dissipating Ballistic Impact Energy in Kevlar® KM-2 Fabric

Abstract

Yarn pull-out can be an important energy absorption mechanism during the ballistic impact of woven Kevlar® fabric. This study reports the effects of fabric length, number of yarns pulled, arrangement of yarns, and transverse tension on the force-displacement curves for yam pull-out tests on Kevlar® KM-2 fabric under laboratory conditions. A semi-empirical model is presented for predicting the yam pull-out force and energy as a function of pull-out distance, including both yarn uncrimping and subsequent yam translation. This model is found to replicate the experimental data with a high degree of accuracy, and should prove useful for understanding ballistic experiments and improving computational modeling of fabrics.

Shear behavior of a shear thickening fluid-impregnated aramid fabrics at high shear rate

“…The STF effect has been quantified from yarn pull-out tests of STF-im-AR fabrics where the pulling force was measured. A clear enhancement of the pull-out force of a single yarn at pulling rates in the 1-1,000 mm/min range was reported [22,41,42]. The maximum pull-out force increased sharply beyond a certain pulling rate (the critical pulling rate).…”

Analytical investigation of high-velocity impact on hybrid unidirectional/woven composite panels

“…Kirkwood [22] reported by increasing the transverse fabric tension, the yarn pullout energy increases. In fact increasing the tension on the transverse yarns increases normal forces between yarns, resulting in more frictional resistance to yarn pull-out and also a more tortuous path during yarn translation in the pull-out phenomena.…”

“…As the number of neighboring yarns pulled during a test increases, the peak load and displacement at peak load point increase too. Kirkwood et al [22] presented the following equation for pull out n yarn simultaneously:…”

Numerical Simulation in Steady Flow of Non-Newtonian Fluids in Pipes with Circular Cross-Section

“…Although shear thickening fluids (STFs) are much less common than shear thinning materials in industry, an increasing number of applications take advantage of the shear thickening behaviour to improve their performance, i.e. the incorporation of STFs to Kevlar R fabrics in order to improve the ballistic protection (Lee et al, 2003;Kirkwood et al, 2004) and enhance stab resistance (Decker et al, 2007). However, shear thickening is an undesirable behaviour in many other cases and it should never be ignored, because this could lead to technical problems and even to the destruction of equipment, i.e.…”