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This study examines the resistance of three-dimensional (3D) weft-knitted fabrics to mechanical risks to determine the influence of varying percentage contents of high molecular weight polyethylene and basalt on cut, puncture, abrasion, and tear resistance. The three-dimensional weft-knitted fabrics are designed by separating functional layers: the outer (protective) layer contains varying percentage contents of high molecular weight polyethylene and basalt; the inner layer (suitable for contact with the skin) contains polyester; both layers are connected using polyamide. The strength properties of knits in response to mechanical impact were evaluated by performing cut, puncture, abrasion, and tear resistance tests. Basalt was found to improve the cut resistance of knits significantly, even with its content as low as 5% in the outer layer. The knit with the highest high molecular weight polyethylene content in the outer layer demonstrated the best puncture and tear resistance. No correlation was established between the varying percentage contents of high molecular weight polyethylene and basalt and the maximum number of abrasion cycles, as the three-dimensional weft-knitted fabrics showed no noticeable wear. The test results show that the structure of three-dimensional weft-knitted fabric with the outer layer designed to withstand mechanical impact and the inner layer suitable for direct contact with the skin protects against a wide range of mechanical impacts. This applies even when varying percentage contents of high molecular weight polyethylene and basalt are used only in the outer layer. [ABSTRACT FROM AUTHOR]

This study investigates the resistance of three-dimensional (3D) weft-knitted fabrics to mechanical risks in order to determine the impact of the percentage content of raw materials in the knits on mechanical loads. For this purpose, 3D weft-knitted fabrics, consisting of a front side, binding, and back side layers, were designed and produced on an E20 circular weft-knitting machine using organic multifilament yarns (high molecular weight polyethylene, HMWPE) and inorganic multifilament (basalt, BS) yarns for the front and back side layers and conventional polyamide yarns for the binding layer. The cut, puncture, abrasion, and tear resistance tests were performed to assess the resistance of 3D weft-knitted fabrics to mechanical risks. According to the testing results, basalt in the structure of 3D weft-knitted fabrics significantly increases the cut resistance, even in cases of a small basalt content in the knit. The puncture, abrasion, and tear resistance testing results showed that the highest HMWPE percentage content in the knitted structure provided the highest resistance to these risks, while increasing the basalt content in the knit did not improve the resistance testing results. Based on the testing results and the assessment of the protection levels provided by the knitted fabrics, the conclusion can be made that the use of HMWPE multifilament yarns and basalt multifilament yarns in the structure of 3D weft-knitted fabrics contributes to the achievement of the highest levels of performance. All the designed 3D weft-knitted fabrics provide complex protection against different mechanical risks (cut, puncture, abrasion, tear). The tests performed may be useful for further development of knitted fabrics designed to provide protection against mechanical risks. [ABSTRACT FROM AUTHOR]

The very thin and lightweight silkworm cocoon has outstanding mechanical properties attributed to its specific composite microstructure. However, the microstructures of the cocoons have not been studied quantitatively, and their anti-puncture performance has not been examined as well. In this study, both domesticated (Bombyx mori) and wild silkworm cocoons (Antheraea pernyi, Antheraea mylitta and Samia canningi) were investigated for their microstructures using fractal theory, and their quasi-static puncture resistance was tested and compared. In addition, the effects of cocoon layers and hot-press treatments on the puncture resistance of two cocoon types (B. mori and A. pernyi) were investigated. The three wild cocoons demonstrated significantly higher fractal dimensions, higher fiber intersectional densities and low porosities, indicating their structures are more optimized. They also displayed better puncture resistance than B. mori. Increased layer numbers could significantly increase the puncture resistance of both cocoon types and A. pernyi showed more remarkable increases. Moreover, the two cocoon types showed optimum puncture resistance after heat treatment with hot-press temperature of 135℃ and pressure of 25 MPa, and A. pernyi showed better puncture resistance after such treatment. Finally, both the maximum puncture force and puncture energy of cocoons displayed a linear increase with the increasing fractal dimensions. The new insights can guide the development of novel protective fiber composites with desirable and predictable anti-puncture performance. [ABSTRACT FROM AUTHOR]

Stab and puncture resistant body armor is widely used by the law enforcement personnel, security and military in many countries. The primary requirement for the armor is to provide protection against various weapons used in an attack. Comfort properties are given increased importance in many countries and considered the second most important requirement. In this research Kevlar was blended with wool and wool–nylon. The resultant fabrics were coated with silica and their stab and puncture resistance in quasistatic conditions was examined using the universal tensile tester. It was hypothesized that the application of coating will generate higher friction to restrict the lateral movement of yarns, and thus present a higher number of yarns for direct resistance to impact during the attack and dissipating the impact energy, whereas the use of wool and nylon will provide the required ergonomics of wearability and stretch. It was observed that the application of the silica coating helped in improving the resistance to the stab and punctures using weapons such as knife (P1, as specified in NIJ 0115.00), ball and pointed impactors. In the quasistatic tests, the highest value of the maximum resistant force was recorded when the ball was used and the lowest was observed for the knife. Furthermore, the application of coating helped in absorbing impact energy. However, the fabric stiffness increased due to the coating, which will negatively impact the ergonomics and wearability. [ABSTRACT FROM AUTHOR]

Since the invention of small arms ammunition, the human torso has required protection from hand-gun bullets, and today’s civil and military personnel are regularly clad in soft body armor systems to cope with these threats. However, increasingly, the threat spectrum has widened to include a plethora of both edged and pointed weapons. Over the past two decades in particular, this has required development of either specific soft armors to defeat that particular threat, or the development of multi-threat vests that can resist both hand-gun bullets and knife and spike attacks. In this review, we provide more details about the various material combinations that are used to defeat a knife or spike, since these armor materials are a lot different from the conventional aramid fabrics, and numerous, widely-different solutions are being pursued. The penetration mechanisms associated with the various forms of attack—stabbing and slashing—are discussed, as well as the use of new fibers, shear thickening fluids, and nano-materials in developing these body armor systems. [ABSTRACT FROM AUTHOR]

The EMI shielding composites consisted of carbon fabric and nonwovens were developed based on needle punching and thermal bonding techniques, and their static and dynamic puncture resistances were also evaluated to resist against different puncture behaviors. The result shows that, needle-punched density and thermal bonding correlate with the EMI shielding effectiveness (SE) at particular medium and high frequency range, and respectively has interaction effect with number of layers. The mechanism of EMI shielding is reflection and absorption loss in medium-frequency, and only absorption loss in high-frequency. The static and dynamic puncture resistances improve linearly with number of layers, but both display an upward and then downward trend at increasing needle-punched density. After thermal bonding, the influence of thickness on static puncture resistance becomes significantly but on dynamic puncture resistance insignificantly. The resultant composites are expected to be used as wall interlayer and package interline in the future. [ABSTRACT FROM AUTHOR]

Glass fabric and Kevlar fabric reinforced recycled nonwovens were produced to form G-Ply and K-Ply high-modulus composites. Three types of composites — non-hot-pressed (N-), hot-pressed (H-) and laminated (L-) composites, were respectively combined by various plies, including non-treated G-Ply or K-Ply, hot-pressed G-Ply or K-Ply, and laminated-together G-Ply or K-Ply. Their acoustic absorption and puncture resistance were respectively discussed in terms of plies number, fabric interlayer, ply sequence and backed air thickness. It is found that the maximum acoustic absorption coefficient occurs at lower frequencies as increase of layers. The K-Ply N-composite shows higher porous acoustic absorption coefficient but lower puncture resistance as compared to G-Ply at more than three layers. The backed air improves acoustic absorption of N-composite almost at entire frequency and H-, L-composites at certain vibrating frequency. For combinations of one K-Ply and four G-Ply, the K-Ply sequence has a significant effect on acoustic absorption of N-composite and L-composite. [ABSTRACT FROM PUBLISHER]