RESUMEN
In this study, five three-dimensional angle-interlock fabrics with different warp and weft densities were fabricated using 1000D Kevlar filaments. The Kevlar/EP composites were prepared by vacuum-assisted molding techniques. The low-velocity impact property of the composite was tested, focusing on the effects of the warp and weft densities, impact energy, impactor shape, and impactor diameter. The damage area, dent depth, and crack lengths in the warp and weft direction were used to evaluate the impact performance, and the specimens were compared with plain-weave composites with similar areal densities. The dominant failure mode of the conical impactor was fiber fracture, while the dominant failure mode of the hemispherical impactor was fiber-resin debonding. The cylindrical impactor showed only minor resin fragmentation. The residual flexural strength of the composite after impact was tested to provide insights into its mechanical properties. The study findings will provide a theoretical basis for the optimization of the design of impact-resistant structures using such materials and facilitate their engineering applications.
RESUMEN
The three-dimensional (3D) shallow cross-bending composite material has many advantages in thickness and in-plane direction, such as high strength, high modulus, inter-layer shear strength, as well as large-area area bearing, energy absorption, etc., which has great application potential in the field of bulletproof armor. To prepare a protective material with both excellent bending performance and good ballistic performance, the effects of weft density and layering method on the bending performance and ballistic performance of three-dimensional ply-to-ply angle interlock (3DPPAI) Kevlar/EP armor materials were studied. The results showed that when the weft density of the material was 33 pieces/cm, its bending performance and ballistic resistance were the best. The 3DPPAI Kevlar/EP armor material prepared by orthogonal layup had more advantages in bending performance, and the unidirectional layup had better anti-ballistic performance. The research results will lay the foundation for structural optimization and engineering applications of such materials.
RESUMEN
Three-dimensional (3D) woven composites have attracted much attention in the lightweight research of protective armor due to their high specific strength and good impact resistance. However, there are still many gaps in terms of the performance and influencing factors of three-dimensional deep-angle-interlock (3DDAI) Kevlar/EP armor materials. Therefore, in order to prepare 3DDAI Kevlar/EP armor materials with excellent ballistic resistance and mechanical properties, this paper studies the bending performance of 3DDAI Kevlar/EP armor materials and the influence of the number of stacking layers, resin content, laying method, and weft density. Finally, we compare it with the traditional two-dimensional (2D) plain laminated Kevlar/EP armor material. The results showed that when the 3DDAI Kevlar/EP armor material was subjected to bending load, the upper and bottom layers of the material had a great influence on the initial stiffness and fracture strength of the material, respectively; when the material's warp and weft density are quite different, the utilization rate of the yarn and the strength of the material are negatively affected; the fracture energy of the 3DDAI Kevlar/EP armor material prepared by the orthogonal laying method was about 20% higher than that of the 3DDAI Kevlar/EP armor material with the unidirectional layering method; and the bending performance of the 3DDAI Kevlar/EP armor material in the weft direction was better than that of the 2D plain laminated Kevlar/EP armor material, with the 3DDAI Kevlar/EP armor material having better delamination resistance. The research results will lay the foundation for structural optimization and engineering applications of such materials.
RESUMEN
Inorganic powders (IPs), namely, SiO2 and Al2O3, were used as reinforcements and thermosetting epoxy resin was utilized as a matrix to manufacture IP/epoxy preform, which was coated on the surfaces of 2/1 twill woven polyethylene terephthalate (PET) fabrics before the final curing process. The effect of curing conditions, including temperature, time, and IP content, on the physical, mechanical, and cutting resistance properties of pure IP/epoxy composites and PET fabrics coated with IP/epoxy composites were investigated. Results indicated that the cutting resistance of PET fabrics could be greatly improved by coating with IP/epoxy composites. Meanwhile, the cutting resistance of fabrics coated with IP/epoxy composites had a close relationship with the shore hardness of the coated IP/epoxy composites, which could be controlled by the curing conditions and IP content.
RESUMEN
A method for situ preparing a hybrid material consisting of silica nanoparticles (SiO2) attached onto the surface of functionalized graphene nanoplatelets (f-GNPs) is proposed. Firstly, polyacrylic acid (PAA) was grafted to the surface of f-GNPs to increase reacting sites, and then 3-aminopropyltriethoxysilane (APTES) KH550 reacted with abovementioned product PAA-GNPs to obtain siloxane-GNPs, thus providing reaction sites for the growth of SiO2 on the surface of GNPs. Finally, the SiO2/graphene nanoplatelets (SiO2/GNPs) hybrid material is obtained through introducing siloxane-GNPs into a solution of tetraethyl orthosilicate, ammonia and ethanol for hours' reaction. The results from Fourier transform infrared spectroscopy (FTIR) showed that SiO2 particles have situ grown on the surface of GNPs through chemical bonds as Si-O-Si. And the nanostructure of hybrid materials was characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). All the images indicated that SiO2 particles with similar sizes were grafted on the surface of graphene nanoplatelets successfully. And TEM images also showed the whole growth process of SiO2 particles on the surface of graphene as time grows. Moreover, TGA traces suggested the SiO2/GNPs hybrid material had stable thermal stability. And at 900°C, the residual weight fraction of polymer on siloxane-GNPs was about 94.2% and that of SiO2 particles on hybrid materials was about 75.0%. However, the result of Raman spectroscopy showed that carbon atoms of graphene nanoplatelets became much more disordered, due to the destroyed carbon domains during the process of chemical drafting. Through orthogonal experiments, hybrid materials with various sizes of SiO2 particles were prepared, thus achieving the particle sizes controllable. And the factors' level of significance is as follows: the quantity of ammonia > the quantity of tetraethyl orthosilicate (TEOS) > the reaction time.