This paper puts forward a new method for measuring the three-dimensional deformation of warp-knitted spacer fabrics under tensile stress. The three-dimensional deformation mechanisms of warp-knitted spacer fabrics have been analyzed using stress–strain curves. Poisson’s ratio of the three-dimensional deformation has also been analyzed. The stress–strain curves obtained for tests in the warp-ward direction and weft-ward direction show a characteristic initial large deformation, followed by minimal-to-no deformation. The stress–strain curves obtained for tests in the thickness direction exhibit different characteristics due to the differences in stretch directions. In the weft-ward direction, the curve shows an approximate linear change with minimal strain. In the warp-wise direction, the curve shows a large stress with small strain, and subsequently, a small stress yielded a large strain. During the stretching process, the surface deformation perpendicular to the direction of tensile force is greater than the tensile deformation, and the deformation in the thickness direction is also minimal compared to that in the direction of the tensile deformation.
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Single-layered warp knitted fabrics were produced by the 60D/36F (containing 36 filaments) polyester yarn with differential shrinkage (DS) property in this study. Due to the differential shrinkage property, the fabric becomes curly and bulkier, simulating cotton fabric in terms of its appearance and fabric handle. The performance and appearance of these DS polyester warp knitted fabrics were evaluated objectively and subjectively. The testing results demonstrated that the DS polyester warp knitted fabric had better abrasion property, worse pilling resistance due to the mechanical property of polyester yarn when compared with 100% cotton warp knitted fabric. Meanwhile, lower water vapour permeability and air resistance were found for DS polyester warp knitted fabric resulting from the dense structure of yarn shrinkage after heat-moisture treatment. Besides, the fabric handle was evaluated by Kawabata evaluation system and subject to trial under dry and wet fabric condition. DS polyester warp knitted fabrics provide better recovery under low stress mechanical pressure. The subjective evaluation result shows that the warp knitted fabrics made of DS polyester had similar handle against cotton warp knitted fabric in terms of prickle, smooth, comfort and dry feeling in both dry and wet testing conditions.
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The aim of this study was to investigate the flexural behaviours of syntactic foam reinforced by warp knitted spacer fabric (SF-WKSF). Seven kinds of SF-WKSF samples were fabricated by warp knitted spacer fabric (WKSF) with structural parameters including surface layer structures, inclination-angle and fineness of spacer yarns, different microballoons types and contents. The flexural tests were carried out and the bending properties of SF-WKSF were analysed based on the strength and modulus values obtained from the test results. It is indicated that the SF-WKSF shows higher flexural strength and modulus compared to neat syntactic foam with almost no impact on the density of composites. The results also demonstrate that the surface layer structure, inclination-angle of spacer yarns, microballons content and type have significant effects on the flexural responses of SF-WKSF. The composites exhibit better antibending capacities by selecting larger inclination-angle, closer surface layer structure, higher density and relatively higher content of S60HS microballoons.
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