| Spacer fabric is a three-dimensional fabric, which is composed of an upper layer, a lowerlayer, and a spacer layer that connects the upper layer and the lower layer, which has good airpermeability, moisture transmission, shock resistance, resilience, resistance to compression,filtering and sound insulation, etc, and gradually become the preferred cushion materials. Theseproperties are mainly dependent on the special structure of the spacer layer and its compressionproperty, whereby, this article focuses on the relationship analysis between the structuralparameters and compression performance, expecting to provide structural guidance for optimizingthe design and application of protecting cushion material. The main researching contents include:(1) Effect of structural parameters on the compression performance of spacer fabric. The platecompression and spherical compression experiment were utilized to analyze effect of differentstructural parameters on compression performance of woven spacer fabric and warp knittingspacer fabric (2) Comparison of comfortable performance between spacer fabric and other cushionproducts. By comparing warp knitted spacer fabric with non-woven materials and foam, wemeasured the temperature and humidity of microenvironment at contact area to find out the bestmaterial for cushion products.(3) Finite element simulation of the compression performance. Thedistribution of stress and strain of whole fabric and spacer filament was obtained during thecompression process based on the finite element analysis software ABAQUS. The above researchwork is concluded as follows:(1) Effect of structural parameters on compression performance of warp-knitted spacer fabric.Fabric thickness increases from7.45mm to13.81mm, the compression work increases from148.21mJ to186.75mJ, the initial stage of the compression secant modulus reduces from148.03Kpa to71.25Kpa, which indicates that the thicker the fabric, the more energy required forthe compression process, the smaller the compression secant modulus. Spacer fabric is easier to be compressed and shows to be softer. With the increasing of the diameter of spacer filament (from137.64μm to185.54μm), the compression work increases from148.21mJ to186.75mJ, therecovery rate increases from0.55to0.61and the initial stage of the compression secant modulusascends from92.68Kpa to148.03Kpa, the maximum force that spacer fabric can withstandincreases from233.27N to373.23N, it means that properties of recovery, the initial stage of thecompression secant modulus, maximum force increases with the increases of the diameter ofspacer filament, it is also difficult to be compressed at the initial stage. With spacer angle beingincreased, when spacer angle ranges from28.54°to55.60°, the compression work increases from71.74mJ to108.29mJ, the fabric is more difficult to be compressed, and recovery rate(from0.57to0.72) and initial modulus (from38.15Kpa to83.41Kpa)are also meeting the trends. Thearrangement of spacer yarn has X-shaped and V-shaped, the whole structure of spacer fabric ismore stable when spacer filament arrangement is X-shaped compared with V-shaped, when thespacer yarn arrangement is X-shaped, they can form a double zigzag pattern between the twosurfaces and the spacer filament, improving the compressive performance of spacer fabric, theresilience and recovery performance are also better than V-shaped, but it needs more energyrequired for the compression process when spacer filament arrangement is X-shaped. With spacerfilament density increasing (from644.27g/m2to974.97g/m2), recovery properties descends from0.72to0.69, the spacer fabric is more difficult to be compressed, the fabric exhibits a hard feel,the whole energy required for the compression process increases, and the recovery property isdeteriorated. Meanwhile, we also analyzed the correlation of the results between five differentdiameter spherical indenters(5cm,8cm,12cm,16cm,18cm), and obtained that the minimumcorrelation coefficient was as high as0.91, indicating that spherical indenter can simulatecompression behaviour of human contact part. And we also analyzed the correlation of the featureindices (e.g., compression work, recovery compression work, etc) of the results between differentspherical indenters, the correlation coefficients are almost above0.85, except that the minimumcorrelation coefficient of recovery rate is0.73, so we can use the compression results of a certainkind of spherical indenter to predict the feature indices that correspond to the compression resultsof any size spherical indenters.(2) Heat and moisture permeability and air permeability of spacer fabric are mainly affectedby the thickness (from7.45mm to13.81mm), spacer filament density (from644.27g/m2to974.97g/m2) and mesh number (from2.43n/cm2to1.55n/cm2).Heat and moisture permeability andair permeability (from8856.20mm/s to3652.43mm/s) of spacer fabric become worse as theincrease of the thickness, spacer filament density and mesh number. On the contrary, theproperties become better. The properties of relief pressure, air permeability, heat and moisturepermeability, bending performance of spacer fabric are better than nonwoven material and foam products. The experimental results of temperature and humidity of microenvironment at contactarea show that spacer fabric can maintain the balance of the temperature and humidity ofmicroenvironment at contact area, which is better than the other two materials and is helpful forpreventing bedsores and other diseases resulted from prolonged sitting or lying, so spacer fabric isthe preferred alternative for foam cushion and nonwoven material products.(3) Finite element simulation of woven spacer fabric and warp-knitted spacer fabric: Forwoven spacer fabric, we mainly simulated effect of structure parameters on the compressionperformance of woven spacer fabric.①Warp and weft density, four different warp densities(2:2:1,3:3:2,5:5:2,7:7:2) and two different weft densities (3:8,5:11) of woven spacer fabrics aredesigned. The results showed that the greater the warp or the weft density, the stronger thecompression performance. It consumes relatively more energy when compressed to a certain strain.With the increase of spacer warp or weft density, the number of spacer filament is larger within thesame area, so the resistance to compression is better.②Thickness(from5mm to10mm),experimental and simulated results show that with the increase of the thickness of woven spacerfabrics, the compression work (from50.12mJ to27.84mJ), the recovery rate, compressivemodulus(from17.57N/mm to1.43N/mm) relatively reduce, mainly due to the increase inthickness, the spacer filament becomes more instable, when compressed, the thicker the fabric, theeasier the spacer filament is bent, the smaller force spacer filament withstand.③The diameter ofspacer filament(from0.2mm to0.4mm). With the increase of the diameter of spacer filament, thecompression performance of spacer fabric enhances, it also consumes relatively more energy(from50.12mJ to387.98mJ) when compressed to a certain strain, and the diameter has asignificant impact on compression performance.Finite element simulation of warp-knitted spacer fabric:①Simulating the sphericalcompression process of spacer fabric under five spherical indenters with differentdiameters(5cm,8cm,12cm,16cm,18cm), the results show that the greater the diameter is, thegreater the force(from86.42N to25.20N) will be.②Establishing a path along longitudinaldirection, then outputting the displacement curve in this direction, and obtained the displacementcurves of different spherical indenters. Taking the axis of symmetry as the rotation axis to rotateeach curve with360°, and the result surface can approximately calculate the deformation surfaceof spacer fabric after compressing with the spherical indenter.③We extract a point at intervalsabout18°where the displacement is zero, and connect each point with a curve. According to thesymmetry of the model, we can basically get the compression surface to be approximatelyoval–shaped, indicating that the diffusion of the compression force is as a shape of vocalization tospread out.④Outputting the stress plot contour when time increment is0,0.004,0.008,0.012,0.016,0.02, we can observe intuitively that the stress is continued to spread out with the compression process, the maximum stress appears at the most serious bending partsafter compressing. |
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