| Warp-knitted spacer fabrics(WKSFs)are a class of textile products formed by several groups of filaments with a three-dimensional effect,the upper and lower surface layers have excellent breathability and moisture permeability,and the middle spacer filaments can provide suitable resilience and support,which has great application value in the material for mattresses.The current research on the compression performance of WKSFs mainly focuses on the compression of flat and spherical indenters,the study of hip and waist-back shaped surface compression is often overlooked.Therefore,this topic selected four kinds of WKSFs with different finenesses of 0.12 mm,0.15 mm,0.18 mm and 0.25 mm,and used comparative tests,experimental analysis and finite element simulation to analyse the compression performance of flat,spherical,waist-back and hip fabrics,in order to provide a theoretical basis for the selection of mattress materials,and also to provide practical significance for the development and promotion of products.Firstly,the paper summarised the current research status of WKSFs in terms of compression properties and their applications in medical,textile and other fields.This paper therefore analysed the raw material selection,loop formation process and parameter measurement of WKSFs to provide the basis for the subsequent analysis of the compression properties.Secondly,compression performance tests were carried out on flat and spherical shape for WKSFs with different fineness of spacer filaments.They were compressed to 25%,40%and65%of the fabric thickness and the compression stress values,indentation measurements,data comparison between flat and spherical indenter in terms of compression performance,and pressure dispersion ratio of the fabric were observed respectively.The results showed that the compression stress,Indentation Force Deflection(IFD)and support factor(SF)of the WKSFs under flat and spherical compression all increase with the increase in spacer filament fineness;the stress values and IFD suffered by the fabric under flat compression were much greater than those under spherical compression,while the SF under spherical compression was greater than that under flat compression;in the pressure dispersion ratio,the pressure dispersion capacity gradually decreases with the increase in indentation depth.Then,for the waist-back and hip models,WKSFs with four different finenesses of spacer filaments were compressed to 25%,40%and 65%of the fabric thickness for surface compression tests,and the stress-strain and indentation measurements under compression for the waist-back and hip models,as well as the compression characteristics under shaped surfaces were compared with those of flat and spherical surfaces.The results showed that the stress-strain curves under compression for the waist-back and hip models were non-linear,which was similar to the stress-strain curves under compression for the spherical indenter,and that the stresses in the heteromorphic surfaces increase with the increase in the fineness of the spacer filaments;in terms of indentation measurements,the indentation hardness values range from 8.60 N to 126.16 N for the waist-back indenter and 7.00 N to 110.25 N for the hip indenter,and the IFD for the two heteromorphic surfaces.The distribution is between the flat IFD and the spherical IFD,and favours the spherical indenter;in terms of the SF,it is 3.09-3.66 for the waist-back indenter and 3.2-4.31 for the hip indenter,which is basically the similar as the SF of 3.05-4.31 for the spherical indenter.Whereas the SF reflects the comfort of the fabric to a certain extent,this suggested that to a certain extent the spherical surface can be used instead of the waist-back and hip for the comfort measurement.Finally,ANSYS software was used to model the WKSFs under compression with flat and spherical indenters,and the constructed models were set to 25%,40%and 65%of the fabric thickness to observe the displacement changes and stress distribution of the individual spacer filaments and the fabric as a whole.It was concluded that the optimum compression depth for WKSFs as a mattress material was 40%,to achieve good compression resistance and comfort;and that the pressure around the indenter at 40%compression for a 0.25 mm spacer filament was 0.75 N/cm~2-2.01 N/cm~2,meeting the corresponding demand values for mattress materials.This means that a WKSF with a fineness of 0.25 mm can combine comfort and pressure resistance as a mattress material,which is of great practical importance for the development and application of the product. |
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