The Compression Mechanism Of Warp-knitted Mesh Spacer Fabric

Three-dimensional mesh fabric is a special type of knitted spacer fabric,which is made up of two separate meshed multifilament outer layers linked together with a layer of spacer monofilaments.It has found wide applications in home textiles and automotive industry for replacing sponge and PU foam due to its excellent compression resistance,good energyabsorbing performance and ventilation property.Although a lot of researches has been carried out on warp-knitted mesh spacer fabrics,the design and production of meshed spacer fabrics is still based on experience.The precise design of 3D mesh fabric requires an in-depth understanding of their compression deformation mechanism.This thesis aims to reveal the compression deformation mechanism of 3D mesh fabric by using finite element（FE）-simulation.The findings from this work would provide a guidance to quantitatively engineer the compression performance of 3D mesh fabrics.A typical warp-knitted mesh spacer fabric was studied.The fabric was scanned by using Micro X-ray computed tomography（μCT）to reconstruct a unit cell.The nonlinear compression deformation mechanism of the fabric was revealed by analyzing the global and local deformation behavior of the fabric under compression based on the FE simulation.Furthermore,the unit cell was simplified to have regular and symmetric chains to build another FE model.The effect of number and arrangement of unit cells on the compression properties of the mesh fabric was compared.Finally,a parametric study is conducted by adjusting the fabric thickness,monofilament diameter,material properties and the degree of freedom（DOFs）to explore the influence of various parameters on the compression behavior of the mesh spacer fabric.The following conclusions can be drawn by comparing experiments and numerical simulations.Three distinct stages are found in the compression load–displacement curves.In the linear elasticity stage,the deformation of the spacer monofilaments is mainly post-buckling.When entering the plateau stage,the spacer monofilaments undertake bending,rotating and twisting.In the process of the fabric compression,the curvature of the spacer monofilaments gradually increases along its ends to the middle.The curvature and torsion of the left and right sides are not symmetrical.The contact between adjacent unit cell monofilaments has less effect on the overall compression performance of the fabric.The parameters such as fabric thickness,spacer monofilament fineness and material properties have a great influence on the compression performance of the fabric.