Research On Preparation And Performance Of Yarn-embedded Nonwoven Composites

The forming principle of needle-punched nonwoven fabric is to repeatedly needle the fluffy fiber web,causing the fibers in the structure to intertwine and generate cohesion,forming a fiber fabric with certain strength.This process has a short production cycle,high efficiency,and convenient forming,but the products produced by this process have poorer mechanical properties compared to textiles and are widely used in fields such as filtration and geotextiles.To improve the mechanical properties of needle-punched nonwoven fabric and expand its application fields,this paper proposes a yarn-embedded needle-punched nonwoven composite material with a "sandwich" structure from the perspective of the yarn scale and tests the relevant mechanical properties of the composite material.Finite element method is used to simulate and compare the mechanical properties of the composite material with experimental verification.Through relevant mechanical experiments and finite element mechanical simulations,it is concluded that the composite material not only inherits the advantages of needle-punched nonwoven fabric but also improves its mechanical properties.In order to achieve the automated and continuous production of this structure,based on the proposed structure and weaving process principles of the yarn-embedded needle-punched nonwoven composite material,this paper designs and manufactures a yarn-embedding equipment to complete the yarn-embedding process automatically.The main research of this paper is as follows:(1)The proposed yarn-embedded needle-punched nonwoven composite material with a "sandwich" structure consists of a "top-middle-bottom" three-layer structure,with all layers being pre-needled fiber webs.Yarns are embedded in the middle layer in a warp and weft interweaving manner,and then the three layers of fabric are combined and formed through the needle-punching process.In this composite material structure,the middle layer is the reinforcing layer,and the yarns are combined with the pre-needled fiber web based on a weaving process similar to that of a machine weaving process.According to this process principle,this paper designs and manufactures a yarn-embedding equipment to automate the process of yarn embedding into the pre-needled fiber web.(2)Based on the proposed structure and equipment,low-melting-point polyester filament is used to wrap aramid filaments,and the resulting yarns are combined with polyester pre-needled fiber webs to prepare the yarn-embedded needle-punched nonwoven composite material.The influence of different yarn spacing combinations and different outer yarn twist on the mechanical properties of the material,such as tensile strength,bursting strength,and bending,is studied,and the experimental results are theoretically analyzed.(3)The composite material is cured with resin,and the path and cross-sectional shape of the yarns in the composite material are observed to establish a three-dimensional geometric structure model of the composite material.Finite element software is used to fit the material properties of each component material in the composite material,simulate the boundary conditions of the composite material under tensile testing,and perform finite element simulation of the tensile failure of the composite material.The difference between the simulation results and the experimental results,as well as the failure mechanism of the composite material,are analyzed.