Influences Of Monofilaments-Structures On The Compression Property Of Warp-knitted Spacer Fabric

Warp-knitted spacer fabrics have three-dimensional structure,including two surface layers and a spacer structure.The fabrics have excellent breathable moisture permeability,anti-resistance and fatigue resistance,as well as stable spacer structure,which are greatly applied in garments,automotive interior,building materials and composite materials,especially lining materials.However,the repeated compression would cause compression fatigue of the spacer monofilament and unrecoverable deformation of the fabrics,influencing the use and beauty.Among the present studies,the widely used methods to improve the compression property contain the combination of several fabrics,the increasing of the monofilaments’ diameter,adjusting of the density and the angle of the monofilaments.While those methods increase the weight of the fabrics,affect the stiffness and weaken the breathable moisture permeability.Warp-knitted spacer fabrics with better compression property,breathable moisture permeability and lightweight are the development trend.Hollow structure materials are defined as material with internal cavities,which contain simple structure and complex structure based on the quantity of the cavity.On one hand,the internal cavity can store still air and improve the warmth preservation.On the other hand,hollow structure has better compression property for larger moment of inertia than solid structure with identical area.In textile field,hollow fiber gives excellent compression property with light weight for the cavity.At present,studies on hollow monofilaments focus on the warmth preservation,hollow fiber membrane and hollow fiber in enhancing composite materials.In nature,the structure of bamboo is the typical type of hollow monofilament.Bamboo effect improves the mechanic property without increasing the weight.Therefore,the article combines the excellent compression property of hollow fiber and bamboo effect with warp-knitted spacer fabrics,which concentrates on studying the compression property influenced by interior structure of monofilament and provide theoretical reference for the development of hollow fiber applying in warp-knitted spacer fabric.Firstly,the subject summarized present studies on the compression property of warp-knitted spacer fabrics and found that the compression deformation of warp-knitted spacer fabrics was the bending deformation of spacer monofilament in fact.The compression property of spacer monofilament was vital to the compression property of fabrics.Hollow polyester monofilament and solid one with the same external diameter were chosen to investigate the mechanic properties,especially the effect of hollow part on the tensile and compression property.It was found that the tensile-fracture mechanism was decided by the fabrication method of the monofilament.Actually,the tensile strength of hollow monofilament was the tensile strength of the part that fractured finally among the three parts.Tensile strength of hollow monofilament was small than solid one.While hollow monofilament had better tensile deformation and lager breaking elongation as the facture of hollow monofilament was the sequential fracture of the three parts.Hollow monofilament had greater breaking stress than solid one.The possible reason was that the thin-wall structure of hollow monofilament reduced the defects on cross-section area and improved the molecular chain orientation.Hollow monofilament had the same compression mechanism with solid monofilament,which showed the hollow part only affected the maximum compression load,not the compression behavior.Then,continuous hollow monofilament and bamboo-like hollow monofilament were proposed based on the hollow polyester monofilament.3D printing technology was applied on the design and fabrication of complex structures.Compression property of 3D printing monofilament was conducted and finite element analysis based on ABAQUS on compression behavior to clarify the distribution of stress during the compression process.Comparing with solid monofilament and continuous hollow monofilament,bamboo-like hollow monofilament would endure more loads per unit mass and the ability to endure the load improved gradually with the increasing percentage of hollow parts.Bamboo-like hollow monofilament gave better stress distribution at the initial stage of compression.Hollow monofilament had better compression resilience and the continuous hollow monofilament gave best resilience,followed by bamboo-like hollow monofilament with lager percentage of hollow part.Larger percentage of hollow part of bamboo-like hollow monofilament showed better compression resilience.Finally,based on the compression test of 3D printing monofilament,simulation of warp-knitted spacer fabric was built to study the effect of the structures of monofilament and the interaction among monofilaments on the compression property of warp-knitted spacer fabrics.Finite element(FEM)analysis results showed that warp-knitted spacer fabric prepared by bamboo-like hollow monofilaments endured more load per unit mass,indicating the better compression properties.The load propagated outward in an ellipse when spacer fabrics are compressed by spherical indenter,showing the spacer fabric is anisotropic material.The article focuses on the effect of the structure of monofilaments on the compression behavior of warp-knitted spacer fabrics.Bamboo-like hollow monofilament was proposed and the compression property of solid monofilament,continuous hollow monofilament and bamboo-like hollow monofilament and the compression property of warp-knitted spacer fabrics fabricated by those monofilaments were conducted,which would provide new idea for the design of monofilaments and theoretical references for the development of warp-knitted spacer fabric with excellent mechanic properties.