scholarly journals Knitting Technologies And Tensile Properties Of A Novel Curved Flat-Knitted Three-Dimensional Spacer Fabrics

2015 ◽  
Vol 15 (3) ◽  
pp. 191-197 ◽  
Author(s):  
Xiaoying Li ◽  
Gaoming Jiang ◽  
Xiaolin Nie ◽  
Pibo Ma ◽  
Zhe Gao
Keyword(s):  
Tensile Stress ◽  
Tensile Properties ◽  
Dimensional Stability ◽  
Three Dimensional ◽  
Tensile Tests ◽  
Weft Direction ◽  
Aramid Fibres ◽  
Spacer Fabric ◽  
Fabric Deformation ◽  
Spacer Fabrics

AbstractThis paper introduces a knitting technique for making innovative curved three-dimensional (3D) spacer fabrics by the computer flat-knitting machine. During manufacturing, a number of reinforcement yarns made of aramid fibres are inserted into 3D spacer fabrics along the weft direction to enhance the fabric tensile properties. Curved, flat-knitted 3D spacer fabrics with different angles (in the warp direction) were also developed. Tensile tests were carried out in the weft and warp directions for the two spacer fabrics (with and without reinforcement yarns), and their stress–strain curves were compared. The results showed that the reinforcement yarns can reduce the fabric deformation and improve tensile stress and dimensional stability of 3D spacer fabrics. This research can help the further study of 3D spacer fabric when applied to composites.

Design and manufacture of three-dimensional auxetic warp-knitted spacer fabrics based on re-entrant and rotating geometries

2021 ◽  
pp. 004051752110372
Author(s):  
Chang Yuping ◽  
Yanping Liu ◽  
Zhao Shuaiquan ◽  
Hu Hong
Keyword(s):  
High Efficiency ◽  
Three Dimensional ◽  
Fabric Structure ◽  
Spacer Fabric ◽  
Wide Range ◽  
Yarn Guide ◽  
Tensile Strains ◽  
Spacer Fabrics ◽  
Fabric Structures ◽  
Design And Manufacture

Warp knitting technology is a fabric-forming technologies that is very suitable to fabricate three-dimensional (3D) auxetic fabrics due to its high efficiency and powerful pattern designing possibilities. In this study, two typical auxetic geometries, namely the re-entrant hexagonal network and rotating square solids, were selected as the design prototypes for the design and manufacture of 3D warp-knitted spacer fabrics. While two 3D warp-knitted spacer fabric structures with representative units of different sizes designed based on the re-entrant hexagonal geometry were manufactured by using a RD7 double needle bar Raschel machine with seven yarn guide bars, two 3D jacquard warp-knitted spacer fabrics with different base fabric structures designed based on the rotating squares geometry were fabricated by using a RDPJ4/2 double needle bar jacquard machine with two ground yarn guide bars and four jacquard guide bars. The Poisson’s ratios of these 3D warp-knitted fabrics in the course direction and wale direction were evaluated respectively through constant-rate tensile tests. The results revealed that the re-entrant hexagonal fabric structure with double chain stitches has auxetic behavior across a wide range of tensile strains along the course direction, while the rotating square fabric structure with elastic chain stitches as the base is auxetic within a narrow range of tensile strains along the wale direction. The study provides an alternative method to directly produce auxetic warp-knitted spacer fabrics through a single knitting process instead of using an additional post-compression and heat-setting process.

Simulation of plate compression behavior of warp-knitted spacer fabrics based on geometry and property parameters

2018 ◽  
Vol 89 (6) ◽  
pp. 1051-1064 ◽  
Author(s):  
Fengxin Sun ◽  
Mingying Ma ◽  
Xingxing Pan ◽  
Gui Liu ◽  
Shu Yang ◽  
...  
Keyword(s):  
Young’S Modulus ◽  
Young's Modulus ◽  
Three Dimensional ◽  
Strain Curve ◽  
Dimensional Structure ◽  
Bending Angle ◽  
Compression Behavior ◽  
Compression Property ◽  
Spacer Fabric ◽  
Spacer Fabrics

The plate compression property of warp-knitted spacer fabrics greatly determines their industrial application in cushions and mattresses, which can be regulated by the structure and property of spacer filaments of spacer fabrics. To better meet application requirements, this paper detailed a study on the relationships between the geometry and property parameters of spacer filaments and the plate compression property of spacer fabrics. A three-dimensional structure model was firstly developed using the finite element method based on a typical spacer fabric. The model shows a satisfactory prediction of the compression force–strain curve of the spacer fabric compared with the corresponding experimental curve. Consequently, the effects of geometry parameters, including height, diameter, arrangement density and bending angle of spacer filaments, and Young’s modulus of the filaments on the compression behavior of spacer fabrics were investigated using the validated model by adjusting the corresponding geometry and property parameters. The stress nephogram and stress distribution along the filaments at compression strain 0.6 were analyzed to discover the deformation mechanism of spacer filaments under compression. It was found that the spacer fabric with smaller filament height, courser filament diameter, larger bending angle, higher arrangement density and Young’s modulus of filaments had higher compression resistance. This study is useful to optimize the performance of spacer fabrics in design and manufacturing by purposefully tuning the geometry and property parameters.

Study on Structure and Mechanical Properties of Spacer Fabric

2011 ◽  
Vol 332-334 ◽  
pp. 1093-1096
Author(s):  
Xiao Liu ◽  
Zhao Qun Du ◽  
Wei Dong Yu
Keyword(s):  
Mechanical Properties ◽  
Tensile Properties ◽  
Sandwich Structures ◽  
Experimental Results ◽  
Spacer Fabric ◽  
Spacer Fabrics ◽  
The Relationship

3D spacer fabrics have obviously better performance compared with ordinary fabrics due to their special "sandwich" structures. The paper is to investigate the structures and their compression performances, tensile properties and bending performances on 20 kinds of 3D spacer fabrics. The experimental results showed the relationship between mechanical properties and structures of spacer fabric, and obtained the correlation between each mechanics index and fabric, stiffness. It is useful in expressing the special behaviors of spacer fabrics.

scholarly journals Compressibility Behaviour of Warp Knitted Spacer Fabrics Based on Elastic Curved Bar Theory

2011 ◽  
Vol 6 (4) ◽  
pp. 155892501100600 ◽  
Author(s):  
Fatemeh Mokhtari ◽  
Mahnaz Shamshirsaz ◽  
Masoud Latifi ◽  
Mohammad Maroufi
Keyword(s):  
Mechanical Characterization ◽  
Theoretical Models ◽  
Simulation Data ◽  
Weft Direction ◽  
Spacer Fabric ◽  
Improved Model ◽  
Spacer Fabrics ◽  
Model C ◽  
Direction Model

Nowadays, the mechanical characterization of 3-D spacer fabrics has attracted the interest of many textile researchers. These Spacer fabrics present special mechanical and physical characteristics compared to conventional textiles due to their wonderful porous 3-D structures. These fabrics, produced by warp knitting method, have extensive application in automobile, locomotive, aerospace, building and other industries. In these applications, the compressibility behaviour plays a significant role in the fabric structural stability. This compressibility behaviour could be affected by different knitting parameters such as density of pile yarn, fabric thickness, texture design etc. The aim of this paper is to introduce and develop an appropriate elastic theoretical model to predict the compressibility behaviour of warp knitted spacer fabric (WKSF). Three theoretical models are proposed, based on modelling pile yarns as the curved bars and are improved in three steps: a) with same curvatures in weft and warp directions (model A), b) curved bar for warp direction and cantilever bar for weft direction (model B), and c) curved bars with two different curvatures in weft and warp directions considering the curvature variations under loading (model C: improved model). The results obtained by the proposed models have been compared with previous model based on simply cantilever bars theory in literature. The results show that the simulation data obtained by the model C are closer to the experimental results comparing to the models A and B. Model C based on different weave parameters could better predict the elastic compressibility behaviour of this kind of WKSF in order to compare with previous models.

Spacer fabric-based exuding wound dressing – Part II: Comparison with commercial wound dressings

2016 ◽  
Vol 87 (12) ◽  
pp. 1481-1493 ◽  
Author(s):  
Yadie Yang ◽  
Hong Hu
Keyword(s):  
Water Vapor ◽  
Transmission Rate ◽  
Three Dimensional ◽  
Air Permeability ◽  
Layered Composite ◽  
Wound Dressings ◽  
Water Contact ◽  
Spacer Fabric ◽  
Spacer Fabrics ◽  
Selection Of

In this study, a three-layered composite structure based on spacer fabric was designed for absorbent wound dressings. The fabrication and selection of spacer fabrics were discussed in Part I. In this part, two selected spacer fabrics were further modified by covering a polyurethane or a polystyrene electrospun nanofibrous membrane onto their outer layer surface to form the final spacer fabric-based dressing products. In order to confirm the performance of these new spacer fabric-based dressings, the comparisons were conducted with three types of commercial wound dressings. The comparison indicators included the water contact angle, wettability, absorbency, air permeability and water vapor transmission rate. The results showed that in addition to very good water vapor and air permeability, the developed spacer fabric-based dressings had better absorbing properties than commercial foam dressings. Furthermore, their wettability was also good for application as wound dressings. The study has paved a new way to produce advanced wound dressings using three-dimensional textile structures.

scholarly journals Cooling under Applied Stress Rejuvenates Amorphous Alloys and Enhances Their Ductility

Metals ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 67
Author(s):  
Nikolai V. Priezjev
Keyword(s):  
Glass Transition ◽  
Tensile Stress ◽  
Potential Energy ◽  
Applied Stress ◽  
Three Dimensional ◽  
Tensile Tests ◽  
Maximum Tensile Stress ◽  
Amorphous Structure ◽  
Glass Transition Point ◽  
Dynamics Simulations

The effect of tensile stress applied during cooling of binary glasses on the potential energy states and mechanical properties is investigated using molecular dynamics simulations. We study the three-dimensional binary mixture that was first annealed near the glass transition temperature and then rapidly cooled under tension into the glass phase. It is found that at larger values of applied stress, the liquid glass former freezes under higher strain and its potential energy is enhanced. For a fixed cooling rate, the maximum tensile stress that can be applied during cooling is reduced upon increasing initial temperature above the glass transition point. We also show that the amorphous structure of rejuvenated glasses is characterized by an increase in the number of contacts between smaller type atoms. Furthermore, the results of tensile tests demonstrate that the elastic modulus and the peak value of the stress overshoot are reduced in glasses prepared at larger applied stresses and higher initial temperatures, thus indicating enhanced ductility. These findings might be useful for the development of processing and fabrication methods to improve plasticity of bulk metallic glasses.

scholarly journals Evaluation of Tensile Properties and Damage of Continuous Fibre Reinforced 3D-Printed Parts

2018 ◽  
Vol 774 ◽  
pp. 161-166 ◽  
Author(s):  
Octavio Andrés González-Estrada ◽  
Alberto Pertuz ◽  
Jabid E. Quiroga Mendez
Keyword(s):  
3D Printing ◽  
Tensile Properties ◽  
Mechanical Performance ◽  
Volume Fraction ◽  
Three Dimensional ◽  
Tensile Tests ◽  
Fused Deposition Modelling ◽  
Printing Process ◽  
Fused Deposition ◽  
3D Printed

Three-dimensional (3D) printing technology has been traditionally used for the production of prototypes. Recently, developments in 3D printing using Fused Deposition Modelling (FDM) and reinforcement with continuous fibres (fiberglass and carbon fibre), have allowed the manufacture of functional prototypes, considerably improving the mechanical performance of the composite parts. In this work, we characterise the elastic tensile properties of fibre reinforced specimens, considering the variation of several parameters available during the printing process: fibre orientation, volume fraction, fill pattern, reinforcement distribution. Tensile tests were performed according to ASTM D638 to obtain Young’s modulus and ultimate strength for different material configurations available during the printing process. We also perform a fractographic analysis using Scanning Electron Microscopy (SEM) to give an insight of the failure mechanisms present in the specimens.

scholarly journals A NEW TEST METHOD TO MEASURE THE COMPRESSIBILITY OF SPACER FABRICS

2019 ◽  
Vol 2019 ◽  
pp. 140-143
Author(s):  
Musa KILIC ◽  
Gonca BALCI KILIC ◽  
Murat DEMIR ◽  
Gulsah CELIK ◽  
Izzet Onal BUGDUZ ◽  
...  
Keyword(s):  
Shear Deformation ◽  
Three Dimensional ◽  
Test System ◽  
Test Methods ◽  
Test Method ◽  
Dimensional Structure ◽  
Spacer Fabric ◽  
The Difference ◽  
Spacer Fabrics ◽  
Fabric Structures

Spacer fabric is a three-dimensional structure that obtained by the connection of two parallel fabric surfaces with the connection threads. Spacer fabrics are widely used for their several functional advantages that they provide unlike conventional fabrics. Compressibility is one of the important functional parameters for these fabric structures. The compressibility values of the spacer fabrics are measured based on the ISO 3386-1 standard. However, this standard is used for structures that have non-axial shear during compression such as foam, sponge and so on. It is thought that this standard is not suitable for spacer fabric structures due to the shear deformation which occurs during the measurement of compressibility. For this purpose, as in accordance with spacer fabrics end-use area, a new test system been proposed to measure of compressibility that prevents shear during the test. Thus, it is aimed to prevent the shear deformation and the deviant results obtained during the test. Within the scope of the study, the compressibility properties of spacer fabric structures, which have undergone different thicknesses and different finishing processes, were measured according to both ISO 3386-1 and the new proposed test method. When the results were compared, it was observed that the results obtained in the new proposed test setup were higher and the difference between the measured results according to both test methods was statistically significant for α = 0.05.

Flat-knitted innovative three-dimensional spacer fabrics: a competitive solution for lightweight composite applications

2011 ◽  
Vol 82 (3) ◽  
pp. 288-298 ◽  
Author(s):  
MD Abounaim ◽  
Chokri Cherif
Keyword(s):  
Mechanical Properties ◽  
Sensor Networks ◽  
Health Monitoring ◽  
Complex Shape ◽  
Three Dimensional ◽  
Surface Layers ◽  
Fabric Structure ◽  
Spacer Fabric ◽  
Processing Step ◽  
Spacer Fabrics

Flat-knitted spacer fabrics offer a strong potential for complex shape preforms, which could be used to manufacture composites with reduced waste and shorter production times. A reinforced spacer fabric made of individual surface layers and joined with connecting layers shows improved mechanical properties for lightweight applications, such as textile-based sandwich preforms. We report the development of flat-knitted multi-layered innovative three-dimensional (3D) spacer fabrics from hybrid yarns consisting of glass and polypropylene filaments. Moreover, for structural health monitoring of composites, sensor networks could be created into a 3D spacer fabric structure in a single processing step through innovative integration of functional yarns.

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