Characterization of plantar press-comfort performance of warp-knitted spacer fabrics

2016 ◽  
Vol 88 (4) ◽  
pp. 357-366 ◽  
Author(s):  
Ming Li ◽  
Yuanxin Wu ◽  
Chaoyu Chen ◽  
Zhaoqun Du
Keyword(s):  
Cluster Method ◽  
Structure Parameters ◽  
Objective Method ◽  
Compression Force ◽  
Work Recovery ◽  
Spacer Fabric ◽  
Spacer Fabrics ◽  
Force Displacement ◽  
Objective Cluster

The main content dealt with in this paper was to present an objective method to evaluate the plantar press-comfort performance of warp-knitted spacer fabrics. It aimed to explain the plantar press-comfort performance of spacer fabric by the compression property and structure parameters of spacer fabric. The compression indexes (compression work, recovery work, hysteresis work and maximum compression force) and structure parameters (diameter and thickness) were utilized to classify the plantar press-comfort performance of warp-knitted spacer fabrics by regression analysis and the K-means cluster method. In order to verify the validity, subjective judgments were also made and compared with the objective K-means cluster method. The experimental results showed that a good correlation existed between the subjective judgment method and objective cluster method. This demonstrates that the compression indexes featured, from spherical compression force–displacement curves and structure parameters, can be utilized to characterize the plantar press-comfort performance of warp-knitted spacer fabrics and is effective in obtaining the fabric evaluation score of plantar press-comfort performance.

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.

Effect of the structure of cellulose acetate membranes on their permeability, electrical conductivity and rejection

1990 ◽  
Vol 55 (12) ◽  
pp. 2933-2939 ◽  
Author(s):  
Hans-Hartmut Schwarz ◽  
Vlastimil Kůdela ◽  
Klaus Richau
Keyword(s):  
Electrical Conductivity ◽  
Electrical Properties ◽  
Cellulose Acetate ◽  
Reverse Osmosis ◽  
Water Flux ◽  
Cellulose Acetate Membrane ◽  
Structure Parameters ◽  
Dc Electrical Conductivity ◽  
Cellulose Acetate Membranes

Ultrafiltration cellulose acetate membrane can be transformed by annealing into reverse osmosis membranes (RO type). Annealing brings about changes in structural properties of the membranes, accompanied by changes in their permeability behaviour and electrical properties. Correlations between structure parameters and electrochemical properties are shown for the temperature range 20-90 °C. Relations have been derived which explain the role played by the dc electrical conductivity in the characterization of rejection ability of the membranes in the reverse osmosis, i.e. rRO = (1 + exp (A-B))-1, where exp A and exp B are statistically significant correlation functions of electrical conductivity and salt permeation, or of electrical conductivity and water flux through the membrane, respectively.

scholarly journals Genetic diversity of table grape based on morphoagronomic traits

2011 ◽  
Vol 68 (1) ◽  
pp. 42-49 ◽  
Author(s):  
Patrícia Coelho de Souza Leão ◽  
Cosme Damião Cruz ◽  
Sérgio Yoshimitsu Motoike
Keyword(s):  
Genetic Diversity ◽  
Clustering Analysis ◽  
Germplasm Collection ◽  
Table Grape ◽  
Cluster Method ◽  
Breeding Programs ◽  
Method Analysis ◽  
Vitis Spp ◽  
Grape Cultivars

The conservation and characterization of grape (Vitis spp) genetic resources in germplasm banks have been the basis of its use in breeding programs that result in development of new cultivars. There are at least 10,000 grape cultivars kept in germplasm collection. The genetic diversity in 136 table grape accessions from the state of Bahia, Brazil, was evaluated. Continuous and discrete morphoagronomic traits were assessed. The clustering analysis by the Tocher otimization method resulted in 30 clusters (considering continuous morphoagronomic traits), and 9 clusters (taking into consideration multicategorical traits). There was no agreement between clusters obtained by both, continuous or discrete phenotypic descriptors, independent of the cluster method analysis used. A satisfactory genetic variability among the table grape accessions was observed.

Open Uniaxial Test Machine (OpenUTM): Part 1 — A Low-Cost Electrohydraulic Test Frame for Additive Manufacturing Part Qualification

2018 ◽  
Author(s):  
John C. Steuben ◽  
Athanasios P. Iliopoulos ◽  
John G. Michopoulos
Keyword(s):  
Additive Manufacturing ◽  
Low Cost ◽  
Test Machine ◽  
Mechanical Stiffness ◽  
Uniaxial Test ◽  
Bill Of Materials ◽  
Test Frame ◽  
Force Displacement

A wide variety of scientific and engineering activities require the use of testing machines in order to acquire data regarding the response of materials subjected to mechanical loads. This is particularly applicable to the domain of Additive Manufacturing (AM), where mechanical qualification is essential. Such machinery should be capable of applying loads at required levels and exhibit high mechanical stiffness. Accurate force, displacement, and strain measurements are also required. As a consequence, such testing machines are typically very costly. In the present paper we introduce the Open Uniaxial Test Machine (OpenUTM) project, aimed at providing a low-cost (less than $2500.00) material testing hardware/software framework. This paper will focus on the engineering design and hardware aspects of the OpenUTM project, with particular attention paid to the use of an electrohydraulic actuator (EHA) to provide test loads. A full bill of materials and drawings package is provided, in order to enable the use of the OpenUTM framework by research groups with minimal machine tooling. We introduce several case studies demonstrating the successful use of the OpenUTM frame in AM research efforts, including the testing and characterization of AM polymers and ceramics. We conclude with discussion of the software aspects of the OpenUTM framework, which will be elaborated upon in a follow-up paper (part two). We also present a series of potential avenues towards the improvement of the OpenUTM frame in future hardware iterations.

scholarly journals Seismic Behavior and Force-Displacement Characterization of Neotype Column-Slab High Piers

2014 ◽  
Vol 2014 ◽  
pp. 1-10
Author(s):  
YanQun Zhou ◽  
YeZhi Zhang ◽  
MeiXin Ye ◽  
MengSi Zhan
Keyword(s):  
Seismic Behavior ◽  
Large Scale ◽  
Scale Model ◽  
Test Results ◽  
Lateral Displacements ◽  
High Pier ◽  
Experimental Values ◽  
Large Scale Tests ◽  
Force Displacement

The seismic behavior and plasticity spreading of a neotype column-slab high pier are researched in this paper. Four scale model tests of a web slab with two boundary columns are carried out under cyclic inelastic lateral displacements simulating seismic response. The test results show that the neotype column-slab high pier has strong and stable bearing capacity, good ductility, and energy dissipation capacity. The experimental values pertaining to the spread of plasticity are derived. An approach for deriving the spread of plasticity analytically is deduced and applied to the four tests. This method accurately assesses a pier’s spread of plasticity for most ductility levels. At nearly all ductility levels, the mean difference between analytical assessments of the spread of plasticity and results from 4 large-scale tests is 12% with a 9% coefficient of variation.

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.

Mechanical properties of the surface membrane of lattice spacer-fabric flexible inflatable composites

2021 ◽  
pp. 004051752110466
Author(s):  
Tong Yang ◽  
Min Luo ◽  
Zhuanyong Zou ◽  
Pibo Ma
Keyword(s):  
Mechanical Properties ◽  
Surface Membrane ◽  
Composite Membranes ◽  
Vital Role ◽  
Specific Strength ◽  
Spacer Fabric ◽  
Bearing Loads ◽  
Spacer Fabrics ◽  
Woven Structure ◽  
Performance Research

The surface membrane plays a vital role in bearing loads of flexible inflatable composites. In this work, the mechanical properties of the upper and lower surfaces of inflatable composites and spacer fabrics were studied. It focused on the changes in mechanical properties of surfaces of spacer fabrics with different structures after coating and damage characteristics. The results show that the PVC resin improves the mechanical properties of the surface, which penetrates into the structure to make the yarns bond to each other and adhere to the resin on the surface. And compared with knitted structures, composite membranes with a woven structure have the characteristics of specific strength. This provides data accumulation for performance research of flexible inflatable composites, finite element calculation analysis, and the experimental reference for broadening the application in military pontoons and marching tents.

Development and characterization of warp knitted spacer fabrics for helmet comfort liner application

2020 ◽  
pp. 152808372093921
Author(s):  
N Muthu Kumar ◽  
G Thilagavathi ◽  
S Periasamy
Keyword(s):  
Air Permeability ◽  
Compression Properties ◽  
Motorcycle Helmet ◽  
Evaporative Heat Transfer ◽  
Fabric Layer ◽  
Water Vapour Resistance ◽  
Standard Liner ◽  
Spacer Fabrics ◽  
Flexible Polyurethane

The inner padding layer of the motorcycle helmet is one of the important components that control the factors of comfort during wearing the helmet and provides a perfect fit and stability of the helmet on the head. The inner padding consists of a low-density flexible polyurethane layer attached to a soft fabric layer that is in direct contact with the head. The present study aims to replace foam in the comfort liner of a helmet with spacer fabrics to avoid the risk of heat stress during the use of the helmet. In this work, 9 warp-knitted spacer fabrics were produced by varying the course/cm (10, 12 & 14) and thickness (3, 3.5, and 4 mm). Air permeability, thermal, and water vapour resistance of the developed spacer fabrics were characterized along with compression properties and compared with commercially available standard liner. The results showed that warp-knitted spacer fabrics had better energy absorption compared to the standard liner. Also, the developed spacer fabrics had better breathability and evaporative heat transfer compared to the standard liner.

FORCE CHARACTERIZATION OF A TUBULAR LINEAR ELECTROMAGNETIC ACTUATOR USING FINITE ELEMENT ANALYSIS METHOD (FEM)

2016 ◽  
Vol 78 (11) ◽  
Author(s):  
Mariam Md Ghazaly ◽  
Tawfik Ahmed Yahya ◽  
Aliza Che Amran ◽  
Zulkeflee Abdullah ◽  
Mohd Amran Md Ali ◽  
...  
Keyword(s):  
Finite Element ◽  
Ansys Software ◽  
Element Analysis ◽  
Electromagnetic Actuators ◽  
Halbach Array ◽  
Output Characteristics ◽  
Actuator Design ◽  
Force Displacement ◽  
The Magnetic Field

This paper presents an extensive characterising study of two novel electromagnetic actuators, each with different constructions and characteristics aiming to analyse the behaviour and output characteristics of the two designs. The two actuators are Tubular Linear Reluctance Actuator (TLRA) and Tubular Linear Permanent magnet (TLPM) with Halbach array actuator. The study covered the variation of three parameters, which are the actuator air gap, number of turns and actuator size. A comparative section was also presented for the purpose of comparison. The study concentrated extensively on the two characteristics of both actuators known as output thrust force and working range as they are considered as two main concerns of any actuator design. The simulation was used to show the differences between the two designs in many design aspects such as force, displacement and effects of parameters variations. The applied simulation was performed using 3D Finite-element Ansys software, which is capable of showing the magnetic field distribution in the whole actuator and predicting the strength and length of the output stroke.

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