scholarly journals SOFTWARE MODULES AND PROCEDURES OF A COMPUTER PROGRAM FOR DETERMINING THE TENSION OF A KEVLAR THREAD WHEN KNITTING USING A RECURSOR ALGORITHM

2021 ◽  
Vol 295 (2) ◽  
pp. 271-274
Author(s):  
V. SHCHERBAN ◽  
◽  
A. PETKO ◽  
O. KOLISKO ◽  
Y. SHCHERBAN ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Computer Program ◽  
Structural Parameters ◽  
Physical And Mechanical Properties ◽  
Knitted Fabric ◽  
Structural Elements ◽  
Feed System ◽  
Thread Diameter ◽  
Software Modules ◽  
Control Devices

Improving the process of knitting fabrics from Kevlar complex threads on flat knitting machines is to create the minimum necessary tension in the area of formation of the knitted fabric. To ensure this, it is necessary to determine the change in relative tension in the refueling zones of Kevlar complex threads on flat knitting machines. These zones are formed by arranging the thread guides, tension compensation devices, tension devices and thread break control devices in the working area of the supply system to form a spatial filling line for each specific knitting machine. This complex task for flat knitting machines should be based on the use of specially designed computer programs. Given the specifics of processing Kevlar complex threads on flat knitting machines, when determining the relative tension in each zone, it is necessary to use a recursion algorithm, when the output tension of Kevlar complex threads from the previous zone will be the input for the next zone. When determining the tension of Kevlar complex threads, their interaction with the guides of Kevlar complex threads, tension compensation devices, tension devices and devices for controlling the breakage of Kevlar complex threads, it is necessary to take into account the value of Kevlar complex thread diameter, its physical and mechanical properties, deformation, deformation the coefficient of bending stiffness when determining the actual angle of coverage of the guide surface. Ensuring the minimum necessary tension in the area of formation of the knitted fabric will allow to obtain the parameters of the loop structure of property and tactical equipment of servicemen capable of protecting the human body from fire, cold, cutting, barbed weapons, shock and shotgun impact. Minimizing the tension in each zone of the line of Kevlar complex threads on flat knitting machines will reduce the probability of breakage, which is important for improving knitting processes from the standpoint of improving the productivity of flat knitting machines and product quality. Mathematical support of a computer program requires the development of models of thread guides, tension compensation devices, tension devices and thread break control devices, taking into account the real physical and mechanical properties of Kevlar complex threads and real geometric and structural parameters of structural elements of the feed system.

scholarly journals The Effect of Number and Position of Tuck Stitches within the Pattern Repeat on Air Permeability of Weft-knitted Fabrics from Glass Yarn

2019 ◽  
Vol 2 (3) ◽  
pp. 317-323
Author(s):  
Mehmet Erdem İnce
Keyword(s):  
Mechanical Properties ◽  
High Performance ◽  
Physical And Mechanical Properties ◽  
Air Permeability ◽  
Knitted Fabric ◽  
Knitted Fabrics ◽  
Synthetic Fibers ◽  
Fabric Structure ◽  
Knit Fabrics ◽  
Weft Knitted Fabric

The fact that weft knitted fabrics has a stretchable, 3D, porous and interlocking structure makes them unique when manufactured from high performance fibers. Knitted fabrics with different architectures exhibit different properties. Different loop forms like tuck and skip stitches with various loop lengths reveal different physical and mechanical properties. Literature review indicated that wisely arrangement of tuck stitches within the pattern repeat alter the weft-knitted fabric structure from natural and synthetic fibers. Therefore, we studied the effect of number and location of tuck stiches on air permeability of weft-knitted fabrics from glass yarn. Single-bed, flat weft knitting machine was used to knit fabrics with different architectures from three-ply glass yarn. The nominal single-end count of used E-glass yarn was 136 tex. It is anticipated that the number and location of tuck stitches within knit pattern effect physical and air permeability properties of weft-knitted fabrics from glass yarn.

Poisson’s Ratios for Wood Species for Structural Purposes

2015 ◽  
Vol 1088 ◽  
pp. 690-693
Author(s):  
Francisco Antonio Rocco Lahr ◽  
André Luis Christoforo ◽  
Eduardo Chahud ◽  
Luiz A. Melgaço N. Branco ◽  
Rosane A.G. Battistelle ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Confidence Intervals ◽  
Wood Species ◽  
Physical And Mechanical Properties ◽  
Timber Structures ◽  
Structural Elements ◽  
Poisson's Ratios ◽  
Poisson’S Ratios

The broader knowledge about physical and mechanical properties of wood allows reliable timber structures design. Even little addressed in the literature, in several situations Poisson's ratios are required for the evaluation of stresses acting on structural elements. This study aimed to obtain values of Poisson's ratios (ν), plans Longitudinal-Radial (νLR) and Longitudinal-Tangential (νLT), for species Peroba Rosa (Aspidosperma polyneuron) and Jatobá (Hymenaea courbarilL.). For this purpose, forty samples Peroba Rosa and eight samples of Jatobá were prepared for testing in compression parallel to the grain, following the recommendations of ABNT NBR 7190 standard. The results of means confidence intervals, considered at the level of 5% significance, revealed that the Poisson's ratios νLR e νLT to Peroba Rosa are 0.27 and 0.42, respectively, and 0.25 and 0.43 to Jatobá.

scholarly journals Evaluation of Eucalyptus triantha Timber for Structural Applications

2020 ◽  
Vol 28 (1) ◽  
pp. 1-13
Author(s):  
Marta C.J.A. Nogueira ◽  
Victor A. de Araujo ◽  
Juliano S. Vasconcelos ◽  
André L. Christoforo ◽  
Francisco A.R. Lahr
Keyword(s):  
Mechanical Properties ◽  
Physical And Mechanical Properties ◽  
Fiber Saturation Point ◽  
Raw Material ◽  
Structural Elements ◽  
Saturation Point ◽  
Bending Elasticity ◽  
Structural Applications ◽  
American Standard ◽  
Standard Documents

Eucalypt wood is an important raw material with multiple uses applied for furniture, pulp and paper, charcoal, biomass, and construction. Sixteen tests were performed to evaluate physical and mechanical properties of Eucalyptus triantha, which could estimate the possibility of utilization of this woody material in construction. In all, about 267 repeats were realized. Two moisture contents were regarded according to the Brazilian and American standard documents: fiber saturation point (30%) and standard dried point (12%). Results were statistically treated with t-test and demonstrated increases in six mechanical properties from Eucalyptus triantha wood species: rupture moduli in perpendicular and parallel compressions and static bending; elasticity moduli in parallel tensile, perpendicular compression, and static bending. Volumetric mass and bulk densities were practically stable. Physical and mechanical properties estimation evinced that Eucalyptus triantha wood can be used in structural elements.

scholarly journals Parametric analysis related to dimensioning of tubular steel columns filled with concrete in a fire situation

2022 ◽  
Vol 15 (2) ◽  
Author(s):  
Fábio Masini Rodrigues ◽  
Armando Lopes Moreno Júnior ◽  
Jorge Munaiar Neto
Keyword(s):  
Mechanical Properties ◽  
Numerical Modeling ◽  
Temperature Field ◽  
Moisture Content ◽  
Numerical Models ◽  
Physical And Mechanical Properties ◽  
Sensitivity Study ◽  
Steel Tube ◽  
Structural Elements ◽  
Steel Columns

ABSTRACT For the dimensioning of structural elements in fire situation, simplified equations and parameters are commonly used in analytical equations or numerical models. More complex equations or simplified values can be chosen by the designer for determine materials properties in high temperature in numerical models, however, numerical modeling can be quite sensitive to the variation of some of the physical and mechanical properties. In this paper, the sensitivity of the numerical model in relation to the values according to the level of simplification chosen was evaluated, presenting an analysis in relation to the results found to contribute to the choice of these parameters and presenting the indications found in the literature. In this sense, this work presents a study of sensitivity to the variation of the values of steel and concrete properties, presented in the Eurocode and Brazilian standards, in addition to the moisture content and emissivity of the surface exposed to fire, for the dimensioning, in a fire situation, of steel tube columns, of circular and square section, filled with concrete. The studies were carried out via numerical modeling developed in the software ABAQUS. It was verified that the resulting emissivity values equal to 0.7 or 0.8, recommended in the literature, are conservative, and the choice of either does not bring significant changes in the temperature field obtained for the structural elements under analysis. It was also verified that the concrete moisture content is a relevant aspect for the formation of its temperature field, also affecting, but to a lesser extent, the steel temperature. Regarding the physical and mechanical properties of the materials, this sensitivity study suggests the adoption of the values from the equations presented in Eurocodes, without simplifications, and with the specific heat and thermal conductivity of the concrete, adopted in accordance with the Eurocode 4.

Influence of Structural Parameters of Nonwoven Geotextiles on Separation and Filtration in Road Construction

2020 ◽  
Vol 20 (4) ◽  
pp. 449-460
Author(s):  
Špela Bezgovšek ◽  
Dunja Šajn Gorjanc ◽  
Boštjan Pulko ◽  
Stanislav Lenart
Keyword(s):  
Mechanical Properties ◽  
Structural Properties ◽  
Structural Parameters ◽  
Physical And Mechanical Properties ◽  
Road Construction ◽  
Knitted Fabrics ◽  
Compression Creep ◽  
Filtration Properties ◽  
Mechanical Bonding ◽  
Bonding Technique

AbstractNonwoven geotextiles are often used in road construction as a separation layer. They consist of the web of fibers with different orientations. The orientation of fibers has an important influence on physical and mechanical properties of nonwoven geotextiles. The production of nonwoven geotextiles is cheaper in comparison to woven or knitted fabrics which can also be used as separation geotextiles. The purpose of this research was to study the influence of structural properties of nonwoven geotextiles, namely the diameter of fibers and mass and thickness of nonwoven geotextiles, on their mechanical and hydraulic properties. Six types of nonwoven geotextiles were used in the research. They were produced by the drylaid process (carded) using mechanical bonding technique and also with the combination of mechanical and thermal bonding technique. The research confirmed that the bonding technique and structural properties significantly influence the separation and filtration properties of nonwoven geotextiles, such as opening size and water permeability. It was also found that there are no significant differences in mechanical properties, such as viscoelastic properties and compression creep, between the samples in the dry and wet conditions.

scholarly journals Study of the effect of the introduction of the back yarn on two-layer knitted fabric’s physical and mechanical properties

2021 ◽  
Vol 304 ◽  
pp. 03034
Author(s):  
Sadoqat Rahmatova ◽  
Nozimjon Jurabayev ◽  
Qurbonali Holikov
Keyword(s):  
Mechanical Properties ◽  
Raw Materials ◽  
Research Work ◽  
Physical And Mechanical Properties ◽  
Knitted Fabric ◽  
Knitted Fabrics

In this research work, the physical and mechanical properties of 3 variants of jacquard knitted fabric obtained in order to increase the heat retention properties and increase the range of knitted fabrics by adding back yarn to the base of glad, rubber cuts in 20 grade double-needle jacquard knitting machine using local raw materials effectively The technological indicators were obtained experimentally and tabulated and recommendations for production sectors are given.

scholarly journals Effect of Lycra Percentages and Loop Length on the Physical and Mechanical Properties of Single Jersey Knitted Fabrics

2016 ◽  
Vol 2016 ◽  
pp. 1-7 ◽  
Author(s):  
Eman Eltahan
Keyword(s):  
Mechanical Properties ◽  
Permanent Deformation ◽  
Physical And Mechanical Properties ◽  
Knitted Fabric ◽  
Loop Length ◽  
Knitted Fabrics ◽  
Fabric Hand ◽  
Knit Fabrics ◽  
The Individual ◽  
Single Jersey

Single jersey knitted fabrics are generally used to make underwear and outerwear such as T-shirts. Knit fabric can more easily deform or stretch by compressing or elongating the individual stitches that form the fabric. Cotton yarns, which are not elastomeric, do not have the ability of recovery to rearrange the stitches. As a consequence, single-knit fabrics may have permanent deformation. To improve the recovery performance of circular single-knit fabrics, it is now a common practice to knit a small amount of spandex fiber or yarn with companion cotton yarn. In this study the physical, dimensional, and mechanical properties of back plaited cotton/spandex single jersey knitted fabrics were investigated and the results are compared with knitted fabrics made from 100% cotton and the effect of spandex percentage was also studied. It was found that as the loop length increases, the wales density was not affected and specific fabric hand and extension increased, but bursting strength and fabric recovery decreased. The presence of Lycra in single jersey knitted fabric increases of course density, fabric thickness, and knitted fabric recovery, while fabric width, fabric porosity, and extension were decreased.

scholarly journals Justification of the parameters of the stable course in depth at vibration exposure of the working body to the soil

2020 ◽  
Author(s):  
L.F. Babitsky ◽  
◽  
V.A. Kuklin ◽  
Keyword(s):  
Mechanical Properties ◽  
Rheological Model ◽  
Structural Parameters ◽  
Physical And Mechanical Properties ◽  
Vibration Exposure ◽  
Theoretical Justification ◽  
Working Bodies

The aim of the research is to substantiate the parameters of the stable stroke along the depth of the vibrating tillage working bodies on spring struts. The article proposes an elastic-viscous rheological model of the soil and provides a theoretical justification for the parameters of the stable course along the depth of the vibrating working bodies on spring struts. The resulting expression includes agrotechnological and structural parameters, as well as physical and mechanical properties of the soil.

Sign in / Sign up

Export Citation Format

Share Document