Geometrical analysis of auxetic woven fabrics based on foldable geometry

2021 ◽  
pp. 004051752110086
Author(s):  
Hasan Kamrul ◽  
Adeel Zulifqar ◽  
Yadie Yang ◽  
Shuaiquan Zhao ◽  
Minglonghai Zhang ◽  
...  
Keyword(s):  
Principal Direction ◽  
Tensile Tests ◽  
Geometrical Model ◽  
Woven Fabrics ◽  
Experimental Results ◽  
Geometrical Parameters ◽  
Empirical Equations ◽  
Geometrical Analysis ◽  
Principal Directions ◽  
Semi Empirical

This paper reports a geometrical analysis of auxetic woven fabrics based on foldable geometry. Two fabrics having different geometrical parameters were first designed and fabricated and then subjected to tensile tests in two principal directions. Based on the experimental observations of the geometry of one fabric structural unit cell at different tensile strains, a geometrical model was first proposed and a relationship between the Poisson’s ratio and tensile strain was then established for each principal direction. Two semi-empirical equations are subsequently obtained for both principal directions by fitting the established relationships with experimental results. After validation by the experimental results of the other fabric, the obtained semi-empirical equations were finally used to predict the auxetic behavior of the fabric with a given geometrical parameter. The calculated and experimental results are found to be in excellent agreement with each other. Therefore, the semi-empirical equations obtained in this study could be useful in the design and prediction of the auxetic behavior of auxetic woven fabrics made with the same type of materials and foldable geometry but with different values of geometrical parameters.

Geometrical analysis of bi-stretch auxetic woven fabric based on re-entrant hexagonal geometry

2019 ◽  
Vol 89 (21-22) ◽  
pp. 4476-4490 ◽  
Author(s):  
Adeel Zulifqar ◽  
Hong Hu
Keyword(s):  
Tensile Tests ◽  
Geometrical Model ◽  
Woven Fabrics ◽  
Woven Fabric ◽  
Geometrical Parameters ◽  
Empirical Equations ◽  
Geometrical Analysis ◽  
Weft Direction ◽  
Semi Empirical ◽  
The Relationship

This paper reports a study on the geometrical analysis of bi-stretch auxetic woven fabric based on a re-entrant hexagonal geometry. The fabric was first designed and fabricated. Then, the fabric was subjected to tensile tests, and changes in the geometry of the fabric structural unit cell at different tensile strains were observed when stretched either in the warp or weft direction. Based on the observations, a geometrical model was proposed for each stretch direction and used to establish the relationship between Poisson’s ratio and tensile strain. The semi-empirical equations for both stretch directions were finally obtained by fitting geometrical parameters with experimental results. It is expected that the semi-empirical equations obtained in this study could be used in the design and prediction of the auxetic behavior of bi-stretch auxetic woven fabrics made with the same type of materials and geometry, but with different values of geometrical parameters.

Microscopic Investigation of Quartz Fiber Fabrics: Geometry Model

2011 ◽  
Vol 332-334 ◽  
pp. 791-794
Author(s):  
Yan Lv ◽  
Li Chen ◽  
Fei Sun
Keyword(s):  
Cross Section ◽  
Structural Parameters ◽  
Geometrical Model ◽  
Microscopic Investigation ◽  
Woven Fabrics ◽  
Woven Fabric ◽  
Geometrical Parameters ◽  
Sem Image ◽  
Geometry Model ◽  
The Individual

In response to the relationship between perform structural parameters and the composites properties, a newly geometrical modeling of 2D biaxial orthogonal woven fabric was established in this paper. Based on the yarn’s true configuration, the SEM image of the yarn cross-section was taken, geometrical parameters (the individual tow geometry and weaving pattern of the fabrics) are introduced in order to describe the general families of woven fabrics. The tow waviness can be described by combinations between undulated and straight segments and the tow cross-section can be described by lenticular shape. When the geometrical model was used to predict the structural properties of the fabric, the predicted values show good agreement with the measured ones. The geometrical model proposed here is intended as the foundation for further design and analytical of the mechanical properties of the composite materials reinforced with these fabrics.

scholarly journals Surface Area Evaluation of Electrically Conductive Polymer-Based Textiles

Materials ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 1931 ◽  
Author(s):  
Lukas Vojtech ◽  
Marek Neruda ◽  
Tomas Reichl ◽  
Karel Dusek ◽  
Cristina de la Torre Megías
Keyword(s):  
Surface Area ◽  
Conductive Polymer ◽  
Polyester Fabric ◽  
Geometrical Model ◽  
Woven Fabrics ◽  
Experimental Results ◽  
Woven Fabric ◽  
Electrically Conductive ◽  
Uniform Sample ◽  
Multifilament Yarns

In this paper, the surface area of coated polymer-based textiles, i.e., copper and nickel plated woven polyester fabric, copper and acrylic coated woven polyester fabric, and copper and acrylic coated non-woven polyamide fabric, is investigated. In order to evaluate the surface area of the woven fabrics, Peirce’s geometrical model of the interlacing point and measurement using an electron microscope are used. Non-woven fabrics are evaluated using an optical method, handmade method, and MATLAB functions. An electrochemical method, based on the measurement of the resistance between two electrodes, is used for relative comparison of the effective surface area of the coated woven and non-woven fabrics. The experimental results show that the measured and calculated warp lengths do not differ within the standard deviation. The model for the surface area evaluation of the Pierce’s geometrical model for monofilament (non-fibrous) yarns is extended to multifilament yarns and to a uniform sample size. The experimental results show the increasing trend of surface area evaluation using both modeling and electrochemical methods, i.e., the surface area of the copper and acrylic coated woven Polyester fabric (PES) is the smallest surface area of investigated samples, followed by the surface area of the copper and acrylic coated non-woven fabric, and by copper and nickel plated woven PES fabric. These methods can be used for surface area evaluation of coated polymer-based textiles in the development of supercapacitors, electrochemical cells, or electrochemical catalysts.

Prediction of internal geometry and tensile behavior of 3D woven solid structures by mathematical coding

2021 ◽  
pp. 152808372110013
Author(s):  
Vivek R Jayan ◽  
Lekhani Tripathi ◽  
Promoda Kumar Behera ◽  
Michal Petru ◽  
BK Behera
Keyword(s):  
Volume Fraction ◽  
Three Dimensional ◽  
Areal Density ◽  
Woven Fabrics ◽  
Tensile Behavior ◽  
Geometrical Parameters ◽  
Fiber Volume ◽  
Acceptable Error ◽  
Internal Geometry ◽  
Unit Cells

The internal geometry of composite material is one of the most important factors that influence its performance and service life. A new approach is proposed for the prediction of internal geometry and tensile behavior of the 3 D (three dimensional) woven fabrics by creating the unit cell using mathematical coding. In many technical applications, textile materials are subjected to rates of loading or straining that may be much greater in magnitude than the regular household applications of these materials. The main aim of this study is to provide a generalized method for all the structures. By mathematical coding, unit cells of 3 D woven orthogonal, warp interlock and angle interlock structures have been created. The study then focuses on developing code to analyze the geometrical parameters of the fabric like fabric thickness, areal density, and fiber volume fraction. Then, the tensile behavior of the coded 3 D structures is studied in Ansys platform and the results are compared with experimental values for authentication of geometrical parameters as well as for tensile behavior. The results show that the mathematical coding approach is a more efficient modeling technique with an acceptable error percentage.

An advanced geometrical model for laminated woven fabrics using Lamé exponents with enhanced accuracy

2017 ◽  
Vol 52 (11) ◽  
pp. 1443-1455
Author(s):  
Mike Mühlstädt ◽  
Wolfgang Seifert ◽  
Matthias ML Arras ◽  
Stefan Maenz ◽  
Klaus D Jandt ◽  
...  
Keyword(s):  
High Performance ◽  
Volume Fraction ◽  
Level Structure ◽  
Three Dimensional ◽  
Geometrical Model ◽  
Woven Fabrics ◽  
Fiber Volume ◽  
Meso Level ◽  
Precise Prediction ◽  
Microscopy Images

Three-dimensional stiffness tensors of laminated woven fabrics used in high-performance composites need precise prediction. To enhance the accuracy in three-dimensional stiffness tensor prediction, the fabric’s architecture must be precisely modeled. We tested the hypotheses that: (i) an advanced geometrical model describes the meso-level structure of different fabrics with a precision higher than established models, (ii) the deviation between predicted and experimentally determined mean fiber-volume fraction ( cf) of laminates is below 5%. Laminates of different cf and fabrics were manufactured by resin transfer molding. The laminates’ meso-level structure was determined by analyzing scanning electron microscopy images. The prediction of the laminates’ cf was improved by up to 5.1 vol% ([Formula: see text]%) compared to established models. The effect of the advanced geometrical model on the prediction of the laminate’s in-plane stiffness was shown by applying a simple mechanical model. Applying an advanced geometrical model may lead to more accurate simulations of parts for example in automotive and aircraft.

Mechanical properties of PVDF-coated fabric under tensile tests

2015 ◽  
Vol 35 (4) ◽  
pp. 377-390 ◽  
Author(s):  
Andrzej Ambroziak
Keyword(s):  
Mechanical Properties ◽  
Polyvinylidene Fluoride ◽  
Cyclic Load ◽  
Tensile Tests ◽  
Woven Fabrics ◽  
Uniaxial Tensile ◽  
Cyclic Tests ◽  
Comprehensive Investigation ◽  
Coated Fabric ◽  
Coated Fabrics

Abstract This article describes the laboratory tests necessary to identify the mechanical properties of the polyvinylidene fluoride (PVDF)-coated fabrics named Precontraint 1202S and Precontraint 1302S. First, a short survey of the literature concerning the description of coated woven fabrics is presented. Second, the material parameters for PVDF-coated fabrics are specified on the basis of biaxial tensile tests. A comparison of the 1:1 biaxial and the uniaxial tensile tests results is also given. Additionally, biaxial cyclic tests were performed to observe the change of immediate mechanical properties under cyclic load. The article is aimed as an introduction to a comprehensive investigation of the mechanical properties of coated fabrics.

scholarly journals Undergraduate Study of Thermal Conductivity of Metals

2002 ◽  
Vol 24 (3) ◽  
pp. 296-305
Author(s):  
T. B. Ferrari ◽  
S. H. Hara ◽  
J. L. Aziani ◽  
L. Rocha ◽  
E. de Paula ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Experimental Results ◽  
Empirical Results ◽  
Undergraduate Study ◽  
Link Theory ◽  
Semi Empirical ◽  
Empirical Corrections

In this work we analyze an undergraduate experiment used to determine the thermal conductivity of metals (K). We introduce few modifications in order to offer the student the chance to explore dierent models, learning the basic scientiffic method of developing appropriate and improved explanations for each experiment in order to better link theory and empirical results. Semi-empirical corrections are introduced in the system in order to check the experimental results according to previously reported K values. As specific cases we use copper [K = 0.92 cal /(°C s cm)], aluminum [K = 0.49 cal /(°C s cm)] and brass [K = 0.26 cal /(°C s cm)] cylinders.

scholarly journals Reaeration and oxygen dissipation into a circular hydraulic channel: experimental and dimensionless approach

RBRH ◽  
2018 ◽  
Vol 23 (0) ◽  
Author(s):  
Felipe Keiji Feital Harano ◽  
Murilo de Souza Ferreira ◽  
Marcos Vinícius Mateus ◽  
Deusmaque Carneiro Ferreira ◽  
Julio Cesar de Souza Inácio Gonçalves
Keyword(s):  
Interfacial Phenomena ◽  
Linear Regression Method ◽  
Hydraulic Parameters ◽  
Empirical Equations ◽  
Hydraulic Conditions ◽  
Do Concentration ◽  
Hydraulic Channel ◽  
M Estimates ◽  
Semi Empirical ◽  
Key Parameter

ABSTRACT Dissolved oxygen (DO) is a key parameter in water quality. The DO concentration in a water body can be changed by interfacial phenomena such as reaeration and oxygen dissipation, which can be represented by the coefficients K2 and KD, respectively. Few studies have jointly correlated K2 and KD with physical and hydraulic parameters of the channel. The present work investigated the behavior of these coefficients over a range of hydraulic conditions, and developed semi-empirical equations capable of relating both coefficients. Reaeration and DO dissipation tests were conducted in a circular hydraulic channel with flow velocity ranging from 0.20 to 0.79 m.s-1 and depth ranging from 0.09 to 0.15 m. Estimates of K2 and KD were performed using the non-linear regression method. Semi-empirical equations were obtained based on classical dimensional analysis and multiple regression analysis. The comparison between measured and estimated coefficients yielded R2 for reaeration and dissipation of 0.940 and 0.844, respectively. KD was higher than K2 for all turbulence levels applied at the hydraulic channel. An estimate obtained by the relation between the semi-empirical equations indicates that the transfer of oxygen in the water-air direction (dissipation) is approximately twice as fast as the transfer in the air-water direction (reaeration).

scholarly journals Theoretical Analysis of Brush Seals Leakage Using Local Computational Fluid Dynamics Estimated Permeability Laws

2018 ◽  
Vol 140 (6) ◽  
Author(s):  
Lilas Deville ◽  
Mihai Arghir
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Reynolds Number ◽  
Principal Direction ◽  
Experimental Results ◽  
Leakage Flow ◽  
Cfd Analysis ◽  
Brush Seal ◽  
Brush Seals ◽  
Local Reynolds Number

Brush seals are a mature technology that has generated extensive experimental and theoretical work. Theoretical models range from simple correlations with experimental results to advanced numerical approaches coupling the bristles deformation with the flow in the brush. The present work follows this latter path. The bristles of the brush are deformed by the pressure applied by the flow, by the interference with the rotor and with the back plate. The bristles are modeled as linear beams but a nonlinear numerical algorithm deals with the interferences. The brush with its deformed bristles is then considered as an anisotropic porous medium for the leakage flow. Taking into account, the variation of the permeability with the local geometric and flow conditions represents the originality of the present work. The permeability following the principal directions of the bristles is estimated from computational fluid dynamics (CFD) calculations. A representative number of bristles are selected for each principal direction and the CFD analysis domain is delimited by periodicity and symmetry boundary conditions. The parameters of the CFD analysis are the local Reynolds number and the local porosity estimated from the distance between the bristles. The variations of the permeability are thus deduced for each principal direction and for Reynolds numbers and porosities characteristic for brush seal. The leakage flow rates predicted by the present approach are compared with experimental results from the literature. The results depict also the variations of the pressures, of the local Reynolds number, of the permeability, and of the porosity through the entire brush seal.

scholarly journals Determination of Forming Limits Based on Finite Element Simulations

2021 ◽  
Author(s):  
Fuhui Shen ◽  
Kai Chen ◽  
Junhe Lian ◽  
Sebastian Münstermann
Keyword(s):  
Finite Element ◽  
Damage Mechanics ◽  
Tensile Tests ◽  
Finite Element Simulations ◽  
Experimental Results ◽  
Uniaxial Tensile ◽  
Anisotropic Plasticity ◽  
Forming Limits ◽  
Dog Bone ◽  
Spatio Temporal

Two categories of experiments have been performed to obtain the experimental forming limits of a ferritic stainless steel from uniaxial to equibiaxial tension, including Nakajima tests and tensile tests of flat specimens with different geometries of the central hole as well as the notched dog bone. The plasticity behavior of the investigated material is described using an evolving non-associated anisotropic plasticity model, which is calibrated based on experimental results of uniaxial tensile tests along different loading directions. A damage mechanics model is calibrated and validated based on the global force and displacement response of tensile tests. Finite element simulations of the Nakajima tests and the tensile tests of various geometries have been performed using the anisotropic material model. A novel spatio-temporal method is developed to evaluate the forming limits under different stress states by quantitatively characterizing the plastic strain distribution on the specimen surface. The forming limits have been independently determined from finite element simulation results of tensile specimens and Nakajima specimens using the spatio-temporal evaluation method. The forming limits obtained from numerical simulations of these two types of experiments are in good agreement with experimental results.

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