Tensile characteristics of flexible PU-coated multi-axial warp-knitted fabrics

2016 ◽  
Vol 47 (1) ◽  
pp. 38-56 ◽  
Author(s):  
Lingxiao Jing ◽  
Nangkuo Guo ◽  
Haiyan Xu ◽  
Jinhua Jiang ◽  
tonghua Zhang ◽  
...  
Keyword(s):  
Failure Mechanism ◽  
Shear Failure ◽  
Small Strain ◽  
Image Correlation ◽  
Knitted Fabrics ◽  
Apparent Modulus ◽  
Coated Fabric ◽  
Plane Direction ◽  
Coated Fabrics ◽  
Warp Knitted Fabric

In practice, the coated fabric is available in many shapes and sizes, not just rectangle and plane. In order to increase the shape-shifting abilities of coated fabrics, polyurethane-coated multi-axial warp-knitted fabric (PU-CMWKF) is developed. In this paper, the tensile characteristics of PU-CMWKF were investigated. Five groups of tensile experiments, with off-axial angles of 0°, 22°, 45°, 67.5°, and 90°, were conducted under constant velocity. The failure mechanism was explored by analyzing the damaged specimens. Additionally, the deformation behavior of PU-CMWKF in three regions was investigated by utilizing the digital image correlation (DIC) system, and an orthogonal anisotropic model was used to predict the modulus and Poisson’s ratio of 22.5° and 67.5°. Research results showed that the apparent modulus of PU-CMWKF strongly depended on the cut of directions. And the failure mechanism under in-plane direction loading suggests that tensile and shear failure act together. The analytical model is validated along five directions in the representation of elastic constant under corresponding small strain.

Thermal resistance of polyurethane-coated knitted fabrics before and after weathering

2014 ◽  
Vol 84 (19) ◽  
pp. 2015-2025 ◽  
Author(s):  
Vesna Marija Potočić Matković ◽  
Ivana Salopek Čubrić ◽  
Zenun Skenderi
Keyword(s):  
Thermal Resistance ◽  
Thermal Protection ◽  
Winter Season ◽  
Outdoor Exposure ◽  
Woven Fabrics ◽  
Knitted Fabric ◽  
Knitted Fabrics ◽  
Coated Fabric ◽  
Before And After ◽  
Coated Fabrics

Polyurethane-coated knitted fabrics are of interest because they exhibit several positive properties, they are more stretchable, elastic and comfortable than coated woven fabrics and yet they are little studied. Information of weather durability, as well as thermal properties, is essential to ensure thermal protection for textile materials intended for outdoor use. In the presented research, a series of coated knitted fabrics for protective clothing were developed and exposed to weathering in summer and winter seasons. After three months of outdoor exposure, thermal resistance of all the tested materials decreased by 13% after the summer season and 25% after the winter season. A very good correlation of knitted fabric mass per unit area and thermal resistance of knitted fabric, coated fabric and aged coated fabric occurred. The studied materials experienced a partial degradation of the polyurethane layer, which is not related to the deterioration of the knitted substrate. The presented investigation of thermal resistance of coated fabrics and their dependence on the knitted substrate, as well as the influence of environmental conditions, allows the improvement of coated fabrics with the aim of better thermal protection.

scholarly journals Experimental Investigation on Shear Failure Mechanism of Rock Mass with Intermittent Joints

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Minghui Ma ◽  
Fenhua Ren ◽  
Wensheng Liu
Keyword(s):  
Rock Mass ◽  
Shear Strain ◽  
Failure Mechanism ◽  
Shear Failure ◽  
Shear Fracture ◽  
Shear Loading ◽  
Surface Strain ◽  
Image Correlation ◽  
Maximum Shear Strain ◽  
Natural Rock

There are a large number of discontinuous weak planes distributed in the natural rock mass, which makes the sliding failure of rock mass along the intermittent structural plane very complex. To investigate the shear failure mechanism of rock mass with intermittent joints and study the influence of different joint heights on the shear failure mode of the rock mass, direct shear tests were carried out by presetting a series of jointed rock specimens with different undulating heights. During the shear loading, digital image correlation (DIC) technology was employed to monitor the surface strain field of the specimens in real time. The results show that the fluctuation height has a significant effect on the evolution of shear strain. With the increase of shear load, the maximum shear strain of the jointed specimens with different undulating heights first increases slowly and then increases rapidly. When the undulating height is 5 mm, the failure of the specimen is dominated by the rock sliding along prefabricated joints. When the undulating height is larger than 10 mm, the shear fracture of the rock becomes dominant. With the increase of the undulating height, more penetrating cracks perpendicular to the preexisting joints appear between the serrated surfaces, and the shear fracture phenomenon is more obvious.

Strength characteristic and failure criterion of flexible multi-axial warp-knitted fabrics coated with polyurethane on single side

2018 ◽  
Vol 49 (3) ◽  
pp. 318-327 ◽  
Author(s):  
Nangkuo Guo ◽  
Min Sun ◽  
Lan Cheng ◽  
Chenlong Jiang ◽  
Wenhao Chen ◽  
...  
Keyword(s):  
Great Influence ◽  
Material Design ◽  
Failure Stress ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Test ◽  
Knitted Fabrics ◽  
Stress Criterion ◽  
Single Side ◽  
Coated Fabric ◽  
Coated Fabrics

Coated fabrics are widely used in tension structures. In order to investigate the tensile behaviors of the coated fabrics, one group of specimens was cut out from multi-axial warp-knitted polyester fabrics coated with polyurethane on one side. These failure strengths of polyurethane-coated multi-axial warp-knitted fabrics were obtained by the method of uniaxial tensile test and a failure stress criterion is presented for the kind of materials. The results show that the coated fabric is anisotropic material, and the coating has great influence on the mechanical properties of the material. Furthermore, the failure stress criterion can be used for references in material design and application.

scholarly journals Influence of Modification on the Structural and Tensile Properties of Polyurethane Coated Knitted Fabrics after Natural Weathering

2017 ◽  
Vol 25 (0) ◽  
pp. 89-94 ◽  
Author(s):  
Vesna Marija Potočić Matković ◽  
Zenun Skenderi
Keyword(s):  
Solar Radiation ◽  
Tensile Properties ◽  
Environmental Conditions ◽  
Natural Weathering ◽  
Knitted Fabrics ◽  
Mass Thickness ◽  
Coated Fabric ◽  
Different Seasons ◽  
Positive Correlations ◽  
Coated Fabrics

The intention of this study was to investigate the changes in properties of polyurethane coated knitted fabrics intended for sportswear or casual wear, i.e outdoor use after natural weathering, in two different seasons. The exposure of coated fabrics to outdoor natural weathering affected all properties investigated, namely, the mass, thickness, shrinkage, elongation and breaking forces. Summer exposure made greater modification of every parameter measured than winter exposure, except for the thickness. Solar radiation has a greater impact on the decrease in breaking forces of coated fabrics than on other properties measured. Strong positive correlations between the thickness of coated fabric and breaking forces were observed which can be used to design coated fabric with better tensile properties. The prediction of change under the influence of environmental conditions allows to improve coated fabrics with the aim of better protection of the wearer.

Biaxial tearing properties of woven coated fabrics using digital image correlation

2021 ◽  
pp. 114206
Author(s):  
Rijin He ◽  
Xiaoying Sun ◽  
Yue Wu ◽  
Guowen Tang ◽  
Valter Carvelli
Keyword(s):  
Digital Image Correlation ◽  
Digital Image ◽  
Image Correlation ◽  
Coated Fabrics

scholarly journals Buckling Failure Mechanism of a Rock Dam Foundation Fractured by Gentle Through-Going and Steep Structural Discontinuities

2020 ◽  
Vol 12 (13) ◽  
pp. 5426
Author(s):  
Donghui Chen ◽  
Huie Chen ◽  
Wen Zhang ◽  
Chun Tan ◽  
Zhifa Ma ◽  
...  
Keyword(s):  
Numerical Method ◽  
Failure Mechanism ◽  
Shear Failure ◽  
Distinct Element ◽  
Mechanism Analysis ◽  
Rock Masses ◽  
Dam Foundation ◽  
Deformation Features ◽  
Universal Distinct Element Code ◽  
Distinct Element Code

The failure mechanism analysis of dam foundations is key for designing hydropower stations. This study analyses the rock masses in a sluice section, which is an important part of the main dam of the Datengxia Hydropower Station currently built in China. The stability of the sluice rock masses is predominantly affected by gentle through-going soft interlayers and steep structural fractures. Its foundation failure mechanism is investigated by means of a numerical method, i.e., Universal Distinct Element Code (UDEC) and the geomechanical model method. The modeling principle and process, and results for the rock dam foundation are introduced and generated by using the abovementioned two methods. The results indicate that the failure mechanism of the foundation rock masses, as characterized by gentle through-going and steep structural discontinuities, is not a conventional type of shear failure mechanism but a buckling one. This type of failure mechanism is verified by analyzing the deformation features resulting from the overloading of both methods and strength reduction of the numerical method.

scholarly journals Strength and Failure Mechanism of Composite-Steel Adhesive Bond Single Lap Joints

2018 ◽  
Vol 2018 ◽  
pp. 1-10
Author(s):  
Kai Wei ◽  
Yiwei Chen ◽  
Maojun Li ◽  
Xujing Yang
Keyword(s):  
Failure Mechanism ◽  
Shear Failure ◽  
Failure Load ◽  
Lap Joints ◽  
Adhesive Joints ◽  
Adhesive Failure ◽  
Interface Failure ◽  
Element Analysis ◽  
Single Lap Joints ◽  
Structural Adhesive

Carbon fiber-reinforced plastics- (CFRP-) steel single lap joints with regard to tensile loading with two levels of adhesives and four levels of overlap lengths were experimentally analyzed and numerically simulated. Both joint strength and failure mechanism were found to be highly dependent on adhesive type and overlap length. Joints with 7779 structural adhesive were more ductile and produced about 2-3 kN higher failure load than MA830 structural adhesive. Failure load with the two adhesives increased about 147 N and 176 N, respectively, with increasing 1 mm of the overlap length. Cohesion failure was observed in both types of adhesive joints. As the overlap length increased, interface failure appeared solely on the edge of the overlap in 7779 adhesive joints. Finite element analysis (FEA) results revealed that peel and shear stress distributions were nonuniform, which were less severe as overlap length increased. Severe stress concentration was observed on the overlap edge, and shear failure of the adhesive was the main reason for the adhesive failure.

Flexural failure mechanism of 2.5D woven SiCf/SiC composites: Combination of acoustic emission, digital image correlation and X-ray tomography

2021 ◽  
pp. 100921
Author(s):  
Yadi Duan ◽  
Haipeng Qiu ◽  
Tiantian Yang ◽  
Ling Wang ◽  
XiaoMeng Wang ◽  
...  
Keyword(s):  
Acoustic Emission ◽  
Digital Image Correlation ◽  
Failure Mechanism ◽  
Digital Image ◽  
Image Correlation ◽  
X Ray ◽  
Flexural Failure ◽  
Sic Composites

Analysis of warp knitted fabric structure. Part I: a 3D straight line model for warp knitted fabrics

2011 ◽  
Vol 102 (12) ◽  
pp. 1065-1074 ◽  
Author(s):  
Hadi Dabiryan ◽  
Ali A.A. Jeddi
Keyword(s):  
Knitted Fabric ◽  
Knitted Fabrics ◽  
Line Model ◽  
Fabric Structure ◽  
Straight Line ◽  
Warp Knitted Fabric

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.

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