In recent years, coated fabrics have become the major material used in membrane structures. Due to the special structure of base layer and mechanical properties, coated biaxial warp-knitted fabrics are increasingly applied in pneumatic structures. In this article, the mechanical properties of coated biaxial warp-knitted fabrics are investigated comprehensively. First, off-axial tensile tests are carried out in seven in-plane directions: 0°, 15°, 30°, 45°, 60°, 75°, and 90°. Based on the stress–strain relationship, tensile strengths are obtained and failure modes are studied. The adaptability of Tsai–Hill criterion is analyzed. Then, the uniaxial tensile creep test is performed under 24-h sustained load and the creep elongation is calculated. Besides, tearing strengths in warp and weft directions are obtained by tearing tests. Finally, the biaxial tensile tests under five different load ratios of 1:1, 2:1, 1:2, 1:0, and 0:1 are carried out, and the elastic constants and Poisson’s ratio are calculated using the least squares method based on linear orthotropic assumption. Moreover, biaxial specimens under four load ratios of 3:1, 1:3, 5:1, and 1:5 are further tensile tested to verify the adaptability of linear orthotropic model. These experimental data offer a deeper and comprehensive understanding of mechanical properties of coated biaxial warp-knitted fabrics and could be conveniently adopted in structural design.
KomeiliMMilaniAS. The effect of meso-level uncertainties on the mechanical response of woven fabric composites under axial loading. Comput Struct2012; 90–91: 163–171.
2.
BridgensBGoslingPBirchallM. Membrane material behaviour: concepts, practice & developments. The Struct Engineer2004; 82(14): 28–33.
3.
DemircanOKosuiTAshibeS, et al.Effect of stitch and biaxial yarn types on tensile, bending, and impact properties of biaxial weft-knitted composites. Adv Compos Mater2014; 23: 239–260.
4.
XuJZhangYWuM, et al.Experimental analysis of off-axis mechanical behaviors of PVC coated fabrics subjected to cyclic loading. Polym Test2019; 80: 106090.
5.
HuJGaoCHeS, et al.Effects of on-axis and off-axis tension on uniaxial mechanical properties of plain woven fabrics for inflated structures. Compos Struct2017; 171: 92–99.
6.
PenavaZPenavaDKnezicZ. Determination of the elastic constants of plain woven fabrics by a tensile test in various directions. Fibers Text East Eur2014; 22(2): 57–63.
7.
YiHDingXChenS. Orthotropic behavior and strength criterion of PES/PVC membrane materials under tensile loading. Acta Mater Compos Sinica2005; 22(6): 98–102.
8.
GalliotCLuchsingerRH. The shear ramp: a new test method for the investigation of coated fabric shear behaviour–Part II: experimental validation. Compos A: Appl Sci Manuf2010; 41: 1750–1759.
9.
KongFChangMWangZ. Comprehensive analysis of mechanical properties of CB/SiO2/PVDF composites. Polymers2020; 12(1): 146.
AmbroziakAKłosowskiP. Mechanical properties for preliminary design of structures made from PVC coated fabric. Constr Build Mater2014; 50: 74–81.
12.
AmbroziakAKłosowskiP. Influence of thermal effects on mechanical properties of PVDF-coated fabrics. J Reinf Plast Compos2014; 33(7): 660–670.
13.
AmbroziakAKłosowskiP. Mechanical properties of polyvinyl chloride-coated fabric under cyclic tests. J Reinf Plast Compos2014; 33(3): 225–234.
14.
AmbroziakAKłosowskiP. Mechanical properties of precontraint 1202 S2 based on uniaxial tensile and creep tests. J Reinf Plast Compos2017; 36(4): 254–270.
15.
ParkE-TLeeYKimJ, et al.Experimental study on microwave-based curing process with thermal expansion pressure of PTFE for manufacturing carbon fiber/epoxy composites. Materials2019; 12(22): 3737.
16.
QuCHuJLiuX, et al.Morphology and mechanical properties of polyimide films: the effects of UV irradiation on microscale surface. Materials2017; 10(11): 1329.
17.
LuoYHuHFangueiroR. Tensile and tearing properties of biaxial warp knitted coated fabrics. Autex Res J2008; 8: 17–20.
18.
LuoYHuH. Mechanical properties of PVC coated bi-axial warp knitted fabric with and without initial cracks under multi-axial tensile loads. Compos Struct2009; 89: 536–542.
19.
ChenJZhouHZhaoB, et al.A new theoretical equation to estimate Poisson's ratio for coated bi-axial warp knitted fabrics under bias tensile loading. Fibers Polym2018; 19: 2631–2641.
20.
ChenJZhouHChenW, et al.Full-strain range characteristics of the Poisson's ratio for coated biaxial warp-knitted fabrics under bias tensile loading. Text Res J2018; 89: 1997–2009.
21.
DinhTDWeegerOKaijimaS, et al.Prediction of mechanical properties of knitted fabrics under tensile and shear loading: Mesoscale analysis using representative unit cells and its validation. Compos B: Eng2018; 148: 81–92.
22.
GaoZJiangGMaP, et al.Tear properties and meso-scale mechanism of multi-axial warp-knitted fabric from various architectures: Studied by photography. Fibers Polym2013; 14: 1953–1963.
23.
JingLGuoNXuH, et al.Tensile characteristics of flexible PU-coated multi-axial warp-knitted fabrics. J Ind Text2016; 47: 38–56.
24.
KongHMouritzAPPatonR. Tensile extension properties and deformation mechanisms of multiaxial non-crimp fabrics. Compos Struct2004; 66: 249–259.
25.
DinhTDRezaeiADe LaetL, et al.A new elasto-plastic material model for coated fabric. Eng Struct2014; 71: 222–233.
26.
GalliotCLuchsingerRH. A simple model describing the non-linear biaxial tensile behaviour of PVC-coated polyester fabrics for use in finite element analysis. Compos Struct2009; 90: 438–447.
27.
YangBYuZZhangQ, et al.The nonlinear orthotropic material model describing biaxial tensile behavior of PVC coated fabrics. Compos Struct2020; 236: 111850.
28.
GuoHLuCChenY, et al.Thermal-mechanical coupling behavior of directional polymethylmethacrylate under tension and compression. Polymers2018; 10(11): 1279.
29.
ZhangQYangL, et al. Technical specification for inspection of membrane structures (DG/TJ08-2019-2007). Shanghai China, 2007.
30.
WuMLiYShangY. Statistical characteristics of ethylene tetrafluoroethylene foil's mechanical properties and its partial safety factors. J Mater Civil Eng2016; 28(5): 04016004.
31.
ISO. Plastics-determination of tensile properties. Switzerland, 2012. ISO 527-1:2012.
32.
ZhaoBHuJChenW, et al.Simultaneous uniaxial creep testing of time-dependent membrane materials with optical devices. Mater Today Commun2019; 21: 100655
33.
CaiyuanCDhingraRPostleR. A study of tearing properties of membrane coated fabrics. J China Text Univ1991; (4): 1–9.
34.
ScelzoWABackerSBoyceMC. Mechanistic role of yarn and fabric structure in determining tear resistance of woven cloth. Text Res J1994; 64: 291–304.
35.
Membrane Structures Association of JapanMSAJ/M-02-1995.Testing method for elastic constants of membrane materials. Japan: Membrane Structures Association of Japan, 1995.
36.
YangBShangYWuM, et al.Statistical characteristics of naturally aged PVDF-coated fabrics’ mechanical properties and structural reliability index. Polym Test2019; 80: 106143. DOI: 10.1016/j.polymertesting.2019.106143.
37.
Teixeira PintoJMTouchardFCastagnetS, et al.DIC strain measurements at the micro-scale in a semi-crystalline polymer. Exp Mech2013; 53: 1311–1321. DOI: 10.1007/sll340-013-9753-2.
38.
YuM-h. Advances in strength theories for materials under complex stress state in the 20th Century. Appl Mech Rev2002; 55: 169–218.
39.
MengLWuM. Study on stress relaxation of membrane structures in the prestress state by considering viscoelastic properties of coated fabrics. Thin-Walled Struct2016; 106: 18–27.
