Effect of Self-stitched Double Fabric’s Properties on Tensile and Permeability Performances

The double fabrics having a complex structure are used in different areas both technically and aesthetically. In this study, tensile and air permeability properties of self-stitched double fabrics were investigated. Firstly, six different self-stitched double fabrics having the same yarn type, same settings, two different weave types, and three different stitching arrangements were designed and manufactured. Then, the tensile properties of these double fabrics were tested by applying tensile test at warp and weft directions, and bias-extension test at 45° bias direction. The effect of structural properties on tensile and air permeability results was discussed statistically. The tensile properties of self-stitched double fabrics having plain weave types are mostly better than 2/2 twill ones. The differences between tensile properties of self-stitched double fabrics generally were not found statistically significant according to stitching arrangement except the double fabric having plain weave type and higher stitching points. On the other hand, the differences between air permeability properties of all self-stitched double fabrics were found statistically significant at 95 % confidence level in terms of both stitching arrangement and weave type.

The influence of yarn fineness and number of yarn layers on in-plane shear properties of 3-D woven fabric

The 3-D layer-to-layer angle-interlock woven fabric (LLAIWF) has good deformability on a complicated contour, which offers them a large application potential in the field of aerospace. This article mainly focuses on the influence of yarn fineness and number of yarn layers on in-plane shear properties of 3-D LLAIWF during bias extension. Two methods of varying the thickness of 3-D LLAIWF were designed: changing yarn fineness and changing the number of yarn layers. The deformation mechanism of LLAIWF in bias-extension test was analyzed. The effects of two methods on in-plane shear deformation were compared and analyzed. In addition to the data processing on the experimental curve, digital image correlation analysis was conducted on the test photographs, from which shear angles in different area shear angle were measured. The mesostructure of fabric during the bias-extension test was observed. The effect of decreasing yarn layers on the mesostructure of fabric was observed by cutting fabric. The results demonstrated that the yarn fineness and the number of yarn layers play a key role in the in-plane shear properties of 3-D LLAIWF. In addition, the changing of fabric thickness causes that the deformation is asymmetrical. The effect of warp yarn fineness is similar to that of weft yarn fineness during the bias-extension test. Reducing the internal yarns of the fabric created a gap, where the yarns were reduced. This gap will affect the deformability of the fabric.

Experimental measurements and numerical modelling of the mechanical behaviour of a glass plain weave composite reinforcement

The study deals with the mechanical behaviour of a glass plain weave composite reinforcement. The experimental activities were focused mainly on uniaxial and biaxial extension tests. Besides, in-plane shear deformation was measured by bias extension test, and for the sake of completeness out-of-plane bending behaviour. In the numerical study, a hyperelastic constitutive model for the yarn material was adopted and validated for the meso scale prediction of the mechanical behaviour of the glass plain weave reinforcement. The model was validated for biaxial tensile and in-plane shear deformation.