Electrically conductive yarns (ECYs) are gaining increasing applications in woven textile materials, especially in woven sensors suitable for incorporation into clothing. In this paper, the effect of the yarn count of ECYs woven into fabric on values of electrical resistance is analyzed. We also observe how the direction of action of elongation force, considering the position of the woven ECY, effects the change in the electrical resistance of the electrically conductive fabric. The measurements were performed on nine different samples of fabric in a plain weave, into which were woven ECYs with three different yarn counts and three different directions. Relationship curves between values of elongation forces and elongation to break, as well as relationship curves between values of electrical resistance of fabrics with ECYs and elongation, were experimentally obtained. An analytical mathematical model was also established, and analysis was conducted, which determined the models of function of connection between force and elongation, and between electrical resistance and elongation. The connection between the measurement results and the mathematical model was confirmed. The connection between the mathematical model and the experimental results enables the design of ECY properties in woven materials, especially textile force and elongation sensors.

Shear behavior is one of the most important mechanical characteristics that contributes to the performance and appearance of woven fabrics. Because of anisotropy, shear properties of woven fabric are tested in various directions. This research is focused on the experimental study of shear properties of plain woven fabric when shear force acts on specimens that are cut at different angles to the direction of the weft. Tests were conducted on woven fabric specimens that were fastened in two parallel clamps of the tensile tester. Five cotton woven fabrics of different weft density and of the same warp density were used. The research results show a very high degree of correlation between shear force and its axial component for all directions of the cutting specimen, and likewise between the relative extension of the diagonal of the specimen and the vertical displacement of the specimen. The initial shear modulus of woven fabrics was determined experimentally and theoretically.

Determination of mechanical properties and predicting the behavior of knitted fabrics during the manufacturing process and finally in the use is an important part of textile science. In this study the influence of knitted fabric anisotropy on the values of maximum force, corresponding extension and total work when axial tensile forces act on specimens cut at different angles with respect to the course direction of the knitted fabric were analyzed. A plain double weft knit fabric made of single cotton yarns was studied. For different angles of cutting samples, the curves of the relation between the values of the tensile forces and the extension at break were experimentally obtained. The mathematical models obtained were compared with the experimental results, and the corresponding correlation coefficients were calculated.

This paper deals with the impact of fabric density on fabric thickness change when samples are subjected to uniaxial tensile forces in the weft direction. During stretching, fabric thickness changes depending on the value of the tensile force. In an effort to be as precise as possible in measuring fabric dynamic thickness changes and the area on which the tensile force acts, a new measuring apparatus was designed and constructed. This measuring apparatus allows the simultaneous measurement of fabric dynamic thickness, related tensile axial forces and extension. Measurements of the fabric dynamic thickness, breaking force and breaking extension during the stretching process were carried out on five samples of cotton woven fabric with a constant warp density and different weft densities in the same structural plain weave. Based on the experimentally obtained values, the paper presents diagrams of the relationship between dynamic changes in fabric thickness in relation to the tensile force and extension. The research presented in this paper shows that an increase in the tensile force increases fabric thickness for all weft densities. Also, the out-of-plane woven fabric ratio was calculated as a relation between the relative thickness strain and relative axial strain. The characteristic curve shows this ratio.

SummaryThe paper analyses the impact of lateral restraining by trapezoidal steel sheeting on the structural stability of thin-walled C-cross section columns subjected to axial forces. Firstly, mechanical properties of the column material (steel) and lateral stiffness of the rotational restraint are determined by testing standard specimens in a laboratory. Based on the obtained data, a stability analysis of unrestrained columns and of columns laterally restrained by trapezoidal steel sheeting has been carried out and critical forces have been determined analytically by using the theory of thin-walled beams, numerically by using the finite element method (FEM), and experimentally by testing the C-cross section columns in a laboratory. The analysis of critical forces and stability shows that the calculation according to the theory of thin-walled beams and the FEM calculation gives results similar to the results of the experimental tests. By comparing the results of the investigation into thin-walled C-cross section columns with and without lateral restraints a significant influence of lateral restraints on the stability of thin-walled C-cross sections subjected to axial forces has been proven: lateral restraint significantly affects final results of the level of the critical force, raising the possibility of optimizing the use of such structures in practice.