Geometry of plain weave fabric under shear deformation. Part I: measurement of exterior positions of yarns

Behaviour of woven fabrics in all directions is important in some fabric applications. Dealing with geometrical deformation of fabric under shear stress is the main attempt of this paper. A method for detecting exterior positions of yams in fabric, namely variation in warp-weft yams angle and sett of yarns is developed in the present part. For this purpose, the fast Fourier transform (FFT) method is modified for detecting exterior position of yams in sheared fabric. In an empirical work, two kinds of plain weave fabrics, cotton and polypropylene, are considered and specimens are prepared in different dimensions with identical aspect ration. Exterior positions of yams in certain elongations are computed by proposed method for each specimen. It was found that the modified FFT technique is valid for evaluating exterior positions of yarns in sheared fabric. Moreover, it is observed that there is a critical state in behaviour of woven fabric under shear deformation. In subsequent parts, the treatment of fabric under shear deformation will be simulated and compared with results of present part.