A generalized method of measuring the Poisson's ratio of warp knitted fabrics under uniaxial loading based on image processing technique

Abstract

In this work, a generalized method for measuring the Poisson's ratio of fabrics is presented. The basis of this method is the two-dimensional nature of the fabric deformation. Through this method, the measurement error is very low compared to conventional methods. In the following, the error of measurement in the conventional methods has been proved theoretically then an experiment with five different knitted fabrics and an elastic sheet is designed. In addition, an algorithm based on the image processing technique is presented to measure longitudinal, transverse and area strain. The results of fabrics showed that the theoretical prediction about the error of conventional methods was predicted correctly. In the case of the elastic sheet, the same result has been found, but it was not significant statistically. It is suggested that the proposed method is capable of replacing all available methods of measuring the Poisson's ratio of fabrics and structures like them.