A New Method for Measuring Fabric Plain Strain Using the Gray-Scale Intensity Index of Image

Every part in a fabric is affected by various forces and strains to accommodate three dimensional objects. When a fabric is stretched, its constituent yarns can be stretched, thinned or displaced. A change in size of pores in a fabric can also result in different reflections of light. The present study is an attempt to measure the longitudinal and lateral strains on a fabric with warp and weft by evaluating the number of pixels of a certain line in the images before and after a strain. It also investigates the intensity of the gray scale of an image as an index of strain on a fabric surface when stretched at warp, weft and 45 degrees (Bias). The results indicate that gray surface intensity is affected by the space between the yarns in a fabric, and can be used as a suitable index for the changes in the surface of a fabric. It is suggested that the proposed method, by employing only a few simple tensile tests, can explain, through fitting an equation, the relationship between the strain obtained by the change in the number of pixels and the changes in the intensity of the gray surface. The gray scale intensity index of an image can be used to measure the longitudinal and lateral strains of parts in a fabric in a three dimensional shape (before buckling).

Automated summary

The study measures longitudinal and lateral strains on a fabric by evaluating the number of pixels of a certain line in images before and after a strain, and investigates the intensity of the gray scale as a strain index. The results suggest that gray surface intensity is affected by the space between yarns in a fabric, serving as a suitable index for fabric surface changes.