: A simple supported beam system was used to measure the bending rigidity of yarn. The yarn was treated as an elastic beam fixed in one end and supported by a simple support in another end and loaded somewhere near the middle. Using the dir=ltr A simple support beam system deflected under its own weight was used to measure the bending modulus and the bending rigidity of fabrics. Using the elastica dir=ltr The ratio of the bending rigidity of fabric per yarn to bending rigidity of yarn ( b/b y ) was also investigated. Experimental results showed that increase in the weft density leads to decrease in b/b y in the weft direction and increase in b/b y in the warp direction whereas available theoretical formulas predict increase in b/b y in both directions. This contradiction between experimental and theoretical results is consequence of yarn cross-sectional deformation during fabric formation or in later processes, for low twist yarn woven fabrics. Images from the fabric surface showed flattening of the yarns and the theoretical formulas which are based on the circular cross-section of the yarn can not be applied in this case.
