The shearing deformation behaviours-apparent modulus of fabric shear τ1, frictional force at intersecting points of fabrics F, and critical angle of shearing deformation α for 27 kinds of fabrics made from same yarns and have same densities in warp and weft ways, have been measured under identical conditions. (Details of samples used in the experiments are shown in Table. 1).
The modulus of shearing deformation τ1 is smaller in open or tightless fabrics, that is, in the fabrics having a large freeness of shearing deformation. In the identical harness twills having same freeness, τ, is small and α is large in asymmetrical twills i. e. 2/2 twills or 4/4 twills etc. The satins have smaller τ1, and larger α among the various weaves as well as the mat.
We found the following relations that the logarithm of the critical angle α and shearing modulus τ1, are roughly inversely proportional to the freeness of shearing deformation and to the critical angle α respectively. These are in Fig. 2 and Fig. 3.