Effects of on-axis and off-axis tension on uniaxial mechanical properties of plain woven fabrics for inflated structures

The use of enhanced plain woven fabrics for aerospace engineering needs essential and accurate mechanical parameters for analyzing structural behavior and performing numerical simulations. The uniaxial tensile tests are direct and effective approaches to investigate these mechanical properties. This study focused on uniaxial monotonic and cyclic mechanical properties of an enhanced plain woven fabrics URETEK 5893 in on-axis and off-axis tension. For uniaxial monotonic mechanical properties, an improved method to determine yield stress was proposed and digital image correlation (DIC) technique was utilized to investigate detailed breaking mechanism. It is found that yield stresses were stable in each loading direction and typical yield stresses in the warp, weft and 45° directions were 5.56 MPa, 8.84 MPa and 1.96 MPa, respectively. Moreover, the breaking mechanism in terms of strain propagation process was identified. For cyclic mechanical properties, approximate stable ratcheting strain and elastic modulus were investigated. Nonlinear ratcheting strain was more sensitive near 45° than other directions. Moreover, Poisson ratios in three directions were obtained with DIC technique and the maximum Poisson ratio existed in the 45° direction. The comparisons between experimental and theoretical elastic moduli showed that the best agreement existed in the warp and weft directions and the accuracy of using the theoretical equation to calculate elastic modulus was dependent on material linearity.In general, this study could provide basic observations and useful values for understanding mechanical properties of plain woven fabrics in use for inflated membrane structures.