Experimental characterization of orthotropic technical textiles under uniaxial and biaxial loading

The paper deals with the development of an experimental protocol for the mechanical characterization of plain weave technical textiles. The textiles are modelled as orthotropic materials with known directions of material symmetry, and a ‘‘linear-by-step’’ approximation is introduced to account for the nonlinearity exhibited by the stress–strain behaviour. Material coefficients are determined by fitting uniaxial stress–strain curves along the warp, weft and 45 directions. The full-field evaluation of the strain distribution on the specimen surface, carried out by an optical approach, allows to assess the absence of edge effects and to quantify the shear strains introduced by off-axis loading. The protocol is applied to the characterization of a monofilament polyester textile and the model identified upon uniaxial data is validated by comparing analytical simulations with experimental data obtained under biaxial stress conditions. Finally the reliability of failure criteria based upon both uniaxial and biaxial data is investigated.