Deformation of a spunbonded nonwoven fabric specimen is extremely nonuniform during a uniaxial tensile test. Complex stress/strain fields are generated in the specimen due to the effect of the jaws, the nonlinear nature of deformation, and the low shear stiffness of the fabric, causing "necking" to take place in the unrestricted region. A finite element model is presented to model the nonuniform deformation of the fabric. Nonuniform stress/strain fields developing in the fabric during a uniaxial test are modeled for the first time. Data from representative tests are reported for comparison to the results obtained with the model. The model correctly predicts the variation of Poisson's ratio with longitudinal strains. Unlike previous studies, correct boundary conditions and force equilibrium conditions are incorporated in the model. The important effects of fiber buckling and material nonlinearity are discussed.
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