Off-axial failure analysis of polytetrafluoroethylene-coated woven glass fibers under different loading rates

This paper presents the research on off-axial tensile behaviors of polytetrafluoroethylene-coated woven glass fibers under different loading rates. First, groups of off-axial tensile tests were carried out, and the corresponding failure mechanisms were analyzed. Then, the effect of loading rate on the tensile behaviors of off-axial specimens was studied. Finally, several current strength criteria were compared to predict the material failure strength under different loading rates. Results show the tensile behaviors of polytetrafluoroethylene-coated woven glass fibers are typical orthotropic. The material failure strength is strongly related with failure modes and yarn orientations. Three typical failure modes are observed in the tests, including interface failure, yarn breakage, and composite failure. The loading rate has significant effects on the material tensile strength and the elongation at break. With loading rate increasing, the tensile strength increases and the elongation at break decreases. The tensile strength shows a good linear correlation with the loading rate’s logarithm. Most of current quadratic strength criteria can be used to predict the material failure strength, except for the specimens of small bias angles. This is because traditional quadratic criteria are always based on the strain energy theory of homogeneous materials, which may not reflect the failure mechanisms of coated fabrics and other important details.