Tearing analysis of PVC coated fabric under uniaxial and biaxial central tearing tests

In this study, detailed uniaxial and biaxial central tearing tests of a type of PVC coated polyester fiber fabric for buildings were carried out. The characteristics of the damage morphology, the formation of the triangle area at the crack tip, crack propagation, and failure modes during the entire tearing process were studied. The influence of crack orientation, crack length, and load ratio on tearing behaviors were analyzed, and it was found that the two parameters of crack orientation and length could be combined into a single variable of the number of cutting-off yarns in the direction perpendicular to crack propagation. For the uniaxial central tearing test, four widely used theoretical models were used to fit the experimental results, which led to the conclusion that Thiele’s empirical formula was the most suitable theory for predicting the tearing strength of PVC fabrics. Finally, the strain of all yarns across the crack section before and at the moment of crack propagation was recorded by the DIC equipment, and the load borne by each yarn was calculated based on the uniaxial tension curve of this material. In this way, the strain and load distributions were obtained for the first time, from which it was observed that the maximum strain almost always concentrated in the del-zone at crack tips, and the number of cutting-off yarns significantly affected the strain distribution. Specifically, the more yarns were cut off, the more difficult it was for other yarns far from the crack to exert their load-carrying capacity.