Off-axial tensile properties and failure analysis of PVC-coated fabric with multiple-layer welded seam

Weld seam connection is a common form of connection for the main stress joints in membrane structures. However, current research overlooks the impact of off-axis angles of coated fabric on stress distribution. To thoroughly understand the welding connection performance and tensile failure mechanisms, this paper investigated the tensile properties of PVC-coated fabrics with single-layer off-axis patch and double-layer off-axis patch. The effects of off-axial angle, overlapping connection method, and weld width on tensile strength and elongation at break were examined. The results indicate that, as the off-axis angle varies, the tensile strength and elongation at break of the coated fabric welding-covered connection specimens display two distinct trends. According to Digital image correlation (DIC) testing, warp patch coverage is beneficial for the coordinated stress and reasonable distribution of strain field in the coated fabric. In the design of PVC-coated fabric connection with weld seam cover treatment, it is necessary to consider the strength reduction at the welding site based on the connection type, weld width, and off-axis angle. Double-layer connections with patch widths exceeding 70 mm are recommended when the substrate material and patch are in warp-weft orientation; For off-axis designs, a 45° material offset angle may be adopted with patch widths greater than 50 mm.