Experimental study on mechanical properties and failure mechanisms of coated fabrics with different welding lengths

Node design is the most important aspect in membrane structure design, and an appropriate welding length is a prerequisite to ensure the reasonable stress distribution of the membrane structures. This paper presents the research on off-axial tensile behaviors of welding seam of the coated fabrics under different welding lengths. First, groups of off-axial tensile tests were carried out, and the effect of off-axial angle and welding length on the tensile strength and elongation at break of off-axial specimens with welding seam were studied. Then, the failure modes of these specimens were analyzed. Results show the change law of stress-strain curves of off-axial specimens with welding seam is similar to the base material, but the tensile strength and the elongation at break of off-axial specimens with welding seam are less than that of the base material. The tensile strength is maximum at 0° (Warp) or 90° (Weft). The tensile strength and the elongation at break are all minima at 15° or 75°. The tensile strength is second only to that of warp and weft at 45°, but the elongation at break is maximum. As the welding length increases, the tensile strength of specimens with welding seam shows an increasing trend. Four typical failure modes are observed in this test: yarn extract, yarn breakage (in the weld edge and in base material), shear failure, and composite failure.