Tearing Property and Allowable Tearing Stress of PVC-Coated Polyester Fabric Membranes at High Temperature

Abstract

PVC-coated polyester fabric is a widely used building material whose tearing strength is much lower than its tensile strength. Extreme loads such as fire, unexpected winds, or hail may cause cracks in the membrane. The tearing properties of PVC-coated fabrics were researched in this paper. Tensile tests with precracked specimens and tongue tear tests are the two most commonly used methods to research the tear strength of coated fabric membranes. The tearing properties of coated fabric membranes at high temperature were researched by tensile test with precracked specimen. Refined finite-element (FE) models with yarns were built and verified according to the experiment. The effects of initial crack length, off-axis angle single-yarn cross-sectional area, and coating thickness on the tearing properties of coated fabric membranes were studied. With the increase of temperature, the tear strength of a coated fabric membrane decreases significantly. The theory of linear-elastic fracture mechanics is still applicable to coated fabric membranes, and the sensitivity of a coated fabric membrane to crack length is lower than that of homogenous materials. The tensile mode stress intensity factor (SIF) of the coated fabric decreased only by 15.2% with the crack length increasing from 0.2 to 0.6 times the specimen width, whereas the tensile mode SIF of a homogenous material decreases by 66.5%. Coated fabrics with thicker yarns have higher tear strength and smaller fracture displacement. The strength of a coated fabric increased 53% and the section area of single yarn increased by 2.5 times, but the total section area was not changed. The allowable tearing stress of membranes with internal and edge cracks based on fracture mechanics and design code were proposed.