A phenomenological material model for PTFE coated fabrics

Abstract

Membrane structures have the advantages of excellent mechanical behaviors and beautiful forms, and have been widely used in large-span buildings. The constitutive model of coated fabrics plays an important role in the design, analysis, and construction of membrane structures. However, the coated fabrics are usually assumed to be linear elastic. It reduces the computational accuracy of membrane structural analysis. In this work, a phenomenological model is proposed based on the experimental data obtained from uniaxial monotonic tensile tests, uniaxial cyclic loading tests and picture frame tests. Additional the varying Poisson’s ratio without considering the orthogonal interaction was obtained through the uniaxial tensile tests, and the shear behavior was investigated. The proposed model is implemented in the ABAQUS software as a user material subroutine and subsequently validated with the data obtained from on-axial cyclic loading tests and local full-size model test of membrane roof of Expo Central Axis. The model shows a good performance in computation and the obtained results are also in good agreement with experimental data. In contrast to published models, the proposed model can capture the orthotropic nonlinearity in first loading paths and roughly describe the unloading and reloading behaviors without considering the ratcheting behaviors. Besides, it can also make a good prediction on the failure modes and ultimate tensile strength. The approach can be generally used for different kinds of coated fabric. It can enhance the analysis accuracy and improve the current design theories of tensioned fabric membrane structures.