A Predictive Fabric Model for Membrane Structure Design

Abstract

A predictive model has been developed to determine the biaxial stress-strain response of architectural fabrics, without the need for biaxial testing. Sawtooth and sinusoid models of the fabric unit cell have been formulated, with spring elements between crossovers used to represent the coating. In both models a constant yarn cross-sectional area has been maintained, resulting in a relationship between unit cell length and yarn thickness which eliminates the need to determine the yarn crushing stiffness. A state-of-the-art biaxial test rig and new test protocol have been developed to fully ascertain the stress-strain behaviour of structural fabrics. This enables meaningful comparison to be made between the model output and actual fabric response. The model provides a more accurate representation of fabric behaviour than current industry best practice (i.e. use of elastic constants based on biaxial test data), but without the need for specialist testing or equipment.