Material Testing & Computational Mechanics — A New Philosophy for Architectural Fabrics

Abstract

This paper proposes a new perspective on the analysis of fabric structures – the concept that material testing and computational mechanics are mutually dependent and, by implication, not to be considered as independent. Current representations of fabric stress-strain behaviour are based on plane-stress assumptions, and tend to simplify the available data (e.g. use of secant elastic moduli). Young's moduli and Poisson's ratios were determined for each test so as to provide the best fit plane to the scattered data points. These planar representations provided limited correlation with test data. The elastic constants do not comply with plane stress theory since coated woven fabrics are not homogeneous materials: They are composites with the interaction of orthogonal yarns making them act as a constrained mechanism. A new approach to incorporating fabric test data in structural analysis is proposed here: Use of direct correlation between pairs of stresses and strains. This avoids the inherent approximation in defining elastic constants or other parameters to quantify the fabric behaviour. A simple triangular interpolation scheme is recommended which is robust and avoids the risk of unreliable interpolation and extrapolation when using a functional representation of the data.