A new biaxial and shear protocol for architectural fabrics

Abstract

Architectural fabrics are translucent, lightweight and flexible allowing impressive forms to be achieved unlike any other material. However in order to create the required double curved structural form, flat fabrics must undergo shear deformation during installation. Due to the woven nature of architectural fabrics contact between neighbouring yarns during shearing leads to an increase in shear stiffness, shear lock-up and subsequent wrinkling. A picture frame shear test accessory has been designed for the biaxial test rig which enables a known biaxial stress state to be applied to the fabric and maintained throughout the shear test. A shear testing protocol is proposed for medium term loading conditions. This enables the shear characteristics of architectural fabrics to be identified for use in analysis and design. Shear behaviour is presented from initial experiments and a range of shear modulus values are proposed for loading and unloading in the shear deformation range of zero to 15°.