Longterm Behaviour and geometrical precision of graded CNC knitted Bending Active Textile Hybrids under real world conditions

CNC knitted membranes provide a promising alternative to the traditionally woven materials in textile architectures, as they allow for bespoke material performance, sustainable and efficient production, and integration of functionality in the material itself. However there is a lack of knowledge in terms of the geometrical precision, which can be achieved with the material and its long term behaviour under stress and outdoor conditions. We use the installation Isoropia from the 2018 Venice Biennale, to evaluate the precision and behaviour of a custom made knit structure over a period of 8 months. Our investigation takes into account the multiscalar relations within knitted structures. In order to do so we develop a 3D scan based method to establish ground truth and determine the precision of bending active textile hybrids and link this with the investigations on fibre level. The analysis of the structure and material behaviour confirms the material model for the CNC knit and the structural capacity and longevity of CNC knit with Dyneema® high performance yarns. We furthermore characterise the mechanical properties of the material when used on architectural scale and make suggestions for future projects with knitted membranes.