Additive Fabrication of Anepectic Meshes

This work applies additive manufacturing technology to fabricate bi-dimensional lightweight composite anepectic meshes capable of demonstrating auxetic properties (negative Poisson’s ratio (NPR)) in combination with negative thermal expansion (NTE) behaviour, using as constituent materials polymers that do not exhibit NTE behaviour. Each mesh, obtained from varying either the material combination or the design parameter, was tested on a heated silicone bath to study the effects of the different combinations on the coefficient of thermal expansion (CTE). Photographs were taken at different stages during the heating process and were analysed to determine the CTE of each mesh. It was found that all composite meshes studied demonstrated a successful combination of NPR and NTE behaviours, and it was revealed that there is a possibility to tailor the meshes to activate the NTE behaviour within a chosen range of temperatures. For an extreme case, a Poisson’s ratio of −0.06, along with a CTE of −1568 10-6 (ºC-1) has been achieved. These meshes may be applied to structures and equipment in which the disparity in thermal stress has be carefully managed to extend the life of the device, and also to produce biomedical devices such as stents, surgical hernia meshes (SHM), compression garments and others, with many advantages over current designs, namely the ability to counteract any relaxation effects resulting from increases in the service temperature