Wave propagation in beam-like in-vacuo tuneable structure fabrics

Structured fabrics, such as traditional knitted sheets or chain mail armours, are characterised by a quite loose bending stiffness at ambient pressure. However, recent research has demonstrated that when these types of structures are subjected to a small confinement pressure of about 90 kPa, the chain mails become more than 25 times stiffer than in their relaxed configuration. This aspect paves the way for new lightweight, tunable, and adaptive fabrics for applications in wearable exoskeletons, haptic architectures, and devices for passive and semi-active vibration and noise control, such as tunable vibration absorbers. In this study, the structured fabric consists of chain mail formed by 3D rigid truss-like elements fabricated using material deposition techniques. The mail structures are vacuum-bagged, which induces jamming through interlocking and friction between neighbour particles, resulting in a solid state. This work presents a 1-D wave finite element (WFE) model of these structures, which aims to predict their dispersion curves under varying confinement pressures. The model, implemented in COMSOL Multiphysics using the Floquet boundary condition method, is validated against laboratory experiments.