Uniaxial and buckling mechanical response of auxetic cellular tubes

Auxetic cellular tubes are emerging as potential candidates for a number of critical devices requiring high resistance to kinking, such as angioplasty stents or annuloplasty rings. This work investigates the collapse under pure bending of auxetic tubes based on inverted hexagonal honeycombs, with the aim to identify design strategies suitable for improving their kinking response. First, the mechanical properties of the structure are determined under small deformation by means of analytical approaches, and used to verify the validity of numerical models. These are then used to simulate the tube collapse under pure bending, and identify the influence of the geometric parameters defining the structure on the phenomenon. The study indicates that the adoption of auxetic tubular structures can contribute to improving considerably the resistance to kinking, suggesting the parameters to be controlled in the design of critical applications.