Flexural Behaviour of Auxetic Core Sandwich Beam

Auxetic is a material or a structure which has gained popularity due to its enhanced properties; they are widely used in the field of biomedical, aerospace, automotive, military and textile industry. They exhibit negative Poisson’s ratio, that is, unlike unconventional materials, they become wider when uniaxially stretched and thinner when uniaxially compressed. They exhibit enhancement in physical properties like vibration absorption, shear resistance, indentation resistance, fracture resistance and lower fatigue crack propagation. In this paper, a 3D unit cell was numerically modelled to evaluate the auxetic behaviour, and parametric analysis was done to evaluate the performance of different designs of unit cell, and it was compared with the equivalent monolithic one. Various design parameters considered were the height of the vertical connecting strut and the centre and radius of the curved strut of the core. It was found that a curved strut core shows auxetic behaviour, and as the distance of the centre of the curved strut increases, the deflection of the unit cell increased. This 3D unit cell was then numerically modelled to sandwich beam with auxetic core subjected to three-point bending. The behaviour of the structure was studied numerically using Abaqus/CAE 6.14.