Investigation on Transverse Loading of Auxetic Beams Using Finite Element Methods

Structures that possess negative Poisson’s ratio are termed “Auxetic” structures. They elongate laterally on longitudinal–tensile loading and compress laterally on longitudinal–compressive loading. Auxetic structures are a composition of unit cells that are available in various geometries, which include triangular, hexa-triangular, re-entrant, chiral, star, arrowhead, etc. Due to their unique shape, these structures possess remarkably good mechanical properties such as shear resistance, indentation resistance, fracture resistance, synclastic behavior, energy absorption capacity, etc. However, they have poor load-bearing capacity. To improve the load bearing strength of these structures, this paper presents a numerical analysis of oriented re-entrant structured (ORS) beams with auxetic clusters aligned at various angles (0°, 45° and 90°), using Finite Element Methods. Oriented re-entrant unit cell clusters enclosed by a bounded frame were modeled and a three-point bending test was conducted to perform a comparison study on deformation mechanisms of the different oriented re-entrant honeycomb structures with honeycomb beams. The computational analysis of ORS beams revealed that the directional deformation and normal strain along the x-axis were the lowest in ORS45, followed by ORS90, ORS0, and honeycomb. Among all the beams, ORS45 displayed the best load-bearing capacity with comparably low mass density.