Design of Chiral Honeycomb Meso-Structures for High Shear Flexure

Chiral honeycombs are auxetic cellular structures that exhibits negative Poison’s ratio. Chiral honeycombs are structures arranged in an array of cylinders connected by ligaments. Four different configurations of these geometries with 4- and 6- ligaments attached are investigated for its use in shear layer of non-pneumatic wheel. The objective of the study is to find an ideal geometry for the shear layer while meeting its requirements of shear properties (about 6.5 MPa effective shear modulus and 0.15 maximum effective shear strain) with polycarbonate as base material. Finite Element (FE) based numerical tests are carried out and optimum chiral meso-structures are found for the target shear properties. Parametric studies on geometries are also conducted to find the effect of geometries on the target properties. The effect of cell wall thickness is studied and the optimum thickness is suggested to meet the target requirements. Effect of direction of shear loading has been studied on each different configuration in order to minimize the effect of direction of loading.