A Study of Different In-Plane Elastic Properties of Novel Filler-Based Sinusoidal Re-entrant Honeycomb

Auxetic materials are attractive for a wide range of high-tech applications such as mechanical, aerospace, defence, biomedical due to its novel mechanical properties. Auxetic materials, commonly classified as mechanical metamaterials, exhibit Negative Poisson’s Ratio (NPR). Due to the NPR property, auxetic materials exhibit high indentation resistance properties, high energy absorption properties, high shear modulus etc. Though the auxetic materials are lightweight structures with low stiffness. Several researchers from the past few decades have tried to develop such structures with enhanced stiffness and mostly by modifying the walls of the architected structures. In the present study, the elastic properties of auxetic sinusoidal re-entrant honeycomb (SRH) have been analysed using FE simulation software and validated using previously published results. To overcome the problem of low stiffness, filler materials have been introduced in the voids of the auxetic lattices. Preferential filling technique has been used to obtain comparatively stiffer structures without compromising the auxeticity. Further, studies have been done by varying the stiffness of the filler material while retaining the auxeticity of the overall lattice. Using preferential filling technique, with certain patterns and a certain level of stiffness of the filler materials, it is made possible to attain a greater stiffness with auxeticity. As a result, the enhancement in the stiffness was of the order of about 7.4–9 times compared to empty lattices, whilst retaining the auxetic behaviour. The proposed method of improving the properties of auxetic lattices is versatile—can be adopted for any lattice and can be easily realized with standard 3D printers.