Two-dimensional mechanical metamaterials with adjustable stiffness and damping

Abstract

In mechanical metamaterials, geometry and material properties dictate the structural response to mechanical loads. These materials are comprised of a tessellated array of repeat unit cells, which form a lattice that populates the domain of the structure. While the mechanical behavior of 2D lattices is well understood, recent advances in polymer based Additive Manufacturing (AM) usher in a new era of metamaterials research. However, previous work in this area has failed to address the effects of time and temperature on the transient response of polymerbased mechanical metamaterials. We seek to investigate the effects of thermal loads on the mechanical properties of mechanical metamaterials, in particular, the stiffness and damping properties of lattice structures comprised of bowtie and honeycomb representative unit cells. Towards this goal, in the present paper, an experimental approach is used to investigate the mechanical behaviour of 2D lattice structures. Experimental samples are prepared using Fused Deposition Modeling (FDM) AM. These samples are subject to quasi-static mechanical tests at room temperature. Additionally, we investigate the effects of mismatched unit cells (defects) on the mechanical behavior of the lattice. Mechanical metamaterials with adjustable stiffness and damping properties have applications in the aerospace and automotive industries, including sandwich composites, damping and impact protection.