Parametric shell lattice with tailored mechanical properties

Abstract

Along with the development of additive manufacturing, people can fabricate microstructures with complicated geometry that achieve outstanding mechanical properties beyond traditional materials. Shell lattice is a kind of microstructure that consists of a continuous, smooth shell. It has been fabricated as an ultra-low-density material called Shellular, which provides excellent strength and stiffness and has significant multi-functional applications such as heat radiation, permeability, and diffusivity. Most shell lattices in the literature are based on triply periodic minimal surface (TPMS). However, TPMSs are derived from limited types of implicit functions and thus have limited material space. This work proposes the parametric shell lattice (PSL), a type of shell lattice described by a simple and efficient parametric model. The parametric model consists of a skeleton and a set of generation parameters, from which the shell structure can be derived. Various shell lattices with different topologies can be extracted from the parametric model by controlling the generation parameters. Then, a parametric shape optimization method is used to optimize the generation parameters to obtain the PSL with target mechanical properties. A group of PSLs with tailored mechanical properties, including isotropic elasticity, tailored Young’s modulus, shear modulus, and Poisson’s ratio, are designed. Physical experiments demonstrate that the designed PSLs could realize elastic isotropy and high stiffness compared with TPMS lattices. Thanks to the parametric representation, the geometric characteristics of PSL are preserved during the optimization procedure. In addition, the PSL also possesses high efficiency in storage and slicing for additive manufacturing.