A nature-inspired gradable elliptic-cell lattice structure based on cypress wood texture; theoretical and experimental analysis for mechanical properties

Abstract

The accessibility and commercialization of additive manufacturing allow scientists to design affordable, light weighted cellular-graded structures with customized mechanical properties. This study introduced a new functionally graded lattice structure inspired by the porous wood texture of cypress. This structure can simultaneously alter the relative density and unit cell shapes by gradual cell size grading and its porosity in each repetition which can provide graded properties along the particular axis and in each structural point. Different mechanical properties and geometrical features are easily achievable by altering the unit cell’s shape and dimensions. Elastic modulus, Poisson’s ratio, and specific energy absorption values depend on ellipses radii in cell scales, layers of lattices, and structures. Porosity and surface-to-volume ratio are calculated with high accuracy for different structures, which can be optimized for biomaterial and bioimplant substitution. Numerical simulation is carried out as two perpendicular uniaxial compressions for extracting the structural properties. In addition, an experimental test on the polymeric specimen, made by the DLP technique, validates the results, which shows good agreement with numerical ones. Designs of experiments were set up to determine the parameters’ main and interaction effects on the mechanical properties. RSM function is evaluated for two radii as factors in three levels in both unit cells and layers. Linear tessellation of a layer and parallel array of two perpendicular sets results in a highly porous, ultra-light, weighted structure.