Design of isotropic-tensile-strength lattice structure fabricated by AM

Abstract

In this work, lattice structures appropriate for Additive Manufacturing (AM) are discussed and designed. By using AM, it becomes easy to realize original arbitral mechanical properties, in terms of anisotropy, vibration characteristic, light weight, and so on, by creating objects which have lattice structures inside their bodies. However, since the internal structures are very small, the influence of fabrication conditions such as deposition direction, nozzle diameter, and layer thickness is large. When the size of the cell strut diameter with respect to the nozzle diameter is relatively small, the shape of the struts becomes rough. In this study, the body-centered cubic (BCC) structure fabricated with ABS resign is chosen as a target lattice structure. BCC structure can reduce anisotropic properties due to the AM process. Specimens having different sizes of the same lattice cell structure are modeled by 3D-CAD. These specimens are fabricated by fused filament manufacturing (FFM) process, and tensile strength is examined. After the effect of the deposition direction and the nozzle path on mechanical strength of lattice cell structures was revealed, a design method for isotropic-tensile-strength structures was proposed. By scaling the size of BCC, isotropic-tensile-strength lattice structure was designed and specimens having the structure was fabricated by FFM process. Tensile strength test results showed the isotropy of tensile strength.