Draft Documentation
Version date: 27 January 2015
Lattice Generator Program
Draft Documentation
Early release version – check back for updated version
Background
The Lattice Generator is a simple MatLab program that automatically generates various lattice
geometries direct to STL format. These periodic structures are intended for use with the metallic
additive manufacturing technologies of Selective Laser Melting (SLM) or Electron Beam Melting
(EBM), however could be applied to a number of other additive technologies that require the input
of an STL file.
Developed out the apparent need for a fast and simple way to generate STL lattice structures for
research purposes at RMIT University’s Centre for Additive Manufacture, the program is a part of a
preliminary work in developing a much larger lattice generation capability. In its current state, the
program includes the following uniform lattice types:
- Body Centred Cubic (BCC)
- Face Centred Cubic (FCC)
- Modified FCC variants removing x-y, y-z, and x-z planes
- Combined BCC and FCC cell
- Modified combined BCC and FCC removing x-y plane
- Simple cube (box cell)
In theory, any lattice cell configuration could be added to the program provided that it can occupy a
cubic volume and is able to be tessellated.
In addition, it was observed that creating Finite Element (FE) meshes was incredibly time consuming
via traditional techniques. In response, the lattice generator script has the added functionality of
generating FE meshes automatically in NASTRAN format. Other formats are possible, however for
the purposes of the development project NASTRAN was all that was needed. In its current form, the
lattice FE mesh is a 3D beam element mesh with the properties of the STL lattice applied. Loads or
constraints are not generated, and the material properties are only set as a place holder. These
aspects need to be modified in a pre-processor (HyperMesh, Patran etc.).
