ARL Topologies vs FreeTO

ARL Topologies is free, open-source software for topology optimization, published by USArmyResearchLab as a United States government project. It is intended for research and general use, and runs self-hosted from the command line with an XML input file. The program separates design representation, optimization method, and objective function. Representations include two- and three-dimensional element-based density discretization with SIMP interpolation, plus nodal-based density discretization with Heaviside projection and filtering. Inputs can be ASCII ExodusII or GMSH meshes, or rectangular pixel and voxel regions. Available optimizers include optimality criterion, method of moving asymptotes, BFGS through NLopt, and a genetic algorithm. Its implemented objective performs static structural finite element analysis. Density results can be post-processed to STL, while VTK, GMSH, and Matlab are output formats. A shared-library objective function allows extension to other problems. Building requires a C++11 compiler and listed libraries.

FreeTO is free, open-source MATLAB software for initializing, optimizing, and post-processing free-form 3D topology optimization problems. It accepts STL files for a design domain and load-carrying subdomains, together with mesh controls and a target volume fraction. A structured hexahedral mesh is used, and optimized structures have smooth boundaries. Inputs can define supports, force magnitudes, up to nine additional load cases, and regions that must remain unchanged. SIMP is the documented default optimization method, and SEMDOT is also supported. Topologies can be mirrored across up to three specified symmetry planes. Results include compliance, volume fraction, density arrays, element counts, optimization histories, visual topology displays, and an optional STL file. Sample problems cover a GE bracket, airplane bracket, human hand model, and quadcopter. The repository uses an MIT license and other open-source codes. Its available optimizer is optimality criteria; the MMA implementation is commented out, with code available by email request.