Overview

This package converts density-based topology optimization results (from SIMP method) into smooth geometry defined by Signed Distance Functions (SDFs). The transformation precisely preserves the volume of the original optimized structure while eliminating jagged boundaries and intermediate density regions, making the resulting geometry suitable for manufacturing and further analysis.

Installation

# From Julia REPL, press ] to enter package mode
add https://github.com/kopacja/rho2sdf.jl

Or clone the repository and set up the environment:

git clone https://github.com/kopacja/rho2sdf.jl.git
cd rho2sdf.jl
julia --project=. -e "using Pkg; Pkg.instantiate()"

Then activate the project in Julia:

using Pkg
Pkg.activate(".")
using Rho2sdf

Quick Start

using rho2sdf

# Basic usage with default options
result = rho2sdf("example", X, IEN, rho)

# Custom configuration
options = Rho2sdfOptions(
    threshold_density=0.5,
    sdf_grid_setup=:automatic,
    export_nodal_densities=true
)
result = rho2sdf("example", X, IEN, rho, options=options)

Main Function

rho2sdf(taskName, X, IEN, rho; options=Rho2sdfOptions())

Parameters:

• taskName::String: Base name for output files
• X::Vector{Vector{Float64}}: Mesh node coordinates
• IEN::Vector{Vector{Int64}}: Element connectivity
• rho::Vector{Float64}: Element densities
• options::Rho2sdfOptions: Configuration options (optional)

Returns:

• Tuple: (fine_sdf, fine_grid, sdf_grid, sdf_dists)
• Exports .vti files for ParaView visualization

Configuration Options

Rho2sdfOptions(;
    threshold_density=nothing,          # Density threshold for isosurface (auto if nothing)
    sdf_grid_setup=:manual,            # :manual or :automatic grid setup
    export_input_data=false,           # Export input data to VTU
    export_nodal_densities=false,      # Export nodal densities to VTU
    export_raw_sdf=false,             # Export raw SDF to VTI
    rbf_interp=true,                  # Use RBF interpolation/approximation
    rbf_grid=:same,                   # :same or :fine grid resolution
    remove_artifacts=true,            # Remove small disconnected components
    artifact_min_component_ratio=0.01, # Minimum size ratio for components
    export_analysis=false,            # Export analysis files
    element_type=HEX8                 # Element type (HEX8 or TET4)
)

Element Type Support

The package supports both hexahedral and tetrahedral elements:

# For hexahedral elements (default)
result = rho2sdf_hex8("example", X, IEN, rho)

# For tetrahedral elements
result = rho2sdf_tet4("example", X, IEN, rho)

Test Cases

Release 0.1.0 includes test cases (test_cases.zip) covering:

• SDF validation with geometric primitives
• Grid resolution convergence studies
• Engineering applications (cantilever beam, robot gripper)

Run tests with:

julia --project=. test_cases/run_all_test_cases.jl

Output Files

The package generates several output files for analysis and visualization:

• .vti files: Structured SDF data for ParaView
• .vtu files: Unstructured mesh data with density fields
• .jld2 files: Julia data for post-processing

Requirements

• Julia LTS (1.10.10)
• Dependencies are automatically managed by the package manager