Analyzing the topological properties of 3D STL files

UNCG Author/Contributor (non-UNCG co-authors, if there are any, appear on document)
Sahil Dhawan (Creator)
Institution
The University of North Carolina at Greensboro (UNCG )
Web Site: http://library.uncg.edu/
Advisor
Thomas Weighill

Abstract: Part features in 3D objects that are created for the purpose of rapid prototyping and fabrication using methods such as 3D printing or CNC milling often do not match the measurements of the finished product’s features due to tolerancing and clearance design errors. A solution to measuring the range of potential error that the features of a part can have can be found through the topology and persistent homology of the chosen truth mesh of that part. Variations of the part feature(s) to be measured, such as different diameters of a hole, can be created with a sequence of 3D object files that change the measurements of the selected feature(s) while keeping other features the same. We use FreeCAD to generate these part variations and export them as ASCII STL files. A new mesh is created for each of these files to convert them to Delaunay triangulations. We use the Delaunay triangulation mesh in tandem with the filtered simpliicial complex generated by the Alpha complex. The Alpha complex is modified so all its matching simplicies that were present in the Delaunay triangulation mesh have a birth time of 0 for accurate analysis using persistent homology. We then generate a persistence diagram for each variation of the 3D part feature to see the progression of change in topology for the chosen feature with respect to the chosen truth 3D STL file. Our results show the potential errors of features in a 3D STL file can be calculated through the topology of part variations which represent different measurements in tolerance and clearance.

Additional Information

Publication
Thesis
Language: English
Date: 2024
Keywords
Computer-Aided Design, Delaunay, Persistent Homology, STL, Topological Data Analysis, Topology
Subjects
Three-dimensional modeling
Computer-aided design
Mathematical analysis
Topology

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