Date of Award
Spring 5-3-2024
Level of Access Assigned by Author
Open-Access Thesis
Degree Name
Master of Science (MS)
Department
Mechanical Engineering
Advisor
Bashir Khoda
Second Committee Member
Masoud Rais-Rohani
Third Committee Member
Senthil S. Vel
Abstract
In this work a novel functionally graded infill method, VS-VE, is proposed. This method allows for any density based optimized topology to be post-processed and realized as an optimized lattice that inherently ensures manufacturability and avoids any complex geometric modeling. The algorithm proposed for realizing this functionally graded infill achieves this in two steps: variation of extrusion line spacing and width of the standard rectilinear infill pattern. The g-code for the structure is generated directly rather than first creating a complex 3D model which then must be sliced. To evaluate the feasibility and effectiveness of the proposed algorithm three experiments were performed. In the first, the manipulation of the center of gravity of a simple square region was investigated. Various density distributions with known centers of gravity were created using VS-VE. The theoretical and measured centers of gravity were compared. It was found that the VS-VE algorithm was able to reproduce a density distribution with an accuracy ranging from 3% to 10%. The other two experiments focused on optimization of a beam under two support conditions. In one experiment, the beam was placed under a simply supported 3-point bending load case and optimized for stiffness. It was then compared to a homogenous infill beam of the same relative density. For most cases, the VS-VE algorithm produced beams that were stiffer, except for the beams with a local density below 10% in which a bucking failure mode occurred. As the topology optimization that generated the density distribution does not account for this failure mode, it was concluded that the reduced stiffness was caused by the limitations of the optimization problem and not the VS-VE algorithm. Finally, an optimization for modal response was performed for a cantilever beam with the goal of maximizing its fundamental natural frequency. The results were post-processed using the VS-VE algorithm as well as the traditional shape generating method. The purpose was to show the advantage of VS-VE over an optimized shape generated from the same optimization results. Measurements showed that VS-VE had double the natural frequency of the optimized shape in most cases and at least matched performance. The feasibility and advantage of the proposed algorithm are demonstrated and discussed.
Recommended Citation
Murphy, Patrick, "A Novel Functionally Graded Infill Method for Realizing Topology Optimization for Additive Manufacturing" (2024). Electronic Theses and Dissertations. 3992.
https://digitalcommons.library.umaine.edu/etd/3992