Graduation Semester and Year
Summer 2025
Language
English
Document Type
Dissertation
Degree Name
Doctor of Philosophy in Mechanical Engineering
Department
Mechanical and Aerospace Engineering
First Advisor
Dr. Ankur Jain
Abstract
ABSTRACT
Experimental and Numerical Modeling-Based Optimization of Additive Manufacturing Processes
Vishnu V Ganesan, Ph.D.
The University of Texas at Arlington, 2025
Supervising Professor: Dr. Ankur Jain
Experimental and numerical modeling play a pivotal role in advancing additive manufacturing technologies by enabling a deeper understanding of complex, multi-physics processes that govern part quality, performance, and reliability. These manufacturing techniques—ranging from Powder Bed Fusion (PBF) and Material Extrusion (MEX) to Automated Fiber Placement (AFP)—involve tightly coupled thermal, mechanical, and material phenomena that are challenging to capture through empirical observation alone. Experimental methods offer critical validation and insights into real-world behavior, while numerical models enable systematic exploration of process parameters, uncover underlying mechanisms, and predict performance under varying conditions. The synergy between experimentation and modeling is thus indispensable for driving precision, repeatability, and scalability in modern additive manufacturing systems.
The first segment of this dissertation focuses on Discrete Element Modelling (DEM) simulations to understand and improve powder packing density in metal additive manufacturing. A novel powder compaction technique using horizontal compactors is proposed, which enhances bed densification while reducing stress transfer to previously printed layers. DEM simulations predict void fraction distributions across various process parameters and particle counts, demonstrating strong agreement with existing studies. Further, heterogeneous powder configurations involving two- and three-size particle systems are analyzed, showing that stacking smaller particles beneath larger ones yields denser beds. A rotating churner mechanism is also examined, where granular convection driven by rotation improves layer uniformity, with an optimal speed identified based on competing physical mechanisms. These insights provide valuable design guidelines for improving powder bed quality in PBF and related technologies.
In the second segment, an experimental study investigates fracture toughness improvement in polymer parts fabricated by Material Extrusion using an in situ heated compression roller. Poly-Lactic Acid (PLA) samples with center cracks and varying raster orientations are tested under tensile loading. The results show that the use of a compression roller significantly improves tensile strength—from 6.0 MPa to 20.7 MPa for circular notch samples—while also altering the dominant failure modes. High-speed imaging and microscopy reveal the interplay between crack geometry, raster direction, and failure behavior, offering insight into both fracture-driven and interface-driven mechanisms.
The final segment presents an integrated experimental and numerical approach to study heat transfer mechanisms in Automated Fiber Placement (AFP). A transient model with a moving heat source is developed using experimentally measured heat flux data, applied to a CF-PAEK panel across a range of scan speeds and lamp powers. The model incorporates temperature-dependent thermal properties and shows good agreement with infrared thermographic measurements. Additionally, a two-fluid plug flow model is introduced to simulate steady-state thermal transport between the heated substrate and composite tow. This model captures anisotropic thermal behavior, curvilinear geometry, and interface coupling, offering a predictive framework for thermal management and process optimization in AFP.
The experimental and numerical models developed in this dissertation are expected to contribute towards the optimization, reliability, and performance enhancement of additive manufacturing processes involving powder bed fusion, material extrusion, and automated fiber placement technologies.
Keywords
Additive Manufacturing, Discrete Element Modelling, Finite Element Modelling, IR camera, Powder Bed Fusion, Fused Filament Fabrication, Automated Fiber Placement
Disciplines
Heat Transfer, Combustion | Manufacturing
License
This work is licensed under a Creative Commons Attribution 4.0 International License.
Recommended Citation
Ganesan, Vishnu V., "EXPERIMENTAL AND NUMERICAL MODELLING-BASED OPTIMIZATION OF ADDITIVE MANUFACTURING PROCESSES" (2025). Mechanical and Aerospace Engineering Dissertations. 433.
https://mavmatrix.uta.edu/mechaerospace_dissertations/433