Predicting and Validating Composite Mechanical Behavior Resulting from Voxel-based Microstructural Design and Macroscopic Interfacial Analysis
Restricted (Penn State Only)
- Author:
- Nalubwama Kaweesa, Dorcas Vivian
- Graduate Program:
- Mechanical Engineering
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- November 03, 2021
- Committee Members:
- Nicholas Meisel, Chair & Dissertation Advisor
Timothy Simpson, Major Field Member
Allison Beese, Major Field Member
Michael Hickner, Outside Unit & Field Member
Daniel Haworth, Professor in Charge/Director of Graduate Studies - Keywords:
- Multi-material Additive Manufacturing
PolyJet process
Material design
Composites
Composite laminates
Functionally Graded Materials
Voxel-based design
voxels
Mechanical properties - Abstract:
- Within AM, researchers and designers have mainly focused on the geometric aspect of AM with regards to manufacturing complex geometries, analyzing geometric accuracy, and enabling multi-functionality. Material complexity which enables the creation of parts with varying material compositions and thus, different material property gradients has not been extensively explored. Equal consideration of both geometric and material complexity is essential in the holistic design and manufacturing of complex geometries with varying material compositions. Recent technological advancements in AM’s material complexity and layer-wise material deposition opportunities have introduced the concept of multi-material AM. Multi-material AM allows the fabrication of complex and multifunctional parts with heterogeneous material compositions and varying mechanical properties. Specifically, the material jetting AM process is capable of fabricating multi-material composite structures in a single build using voxel-based design techniques. The variation of different materials along a specified volume within a part’s geometry allows the creation of functionally graded materials (FGMs). Due to the heterogeneous nature of composite structures with FGMs, extensive material design methods are required to understand how FGMs behave through discrete regions at the microscale and macroscale. The research presented herein explores the design and manufacturability of custom-designed composite structures featuring two-phase material compositions of a rigid polymer material and a flexible polymer material. A voxel-based design dithering approach was explored to demonstrate an applicable design method for digital composite structures. Furthermore, the mechanical properties of voxel-based composite structures considering microstructural design decisions and the macroscopic behavior of composite laminates were predicted using micromechanical theoretical models and a computational simulation approach respectively. Experimental demonstrations were performed to validate both theoretical and computational models and demonstrate the importance of predicting the behavior of composite structures prior to fabrication to ensure quality structural performance.