Quantifying the Impact of Functionally Graded Materials on the Fatigue Life of Material Jetted Specimens

Open Access
Kaweesa, Dorcas Vivian
Graduate Program:
Mechanical Engineering
Master of Science
Document Type:
Master Thesis
Date of Defense:
October 12, 2017
Committee Members:
  • Nicholas A. Meisel, Thesis Advisor
  • Functionally Graded Materials
  • Fatigue Life
  • Continuous Gradients
  • Discrete Gradients
  • Additive Manufacturing
  • Multi-materials
  • PolyJet Process
The capability of Additive Manufacturing (AM) to process multiple materials allows the fabrication of complex and multifunctional parts with varying mechanical properties. Multi-material AM involves the fabrication of 3D printed objects with multiple heterogeneous material compositions. The material jetting AM process, specifically the PolyJet process, has the capacity and capability to manufacture multi-material structures with both rigid and flexible material properties. Existing research has investigated the fatigue properties of 3D printed multi-material specimens and shows that there is a weakness at the multi-material interface. This research seeks to investigate the effects of material gradient transitions on the fatigue life and failure predictability of 3D printed multi-material specimens given (1) a constant volume or (2) a constant length of a flexible material. In order to analyze the fatigue life at the material interface, discrete material gradients are compared against continuous material gradients created through voxel-level design. Furthermore, individual material composites are analyzed in relation to their material properties. Results demonstrate the effects of material gradient transitions on the fatigue life as well as the qualitative material properties of the continuous and discrete material gradients. In addition, results from studying individual material composites helps understand the effect of different material gradients on material properties of multi-material parts.