Material Characterization of Additive Manufactured Fiber Reinforced Thermoplastic

Open Access
Author:
Haluza, Rudy
Area of Honors:
Engineering Science
Degree:
Bachelor of Science
Document Type:
Thesis
Thesis Supervisors:
  • Charles E Bakis, Thesis Supervisor
  • Charles E Bakis, Honors Advisor
  • Alicyn Marie Rhoades, Faculty Reader
Keywords:
  • Carbon
  • Fiber
  • 3D
  • Printing
  • Additive
  • Whisker
  • Material
  • Tensile
  • Elastic
  • Modulus
  • Finite
  • Element
  • FEA
  • SEM
  • TGA
  • Cox
  • Halpin
  • Microscopy
Abstract:
Additive manufacturing, especially in regards to 3D printing, is a burgeoning field that has revolutionized the way we design and manufacture parts. Combining 3D printing with the benefits gained from using strong and lightweight composite materials presents new potentials for numerous varieties of structures. This thesis project aims to test and model the mechanical properties of a thermoplastic PLA and carbon whisker composite used for a type of 3D printing called Fused Deposition Modelling. Tensile testing is performed on several samples to measure the elastic moduli of unprinted samples, as well as several solid and semi-hollow printed samples. The semi-hollow samples consist of a solid perimeter around the sides and solid shells on top and bottom which enclose a core that can vary according to infill patterns and infill densities. The project’s modelling aspect involves creating a combination of finite element analysis (FEA) and rule of mixtures (ROM) to predict the elastic modulus of semi-hollow samples with given infill patterns and infill densities. Additionally, composites models such as the Cox and Halpin-Tsai models are utilized to predict the modulus of solid specimens such as solid unidirectional printed parts and unprinted filament material. For these models, optical and scanning electron microscopy, density measurements, and thermogravimetric analysis were used to determine fiber geometry and fiber volume fraction. Using parameters found in literature or through material characterization, the FEA models created slightly over-predicted the experimental results of the infilled specimens, while the Cox and Halpin-Tsai models, as well as the SEM micrographs, showed partial alignment in both printed and unprinted samples.