Document Type

Thesis - Open Access

Award Date


Degree Name

Master of Science (MS)


Mechanical Engineering

First Advisor

Todd Letcher


Studies have been done involving the use of carbon fiber as a reinforcement for three dimensional (3D) printed parts. The Markforged Mark Two is a commercial grade 3D printer capable of printing parts reinforced with continuous fibers such as carbon fiber, Kevlar, and fiberglass. Short Carbon Fiber Composite tensile specimen were printed on both a Markforged Mark Two and Flashforge Creator Pro using Markforged Onyx filament. The results of these parts were compared for their tensile properties, dimensional accuracy, and mass estimates. The Creator Pro was capable of producing stronger parts on average, while the Mark Two produced more dimensionally accurate parts. Parts printed with the Creator Pro achieved higher Ultimate Tensile Strengths and Elastic Moduli than their respective Mark Two counterparts on average. Various analytical models were employed to estimate the Elastic Modulus of these parts printed at 100% infill. The Modified Rule of Mixtures Model was found to be the most accurate estimate of these short fiber composites. Continuous Carbon Fiber Composite tensile specimen were printed with a Markforged Mark Two. Various Carbon Fiber orientations and layer proximities were tested and their effects on Tensile Strength and Modulus of Elasticity were examined. A Volume Average Stiffness (VAS) model was also used to predict the elastic properties of these 3d-printed specimen. Tensile Testing of the 3d-printed specimen showed that material properties were directly related to the number of carbon fiber strands loaded in tension within the part, and that the increase in these material properties was linear. Impact specimen were printed with a Markforged Mark Two. Both short/discontinuous and long continuous carbon fiber specimen were printed. For the Continuous fiber specimen, effects of part orientation, number of carbon fiber layers, and carbon fiber layer proximity were studied. For short fiber specimen, layer height and material infill raster angles were studied.


Includes bibliographical references (pages 118-121)



Number of Pages



South Dakota State University


In Copyright - Educational Use Permitted