Publication Date


Document Type


First Advisor

Sinko, Robert

Degree Name

M.S. (Master of Science)

Legacy Department

Department of Mechanical Engineering


Laminates are a class of composite materials in which several unidirectional laminae are stacked together to create a material with a clear layer-by-layer architecture. Traditionally, each lamina is itself a composite consisting of aligned fibers, such as cellulose, graphite, or glass, embedded within a polymer, ceramic, or metal host matrix. These materials are unique in the sense that their engineering properties can be greatly varied simply by changing the stacking order of lamina within the laminate. While there are several traditional manufacturing approaches for laminates, recent research has focused on assessing the feasibility of using additive manufacturing techniques to create these materials. Additive manufacturing, commonly referred to as 3D printing, is one of the most innovative technologies for manufacturing polymer and metal components. Replicating a traditional laminate using these manufacturing approaches, however, would require 3D printing two materials simultaneously. Although this is possible, in this work we instead aim to investigate the ability to impart laminate-like behavior (i.e. tunability of mechanical properties through changing internal material architecture) to a homopolymer sample. Our hypothesis is that the tunable mechanical properties of laminates are inherent to the underlying layer-by-layer structure rather than the composite nature and can thereby be captured using 3D printing of a single material. In order to evaluate the hypothesis, this work tests the mechanical properties of a 3D-printed dog-bone samples with an underlying bioinspired, layer-by-layer architecture fabricated from polylactic acid (PLA). Fused deposition modeling (FDM) is used to create the PLA samples, which will focus on determining the effect of pitch angle and infill percentage on the resulting mechanical properties. The pitch angle, here referring to the relative angle between alignment of “fibers” in adjacent layers, tested here range from 0° - 180° while the infill percentages examined are 30% and 50%. Tensile tests were performed on the samples up to the failure point to obtain values of the elastic modulus, ultimate tensile strength, and toughness. Experimental results have shown that there is a clear relationship between the mechanical properties and pitch angle as well as a clear dependence on pitch angle. Further, we demonstrate that these experimental trends are in good agreement with classical lamination theory and provide evidence that we can effectively create a structure that exhibits laminate-like mechanical behavior using additive manufacturing techniques of a single material.


56 pages




Northern Illinois University

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