Multiscale Material Modeling of Additively Manufactured Composite Laminates

Additive manufacturing (AM) technology has revolutionized the production of structural parts for many industries. AM methods enable freedom in design of a part and furthermore, make it easier to fabricate a part with tailored microstructure to yield desired mechanical properties. Despite many other benefits, anisotropy in the material properties of 3D printed parts remains of primary concern. Anisotropy is introduced into parts during the printing process. This calls for the need to investigate the material behaviour of printed parts at different scales to enable the effective design and analysis of models for 3D printing. The present work therefore focuses on addressing the material behaviour of 3D printed parts via fused filament fabrication (FFF), a material extrusion AM process. Four aspects of the problem are accordingly examined. First, the material behaviour of printed parts with different materials is assessed by conducting mechanical testing. Second, the mechanical behaviour of printed parts is characterized using laminate mechanics. Furthermore, the microstructure of printed parts is characterized, and its influence on the final properties is investigated. Third, computational micromechanical models are employed to estimate the final material properties of printed parts based on the underlying mesostructure. Finally, the computational models are employed to perform damage analysis of printed parts. The research work revealed that the final material behavior of printed parts was governed by their mesostructure, which was produced during 3D printing process. The behavior of printed parts resembled that of traditional laminates and therefore, the laminate mechanics can be employed in preliminary design and analysis. Computational models predicted accurate final properties of parts by considering their mesostructure, and also their nonlinear behavior under loads. The computational damage model that employed bulk material properties provided ideal material behavior and the other damage model that used results of unidirectional laminates provided actual material behavior of printed parts. In summary, this work presents a processstructureproperty relationship for 3D printed parts, and also outlines the mechanics of the material to characterize the mechanical behaviour of the printed parts. Finally, computational models are developed for the effective design and analysis of models for 3D printing.