Investigation of Traditional and Alternate Living Hinge Designs for Fused Deposition Modeling Additive Manufacturing Process

A manuscript-style thesis composed of three studies covered the application of living hinge designs in the additive manufacturing process of fused deposition modeling. Initial research included comparing numerical and analytical linear analyses on a traditional living hinge design. The second research consisted of tensile testing for the material properties of the Acrylonitrile Butadiene Styrene (ABS) used in fused deposition modeling (FDM) process by the MakerBot 2X as well as adjusting the traditional design to be printed. The third study explored alternate living hinge designs that utilize the geometric freedom provided by additive manufacturing to more evenly distribute stress across the hinge. The traditional living hinge design is not feasible for FDM ABS while alternate designs such as a longer hinge length or wave pattern demonstrated minimal stress experienced across the hinge. Further research on optimizing alternate designs is encouraged

From 3D Models to 3D Prints: an Overview of the Processing Pipeline

Due to the wide diffusion of 3D printing technologies, geometric algorithms for Additive Manufacturing are being invented at an impressive speed. Each single step, in particular along the Process Planning pipeline, can now count on dozens of methods that prepare the 3D model for fabrication, while analysing and optimizing geometry and machine instructions for various objectives. This report provides a classification of this huge state of the art, and elicits the relation between each single algorithm and a list of desirable objectives during Process Planning. The objectives themselves are listed and discussed, along with possible needs for tradeoffs. Additive Manufacturing technologies are broadly categorized to explicitly relate classes of devices and supported features. Finally, this report offers an analysis of the state of the art while discussing open and challenging problems from both an academic and an industrial perspective.Comment: European Union (EU); Horizon 2020; H2020-FoF-2015; RIA - Research and Innovation action; Grant agreement N. 68044

Thermal and Mechanical Numerical Modeling of Extrusion-based 3d Printed Reinforced Polymers for Selecting Manufacturing Process Parameters

Extrusion-based 3D printing of thermoplastic polymer composites manufactures parts that have nonhomogenous, orthotropic, and process-dependent macro-scale material properties. As a part of the dissertation, research works were carried out to: • improve the interlayer mechanical properties and reduce the orthotropy, • use experimentally homogenized orthotropic material properties to numerically model the mechanical behavior of the non-homogenous orthotropic 3D printed parts, • create an efficient numerical thermal model to predict the process-dependent thermal history of the 3D printed part, and • aid the manufacturing process by selecting a suitable set of processing parameters based on a simplified sequentially coupled thermomechanical model. The dissertation presents four studies that improve the understanding of the mechanical behavior and aid the manufacturing process of the 3D printed thermoplastic polymer composites. Three journal publications that resulted from the research work carried out are listed below: • Bhandari, S., Lopez-Anido, R. A., & Gardner, D. J. (2019). Enhancing the interlayer tensile strength of 3D printed short carbon fiber reinforced PETG and PLA composites via annealing. Additive Manufacturing, 30, 100922. iii • Bhandari, S., Lopez-Anido, R.A., Wang, L. et al. (2020). Elasto-Plastic Finite Element Modeling of Short Carbon Fiber Reinforced 3D Printed Acrylonitrile Butadiene Styrene Composites. JOM 72, 475– 484. • Bhandari, S.; Lopez-Anido, R.A. (2020). Discrete-Event Simulation Thermal Model for Extrusion-Based Additive Manufacturing of PLA and ABS. Materials, 13, 4985