Support-free hollowing with spheroids and efficient 3D printing utilizing circular printing motions based on Voronoi diagrams

Choi, Seung-Hwan; Ryu, Joonghyun; Lee, Mokwon; Cha, Jehyun; Kim, Hyun Woo; Song, Chung Kil; Kim, Deok-Soo

doi:10.1016/j.addma.2020.101254

Cited by 12 publications

(10 citation statements)

References 60 publications

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“…The Voronoi diagram is a powerful computational geometry concept with numerous applications in science and engineering [17,18]. Voronoi diagrams of circles and ellipses are a well-investigated topic because the cross-sections of many natural and industrial objects are circular or elliptical, including fibers.…”

Section: Voronoi Diagram Of Circles and Ellipsesmentioning

confidence: 99%

A Voronoi diagram approach for detecting defects in 3D printed fiber-reinforced polymers from microscope images

McMains

2022

Comp. Visual Media

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Fiber-reinforced polymer (FRP) composites are increasingly popular due to their superior strength to weight ratio. In contrast to significant recent advances in automating the FRP manufacturing process via 3D printing, quality inspection and defect detection remain largely manual and inefficient. In this paper, we propose a new approach to automatically detect, from microscope images, one of the major defects in 3D printed FRP parts: fiber-deficient areas (or equivalently, resin-rich areas). From cross-sectional microscope images, we detect the locations and sizes of fibers, construct their Voronoi diagram, and employ α-shape theory to determine fiber-deficient areas. Our Voronoi diagram and α-shape construction algorithms are specialized to exploit typical characteristics of 3D printed FRP parts, giving significant efficiency gains. Our algorithms robustly handle real-world inputs containing hundreds of thousands of fiber cross-sections, whether in general or non-general position.

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Section: Voronoi Diagram Of Circles and Ellipsesmentioning

confidence: 99%

A Voronoi diagram approach for detecting defects in 3D printed fiber-reinforced polymers from microscope images

McMains

2022

Comp. Visual Media

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“…Reducing support structures can be formulated as a constraint in topology optimization (Mirzendehdel and Suresh, 2016). Similarly, there is also flexibility to design support-free hollowing (Wang et al , 2018; Choi et al , 2020) during the generation of internal structures. When the model cannot be altered anymore and needs to be printed as is, advanced manufacturing techniques could be applied to print the part without supports.…”

Section: Literature Reviewmentioning

confidence: 99%

Escaping Tree-Support (ET-Sup): minimizing contact points for tree-like support structures in additive manufacturing

Kwok

2021

RPJ

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Purpose Support structures are often needed in additive manufacturing (AM) to print overhangs. However, they are the extra materials that must be removed afterwards. When the supports have many contacts to the model or are even enclosed inside some concavities, removing them is very challenging and has a risk of damaging the part. Therefore, the purpose of this paper is to develop a new type of tree-support, named Escaping Tree-Support (ET-Sup), which tries to build all the supports onto the build plate to minimize the number of contact points. Design/methodology/approach The methodology is to first classify the support points into three categories: clear, obstructed and enclosed. A clear point has nothing between it and the build plate; an obstructed point is not clear, but there exists a path for it to reach the build plate; and an enclosed point has no way to reach the build plate. With this classification, the path for the obstructed points to come clear can be found through linking them to the clear points. All the operations are performed efficiently with the help of a ray representation. Findings The method is tested on different overhang features, including a lattice ball and a mushroom shape with a concave cap. All the supports generated for the examples can find their way to the build plate, which looks like they are escaping from the model. The computation time is around one second for these cases. Originality/value This is the first time truly realizing this “escaping” property in the generation of tree-like support structures. With this ET-Sup, it is expected that the AM industries can reduce the manufacturing lead time and save much labor work in post-processing.

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“…The extruder is placed on a three-dimensional CNC table that moves in the x, y and z directions and places the molten polymer inside the extruder on the part [31,32]. After nishing one layer, the extruder moves upwards as thick as one layer [33][34][35][36][37]. It is important to note that many parameters affect the quality and nal properties of a sample printed with FDM [38][39][40][41][42].…”

Section: Introductionmentioning

confidence: 99%

Effect of different parameters on the tensile properties of printed Polylactic acid samples by FDM: experimental design tested with MDs simulation

Farazin

Mohammadimehr

2021

Int J Adv Manuf Technol

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Fused Depositional Modeling (FDM) is one of the common methods for 3D printing of polymers, which is expanding in various industrial applications, scienti c researches, and engineering applications due to its ability to make complex parts. In this research, molecular dynamics (MDs) simulation has been used to predict the physical and mechanical properties. Then, the mechanical properties of the printed parts are obtained. The mechanical properties of 3D printed parts strongly depend on the correct selection of processing parameters. In this study, the effect of three important parameters such as in ll density, printing speed, and layer thickness are investigated on the tensile properties of PLA specimens. For this purpose, standard specimens with four in ll densities of 20%, 40%, 60% and 80%, two speeds of 20 mm/s, and 40 mm/s, and two thicknesses of 0.1 mm and 0.2 mm are printed and tested under quasistatic tensile test. In all printed specimens, the print angle is ± 45°. The experimental results show that the in ll density in comparison to the other two parameters has signi cant effect on mechanical properties such as modulus of elasticity, ultimate strength, and failure strain. According to these results, by increasing the in ll density, the stiffness and strength of the specimens increases considerably. At in ll density of 80%, the specimens has the highest stiffness and strength, but it exhibits a brittle behavior. Moreover, it can be deduced that by reducing the layer thickness although the modulus of elasticity increases a little, ductility is greatly affected.

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Support-free hollowing with spheroids and efficient 3D printing utilizing circular printing motions based on Voronoi diagrams

Cited by 12 publications

References 60 publications

A Voronoi diagram approach for detecting defects in 3D printed fiber-reinforced polymers from microscope images

A Voronoi diagram approach for detecting defects in 3D printed fiber-reinforced polymers from microscope images

Escaping Tree-Support (ET-Sup): minimizing contact points for tree-like support structures in additive manufacturing

Effect of different parameters on the tensile properties of printed Polylactic acid samples by FDM: experimental design tested with MDs simulation

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