3D Printing of Parts with Intra-Layer Variable Density

3D Printing can be considered as one of the most innovative manufacturing processes of our time. Part of the innovative potential of 3D Printing is associated with the production of geometrically complex parts in a relatively short time. In the present paper, a methodology for the production of parts with complex internal structure and intra-layer density variability (ILDV) is presented. The proposed methodology may be used to produce structures composed by two materials, such as functionally graded parts and composites. The variability of the internal structure and composition is captured through voxel modeling, where at each voxel a unique relative density value for each material is assigned. These relative density values are then translated to predefined extrusion paths, which the 3D printer follows for the construction of layers composed by one or two materials. Representative cases and examples of parts with ILDV are presented and discussed.

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The modelling and 3D printing of functionally graded foams for tunable crushing performance

10.26226/morressier.5f5f8e69aa777f8ba5bd6152 ◽

2020 ◽

Author(s):

S. Macrae Montgomery

Keyword(s):

3D Printing ◽

Functionally Graded

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The 3D printing and modeling of functionally graded Kelvin foams for controlling crushing performance

Extreme Mechanics Letters ◽

10.1016/j.eml.2021.101323 ◽

2021 ◽

pp. 101323

Author(s):

S. Macrae Montgomery ◽

Haley Hilborn ◽

Craig M. Hamel ◽

Xiao Kuang ◽

Kevin N. Long ◽

...

Keyword(s):

3D Printing ◽

Functionally Graded

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3D‐Printing of Functionally Graded Porous Materials Using On‐Demand Reconfigurable Microfluidics

Angewandte Chemie International Edition ◽

10.1002/anie.201900530 ◽

2019 ◽

Vol 58 (23) ◽

pp. 7620-7625 ◽

Cited By ~ 20

Author(s):

Marco Costantini ◽

Jakub Jaroszewicz ◽

Łukasz Kozoń ◽

Karol Szlązak ◽

Wojciech Święszkowski ◽

...

Keyword(s):

3D Printing ◽

Porous Materials ◽

Functionally Graded ◽

On Demand

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Ceramic-Based 4D Components: Additive Manufacturing (AM) of Ceramic-Based Functionally Graded Materials (FGM) by Thermoplastic 3D Printing (T3DP)

Materials ◽

10.3390/ma10121368 ◽

2017 ◽

Vol 10 (12) ◽

pp. 1368 ◽

Cited By ~ 27

Author(s):

Uwe Scheithauer ◽

Steven Weingarten ◽

Robert Johne ◽

Eric Schwarzer ◽

Johannes Abel ◽

...

Keyword(s):

Additive Manufacturing ◽

3D Printing ◽

Functionally Graded Materials ◽

Functionally Graded ◽

Graded Materials

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The population dynamics of metacercariae of Apatemon gracilis (Trematoda: Digenea) in three species of lake-dwelling leeches

Parasitology ◽

10.1017/s0031182000081221 ◽

1986 ◽

Vol 93 (3) ◽

pp. 517-530 ◽

Cited By ~ 8

Author(s):

S. M. Spelling ◽

J. O. Young

Keyword(s):

Population Dynamics ◽

Relative Density ◽

Sexual Maturity ◽

Egg Production ◽

Seasonal Pattern ◽

Distinct Pattern ◽

The Other ◽

Mean Intensity ◽

Density Values ◽

Host Mortality

SUMMARYMonthly samples of the leeches Erpobdella octoculata, Glossiphonia complanata and Helobdella stagnalis were taken over a two-year period from an eutrophic, English lake to detect metacercariae of the trematode, Apatemon gracilis. In each cohort of each of the three leeches, prevalence was low in young individuals, rose to a peak in autumn/winter, and then declined until the cohort had almost died out; in E. octoculata and H. stagnalis a final brief increase occurred. Mean intensity and relative density values followed a similar seasonal pattern of change to that of prevalence in these last two species, but in G. complanata values fluctuated irregularly with no distinct pattern. The frequency distribution of the parasite in G. complanata was highly over-dispersed, but less so in the other two species. Infected E. octoculata reached sexual maturity. The parasite reduced egg production in G. complanata and H. stagnalis, but only by maximum values of 2·5 and 9% respectively. This reduction in fecundity is low compared to the subsequent high mortality, at 95% or more, of newly recruited young from as yet unidentified causes. Parasite-related host mortality was difficult to assess in young leeches, but there was some evidence for its occurrence in older leeches of E. octoculata and H. stagnalis. However, this is unlikely to play a prominent role in the control and regulation of lacustrine leech populations.

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An Application of Integrated 3D Technologies for Replicas in Cultural Heritage

ISPRS International Journal of Geo-Information ◽

10.3390/ijgi8060285 ◽

2019 ◽

Vol 8 (6) ◽

pp. 285 ◽

Cited By ~ 4

Author(s):

Balletti ◽

Ballarin

Keyword(s):

3D Printing ◽

Cultural Heritage ◽

Laser Scanning ◽

Low Cost ◽

Three Dimensional ◽

Digital Data ◽

Survey Analysis ◽

Critical Issues ◽

Data Acquisition And Processing ◽

Short Time

In recent decades, 3D acquisition by laser scanning or digital photogrammetry has become one of the standard methods of documenting cultural heritage, because it permits one to analyze the shape, geometry, and location of any artefact without necessarily coming into contact with it. The recording of three-dimensional metrical data of an asset allows one to preserve and monitor, but also to understand and explain the history and cultural heritage shared. In essence, it constitutes a digital archive of the state of an artefact, which can be used for various purposes, be remodeled, or kept safely stored. With the introduction of 3D printing, digital data can once again take on material form and become physical objects from the corresponding mathematical models in a relatively short time and often at low cost. This possibility has led to a different consideration of the concept of virtual data, no longer necessarily linked to simple visual fruition. The importance of creating high-resolution physical copies has been reassessed in light of different types of events that increasingly threaten the protection of cultural heritage. The aim of this research is to analyze the critical issues in the production process of the replicas, focusing on potential problems in data acquisition and processing and on the accuracy of the resulting 3D printing. The metric precision of the printed model with 3D technology are fundamental for everything concerning geomatics and must be related to the same characteristics of the digital model obtained through the survey analysis.

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Evaluation of the 3D Printing Accuracy of a Dental Model According to Its Internal Structure and Cross-Arch Plate Design: An In Vitro Study

Materials ◽

10.3390/ma13235433 ◽

2020 ◽

Vol 13 (23) ◽

pp. 5433

Author(s):

Seung-Ho Shin ◽

Jung-Hwa Lim ◽

You-Jung Kang ◽

Jee-Hwan Kim ◽

June-Sung Shim ◽

...

Keyword(s):

3D Printing ◽

Internal Structure ◽

Three Dimensional ◽

In Vitro Study ◽

Thick Shell ◽

Plate Design ◽

Dental Model ◽

3D Printed ◽

Modeling Data

The amount of photopolymer material consumed during the three-dimensional (3D) printing of a dental model varies with the volume and internal structure of the modeling data. This study analyzed how the internal structure and the presence of a cross-arch plate influence the accuracy of a 3D printed dental model. The model was designed with a U-shaped arch and the palate removed (Group U) or a cross-arch plate attached to the palate area (Group P), and the internal structure was divided into five types. The trueness and precision were analyzed for accuracy comparisons of the 3D printed models. Two-way ANOVA of the trueness revealed that the accuracy was 135.2 ± 26.3 µm (mean ± SD) in Group U and 85.6 ± 13.1 µm in Group P. Regarding the internal structure, the accuracy was 143.1 ± 46.8 µm in the 1.5 mm-thick shell group, which improved to 111.1 ± 31.9 µm and 106.7 ± 26.3 µm in the roughly filled and fully filled models, respectively. The precision was 70.3 ± 19.1 µm in Group U and 65.0 ± 8.8 µm in Group P. The results of this study suggest that a cross-arch plate is necessary for the accurate production of a model using 3D printing regardless of its internal structure. In Group U, the error during the printing process was higher for the hollowed models.

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Bend Testing of Parts Made by Rapid Prototyping with Respect to Possible Use in Robotics

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.760.141 ◽

2015 ◽

Vol 760 ◽

pp. 141-146 ◽

Cited By ~ 3

Author(s):

Jan Lipina ◽

Václav Krys ◽

Jiří Marek

Keyword(s):

3D Printing ◽

Rapid Prototyping ◽

Experimental Determination ◽

Internal Structure ◽

Detailed Knowledge ◽

3D Printer ◽

Bend Strength ◽

Bend Testing ◽

Material Parameters

Recently, the Rapid Prototyping technology (RP hereafter) has been increasingly used for a final product, which requires detailed knowledge of designing parts made by the RP technology. In order to apply parts made by the RP technology in robotics, and design in general, in a wider range, one of the most important material parameters is their bend strength. The paper describes an experimental determination of bend strength in parts printed on a 3D printer. The parts were made of polycarbonate. The tests were carried out in parts with various types of internal structure. The achieved results can be implemented when designing parts made by 3D printing provided that professional printers are used.

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Fracture Behavior of Bio-Inspired Functionally Graded Soft–Hard Composites Made by Multi-Material 3D Printing: The Case of Colinear Cracks

Materials ◽

10.3390/ma12172735 ◽

2019 ◽

Vol 12 (17) ◽

pp. 2735 ◽

Cited By ~ 7

Author(s):

Mirzaali ◽

Nava ◽

Gunashekar ◽

Nouri-Goushki ◽

Doubrovski ◽

...

Keyword(s):

3D Printing ◽

Transition Zone ◽

Digital Image ◽

Fracture Resistance ◽

Fracture Behavior ◽

Functionally Graded ◽

Image Correlation ◽

High Tech ◽

Fracture Properties ◽

Gradient Function

The functional gradient is a concept often occurring in nature. This concept can be implemented in the design and fabrication of advanced materials with specific functionalities and properties. Functionally graded materials (FGMs) can effectively eliminate the interface problems in extremely hard–soft connections, and, thus, have numerous and diverse applications in high-tech industries, such as those in biomedical and aerospace fields. Here, using voxel-based multi-material additive manufacturing (AM, = 3D printing) techniques, which works on the basis of material jetting, we studied the fracture behavior of functionally graded soft–hard composites with a pre-existing crack colinear with the gradient direction. We designed, additively manufactured, and mechanically tested the two main types of functionally graded composites, namely, composites with step-wise and continuous gradients. In addition, we changed the length of the transition zone between the hard and soft materials such that it covered 5%, 25%, 50%, or 100% of the width (W) of the specimens. The results showed that except for the fracture strain, the fracture properties of the graded specimens decreased as the length of the transition zone increased. Additionally, it was found that specimens with abrupt hard–soft transitions have significantly better fracture properties than those with continuous gradients. Among the composites with gradients, those with step-wise gradients showed a slightly better fracture resistance compared to those with continuous gradients. In contrast, FGMs with continuous gradients showed higher values of elastic stiffness and fracture energy, which makes each gradient function suitable for different loading scenarios. Moreover, regardless of the gradient function used in the design of the specimens, decreasing the length of the transition zone from 100%W to 5%W increased the fracture resistance of FGMs. We discuss the important underlying fracture mechanisms using data collected from digital image correlation (DIC), digital image microscopy, and scanning electron microscopy (SEM), which were used to analyze the fracture surface.

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