scholarly journals Voxel based method for predictive modelling of solidification and stress in digital light processing based additive manufacture

Soft Matter ◽  
2021 ◽  
Author(s):  
Andrew Reid ◽  
Joseph C. Jackson ◽  
J. F. C. Windmill
Keyword(s):  
Predictive Modelling ◽  
Degree Of Polymerization ◽  
Additive Manufacture ◽  
Layer Model ◽  
Digital Light Processing ◽  
3D Print ◽  
Print Process

A method for predicting the solidification and stress of a digital light processing 3D print process is presented, using a voxel-based, multi-layer model to predict the degree of polymerization of the material at every stage during the print.

Design for Additive Manufacture of Fine Medical Instrumentation—DragonFlex Case Study

2015 ◽  
Vol 137 (11) ◽  
Author(s):  
Filip Jelínek ◽  
Paul Breedveld
Keyword(s):  
Medical Device ◽  
Ceramic Composite ◽  
Design Stage ◽  
Additive Manufacture ◽  
Digital Light Processing ◽  
Advantages And Disadvantages ◽  
Material Choice ◽  
Superior Mechanical Properties ◽  
High Flexibility ◽  
Printing Processes

The recently popularized domain of additive manufacturing (AM) has much to offer to medical device development, especially to the growing field of minimally invasive surgery (MIS). With the advancements in AM materials, one could soon envision materializing not only the proofs of concept but also the final clinically approved instruments. DragonFlex—the world's first AM steerable MIS instrument prototype—was recently devised with the aim to follow this vision. Apart from the medical device design restrictions, several limitations of AM materials and processes had to be considered. The aim of this paper is to present these insights to those opting for this means of manufacture, serving as a helpful design and material guide. Over the course of its development, DragonFlex has gone through four design generations so far, each differing in the AM material and process used. Due to being a prototype of a MIS instrument of miniature dimensions, the printing processes were limited to stereolithography (SLA), as to achieve the best possible precision and accuracy. Each SLA process and material brought along specific advantages and disadvantages affecting the final printout quality, which needed to be compensated for either at the design stage, during, or after printing itself. The four DragonFlex generations were printed using the following SLA techniques and materials in this order: polymer jetting from Objet VeroBlue™; SLA Digital Light Processing™ (DLP) method from EnvisionTEC® NanoCure RCP30 and R5; conventional SLA from 3D Systems Accura® 60; and DLP based SLA process from a ceramic composite. The material choice and the printing orientation were found to influence the final printout accuracy and integrity of thin features, as well as material's postproduction behavior. The polymeric VeroBlue™ proved structurally sound, although suffering from undermined accuracy and requiring postprocessing, hence recommended for prototyping of upscaled designs of looser manufacturing tolerances or overdimensioned experimental setups. The NanoCure materials are capable of reaching the best accuracy requiring almost no postprocessing, thus ideal for prototyping small intricate features. Yet their mechanical functionality is undermined due to the high brittleness of RCP30 and high flexibility of R5. The transparent Accura® 60 was found to lose its strength and appeal due to high photosensitivity. Finally, the ceramic composite shows the best potential for medical use due to its biocompatibility and superior mechanical properties, yet one has to compensate for the material shrinkage already at the design stage.

scholarly journals Determination of geometric and kinematic characteristics of fdm 3d print process

2020 ◽  
Vol 2 (1(52)) ◽  
pp. 19-21
Author(s):  
Vitalii Oleksyshen ◽  
Aleksandr Sokolskyi ◽  
Oleksandr Kolosov ◽  
Vladyslav Solovei
Keyword(s):  
3D Print ◽  
Kinematic Characteristics ◽  
Print Process

Additive Manufacture of Prototype Turbine Blades for Hot-Fired Engine Performance Validation Trials

2019 ◽  
Author(s):  
David Adair ◽  
Michael Kirka ◽  
Daniel Ryan
Keyword(s):  
Elevated Temperatures ◽  
National Laboratory ◽  
Turbine Blades ◽  
Engine Performance ◽  
Nickel Superalloy ◽  
Additive Manufacture ◽  
Machining Processes ◽  
Engine Operation ◽  
Oak Ridge ◽  
3D Print

Abstract Additive manufacturing (AM), also known as 3D printing, is a rapidly developing technology with tremendous potential in both developmental and production applications. Solar Turbines Incorporated is committed to AM technology for gas turbine applications. The ability to metal 3D print novel designs of turbine blades capable of actual turbine engine operation would effectively reduce design validation cycle time, and allow acquisition of key performance data early in a design campaign. In support of Solar’s advanced manufacturing development and ongoing engine efficiency improvement goals, Solar initiated a project to print a full set of Mercury™ 50 stage 2 turbine blades to be run in a development engine. Solar leveraged years of experience with design and serial production of AM components in support of this project. A significant challenge faced when printing turbine blades is producing metal with mechanical properties sufficient to withstand the rigors of engine operation. As a rotating component within the hot section of the engine, turbine blades experience high centrifugal and pressure loads at elevated temperatures. After investigation of possible alloys capable of meeting the requirements of the Mercury™ 50 design envelope, the gamma prime (γ’) strengthened nickel superalloy Inconel™ 738LC was selected to provide the best opportunity for successful development engine testing. Solar partnered with Oak Ridge National Laboratory (ORNL) to produce the Inconel™ 738LC blades with Electron Beam Melting (EBM) powder bed fusion process. Once a rough blade shape was printed, the fir-tree attachment, blade tip shroud, and air flow path surfaces were finished using both conventional and non-conventional machining processes. In-process monitoring, metallurgical evaluations, mechanical testing, and non-destructive inspection techniques were used to validate the printed blade material integrity and conformance to geometric design intent. Planned future activities include assembly of the AM blades onto a disk for spin pit testing to validate the mechanical integrity and design margin of the blades. The final phase of the project will be to install the bladed disk assembly into a Mercury™ 50 engine at Solar Turbines to conduct a series of hot-fired engine performance tests.

Interface-charge-coupled polarization response of Pt-ZnO-BaTiO3-ZnO-Pt heterostructures: Three-layer model expansion

2008 ◽  
Author(s):  
Venkata M. Voora ◽  
Tino Hofmann ◽  
Matthias Brandt ◽  
Michael Lorenz ◽  
Marius Grundmann ◽  
...  
Keyword(s):  
Layer Model ◽  
Interface Charge ◽  
Polarization Response ◽  
Model Expansion

The Pattern of Acetylation Defines the Priming Activity of Chitosan Tetramers

2019 ◽  
Author(s):  
Sven Basa ◽  
Malathi Nampally ◽  
Talita Honorato ◽  
Subha Narayan Das ◽  
Appa Rao Podile ◽  
...  
Keyword(s):  
Biological Activity ◽  
Degree Of Polymerization ◽  
Chitosan Oligosaccharides ◽  
Degree Of Acetylation ◽  
Bona Fide ◽  
First Time ◽  
Priming Activity

The biological activity of chitosans depends on their degree of polymerization (DP) and degree of acetylation (DA). However, information could also be carried by the pattern of acetylation (PA): the sequence of <i>β</i>-1,4-linked glucosamine (deacetylated/D) and <i>N</i>-acetylglucosamine (acetylated/A) units. To address this hypothesis, we prepared partially-acetylated chitosan oligosaccharides from a chitosan polymer (DA=35%, DP<sub>w</sub>=905) using recombinant chitosan hydrolases with distinct substrate and cleavage specificities. The mixtures were separated into fractions DP4–DP12, which were tested for elicitor and priming activities in rice cells. We confirmed that both activities were influenced by DP, <a>but also observed apparent DA-dependent priming activity, with the ADDD+DADD fraction proving remarkably effective</a>. We then compared all four mono-acetylated tetramers prepared using different chitin deacetylases and observed significant differences in priming activity. This demonstrates for the first time that PA influences the biological activity of chitosans, which can now be recognized as <i>bona fide</i> information-carrying molecules

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