Enhancing the Yield Stress in Liquid Polydimethylsiloxane to Allow Its 3D Printing: Hydrogels as Removable Fillers

2021 ◽  
Vol 306 (2) ◽  
pp. 2000553
Author(s):  
Clément Perrinet ◽  
Edwin‐Joffrey Courtial ◽  
Arthur Colly ◽  
Christophe Marquette ◽  
René Fulchiron
Keyword(s):  
3D Printing ◽  
Yield Stress

Testing Procedures on Materials to Formulate the Ink for 3D Printing

2020 ◽  
Vol 2674 (2) ◽  
pp. 21-32 ◽  
Author(s):  
Malo Charrier ◽  
Claudiane Ouellet-Plamondon
Keyword(s):  
3D Printing ◽  
Yield Stress ◽  
Three Dimensional ◽  
Testing Procedure ◽  
Full Potential ◽  
Cement Pastes ◽  
Slump Test ◽  
Testing Procedures ◽  
Transportation Sector ◽  
Printing Ink

Three-dimensional (3D) printing has been used in various fields to tackle applications difficult for conventional manufacturing. To realize the full potential of this technology in the transportation sector, it is imperative to identify suitable tests and mixtures for printing “inks” made of mortar. In this study, several conventional and non-conventional tests on mortars and cement pastes were conducted. This work highlights the correlation between the results of slump test and the deformation test that indicates the comportment of the mixture under a stack of printed layers. Moreover, a strong connection between yield stress and mini-slump is observed, demonstrating a simplification of the testing procedure, and a link between the mortar and the cement paste is developed. In the printing ink design phase, this association enables the prediction of flowability. The yield stress and the final radius of the mini-slump tests were very well correlated for the admixture tested. The use of the mini-slump test simplifies the testing procedure and allows for quicker formulations of admixtures in the printing ink.

scholarly journals The Effect of Accelerator Dosage on Fresh Concrete Properties and on Interlayer Strength in Shotcrete 3D Printing

Materials ◽  
2020 ◽  
Vol 13 (2) ◽  
pp. 374 ◽  
Author(s):  
Inka Dressler ◽  
Niklas Freund ◽  
Dirk Lowke
Keyword(s):  
3D Printing ◽  
Yield Stress ◽  
Fresh Concrete ◽  
Testing Machine ◽  
Image Correlation ◽  
Early Age ◽  
Stress Evolution ◽  
Functional Interaction ◽  
Concrete Properties ◽  
Instantaneous Increase

Recently, the progress in 3D concrete printing has developed enormously. However, for the techniques available, there is still a severe lack of knowledge of the functional interaction of processing technology, concrete rheology and admixture usage. For shotcrete 3D printing technology, we present the effect of accelerator dosages (0%, 2%, 4% and 6%) on fresh concrete properties and on interlayer strength. Therefore, early yield stress development up to 90 min is measured with penetration resistance measurements. Deformation of layers under loading is investigated with digital image correlation and a mechanical testing machine. One point in time (10 min after deposition) is examined to quantify vertical buildability of elements depending on the accelerator dosage. Four different interlayer times (0, 2, 5 and 30 min), which occur for the production of small and large elements as well as due to delay during production, are investigated mechanically as well as quantitatively with computed tomography regarding the formation of cold joints. With increased accelerator dosage, an instantaneous increase in early age yield stress and yield stress evolution was observed. An increase in interlayer time leads to a reduced strength. This is mainly attributed to the observed reduced mechanical interlocking effect of the strands. Finally, a model to describe interlayer quality is presented. In the end, advantages as well as limitations of the findings are discussed.

scholarly journals Silicone rheological behavior modification for 3D printing: Evaluation of yield stress impact on printed object properties

2019 ◽  
Vol 28 ◽  
pp. 50-57 ◽  
Author(s):  
Edwin-Joffrey Courtial ◽  
Clément Perrinet ◽  
Arthur Colly ◽  
David Mariot ◽  
Jean-Marc Frances ◽  
...  
Keyword(s):  
3D Printing ◽  
Yield Stress ◽  
Behavior Modification ◽  
Rheological Behavior ◽  
Object Properties

scholarly journals Assessing Mechanical and Rheological Properties of Potato Puree: Effect of Different Ingredient Combinations and Cooking Methods on the Feasibility of 3D Printing

Foods ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 21
Author(s):  
Iman Dankar ◽  
Amira Haddarah ◽  
Francesc Sepulcre ◽  
Montserrat Pujolà
Keyword(s):  
3D Printing ◽  
Rheological Properties ◽  
Yield Stress ◽  
Network Formation ◽  
High Yield ◽  
Cooking Methods ◽  
Starch Granules ◽  
Food Printing ◽  
3D Food Printing ◽  
Newtonian Behavior

The effects of agar, alginate, butter, olive oil, and carrots on the mechanical and rheological properties of potato puree prepared by two different cooking methods (microwave heating (MP) and boiling (BP)) were investigated and interpreted in terms of starch microstructural changes. Microscopic observations revealed more aggregated and densely concentrated starch granules in MP samples. This consequently led to a significant increase (p < 0.05) in mechanical and rheological properties up to five times more than BP samples. All samples exhibited shear thinning non-Newtonian behavior. Butter proved its ability to maintain stiff network formation with starch molecules forming lipid-starch complexes characterized by high retention properties and increased stability due to high thixotropic and yield stress values. The pseudo-plasticity combined with high self-supporting ability (high yield stress and mechanical values) comprised by MP samples allows them to better behave during advanced technological processes such as extrusion 3D food printing.

scholarly journals Metal Alloys for Filaments in 3D Fusion Filament Modelling Printing Process

2020 ◽  
Vol 31 ◽  
pp. 65-70
Author(s):  
M. Ciornei ◽  
I. D. Savu ◽  
S. V. Savu
Keyword(s):  
3D Printing ◽  
Tensile Test ◽  
Mechanical Stress ◽  
Yield Stress ◽  
Melting Temperature ◽  
Experimental Research ◽  
Specific Resistance ◽  
The Other ◽  
Metal Alloys ◽  
Printing Process

The paper presents experimental research regarding the application of specific low melting metals in the FDM process. Previous trends in the transfer of the filament from the spool to the hot-end showed that the filament undergoes specific mechanical stress during the transfer. To achieve an appropriate transfer the filament should prove stiffness and resistance to the mechanical actions of the transfer wheels. At the same time, the entrance to the hot-end creates specific resistance to the movement of the filament, and the filament undergoes important deformations. The experimental research used three materials characterized by melting temperature below 260oC: Sn-58Bi, Sn-9Zn, and Sn-3.5Ag. Sn-58Bi showed a yield stress above 50 MPa, but very low extension during the tensile test. Sn-9Zn exhibited a yield stress above 30 MPa, and about double the extension during the tensile test. Sn-3.5Ag displayed a yield stress above 25 MPa, and extension in excess of 8%. The analysis of the surface was performed, revealing that the increase of the yield stress influenced the appearance of specific prints given by the transfer wheels. The deepest prints were measured for Sn-3.5Ag and they were maximum 100 μm. The other two materials were stiffer and the prints have depths below 50 μm. According to the obtained results, each of the tested materials can be an appropriate solution to filament use for the FDM 3D printing process.

Fabrication, Mechanics, and Reliability Analysis for 3D Printed Lattice Designs

2021 ◽  
Author(s):  
Nitin Nagesh Kulkarni ◽  
Stephen Ekwaro-Osire ◽  
Paul Egan
Keyword(s):  
Sensitivity Analysis ◽  
3D Printing ◽  
Reliability Analysis ◽  
Yield Stress ◽  
Beam Diameter ◽  
Lattice Structures ◽  
Exponential Increase ◽  
Unit Cells ◽  
3D Printed ◽  
Probabilistic Failure Analysis

Abstract The use of 3D printing for lattice structures has led to advances in diverse applications benefitting from mechanically efficient designs. 3D printed lattices are often used to carry loads, however, printing defects and inconsistencies potentially hinder performance. Here, we investigate the design, fabrication, mechanics, and reliability of lattices with repeating cubic unit cells using probabilistic analysis. Lattices were designed with 500µm diameter beams and unit cell lengths from 0.8mm to 1.6mm. Lattices were printed with stereolithography and had average beam diameters from 509µm to 622µm, thereby demonstrating a deviation from design intentions. Mechanical experiments were conducted to quantify the exponential increase in yield stress for the relative density of lattices that facilitated probabilistic failure analysis. Sensitivity analysis demonstrated performance was most sensitive to fluctuations in beam diameter (74%) and less to lattice yield stress (8%) for lattices with 1.6mm unit cells while lattices with smaller 1.0mm unit cells were most sensitive to yield stress (48%) and to beam diameter (43%) fluctuations. These findings provide new insights linking design, fabrication, mechanics, and reliability analysis for improved system design that is crucial for engineers to consider as 3D printing becomes more widely adopted.

Determining the yield stress of a Biopolymer-bound Soil Composite for extrusion-based 3D printing applications

2021 ◽  
Vol 305 ◽  
pp. 124730
Author(s):  
Adrian Biggerstaff ◽  
Gerald Fuller ◽  
Michael Lepech ◽  
David Loftus
Keyword(s):  
3D Printing ◽  
Yield Stress

scholarly journals Active mixing of complex fluids at the microscale

2015 ◽  
Vol 112 (40) ◽  
pp. 12293-12298 ◽  
Author(s):  
Thomas J. Ober ◽  
Daniele Foresti ◽  
Jennifer A. Lewis
Keyword(s):  
Reynolds Number ◽  
3D Printing ◽  
Yield Stress ◽  
Complex Fluids ◽  
Operating Conditions ◽  
Local Composition ◽  
Scaling Relationships ◽  
Wide Range ◽  
Active Mixing ◽  
Microfluidic Mixers

Mixing of complex fluids at low Reynolds number is fundamental for a broad range of applications, including materials assembly, microfluidics, and biomedical devices. Of these materials, yield stress fluids (and gels) pose the most significant challenges, especially when they must be mixed in low volumes over short timescales. New scaling relationships between mixer dimensions and operating conditions are derived and experimentally verified to create a framework for designing active microfluidic mixers that can efficiently homogenize a wide range of complex fluids. Active mixing printheads are then designed and implemented for multimaterial 3D printing of viscoelastic inks with programmable control of local composition.

scholarly journals Printable homocomposite hydrogels with synergistically reinforced molecular-colloidal networks

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Austin H. Williams ◽  
Sangchul Roh ◽  
Alan R. Jacob ◽  
Simeon D. Stoyanov ◽  
Lilian Hsiao ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
3D Printing ◽  
Yield Stress ◽  
Storage Modulus ◽  
Soft Robotics ◽  
Structure Property ◽  
Interpenetrating Networks ◽  
Precise Control ◽  
Remarkable Increase ◽  
Structure Property Relationships

AbstractThe design of hydrogels where multiple interpenetrating networks enable enhanced mechanical properties can broaden their field of application in biomedical materials, 3D printing, and soft robotics. We report a class of self-reinforced homocomposite hydrogels (HHGs) comprised of interpenetrating networks of multiscale hierarchy. A molecular alginate gel is reinforced by a colloidal network of hierarchically branched alginate soft dendritic colloids (SDCs). The reinforcement of the molecular gel with the nanofibrillar SDC network of the same biopolymer results in a remarkable increase of the HHG’s mechanical properties. The viscoelastic HHGs show >3× larger storage modulus and >4× larger Young’s modulus than either constitutive network at the same concentration. Such synergistically enforced colloidal-molecular HHGs open up numerous opportunities for formulation of biocompatible gels with robust structure-property relationships. Balance of the ratio of their precursors facilitates precise control of the yield stress and rate of self-reinforcement, enabling efficient extrusion 3D printing of HHGs.

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