Additive manufacturing of 3D structures with non-Newtonian highly viscous fluids: Finite element modeling and experimental validation

Liravi, Farzad; Darleux, Robin; Toyserkani, Ehsan

doi:10.1016/j.addma.2016.10.008

Cited by 36 publications

(37 citation statements)

References 35 publications

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“…With specific regard to our case, only a few works are worth to be cited. Lirvani [30] modelled the extrusion process of a fluid with the viscosity of approximately 20 Pa•s via numerical simulation and by using Navier-Stokes equation. Kopplmayr [31] used OpenFOAM software and volume of fluid (VOF) equations to model the extrusion of polyethylene, polypropylene and polyethylene terephthalate.…”

Section: Cooling Sinkmentioning

confidence: 99%

Influence of printing parameters on the stability of deposited beads in fused filament fabrication of poly(lactic) acid

Balani¹,

Chabert²,

Nassiet³

et al. 2019

Additive Manufacturing

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Fused filament fabrication (FFF) is one of the various types of additive manufacturing processes. Similar to other types, FFF enables free-form fabrication and optimised structures by using polymeric filaments as the raw material. This work aims to optimise the printing conditions of the FFF process based on reliable properties, such as printing parameters and physical properties of polymers. The selected polymer is poly(lactic) acid (PLA), which is a biodegradable thermoplastic polyester derived from corn starch and is one of the most common polymers in the FFF process. Firstly, the maximum inlet velocity of the filament in the liquefier was empirically determined according to process parameters, such as feed rate, nozzle diameter and dimensions of the deposited segment. Secondly, the rheological behaviour of the PLA, including the velocity field, shear rate and viscosity distribution in the nozzle, was determined via analytical study and numerical simulation. Our results indicated the variation in the shear rate according to the diameter of the nozzle and the inlet velocity. The shear rate attained its maximum value near the internal wall at high inlet velocities and smaller diameters. Finally, the distribution of the viscosity along the radius of the nozzle was obtained. At high inlet velocity, several defects appeared at the surface of the extrudates. At the highest shear rates, the extrudates underwent severe deformation. The defects predicted via numerical simulation were reasonably consistent with that observed from an optical microscope. Hence, these results are effective for selecting the printing parameters (i.e. nozzle diameter, feed rate and layer height) to improve the quality of the manufactured parts.

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Section: Cooling Sinkmentioning

confidence: 99%

Influence of printing parameters on the stability of deposited beads in fused filament fabrication of poly(lactic) acid

Balani¹,

Chabert²,

Nassiet³

et al. 2019

Additive Manufacturing

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“…Consequently, theoretical modeling of viscosity through various nozzle designs is of critical importance. [16,194] Another direct silicone 3D printing approach, the Drop-on-Demand system (Wacker Chemie AG, Germany), selectively deposits material droplets onto a build area, which are then cured using a UV lamp. [4] Silicone prostheses fabricated using this method demonstrated an acceptable clinical fit due to the precision of the digital processing pipeline, however, the layer thickness of 0.4 mm preventing the achievement of the thin margins of traditionally produced nasal prosthetics which is important for blending with skin.…”

Section: Silicone For 3d Printingmentioning

confidence: 99%

Past, Present, and Future of Soft‐Tissue Prosthetics: Advanced Polymers and Advanced Manufacturing

et al. 2020

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past 30 years, [12,13] it is only the last decade that has seen its rapid development as part of the fourth industrial revolution. [14] This change in practice is evidenced by the significant fraction of recent literature describing advances in 3D printed prostheses, including technological advances [4,15-18] and clinical reports. [19,20] Further innovations involving collaborations between clinicians, academics, and industry, promise even greater capabilities. The future will see 3D printers that can mix materials as desired during fabrication [21] and those that can 3D print organic semiconductors and piezoelectric polymers for sensing and bionics [22-24] (Figure 1). This report is focused on polymers for soft tissue, external, personalized, prosthetics with clinical applications for the ear, [25] nose, [26] eye, [27] face, [28] breast, [29] and hand. [30] The characteristics of both traditional and 3D printable polymeric materials, as well as current advanced manufacturing technologies and those in development, are also reviewed. The earliest evidence of prosthetics dates back to ≈2300 BC, where Egyptian mummies have been discovered with eye, nose, and genital reconstructions fashioned from plaster packed with mud, sand, linen, butter, or soda (Figure 1). [31] Wood, cloth, natural waxes, resins, and metals were later used as the material of choice for rudimentary prostheses. [32] Prostheses remained relatively unchanged for thousands of years until the 16th century, where prosthetic noses and eyes were made from parchment, wax, wood, hard rubber, gold, silver, and copper. [33] Metals continued as a fundamental material throughout the 19th century, largely due to their ability to be shaped and molded as needed. [34,35] One of the first polymers to be used in prosthetics, poly(methyl methacrylate) (PMMA), was developed in response to the glass shortages in the World Wars of the 20th Century. [36] This polymer went on to become the most common prosthetic material of the time, and still finds use today in artificial eyes [33] and prosthetic substructures. [37] Further innovations in the 20th century produced many new polymers, such as vinyls, copolymers, plastisols, and one of the most significant materials in prosthetics, silicone. [38] Discovered in the early 1900s by Fredrick Kipping, silicone was first used in prosthetics by George W Barnhart in 1960. [39] This versatile polymer remains a primary prosthetic material today due to its soft tissue-like properties, ease of manipulation, chemical inertness, durability, and excellent biocompatibility. [40,41] The search for alternative materials Millions of people worldwide experience disfigurement due to cancers, congenital defects, or trauma, leading to significant psychological, social, and economic disadvantage. Prosthetics aim to reduce their suffering by restoring aesthetics and function using synthetic materials that mimic the characteristics of native tissue. In the 1900s, natural materials used for thousands of years in prosthetics were replaced by syntheti...

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“…Extrusion or dispensing is often used for applying the silicone rubber on the printer bed, as shown, e.g., by Envisiontec GmbH (Gladbeck, Germany) or Aceo (Burghausen, Germany). Consequently, since curing is challenging, the viscosity needs to be comparably high in order to print with high shape retention capability [ 11 , 12 , 13 ]. Due to viscous materials and the processability, there are limitations for printing in small dimensions.…”

Section: Introductionmentioning

confidence: 99%

“…However, printing times in this dimension are extremely long and the structure size is only useful for a limited range of applications. In case of using low viscosity materials but larger nozzles, the silicone rubbers spread on the printing bed and dramatically impair minimal structure size and accuracy [ 11 , 12 , 15 ]. To overcome these limitations, processability of low-viscous materials is required.…”

Section: Introductionmentioning

confidence: 99%

Laser-Facilitated Additive Manufacturing Enables Fabrication of Biocompatible Neural Devices

Behrens

Stieghorst

Doll

et al. 2020

Sensors

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Current personalized treatment of neurological diseases is limited by availability of appropriate manufacturing methods suitable for long term sensors for neural electrical activities in the brain. An additive manufacturing process for polymer-based biocompatible neural sensors for chronic application towards individualized implants is here presented. To process thermal crosslinking polymers, the developed extrusion process enables, in combination with an infrared (IR)-Laser, accelerated curing directly after passing the outlet of the nozzle. As a result, no additional curing steps are necessary during the build-up. Furthermore, the minimal structure size can be achieved using the laser and, in combination with the extrusion parameters, provide structural resolutions desired. Active implant components fabricated using biocompatible materials for both conductive pathways and insulating cladding keep their biocompatible properties even after the additive manufacturing process. In addition, first characterization of the electric properties in terms of impedance towards application in neural tissues are shown. The printing toolkit developed enables processing of low-viscous, flexible polymeric thermal curing materials for fabrication of individualized neural implants.

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Additive manufacturing of 3D structures with non-Newtonian highly viscous fluids: Finite element modeling and experimental validation

Cited by 36 publications

References 35 publications

Influence of printing parameters on the stability of deposited beads in fused filament fabrication of poly(lactic) acid

Influence of printing parameters on the stability of deposited beads in fused filament fabrication of poly(lactic) acid

Past, Present, and Future of Soft‐Tissue Prosthetics: Advanced Polymers and Advanced Manufacturing

Laser-Facilitated Additive Manufacturing Enables Fabrication of Biocompatible Neural Devices

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