Characterization of Permeability for Solid Freeform Fabricated Porous Structures

1999 ◽  
Author(s):  
Merve Erdal ◽  
Levent Ertoz ◽  
Selçuk Güçeri
Keyword(s):  
Solid Freeform Fabrication ◽  
Pore Geometry ◽  
Fluid Viscosity ◽  
Porous Structures ◽  
Permeability Measurement ◽  
Porous Flow ◽  
Freeform Fabrication ◽  
Fused Deposition ◽  
Order Of Magnitude

Abstract Fused deposition based solid freeform fabrication technique allows manufacturing of potential functional preforms for subsequent Resin Transfer Molding. In this study, the transport property (permeability) of solid freeform fabricated porous preform geometries are investigated. Specifically the effect of pore geometry and network on the permeability is sought. Wet (saturated) permeability experiments were performed for various pore geometries with different viscosity liquids. For all fluids and preform structures investigated in this study, the porous flow exhibited Darcian behavior. The permeability is affected by changes in order of magnitude of fluid viscosity, the effect considerably significant in low porosity preforms. Current work concentrates on dry permeability measurement and development of numerical permeability models for ordered pore geometries (as produced through SFF) that will be compared with experimental results.

Modeling of Spatially Controlled Biomolecules in Three-Dimensional Porous Alginate Structures

2010 ◽  
Vol 4 (4) ◽  
Author(s):  
Ibrahim T. Ozbolat ◽  
Bahattin Koc
Keyword(s):  
Computer Aided Design ◽  
Solid Freeform Fabrication ◽  
Imaging Techniques ◽  
Release Kinetics ◽  
Three Dimensional ◽  
Control Release ◽  
Stochastic Approach ◽  
Distribution Characteristics ◽  
Porous Structures ◽  
Freeform Fabrication

This paper presents a computer-aided design (CAD) of 3D porous tissue scaffolds with spatial control of encapsulated biomolecule distributions. A localized control of encapsulated biomolecule distribution over 3D structures is proposed to control release kinetics spatially for tissue engineering and drug release. Imaging techniques are applied to explore distribution of microspheres over porous structures. Using microspheres in this study represents a framework for modeling the distribution characteristics of encapsulated proteins, growth factors, cells, and drugs. A quantification study is then performed to assure microsphere variation over various structures under imaging analysis. The obtained distribution characteristics are mimicked by the developed stochastic modeling study of microsphere distribution over 3D engineered freeform structures. Based on the stochastic approach, 3D porous structures are modeled and designed in CAD. Modeling of microsphere and encapsulating biomaterial distribution in this work helps develop comprehensive modeling of biomolecule release kinetics for further research. A novel multichamber single nozzle solid freeform fabrication technique is utilized to fabricate sample structures. The presented methods are implemented and illustrative examples are presented in this paper.

Solid Freeform Fabrication of Silicon Nitride Ceramics

1998 ◽  
Vol 542 ◽  
Author(s):  
C. J. Gasdaska ◽  
R. Clancy ◽  
V. Jamalabad ◽  
D. Dalfonzo
Keyword(s):  
Thermal Expansion ◽  
Silicon Nitride ◽  
Solid Freeform Fabrication ◽  
Freeform Fabrication ◽  
Fused Deposition ◽  
Thermal Expansion Coefficients ◽  
Processed Material ◽  
Nitride Ceramics ◽  
Internal Cavities ◽  
Expansion Coefficients

AbstractSilicon nitride ceramics have been prepared using the fused deposition (FD) process in a Stratasys 1650 modeler. Two types of silicon nitride have been prepared: GS44 and AS800. AS800 is processed and used at higher temperatures than GS44. The strength of machined surfaces of either type of silicon nitride prepared using FD is comparable to conventionally processed material. Using standard build conditions strengths for as-built and as-sintered surfaces are approximately 50% lower. The additive nature of solid freeform processes also allows multi-material combinations to be deposited which result in enhanced performance. For example, combinations of silicon nitride based materials with different thermal expansion coefficients have been prepared which demonstrate strength increases > 20%. In addition, components containing complicated internal cavities may also be fabricated.

Preparation and characterization of hydroxyapatite suspensions for solid freeform fabrication

2002 ◽  
Vol 28 (3) ◽  
pp. 299-302 ◽  
Author(s):  
Jiemo Tian ◽  
Yong Zhang ◽  
Xinmin Guo ◽  
Limin Dong
Keyword(s):  
Solid Freeform Fabrication ◽  
Freeform Fabrication

Design of Fused-Deposition ABS Components for Stiffness and Strength

2000 ◽  
Author(s):  
José F. Rodríguez ◽  
James P. Thomas ◽  
John E. Renaud
Keyword(s):  
Mechanical Performance ◽  
Solid Freeform Fabrication ◽  
Acrylonitrile Butadiene Styrene ◽  
Freeform Fabrication ◽  
Fused Deposition ◽  
Load Carrying ◽  
Volume Production ◽  
Approximate Minimization ◽  
High Degree ◽  
Functional Components

Abstract The high degree of automation of Solid Freeform Fabrication (SFF) processing and its ability to create geometrically complex parts to precise dimensions provide it with a unique potential for low volume production of rapid tooling and functional components. A factor of significant importance in the above applications is the capability of producing components with adequate mechanical performance (e.g., stiffness and strength). This paper introduces a strategy for the optimizing the design of Fused-Deposition Acrylonitrile-Butadiene-Styrene (FD-ABS) components for stiffness and strength. In this strategy, a mathematical model of the structural system is linked to an approximate minimization algorithm to find the settings of select manufacturing parameters which optimize the mechanical performance of the component. The methodology is demonstrated by maximizing the load carrying capacity of a two-section cantilevered FD-ABS beam.

Characterization of Printable Micro-Fluidic Channels for Organ Printing

2012 ◽  
Author(s):  
Yahui Zhang ◽  
Howard Chen ◽  
Ibrahim T. Ozbolat
Keyword(s):  
Oxygen Transport ◽  
Fluid Transport ◽  
Solid Freeform Fabrication ◽  
Structural Formation ◽  
Freeform Fabrication ◽  
Filament Diameter ◽  
Organ Printing ◽  
Scaffold Degradation ◽  
Tissue Scaffolding

Organ printing is a complex and challenging process in execution due to the lack of fundamental understanding of tissue and organ formation, and problems associated with giving the organ-conforming 3D shapes. One of the major challenges is the inclusion of blood vessel-like channels between layers to support cell viability in terms of nutrients and oxygen transport. Tissue scaffolds have been widely used in generation of replacement tissue by providing mechanical support and fluid nutrients, but complications with scaffold degradation and the corresponding adverse effects on extra cellular matrix still present major challenges. This paper introduces a new approach in tissue scaffolding for cellular assembly to minimize these problems. This research investigates the manufacturability of novel printable micro-fluidic channels, where the micro-fluidic channels support mechanical integrity as well as enable fluid transport in 3D. A pressure-assisted solid freeform fabrication platform is developed with co-axial needle dispenser unit to print hollow hydrogel filaments, which will later be used to support nutrients and oxygen transport through the printed cell assembly. The dispensing rheology is studied and the effect of material property on structural formation of hollow filaments is analyzed in this paper. Sample structures are printed through the computer-controlled system. In experiments with sodium alginate, 4% CaCI2-4% alginate solution combination results in the smallest core and filament diameter. In experiments with chitosan on the other hand, 3% chitosan-1% NaOH combination brings the smallest core and filament diameter.

Processing of Novel Electroceramic Components by SFF Techniques

1998 ◽  
Vol 542 ◽  
Author(s):  
A. Safari ◽  
S. C. Danforth ◽  
A. L. Kholkin ◽  
I. A. Cornejo ◽  
F. Mohammadi ◽  
...  
Keyword(s):  
Computer Aided Design ◽  
Composite Structures ◽  
Volume Fraction ◽  
Solid Freeform Fabrication ◽  
Side Lobe ◽  
Electromechanical Properties ◽  
Freeform Fabrication ◽  
Fused Deposition ◽  
Fused Deposition Of Ceramics ◽  
Aided Design

AbstractNovel piezoelectric ceramic and ceramic/polymer composite structures were fabricated by solid freeform fabrication (SFF) for sensor and actuator applications. SFF techniques including fused deposition of ceramics (FDC) and Sanders prototyping (SP) were utilized to fabricate a variety of complex structures directly from a computer aided design (CAD) file. Novel composite structures including volume fraction gradients (VFG) and staggered rods, as well as actuator designs such as tubes, spirals and telescopes were made using the flexibility provided by the above processes. VFG composites were made by SP technique with the ceramic content decreasing from the center towards the edges. This resulted in a reduction of side lobe intensity in the acoustic beam pattern. The FDC technique was used to manufacture high authority actuators utilizing novel designs for the amplification of strain under applied electric field. The design, fabrication and electromechanical properties of these composite and actuator structures are discussed in this paper.

scholarly journals Main 3D Manufacturing Techniques for Customized Bone Substitutes. A Systematic Review

Materials ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2524
Author(s):  
Javier Montero ◽  
Alicia Becerro ◽  
Beatriz Pardal-Peláez ◽  
Norberto Quispe-López ◽  
Juan-Francisco Blanco ◽  
...  
Keyword(s):  
Bone Regeneration ◽  
Fused Deposition Modeling ◽  
Solid Freeform Fabrication ◽  
Bone Substitutes ◽  
Cochrane Library ◽  
3D Scaffold ◽  
Hand Search ◽  
Freeform Fabrication ◽  
Fused Deposition ◽  
Bone Scaffolds

Clinicians should be aware of the main methods and materials to face the challenge of bone shortage by manufacturing customized grafts, in order to repair defects. This study aims to carry out a bibliographic review of the existing methods to manufacture customized bone scaffolds through 3D technology and to identify their current situation based on the published papers. A literature search was carried out using “3D scaffold”, “bone regeneration”, “robocasting” and “3D printing” as descriptors. This search strategy was performed on PubMed (MEDLINE), Scopus and Cochrane Library, but also by hand search in relevant journals and throughout the selected papers. All the papers focusing on techniques for manufacturing customized bone scaffolds were reviewed. The 62 articles identified described 14 techniques (4 subtraction + 10 addition techniques). Scaffold fabrication techniques can be also be classified according to the time at which they are developed, into Conventional techniques and Solid Freeform Fabrication techniques. The conventional techniques are unable to control the architecture of the pore and the pore interconnection. However, current Solid Freeform Fabrication techniques allow individualizing and generating complex geometries of porosity. To conclude, currently SLA (Stereolithography), Robocasting and FDM (Fused deposition modeling) are promising options in customized bone regeneration.

Design of Fused-Deposition ABS Components for Stiffness and Strength

2003 ◽  
Vol 125 (3) ◽  
pp. 545-551 ◽  
Author(s):  
Jose´ F. Rodrı´guez ◽  
James P. Thomas ◽  
John E. Renaud
Keyword(s):  
Mechanical Performance ◽  
Solid Freeform Fabrication ◽  
Acrylonitrile Butadiene Styrene ◽  
Freeform Fabrication ◽  
Fused Deposition ◽  
Load Carrying ◽  
Volume Production ◽  
Approximate Minimization ◽  
High Degree ◽  
Functional Components

The high degree of automation of Solid Freeform Fabrication (SFF) processing and its ability to create geometrically complex parts to precise dimensions provide it with a unique potential for low volume production of rapid tooling and functional components. A factor of significant importance in the above applications is the capability of producing components with adequate mechanical performance (e.g., stiffness and strength). This paper introduces a strategy for optimizing the design of Fused-Deposition Acrylonitrile-Butadiene-Styrene (FD-ABS; P400) components for stiffness and strength under a given set of loading conditions. In this strategy, a mathematical model of the structural system is linked to an approximate minimization algorithm to find the settings of select manufacturing parameters, which optimize the mechanical performance of the component. The methodology is demonstrated by maximizing the load carrying capacity of a two-section cantilevered FD-ABS beam.

Space Filling Curves: Its Design and Fabrication for Extrusion Based SFF Systems

2005 ◽  
Author(s):  
Binil Starly ◽  
Lauren Shor ◽  
Wei Sun ◽  
Andrew Darling
Keyword(s):  
Solid Freeform Fabrication ◽  
Feasibility Studies ◽  
Tissue Scaffolds ◽  
Layered Manufacturing ◽  
Hilbert Curve ◽  
Space Filling ◽  
Interior Space ◽  
Freeform Fabrication ◽  
Space Filling Curves

Scaffolds with designed interior pore architecture, predefined porosity and a well interconnected predetermined network has been the most favored design approach for tissue engineering applications. Solid freeform fabrication technologies have provided the capability of fabricating tissue scaffolds with desired characteristics due to its integration with CAD enabled tools. However, currently the interior macro pore design of scaffolds have been limited to simple regular shapes of either squares or circles due to limited CAD capability. In this paper we seek to enhance the design of the scaffold architecture by using space filling curves within its interior space. The process involves: definition and characterization of space filling curves such as the Hilbert Curve and Sierpinski Curves, applying the principle of layered manufacturing to determine the scaffold individual layered process planes and layered contours; Feasibility studies applying the curve generators to sample models and the generation of fabrication planning instructions for extrusion based SFF systems is presented.

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