A Computational Design Framework for a Rapid Solid Freeform Fabrication Process

2000 ◽  
Author(s):  
Deepesh Khandelwal ◽  
T. Kesavadas
Keyword(s):  
Solid Freeform Fabrication ◽  
Optimization Technique ◽  
Three Dimensional ◽  
Computational Design ◽  
Freeform Fabrication ◽  
3D Cad ◽  
Build Time ◽  
Cad Models ◽  
Efficient Machine ◽  
Novel Concept

Abstract Solid Freeform Fabrication (SFF) techniques in recent years have shown tremendous promise in reducing the design time of products. This technique enables designers to get three-dimensional physical prototypes from 3D CAD models. Although SFF has gained popularity, the manufacturing time and cost have limited its use to small and medium sized parts. In this paper we have proposed a novel concept for rapidly building SFF parts by inserting prefabricated inserts into the fabricated part. A computational algorithm was developed for determining ideal placement of inserts/cores in the CAD model of the part being prototyped using a heuristic optimization technique called Simulated Annealing. This approach will also allow the designers to build multi-material prototypes using the Rapid Prototyping (RP) technique. By using cheaper pre-fabricates instead of costly photopolymers, the production cost of the SFFs can be reduced. Additionally it will also reduce build time, resulting in efficient machine utilization.

Computational Design, Freeform Fabrication and Testing of Nylon-6 Tissue Engineering Scaffolds

2002 ◽  
Vol 758 ◽  
Author(s):  
Suman Das ◽  
Scott J. Hollister ◽  
Colleen Flanagan ◽  
Adebisi Adewunmi ◽  
Karlin Bark ◽  
...  
Keyword(s):  
Tissue Engineering ◽  
Solid Freeform Fabrication ◽  
Selective Laser Sintering ◽  
Three Dimensional ◽  
Computational Design ◽  
Nylon 6 ◽  
Functionally Graded ◽  
Tissue Engineering Scaffolds ◽  
Freeform Fabrication

ABSTRACTAdvanced and novel fabrication methods are needed to build complex three-dimensional scaffolds that incorporate multiple functionally graded biomaterials with a porous internal architecture that will enable the simultaneous growth of multiple tissues, tissue interfaces and blood vessels. The aim of this research is to develop, demonstrate and characterize techniques for fabricating such scaffolds by combining solid freeform fabrication and computational design methods. When fully developed, such techniques are expected to enable the fabrication of tissue engineering scaffolds endowed with functionally graded material composition and porosity exhibiting sharp or smooth gradients. As a first step towards realizing this goal, scaffolds with periodic cellular and biomimetic architectures were designed and fabricated using selective laser sintering in Nylon-6, a biocompatible polymer. Results of bio-compatibility and in vivo implantation studies conducted on these scaffolds are reported.

scholarly journals Automatized Evaluation of Students’ CAD Models

2021 ◽  
Vol 11 (4) ◽  
pp. 145
Author(s):  
Nenad Bojcetic ◽  
Filip Valjak ◽  
Dragan Zezelj ◽  
Tomislav Martinec
Keyword(s):  
Computer Aided Design ◽  
Three Dimensional ◽  
Computer Application ◽  
Test Cases ◽  
Cad Model ◽  
Computer Solution ◽  
3D Cad ◽  
Computer Aided ◽  
Cad Models ◽  
Aided Design

The article describes an attempt to address the automatized evaluation of student three-dimensional (3D) computer-aided design (CAD) models. The driving idea was conceptualized under the restraints of the COVID pandemic, driven by the problem of evaluating a large number of student 3D CAD models. The described computer solution can be implemented using any CAD computer application that supports customization. Test cases showed that the proposed solution was valid and could be used to evaluate many students’ 3D CAD models. The computer solution can also be used to help students to better understand how to create a 3D CAD model, thereby complying with the requirements of particular teachers.

Optimized Mask Image Projection for Solid Freeform Fabrication

2009 ◽  
Author(s):  
Chi Zhou ◽  
Yong Chen ◽  
Richard A. Waltz
Keyword(s):  
Programming Model ◽  
Solid Freeform Fabrication ◽  
Mixed Integer ◽  
Important Process ◽  
Freeform Fabrication ◽  
Part Quality ◽  
Image Projection ◽  
Physical Experiments ◽  
Cad Models ◽  
Effectiveness And Efficiency

Solid freeform fabrication (SFF) processes based on mask image projection have the potential to be fast and inexpensive. More and more research and commercial systems have been developed based on these processes. For the SFF processes, the mask image planning is an important process planning step. In this paper, we present an optimization based method for mask image planning. It is based on a light intensity blending technique called pixel blending. By intelligently controlling pixels’ gray scale values, the SFF processes can achieve a much higher XY resolution and accordingly better part quality. We mathematically define the pixel blending problem and discuss its properties. Based on the formulation, we present several optimization models for solving the problem including a mixed integer programming model, a linear programming model, and a two-stage optimization model. Both simulated and physical experiments for various CAD models are presented to demonstrate the effectiveness and efficiency of our method.

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.

CAD-Integrated Cost Estimation and Build Orientation Optimization to Support Design for Metal Additive Manufacturing

2017 ◽  
Author(s):  
Michael Barclift ◽  
Andrew Armstrong ◽  
Timothy W. Simpson ◽  
Sanjay B. Joshi
Keyword(s):  
Additive Manufacturing ◽  
Cost Estimation ◽  
Application Programming Interface ◽  
External Support ◽  
Support Design ◽  
Build Orientation ◽  
3D Cad ◽  
Build Time ◽  
Cad Models ◽  
Integrated Cost

Cost estimation techniques for Additive Manufacturing (AM) have limited synchronization with the metadata of 3D CAD models. This paper proposes a method for estimating AM build costs through a commercial 3D solid modeling program. Using an application programming interface (API), part volume and surface data is queried from the CAD model and used to generate internal and external support structures as solid-body features. The queried data along with manipulation of the part’s build orientation allows users to estimate build time, feedstock requirements, and optimize parts for AM production while they are being designed in a CAD program. A case study is presented with a macro programmed using the SolidWorks API with costing for a metal 3D-printed automotive component. Results reveal that an imprecise support angle can under-predict support volume by 34% and build time by 20%. Orientation and insufficient build volume packing can increase powder depreciation costs by nearly twice the material costs.

Measured Data Alignments for Monitoring Metal Additive Manufacturing Processes Using Laser Powder Bed Fusion Methods

2020 ◽  
Author(s):  
Shaw C. Feng ◽  
Yan Lu ◽  
Albert T. Jones
Keyword(s):  
Coordinate System ◽  
Computer Aided Design ◽  
Three Dimensional ◽  
Ex Situ ◽  
Powder Bed Fusion ◽  
Powder Bed ◽  
Alignment Procedure ◽  
3D Cad ◽  
Data Alignment ◽  
Cad Models

Abstract The number and types of measurement devices used for monitoring and controlling Laser-Based Powder Bed Fusion of Metals (PBF-LB/M) processes and inspecting the resulting AM metal parts have increased rapidly in recent years. The variety of the data collected by such devices has increased, and the veracity of the data has decreased simultaneously. Each measurement device generates data in a unique coordinate system and in a unique data type. Data alignment, however, is required before 1) monitoring and controlling PBF-LB/M processes, 2) predicting the material properties of the final part, and 3) qualifying the resulting AM parts can be done. Aligned means all data must be transformed into a single coordinate system. In this paper, we describe a new, general data-alignment procedure and an example based on PBF-LB/M processes. The specific data objects used in this example include in-situ photogrammetry, thermography, ex-situ X-ray computed tomography (XCT), coordinate metrology, and computer-aided design (CAD) models. We propose a data-alignment procedure to align the data from melt pool images, scan paths, layer images, XCT three-dimensional (3D) model, coordinate measurements, and the 3D CAD model.

Direct Freeform Fabrication Technique for Bio-Manufacturing of Pre-Seeded, Spatially Heterogeneous, Anatomically-Shaped Alginate Hydrogel Implants

2005 ◽  
Author(s):  
Daniel L. Cohen ◽  
Evan Malone ◽  
Hod Lipson ◽  
Lawrence J. Bonassar
Keyword(s):  
Tissue Engineering ◽  
Solid Freeform Fabrication ◽  
Crosslinking Agent ◽  
Three Dimensional ◽  
Patient Specific ◽  
Efficient Production ◽  
Alginate Hydrogel ◽  
Freeform Fabrication ◽  
Patient Specific Implants ◽  
Multiple Material

A major challenge in orthopaedic tissue engineering is the generation of cell-seeded implants with structures that mimic native tissue, both in terms of anatomic geometries and intratissue cell distributions. By combining the strengths of injection molding tissue engineering with those of Solid Freeform Fabrication (SFF), three-dimensional pre-seeded implants were fabricated without custom-tooling, enabling efficient production of patient-specific implants. The incorporation of SFF technology also enables the fabrication of geometrically complex, multiple-material implants with spatially heterogeneous cell distributions that could not otherwise be produced. Using a custom-built robotic SFF platform and gel deposition tools, alginate hydrogel was used with calcium sulfate as a crosslinking agent to produce pre-seeded living implants of arbitrary geometries. The process was determined to be sterile and viable at 94±5%. The GAG production was found to be about half that of a similarly molded samples. The compressive elastic modulus was determined to be 1.462±0.113 kPa.

Development of HA-PLGA Scaffold Encapsulating Intact BMP-2 Using Solid Freeform Fabrication Technology

2011 ◽  
Author(s):  
Jin-Hyung Shim ◽  
Jong Young Kim ◽  
Kyung Shin Kang ◽  
Jung Kyu Park ◽  
Sei Kwang Hahn ◽  
...  
Keyword(s):  
Tissue Engineering ◽  
Bone Regeneration ◽  
Porous Scaffold ◽  
Solid Freeform Fabrication ◽  
Three Dimensional ◽  
Porous Scaffolds ◽  
Prolonged Release ◽  
Cellular Activity ◽  
Freeform Fabrication

Tissue engineering is an interdisciplinary field that focuses on restoring and repairing tissues or organs. Cells, scaffolds, and biomolecules are recognized as three main components of tissue engineering. Solid freeform fabrication (SFF) technology is required to fabricate three-dimensional (3D) porous scaffolds to provide a 3D environment for cellular activity. SFF technology is especially advantageous for achieving a fully interconnected, porous scaffold. Bone morphogenic protein-2 (BMP-2), an important biomolecule, is widely used in bone tissue engineering to enhance bone regeneration activity. However, methods for the direct incorporation of intact BMP-2 within 3D scaffolds are rare. In this work, 3D porous scaffolds with poly(lactic-co-glycolic acid) chemically grafted hyaluronic acid (HA-PLGA), in which intact BMP-2 was directly encapsulated, were successfully fabricated using SFF technology. BMP-2 was previously protected by poly(ethylene glycol) (PEG), and the BMP-2/PEG complex was incorporated in HA-PLGA using an organic solvent. The HAPLGA/PEG/BMP-2 mixture was dissolved in chloroform and deposited via a multi-head deposition system (MHDS), one type of SFF technology, to fabricate a scaffold for tissue engineering. An additional air blower system and suction were installed in the MHDS for the solvent-based fabrication method. An in vitro evaluation of BMP-2 release was conducted, and prolonged release of intact BMP-2, for up to 28 days, was confirmed. After confirmation of advanced proliferation of pre osteoblasts, a superior differentiation effect of the HA-PLGA/PEG/BMP-2 scaffold was validated by measuring high expression levels of bone-specific markers, such as alkaline phosphatase (ALP) and osteocalcin (OC). We show that our solvent-based fabrication is a non-toxic method for restoring cellular activity. Moreover, the HAPLGA/PEG/BMP-2 scaffold was effective for bone regeneration.

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