Robustness optimization for rapid prototyping of functional artifacts based on visualized computing digital twins

This study presents a robustness optimization method for rapid prototyping(RP)of functional artifacts based on visualized computing digital twins(VCDT).A generalized multiobjective robustness optimization model for RP of scheme design prototype was first built,where thermal,structural,and multidisciplinary knowledge could be integrated for visualization.To implement visualized computing,the membership function of fuzzy decision-making was optimized using a genetic algorithm.Transient thermodynamic,structural statics,and flow field analyses were conducted,especially for glass fiber composite materials,which have the characteristics of high strength,corrosion resistance,temperature resistance,dimensional stability,and electrical insulation.An electrothermal experiment was performed by measuring the temperature and changes in temperature during RP.Infrared thermographs were obtained using thermal field measurements to determine the temperature distribution.A numerical analysis of a lightweight ribbed ergonomic artifact is presented to illustrate the VCDT.Moreover,manufacturability was verified based on a thermal-solid coupled finite element analysis.The physical experiment and practice proved that the proposed VCDT provided a robust design paradigm for a layered RP between the steady balance of electrothermal regulation and manufacturing efficacy under hybrid uncertainties.

Influence of Tomographic Slice Thickness and Field of View Variation on the Reproduction of Thin Bone Structures for Rapid Prototyping Purposes-An in Vitro Study

This study assessed the influence of acquisition parameters of tomographic volumes on the reproduction of thin bone structures for rapid prototyping purposes. Two parameters were investigated: Field of View (FOV) and Slice Thickness (ST). The specimen was comprised of five pairs of 0.6 mm, 1.1 mm, 1.5 mm, 2.0 mm and 2.8 mm thick cortical bone plates. The plates were stuck into utility wax;the first plate of the pair was in vertical position while the second plate was oblique to the first one. Forty-five tomographic images were captured and separated into 3 groups of fifteen images. Each group had a specific FOV: 180 mm;250 mm and 430 mm, respectively. Within each of these three groups, tomographic slice thickness was varied for every five of the fifteen slices. Acquisitions were carried out with STs of 1 mm, 2.5 mm and 5 mm. The Cyclops Medical Station software was used in the voxel-to-voxel analysis of radiologic density, reaching a total of 1350 assessed images. ST and FOV variation influenced the reproduction of thin bone walls, and FOV was shown to be a very important parameter. The larger the acquisition FOV, the more reduction in the number of voxels within the range of reconstruction for cortical bone in all of the bone plates. The visual analysis of the images of very thin bone walls showed that there could be a sharp drop in the radiologic density value in several adjacent voxels, resulting in areas which might not be reproduced in the reconstruction.

Development of a welding system for 3D steel rapid prototyping process

Metal device rapid prototyping with welding is one of the research interests at present. A controlled inertial droplet transfer MAG welding (CIDTMAGW) process was developed for the 3D steel device rapid prototyping with metal deposition. In this process, by using a special designed wire feeder, a controlled inertia is imposed on the droplet formed on the wire tip and combines with the arc force to make it detached. Thus, according to the requirements of rapid prototyping, the arc heat and the droplet detaching force can be separately controlled to attain a stable and satisfactory metal deposition process. A CIDTMAGW system and a testing manipulator for the 3D steel device rapid prototyping are presented. The required software is completed as well. The experiments proved that the geometric formation of the rapid prototyping device with welding deposition is well agreed the data of the device CAD modeling. The surface of the deposited device is comparatively smooth.

Effects of processing parameters on figuration during the GMAW rapid prototyping process

As a deposition technology, gas metal arc welding （GMAW） has shown new promise for rapid prototyping of metallic parts. During the process of metal forming using the arc of GMA W, low heat input and stable droplet transition are critical to high quality figuration. The effects of various processing parameters on figuration quality were studied in the experiment of GMA W rapid prototyping using the wire of ERSO-6 , including welding voltage, wire feeding rate, welding speed and so on. The optimal parameters for ERSO-6 are obtained. Simultaneously, it is verified that the rapid prototyping parts with favorable structures and quality can be achieved under the conditions of low heat input and stable droplet transition.

Finite element analysis of temperature field during multi-layer multi-pass weld-based rapid prototyping

During weld-bused rapid prototyping, the component experiences complex thermal process. In this paper, the temperature field evolution, thermal cycle characteristics, and temperature gradients of multi-layer multi-puss weld-based rapid prototyping are investigated using three-dimensional finite element models presented. The single-puss weld-bused rapid prototyping experiment is carried out. Thermal cycles calculated agree with experimental measurements. Furthermore, simulated results indicate that there exist the pre-heating effect of the fore layer and the post-heating effect of the rear layer in the multi-layer multi-pass weld-based rapid prototyping. In the first layer, the heat accumulates obviously. After the first layer, the dimension increase of the high temperature region behind the molten pool is not obvious. The heat diffusion condition in the first layer is the best, the heat diffusion condition in the second layer is the worst, and the heat diffusion conditions in the higher layers improve gradually.

On-line detection system of weld-based rapid prototyping process based on structured light

In order to realize the closed-loop control for rapid prototyping process based on gas metal arc welding, the geometric parameters of weld beads should be detected. In this study, a vision sensor system consisting of a linear laser projector and a CCD camera was designed to collect images of weld beads. Then, an image processing approach which combines with a Gaassian filter and an improved gravity method was used to extract the centerline of a light stripe based on VC ＋＋. Feature points of the centerline were identical directly by means of an image fusion algorithm. Experimental results show that image fusion is an effective approach to measure the width and height of the weld bead with high accuracy. This method can identify beads effectively in multi-pass welding and avoid designing different modes to suit all kinds of shapes.

Modeling of welded bead profile for rapid prototyping by robotic MAG welding

As a deposition technology, robotic metal active gas （MAG） welding has shown new promise for rapid prototyping （ RP） of metallic parts. During the process of metal forming using robotic MAG welding, sectional profile of single-puss welded bead is critical to formed accuracy and quality of metal pans. In this paper, the experiments of single-pass welded bead for rapid prototyping using robotic MAG welding were carried out. The effect of some edge detectors on the cross-sectional edge of welded bead was discussed and curve fitting was applied using least square fitting. Consequently, the mathematical model of welded bead profile was developed. The experimental results show that good shape could be obtained under suitable welding parameters. Canny operator is suitable to edge detection of welded bead profile, and the mathematical model of welded bead profile developed is approximately parabola.

A Photo-Modeling Approach to Restituting 3D Model Data from Single 2D Imagery for Rapid Prototyping of Artifact Products

This article first generalizes the basic engineering phases of modern rapid prototyping processes, and then describes the techniques of data capture for data modeling and model making. The article also provides a brief overview of the photogrametric techniques of restitution of 3D objects, and highlights the difficulties and limitations of existing methods. It therefore presents a novel approach to photo-modeling for acquiring 3D model data from single 2D photorealistic images. Implementation of the approach is then described against a effectiveness of photo-modeling practice. background of rapid prototyping processes to demonstrate the

3D Nanocomposite Hydrogel Scaffolds Fabricated by Rapid Prototyping for Bone Tissue Engineering

Colloidal gels made of oppositely charged nanoparticles are a novel class of hydrogels and can exhibit pseudoplastic behavior which will enable them to mold easily into specific shapes.These moldable gels can be used as building blocks to self-assemble into integral scaffolds from bottom to up through electrostatic forces.However,they are too weak to maintain scaffold morphology just depending on interparticle interactions such as Van der Waals attraction and electrostatic forces especially for bone tissue engineering.In this study,oppositely charged gelatin nanoparticles were firstly prepared by two-step desolvation method,followed by the mixture with water to form colloid gels.To solve the problem of weak mechanical performance of colloid gels, gelatin macromolecules were introduced into the prepared gels to form blend gels.The blend gels can be easily processed into three-dimensional( 3D) porous scaffolds via motor assisted microsyringe( MAM)system,a nozzle-based rapid prototyping technology,under mild conditions.After fabrication the scaffolds were crosslinked by glutaraldehyde( GA,25% solution in water by weight),then the crosslinked gelatin macromolecules network could form to improve the mechanical properties of colloid gels.The average particle size and zeta potential of gelatin nanoparticles were measured by NanoZS instrument.The morphology and microstructures of scaffolds were characterized by macroscopic images.The mechanical properties of the scaffolds were studied by a universal material testing machine.

3D Flash Display for STL Model in Rapid Prototyping System

A kind of 3D color graphics display system for the STL model is developed by calling the functions from Open GL graphic library through VC++6.0 under the Windows environment in this paper. The STL model is a high quality one that can be quiescent or animated. This system is conducive to find out the disfigurement of the STL model in a rapid prototyping process and to repair it. Therefore, the component quality can be enhanced.

Research on Nanofabrication Technology of Micro-/Nano-Stereo Rapid Prototyping of PCVD

At present, the most common micro/nano-scale fabri ca tion processes include the plane silicon process based on IC technology, stereo silicon process, LIGA, quasi-LIGA based on near ultra violet deep lithography, MEMS, energy beam etching and micro/nano-machining, etc. A common problem for t hese processes is the difficulty to fabricate arbitrary form for 3-dimensional micro/nano-parts, devices or mechanisms. To develop advanced MEMS manufacturin g technology, and to achieve fabrication of true 3-dimensional parts, devices or mechanisms, this paper proposes a nanofabrication technology for rapid proto typing of 3-dimensional parts, using plasma chemical vapor deposition (PCVD). This process can be describes as follows: A laser beam is produced by a low power, quasi molecule laser. It enters the vac uum chamber through a window, and is focused on with the substrate surface. A ga s in the chamber is ionized by the laser beam to produce PCVD on the substrate s urface, and forms a particle of the size of Ф100 nm (its thickness is about 100 nm). When the laser beam moves along X-axis, many particles form a line. Then the laser beam moves one step in Y-axis to form a new line. A plane is complete d by many lines. Then the substrate moves in Z-axis to form new plane. Eventu ally, many planes form a 3-dimensional component. Using available CAD/CAM softw are with this process, rapid prototyping of complex components can be achieved. A nanometer precision linear motor, such as that described in Chinese national p atent (patent No. ZL 98 2 16753.9), can be used to obtain the nanometer precisio n movements in the process. The process does not require mask, can be used for v arious rapid prototyping materials, to obtain high fabrication precision (its sc ale precision is 15 nm), and larger ratio of height to width of micro/nano-stru cture. It can find widespread applications in the fabrication of micro-mechani sm, trimming IC, and fabricating minilens, etc.

Principle and Feasibility of Electric or Magnetic Field Deflection-Projection Based Rapid Prototyping Technique

Rapid prototype manufacturing(RPM) is a new advanced manufacturing technology, which is based on the philosophy of materials increasing of lay by lay forming. Zero adventure rapid design/manufacturing can be realized with rapid prototypes of 3D CAD of products. Rapid prototyping has been an effective tool of R&D of new products. A novel rapid prototyping and manufacturing (RP&M) technique is brought forward. The principle of the process is to form layered sections and to make the prototype or part layer by layer by deflection projection of electric charged powder granules passing through electric or magnetic field and by controllable line and field scan of the powder granule beam. The feasibility issue of the process is theoretically and experimentally investigated.It shows that deflection projection of electric charged powder granules beam passing through electric field can be significant and feasible to the rapid prototyping technique.

Accuracy of Rapid Prototyping Biomodels Plotted by Three Dimensional Printing Technique:Ex Vivo Study

The rapid prototyping biomodels manufacturing is a recent technology with great importance in oral and maxillofacial surgery. It provides a better surgical planning, decrease of anesthesia time and great functional and esthetic results. The aim of this experimental study was to evaluate the accuracy of rapid prototyping biomodels built by three-dimensional printing (3DP) technique, since this is one of the least expensive methods available. Linear measurements of standardized bone defects and anatomic distances were compared using a digital caliper of high precision in nine dry mandibles (gold standard) and their respective biomodels. The Bland-Altman test was used for statistical analysis (5% level of significance). The results showed strong concordance between the dry mandibles and their respective biomodels, with discrepancies smaller than 2 mmin most cases (97.4%). We can conclude that the biomodels built by 3DP technique can be used for surgical planning in Dentistry.

Shape Simulation of Rapid Prototyping Part with ObjectARX

A layered simulation model with stairstep contour is built from AutoCAD through extruding each successive section contour having been compensated in dimensions to meet the application requirements of the RP part. In such a way the shape and size tolerance of the RP product could be verified beforehand promptly and precisely.

Research on Containment Relationships between Rapid Prototyping Part and CAD Model

Aiming at the geometrical features of different containment relationships in Rapid Prototyping （RP）, a general method of achieving the RP layer＇s cusp distribution of the positive, negative and mixed tolerance is proposed to meet the part＇s different applications. The procedure is executed by projecting the current and the next section of the CAD model onto a horizontal plane, computing the union and the intersection of the sections to get the outer and the inner boundary, and then blending the boundaries using a rotary vector through a proper inner point in the intersection to achieve the current layer＇s scanning contour. The method can realize the layer＇s cusp distribution of the mixed tolerance with unequal cusp height, expanding the connotation of the mixed tolerance.

Rapid Tooling-Rapid Abrading Process Integratedwith Rapid Prototyping

The paper is to outline a new process for manufacturing rapid graphite electrode. It detailsthe steps in Providing integration with Rapid Prototyping (RP) into rapid electrode abrading Process.The key to this combination is the successful model or patted creating using the RP technology.Significantly reduced lead-time, shortened learns curve, lowered revision changes cost and eliminatedor reduced mold polishing are the consequent results. high quality Electrical Discharge Machining(EDM) electrodes are sometimes difficult to be manufactured rapidly and are very time-consumingby conventional methods, even using Computer Numerical Control (CNC) machines. Abradingprovides a simple way to create etuemely detailed and complex electrode to make molds in toolingmaking industries. Integration with the rapid development of the Rapid Prototyping & Manufacturing(RP&M) technology, the rapid electrode abrading process has been regarded as one of the majorbreakthrough in tooling making technology.

Rapid Prototype Development Approach for Genetic Programming

Genetic Programming (GP) is an important approach to deal with complex problem analysis and modeling, and has been applied in a wide range of areas. The development of GP involves various aspects, including design of genetic operators, evolutionary controls and implementations of heuristic strategy, evaluations and other mechanisms. When designing genetic operators, it is necessary to consider the possible limitations of encoding methods of individuals. And when selecting evolutionary control strategies, it is also necessary to balance search efficiency and diversity based on representation characteristics as well as the problem itself. More importantly, all of these matters, among others, have to be implemented through tedious coding work. Therefore, GP development is both complex and time-consuming. To overcome some of these difficulties that hinder the enhancement of GP development efficiency, we explore the feasibility of mutual assistance among GP variants, and then propose a rapid GP prototyping development method based on πGrammatical Evolution (πGE). It is demonstrated through regression analysis experiments that not only is this method beneficial for the GP developers to get rid of some tedious implementations, but also enables them to concentrate on the essence of the referred problem, such as individual representation, decoding means and evaluation. Additionally, it provides new insights into the roles of individual delineations in phenotypes and semantic research of individuals.

Rapid Prototyping and Manufacturing Technology:Principle, Representative Technics, Applications, and Development Trends

The rapid prototyping and manufacturing technology (RPM), is an integration of many different disciplines. It is based on an advanced dispersed-accumulated forming principle and originated from 1980s. It generates an entity by first forming a series of layers according to the dispersed section information of the digital model, and then piling the formed layers sequentially together. It is capable of forming parts with complicated structures and non-homogeneous materials. Traditional RPM techniques are mainly used as prototypes in product invention process, such as stereolithography, three-dimensional printing, laminated object manufacturing, and fused deposition modeling. Later, with the progress of material and enabling technology, many new RPM techniques emerged out and have been already applied in the fields such as rapid tooling/moulding, direct formed usable part, nano-/micro-RPM, and biomanufacturing. This high flexible digital manufacturing method has a likely ability to become an almighty forming technology.

Application of customized augments fabricated by rapid prototyping for severe bone defects of the knee

With the population aging and an increasing desire for a high quality of life,millions of patients who suffered knee arthropathy have undergone total knee arthroplasty （TKA）.Although the success rate for primary TKA has been quite high,the number of revision surgeries can not be ignored.Bone loss is one of the challenges confronting surgeons who perform revision TKAs as it can impair alignment accuracy and the long-term stability of the implant.Although several options are available for bone loss after TKA--cement,bone grafting,standard augments,and hinged implants--there is no single ideal option available for all patients with a severe bone defect because of the variety and severity of the defects.1 The burgeoning rapid prototyping （RP） technique,which has been used to fabricate components with complex and unique structures,may offer a novel option in these cases.Keywords：rapid prototyping; severe bone defects; knee

Rapid prototyping technology and its application in bone tissue engineering

Bone defects arising from a variety of reasons cannot be treated effectively without bone tissue reconstruction.Autografts and allografts have been used in clinical application for some time,but they have disadvantages.With the inherent drawback in the precision and reproducibility of conventional scaffold fabrication techniques,the results of bone surgery may not be ideal.This is despite the introduction of bone tissue engineering which provides a powerful approach for bone repair.Rapid prototyping technologies have emerged as an alternative and have been widely used in bone tissue engineering,enhancing bone tissue regeneration in terms of mechanical strength,pore geometry,and bioactive factors,and overcoming some of the disadvantages of conventional technologies.This review focuses on the basic principles and characteristics of various fabrication technologies,such as stereolithography,selective laser sintering,and fused deposition modeling,and reviews the application of rapid prototyping techniques to scaffolds for bone tissue engineering.In the near future,the use of scaffolds for bone tissue engineering prepared by rapid prototyping technology might be an effective therapeutic strategy for bone defects.