Rapid Prototyping Method Research Articles

Reverse Engineering for the Rotor Blades of a Horizontal Axis Micro-hydrokinetic Turbine

The geometric data for a broken blade of a horizontal axis micro-hydrokinetic turbine were obtained by reverse engineering and, reconstructed model was validated by re-engineering process and experiment. A direct scanning procedure was applied in order to verify the blade profile and stagger angles. Two computation methods were used in order to validate technical data of the turbine. For the first was used the classical computation method and, for the second method, the principle of extraction the maximum power from the fluid flow was considered. Differences for stagger angles of the blades were found, and an increased hydraulic power of 7%, when using the second design method comparing to the initial data. After re-engineering, the new runner was manufactured by a rapid prototyping method and was tested for data validation. Experiments confirmed the theoretical results with a good precision. Increased hydraulic power by 5% was recorded.

Reconstruction of human thorax from CT images

3D printing, as a rapid prototyping method is become more common nowadays world widely, including medicine too. The purpose of this article is to reveal the potential of using 3D printing in medicine, especially with a specific example of making a human thorax model from the very beginning of imaging diagnose to the physical model. There will be shown in details how the model of bones, lungs and heart had been created. The circumstances of the 3D printing will be discussed too.

Experimental study of canard UAV aerodynamics

The present paper presents the aerodynamic characteristics of a canard fixed-wing unmanned aircraft TERES-02. A wind tunnel experiment is conducted using a specially designed model of the aircraft. The model is produced through the methods of rapid prototyping using a FDM 3D printer. Aerodynamic corrections are made and thorough analysis and discussion of the results is carried out. The obtained results can be used to determine the accuracy of numerical methods for analysis of aircraft performance.

Cost, resources, and energy efficiency of additive manufacturing

Additive manufacturing (AM) is the process of joining materials to make objects from Computer Aided Design (CAD) model data, usually layer upon layer, as opposed to using subtractive manufacturing methods. The use of rapid prototyping technologies has increased significantly in recent years. These new techniques, while still evolving, are projected to exert a profound impact on manufacturing. They can reduce energy use and time to market and offer industry new design flexibility. We include a brief study on the cost and energy efficiency of selected methods of additive manufacturing compared to traditional methods of manufacturing parts. One common claim is that 3D printers are more energy-efficient than other manufacturing technologies. We present energy efficiency and time requirements for producing a typical mechanical part and a very complicated element, using both traditional manufacturing and rapid prototyping methods. This paper represents an attempt to answer the questions of when 3D printing can be used efficiently and of choosing the appropriate technology on the basis of batch size, element size, complexity, and material requirements.

Additive manufacturing in orthopaedics: Clinical implications

BACKGROUND: The reconstruction of complex pelvic trauma or developmental bone abnormalities is challenging as it involves in-depth understanding of a complex three-dimensional structure. Advances in medical imaging and rapid prototyping allow for detailed pre-operative planning and manufacture of planning models, custom jigs and prostheses to make this type of surgery manageable with good results. METHODS: We report the reconstruction of a hip and proximal femur using planning models, jigs and custom prostheses produced by rapid prototyping methods. These tools helped to solve a complex problem and produced a good functional result for the patient RESULTS: In this case report the patient underwent the reconstruction of her right hip joint. She was unable to mobilise well independently prior to the surgery. The surgery provided her with a stable and functional hip joint. This allows her to mobilise independently with an external prosthesis. One year down the line she has a Fair MSTS score (14 of 30) CONCLUSION: Advances in medical imagining and rapid prototyping have produced planning and operative tools with which surgeons are able to solve complex problems safely and with good result. This technology has widespread use not only in orthopaedics but other surgical disciplines, and with increasing availability and improved cost effectiveness will be used more frequently in the future. Level of evidence: Level V (case report)

Virtual and rapid prototyping methods applied in civil engineering: Snow, wind and earthquake simulations on a five storey building

The paper presents a virtual model of a building with five levels, which was subjected to virtual testing. The results are shown in the figures and diagrams. Also, the finite element method for building simulation for the snow load was used. Based on the 3D model of the building and the digitalized displacement diagram the kinematics and dynamics simulation of the building was made similar to the earthquake on March 4, 1977 in Vrancea, Romania, felt throughout the Balkans. Also, the action of the wind in front of building was simulated with Flow simulations analysis module. The results were shown in the maps of pressures, speeds or temperatures. To obtain real similar calculations, the simulations of the building for the situations were made when we have multiple loads (snow, earthquake, wind). Also, the rapid prototyping method was presented, applied on the scaled building using Prusa Mendel I3 3D printer.

Rapid prototyping: An innovative technique in dentistry

Emergence of advanced digital technology has opened up new perspectives for design and production in the field of dentistry. Rapid prototyping (RP) is a technique to quickly and automatically construct a three-dimensional (3D) model of a part or product using 3D printers or stereolithography machines. RP has various dental applications, such as fabrication of implant surgical guides, zirconia prosthesis and molds for metal castings, maxillofacial prosthesis and frameworks for fixed and removable partial dentures, wax patterns for the dental prosthesis and complete denture. Rapid prototyping presents fascinating opportunities, but the process is difficult as it demands a high level of artistic skill, which means that the dental technicians should be able to work with the models obtained after impression to form a mirror image and achieve good esthetics. This review aims to focus on various RP methods and its application in dentistry.

Modeling and Printing of Successive Misaligned Teeth Stages

ABSTRACT Introduction Patients suffering from problems related to teeth crowding and misalignment require braces for realignment and restoring of perfect teeth. This process of realignment is a long-term treatment varying from 6 to 12 months including many stages during which teeth alignments are achieved in small steps. Patients are always eager to view their futuristic teeth alignment condition at the beginning of their treatment. This requires a predictive methodology on the part of the dentist, which is achievable using software tools and finally reproducing these software-designed stages using rapid prototyping. Materials and methods Dental molds, 3D Scanner, 3D Printer, and 3D computer-aided design software, such as 3-Matic, Maestro ortho studio, 3D Orchestrate, or 3Shape ortho studio for manipulations. Results According to the quantitative analysis, average variation between the preprint and postprint is 0.32. Threedimensional (3D) printed models of these stages are within the units of 0.01 mm; hence, the rapid prototyping method supplements automation of the complete procedure of teeth alignment. Whereas, qualitative analysis of the scans after printing shows little-distorted boundaries due to which clarity has been slightly decreased but, according to the experts, this is clinically acceptable. Conclusion In this study, we provide an insight into generating different aligned stages or steps using available 3D software and further 3D printing of these stages using polylactic acid models. Clinical significance These models are expected to provide very important and tangible information related to the treatment purpose to both patients and dentists. These 3D models further provide platform for the manufacturing of customized transparent teeth aligners which are specific to the patient, better in esthetics, easy to wear, and is inexpensive than traditional teeth braces. How to cite this article Thakur N, Chaudhary N, Juneja M, Jindal P. Modeling and Printing of Successive Misaligned Teeth Stages. World J Dent 2017;8(4):309-314.

Zastosowanie systemu optycznego ATOS II w technikach szybkiego prototypowania modeli kół zębatych otrzymywanych na bazie żywicy epoksydowej

The mechanical and processing properties of composites with epoxy resin (EP) matrix and hybrid fillers, especially with regard to their use in rapid prototyping methods for the preparation of gear models, were evaluated. The accuracy assessment of geometric model shape mapping was performed using a non-contact optical system based on the coordinate optical scanner ATOS Triple Scan II Blue Light from GOM company. The produced hybrid composites show much better mechanical properties than those of unfilled epoxy resin. By introducing the hybrid fillers into EP matrix, a reduction in radial and axial shrinkage was achieved, which led to a radical improvement in the accuracy of geometric shape mapping of gear castings.

Enrichment of magnetic particles using temperature and magnetic field gradients induced by benchtop fabricated micro-electromagnets.

The active transport of analytes inside biosensing systems is important for reducing the response time and enhancing the limit-of-detection of these systems. Due to the ease of functionalization with bio-recognition agents and manipulation with magnetic fields, magnetic particles are widely used for active and directed transport of biological analytes. On-chip active electromagnets are ideally suited for manipulating magnetic particles in an automated and miniaturized fashion inside biosensing systems. Unfortunately, the magnetic force exerted by these devices decays rapidly as we move away from the device edges, and increasing the generated force to the levels necessary for particle manipulation requires a parallel increase in the applied current and the resultant Joule heating. In this paper, we designed a study to understand the combined role of thermal and magnetic forces on the movement of magnetic particles in order to extend the interaction distance of on-chip magnetic devices beyond the device edges. For this purpose, we used a rapid prototyping method to create an active/passive on-chip electromagnet with a micro/nano-structured active layer and a patterned ferromagnetic passive layer. We demonstrated that the measured terminal velocities of particles positioned near the electromagnet edge (∼5.5 μm) closely reflect the values obtained by multi-physics modelling. Interestingly, we observed a two orders of magnitude deviation between the experimental and modelling results for the terminal velocities of particles far from the electromagnet edge (∼55.5 μm). Heat modelling of the system using experimentally-measured thermal gradients indicates that this discrepancy is related to the enhanced fluid movement caused by thermal forces. This study enables the rational design of thermo-magnetic systems for thermally driving and magnetically capturing particles that are positioned at distances tens to hundreds of microns away from the edges of on-chip magnetic devices.

Ultraprecision Machining of Silicon Wafer by Micromilling Process

Silicon, being a material which allows light transmission beyond visible spectrum is a good candidate for the integration of microfluidic and optical devices. The lack of rapid prototyping method in particular mechanical-based micromachining process for silicon device processing is due to the brittleness property of silicon. Silicon fails or breaks without significant deformation when subjected to tension or stress. This study presents an experimental investigation on surface of micro-machined single-crystal silicon with (111) orientation. Full immersion slot milling was conducted using solid cubic boron nitride (CBN) micro-end mills. Influences of cutting parameters including spindle speed, feed rate and axial depth of cut on surface roughness were analyzed. Surface and subsurface characterization studies show that the primary material removal mode is ductile or partial ductile using lower feed rate.

Using methods of the reverse engineering to carry personalised preoperative stabilisers out on the example of vertebrae of human spine

There is presented the possibility of using modern rapid prototyping methods in the form of reverse engineering on the example of lumbosacral spine of a human spine at the level of L3-L. Reverse engineering techniques were directly used in the generation and processing of point clouds from a real object. The point clouds were generated by using specialised Mimics software and basing on the results of computer tomography and magnetic resonance imaging using. In the next stage of processing, there was the export of the appropriately converted point clouds to STL format, compatible with CAD programs. The reverse engineering process took four steps: digitisation of the real object, using non-invasive imaging techniques (CT, MRI), processing the point clouds from the digitisation stage, construction of a surface model of the real object basing on the processed point clouds, realising of the real object’s copy by using rapid prototyping techniques. In the final stage, the model of the complex spinal’s part was tested to MES strength analysis.

Three-Dimensional Printed Scaffolds with Multipotent Mesenchymal Stromal Cells for Rabbit Mandibular Reconstruction and Engineering.

Multipotent mesenchymal stromal cells (MSC) derived from both the bone marrow and adipose tissue possess the ability to differentiate into multiple cell lineages, regulate the immune function by secreting numerous bioactive paracrine factors, and hold great potential in cell therapy and tissue engineering. When combined with three-dimensional (3D) scaffolds, MSC can be used for bone defect reconstruction and engineering. This protocol describes the isolation of bone marrow mesenchymal stromal cells (BMMSC) and adipose-tissue derived stem cells (ADSC) from rabbits for subsequent seeding on tissue-engineered 3D-printed scaffolds and transplantation into a rabbit-model with the goal of repairing large osseous mandibular defects (one quarter of the lower jaw is removed surgically). Steps to demonstrate the three cell differentiation lineage potentials of BMMSC and ADSC into osteocytes, adipocytes, and chondrocytes are described. A modified cell seeding method using syringes on scaffold is detailed. Creating a large mandibular bone defect, the rapid prototyping method to print a customized 3D-scaffold, the scaffold implantation procedure in rabbits, and microcomputed tomography (micro-CT) analysis are also described.

Optimization and Rapid Prototyping of Catadioptric Omnidirectional Stereo Sensors

Omnidirectional stereo imaging provides useful depth information for autonomous navigation. In principle, omnidirectional stereo images can be achieved at a low cost, using a single camera and two curved mirrors, but such systems are not widely deployed. Here we describe the optimization and rapid prototyping of a low-cost omnidirectional stereo sensor for a telepresence robot. We consider single-viewpoint and non-single-viewpoint designs. We present a new way of relaxing single-viewpoint constraints, while retaining the ability to vertically rectify images. We also present a method of optimizing the resulting design to minimize depth errors. However, we show that despite these steps, nonsingle-viewpoint designs produce stereo disparities over a more practical range of distances. The lack of a single viewpoint could potentially introduce distortions that affect stereo matching, but these distortions are removed by projecting rays through the mirror geometry. We also describe a new method for rapid prototyping of curved mirrors using 3D printing and vacuum forming.

Study on the Growth of Holes in Cold Spraying via Numerical Simulation and Experimental Methods

Cold spraying is a promising method for rapid prototyping due to its high deposition efficiency and high-quality bonding characteristic. However, many researchers have noticed that holes cannot be replenished and will grow larger and larger once formed, which will significantly decrease the deposition efficiency. No work has yet been done on this problem. In this paper, a computational simulation method was used to investigate the origins of these holes and the reasons for their growth. A thick copper coating was deposited around the pre-drilled, micro-size holes using a cold spraying method on copper substrate to verify the simulation results. The results indicate that the deposition efficiency inside the hole decreases as the hole become deeper and narrower. The repellant force between the particles perpendicular to the impaction direction will lead to porosity if the particles are too close. There is a much lower flattening ratio for successive particles if they are too close at the same location, because the momentum energy contributes to the former particle’s deformation. There is a high probability that the above two phenomena, resulting from high powder-feeding rate, will form the original hole, which will grow larger and larger once it is formed. It is very important to control the powder feeding rate, but the upper limit is yet to be determined by further simulation and experimental investigation.

Comparison of Two Inexpensive Rapid Prototyping Methods for Manufacturing Filament Target Ultrasound Phantoms

Current use of 3-D printers to manufacture ultrasound phantoms is limited to relatively expensive photopolymer jetting printers. The present work investigates the feasibility of using two common and inexpensive 3-D printer technologies, fused deposition modeling (FDM) and digital light processing (DLP), to print custom filament target phantoms. Acoustic characteristics obtained from printed solid blocks indicated that the printing materials—acrylonitrile butadiene styrene and polylactic acid for FDM and a photopolymer for DLP printing—were appropriate for use as scatterers. A regular grid of filaments was printed to study printing accuracy. As a proof of concept of the phantom manufacturing process, a complex pattern of filament targets was placed in de-ionized water to create a phantom, which was then imaged using an ultrasound imager. The pattern was clearly identifiable, although multiple reflections were observed, which underscores the importance of future work to enhance printing resolution. This goal is deemed possible using improvement of the DLP printing setup.

Rhipsalis (Cactaceae)-like Hierarchical Structure Based Microfluidic Chip for Highly Efficient Isolation of Rare Cancer Cells.

The circulating tumor cells (CTCs), originating from the primary tumor, play a vital role in cancer diagnosis, prognosis, disease monitoring, and precise therapy. However, the CTCs are extremely rare in the peripheral bloodstream and hard to be isolated. To overcome current limitations associated with CTC capture and analysis, the strategy incorporating nanostructures with microfluidic devices receives wide attention. Here, we demonstrated a three-dimensional microfluidic device (Rm-chip) for capturing cancer cells with high efficiency by integrating a novel hierarchical structure, the "Rhipsalis (Cactaceae)"-like micropillar array, into the Rm-chip. The PDMS micropillar array was fabricated by soft-lithography and rapid prototyping method, which was then conformally plated with a thin gold layer through electroless plating. EpCAM antibody was modified onto the surface of the micropillars through the thiol-oligonucleotide linkers in order to release captured cancer cells by DNase I treatment. The antibody-functionalized device achieved an average capture efficiency of 88% in PBS and 83.7% in whole blood samples. We believe the Rm-chip provided a convenient, economical, and versatile approach for cell analysis with wide potential applications.

Assessing the influence of feedback-inclusive rapid prototyping on understanding the semantics of parallel UML statecharts by novice modellers

ContextUML diagrams are the de facto standard for analysing, communicating and designing software systems, as well as automated code generation. However there is a certain degree of difficulty in understanding a system represented by means of UML diagrams. ObjectOur previous research demonstrates a significant improvement in understanding the structural aspects of a system represented as a UML class diagram when using a feedback-inclusive prototype of a model. This paper extends our previous work with an empirical validation study for the effectiveness of the feedback-inclusive rapid prototyping (FIRP) method, on the comprehension of system dynamics represented as multiple interacting UML statecharts. Because models often combine structural and behavioural views that are highly intertwined, we additionally evaluate the effectiveness of the proposed method with respect to comprehension of the between-view consistency. MethodThe FIRP environment was built following the principles of Design Science Research in Information Systems. This study targets the empirical validation of the effectiveness of the proposed technique using an experimental study method. Two experiments were conducted with the participation of 65 final-year master students in the context of different modelling courses from different study programs at KU Leuven using two two-group factorial experimental designs. The effectiveness of the FIRP method was measured by comparing students’ performance between the cycles with and without the use of the method, using the understandability (comprehension test results) as the dependent variable and the use of FIRP as the independent variable. Effects from unknown variables were neutralized by means of randomized group compositions. The effectiveness of FIRP was additionally assessed with respect to personal characteristics (age, gender, previous knowledge, self-efficacy) and user acceptance (perceived ease of use, perceived utility, preference, satisfaction). ResultsThe findings reveal a significant positive impact of the use of the prototyping technique on students’ comprehension of system dynamics represented as multiple interacting statecharts. ConclusionsThe findings provide empirical support for the advantage of the use of FIRP over manual inspection of interacting statecharts. The findings also suggest that the method is suitable for training system's analysis and modelling skills when UML statecharts are involved.

Microfluidic 3D Helix Mixers.

Polymeric microfluidic systems are well suited for miniaturized devices with complex functionality, and rapid prototyping methods for 3D microfluidic structures are increasingly used. Mixing at the microscale and performing chemical reactions at the microscale are important applications of such systems and we therefore explored feasibility, mixing characteristics and the ability to control a chemical reaction in helical 3D channels produced by the emerging thread template method. Mixing at the microscale is challenging because channel size reduction for improving solute diffusion comes at the price of a reduced Reynolds number that induces a strictly laminar flow regime and abolishes turbulence that would be desired for improved mixing. Microfluidic 3D helix mixers were rapidly prototyped in polydimethylsiloxane (PDMS) using low-surface energy polymeric threads, twisted to form 2-channel and 3-channel helices. Structure and flow characteristics were assessed experimentally by microscopy, hydraulic measurements and chromogenic reaction, and were modeled by computational fluid dynamics. We found that helical 3D microfluidic systems produced by thread templating allow rapid prototyping, can be used for mixing and for controlled chemical reaction with two or three reaction partners at the microscale. Compared to the conventional T-shaped microfluidic system used as a control device, enhanced mixing and faster chemical reaction was found to occur due to the combination of diffusive mixing in small channels and flow folding due to the 3D helix shape. Thus, microfluidic 3D helix mixers can be rapidly prototyped using the thread template method and are an attractive and competitive method for fluid mixing and chemical reactions at the microscale.

Direct Printing and Electrical Characterization of Conductive Micro-Silver Tracks by Alternating Current-Pulse Modulated Electrohydrodynamic Jet Printing

In this paper, a rapid prototyping method for fabrication of highly conductive micropatterns on insulating substrates was developed and evaluated. Sub-20 μm microstructures were printed on flexible insulating substrates using alternating current (AC) modulated electrohydrodynamic jet (e-jet) printing. The presented technique resolved the challenge of current rapid prototyping methods in terms of limited resolution and conductivity for microelectronic components for flexible electronics. Significant variables of fabrication process, including voltage, plotting speeds, curing temperature, and multilayer effect, were investigated to achieve reliable printing of silver tracks. Sub-20 μm silver tracks were successfully fabricated with resistivity about three times than bulk silver on flexible substrates, which indicates the potential applications of electrohydrodynamic printing in flexible electronics and medical applications, such as lab-on-chip systems.