Advances In Rapid Prototyping Research Articles

Physically Consistent Lie Group Mesh Models for Robot Design and Motion Co-Optimization

With recent advances in rapid prototyping and mechatronics, the problem of simultaneous design and motion optimization, or the co-design problem, is becoming more and more relevant in robotics. For reasons of computational tractability, all existing methods use simplified approximations of a robot’s kinodynamic model. We empirically confirm that any model approximations that are not physically consistent, i.e., the kinodynamic model parameters do not accurately reflect the actual link shapes, can sometimes lead to large errors in the optimization. We then propose a physically consistent, Lie group-based mesh element model for robot links that (i) parametrizes a wide variety of link shapes, and (ii) provides closed-form analytic gradients for the mesh deformations. The latter property is key to developing efficient co-design optimization algorithms that significantly improve numerical convergence and stability. Our co-design methodology is validated through extensive numerical and hardware experiments involving 3D-printed serial and parallel robots.

Use of computer-aided three-dimensional prototyping to surgically assist in tooth autotransplantation

Autotransplantation is a surgical technique in which a donor tooth belonging to the same individual is repositioned into a surgically prepared socket or site of previous tooth extraction. It is beneficial in patients with teeth affected by agenesis, trauma, significant caries, and in teeth in a non-restorable condition or prognostically poor due to other pathology. It is particularly useful in paediatric patients, as properly transplanted teeth have a vital periodontium that allows for continuous growth and functional adaptation leading to preservation of the alveolar ridge. Technological advances in rapid prototyping combined with three-dimensional (3D) computed tomography (CT) have the ability to revolutionise autotransplantation. Preoperative planning for atraumatic extraction of the donor tooth and precise preparation of the recipient site with a rapid prototyped surgical template of the donor tooth considerably reduces the extra-alveolar time, and also reduces manipulation of the root sheath and periodontal ligament, and related trauma. This case series demonstrates the efficient and successful autotransplantation of various types of teeth with the use of a rapid prototyped surgical template produced from 3D CT. The use of this technology is expected to refine the surgical technique and improve treatment outcomes.

Surface plasmon induced enhancement in selective laser melting processes

PurposeSelective laser melting (SLM) is an advanced rapid prototyping or additive manufacturing technology that uses high power density laser to fabricate metal/alloy components with minimal geometric constraints. The SLM process is multi-physics in nature and its study requires development of complex simulation tools. The purpose of this paper is to study – for the first time, to the best of the authors’ knowledge – the electromagnetic wave interactions and thermal processes in SLM based dense powder beds under the full-wave formalism and identify prospective metal powder bed particle distributions that can substantially improve the absorption rate, SLM volumetric deposition rate and thereby the overall build time.Design/methodology/approachWe present a self-consistent thermo-optical model of the laser-matter interactions pertaining to SLM. The complex electromagnetic interactions and thermal effects in the dense metal powder beds are investigated by means of full-wave finite difference simulations. The model allows for accurate simulations of the excitation of gap, bulk and surface electromagnetic resonance modes, the energy transport across the particles, time dependent local permittivity variations under the incident laser intensity, and the thermal effects (joule heating) due to electromagnetic energy dissipation.FindingsLocalized gap and surface plasmon polariton resonance effects are identified as possible mechanisms toward improved absorption in small and medium size titanium powder beds. Furthermore, the observed near homogeneous temperature distributions across the metal powders indicates fast thermalization processes and allows for development of simple analytical models to describe the dynamics of the SLM process.Originality/valueTo the best of the authors’ knowledge, for the first time the electromagnetic interactions and thermal processes with dense powder beds pertaining to SLM processes are investigated under full-wave formalism. Explicit description is provided for important SLM process parameters such as critical laser power density, saturation temperature and time to melt. Specific guidelines are presented for improved energy efficiency and optimization of the SLM process deposition rates.

Virtual bead representation and surface roughness evaluation challenges for additive manufacturing material extrusion processes

Additive manufacturing (AM) processes, such as material extrusion, are part of a popular growing technology field; with limited human assistance required and advanced rapid prototyping capabilities, this technology is advertised to have limitless possibilities. The common challenge faced by users is a lack of design control of the surface roughness, which is highlighted by a characteristic “stair case” layering effect at the boundary. Focusing on material extrusion processes, the goal of this research is to model representative bead shapes, and highlight the surface roughness challenges for assessing boundary-fill regions. Various bead shapes are explored and compared through virtual simulation. Unique material extrusion AM-related issues arise, and it is shown that machining solutions may not provide the desired surface smoothness. This research illustrates that specific physical and virtual assessment tools and standards need to be further developed to convey surface roughness attributes for material extrusion additive manufactured components.

Metal Prototyping the future of Automobile Industry: A review

Metal Prototyping an advanced Rapid Prototyping technique has shown a very high potential to reduce the time of manufacture and cost of product effectively. Implementation of metal prototyping to the extent of 4D Printing improves the future of small, medium and large-scale enterprises of Automobile industry. This paper gives a glance of metal prototyping to Automobile Industry. The implementation of future metal prototyping Automobile industry involves 1. Re- engineering model generation for spare parts of two, three, four-wheeler Automobiles, 2. Mathematical and software simulation by using FEM techniques, 3.3D Printing, 4. Metal prototyping though 3d/ 4d printing, 5. Prototype testing and research labs are described in detail. Finally this review gives a glance on future Automobile Industry through metal Prototyping

A Comparison of Biocompatibility of a Titanium Alloy Fabricated by Electron Beam Melting and Selective Laser Melting.

Electron beam melting (EBM) and selective laser melting (SLM) are two advanced rapid prototyping manufacturing technologies capable of fabricating complex structures and geometric shapes from metallic materials using computer tomography (CT) and Computer-aided Design (CAD) data. Compared to traditional technologies used for metallic products, EBM and SLM alter the mechanical, physical and chemical properties, which are closely related to the biocompatibility of metallic products. In this study, we evaluate and compare the biocompatibility, including cytocompatibility, haemocompatibility, skin irritation and skin sensitivity of Ti6Al4V fabricated by EBM and SLM. The results were analysed using one-way ANOVA and Tukey’s multiple comparison test. Both the EBM and SLM Ti6Al4V exhibited good cytobiocompatibility. The haemolytic ratios of the SLM and EBM were 2.24% and 2.46%, respectively, which demonstrated good haemocompatibility. The EBM and SLM Ti6Al4V samples showed no dermal irritation when exposed to rabbits. In a delayed hypersensitivity test, no skin allergic reaction from the EBM or the SLM Ti6Al4V was observed in guinea pigs. Based on these results, Ti6Al4V fabricated by EBM and SLM were good cytobiocompatible, haemocompatible, non-irritant and non-sensitizing materials. Although the data for cell adhesion, proliferation, ALP activity and the haemolytic ratio was higher for the SLM group, there were no significant differences between the different manufacturing methods.

Three dimensional plotted extracellular matrix scaffolds using a rapid prototyping for tissue engineering application

Naturally derived biomaterials are rarely used in advanced rapid prototyping technology despite their superior biocompatibility. The main problem of natural material plotting is the high sensitivity of materials concentration and viscosity on the plotting nozzle. The aim of the current study was to develop a three dimensional (3D) plotting system capable of dispensing extracellular matrix (ECM)-c (ECM powder blended collagen) and manufacture various shapes of ECM-c scaffolds to apply for irregular defects. We had adapted a powder-based plotting approach to print the stable 3D construct using only cartilage derived ECM materials. This study successfully developed the plotting method for high viscous ECM-c material and showed the 3D plotted scaffolds with high interconnected pores as well as complex shape. Furthermore, cell culture results proved that plotted ECM-c scaffolds were able to provide a suitable environment for cell attachment, proliferation and chondrogenesis. This study shows the 3D printing feasibility of ECM natural material has demonstrated as a first time. We believe our results will offer a meaningful step toward the 3D scaffold printing based on natural ECM materials for future organ printing.

Designing 3D tactile protein models as an introduction to biology research (618.10)

Technological advances in rapid prototyping provide an opportunity for students to understand structure‐function relationships in our three dimensional living world. We are currently examining the impact of a newly developed introductory biology laboratory (BIO207) in which undergraduates investigate Lyme disease by designing 3D tactile models of proteins. Assessments providing direct comparison between this new lab and the concurrent alternative introductory biology lab include CURE (Classroom Undergraduate Research Experience) pre/post survey data, matched exam questions between the two courses, and performance in future coursework. Success and growth of this course has led to the design of a BIO207 alternative for undergraduates interested in neuroscience. Using the cat pre‐Botzinger complex (which is the primary locus of respiratory rhythm generation) as a topical focus, students use high‐resolution structures from RCSB Protein Data Bank to print tactile models and research a structure‐function relationship in this CNS region.Grant Funding Source: Supported by HHMI 52006940

Rapid Prototyping and 3‐D Printing of Experimental Equipment in Soil Science Research

Until recently, the custom manufacture of equipment for laboratory or field experiments in soil science required appreciable know‐how, and was extremely time‐consuming. Technological advances in rapid prototyping and “3‐D printing” in the last decade afford significant, and as yet untapped, opportunities to manufacture equipment in a very different way. In the present note, we demonstrate with two concrete examples that 3‐D printing is not only a very effective and versatile technique to produce laboratory or field equipment. It also alleviates some of the restrictive technical constraints imposed by lathes and molding processes used traditionally, and it permits a much more efficient sharing of information among researchers. Given the tremendous advances in 3‐D printing unfolding at the moment, it is anticipated that this technology will revolutionize the way we design, and especially replicate, experiments in soil science.

Getting in touch—3D printing in Forensic Imaging

With the increasing use of medical imaging in forensics, as well as the technological advances in rapid prototyping, we suggest combining these techniques to generate displays of forensic findings. We used computed tomography (CT), CT angiography, magnetic resonance imaging (MRI) and surface scanning with photogrammetry in conjunction with segmentation techniques to generate 3D polygon meshes. Based on these data sets, a 3D printer created colored models of the anatomical structures. Using this technique, we could create models of bone fractures, vessels, cardiac infarctions, ruptured organs as well as bitemark wounds. The final models are anatomically accurate, fully colored representations of bones, vessels and soft tissue, and they demonstrate radiologically visible pathologies. The models are more easily understood by laypersons than volume rendering or 2D reconstructions. Therefore, they are suitable for presentations in courtrooms and for educational purposes.

Thermal imaging analysis of 3D biological agarose matrices

Advances in rapid prototyping have allowed for the construction of biocompatible materials (hydrogels) to be used in regenerative medicine. Within this area of construction inherent problems arise due to the mechanical instability of such materials that are temperature dependent. This research paper describes a thermal imaging analysis used to circumvent needle blockage when using an RP technology called bioplotting, used for extruding high temperature hydrogels, where agarose was the experimental biomaterial. The investigation describes how we have overcome these inherent problems through thermal imaging analysis, allowing us to accurately construct 3D biological matrices that have satisfied the in-vitro cell requirements for producing artificial tissue scaffolds. By properly insulating the needle and chamber, we have reduced the time taken for the needle to reach a sufficient plotting temperature. The analysis has allowed us to produce 3D biological matrices that have satisfied the in vitro cell requirements for producing artificial tissue. The analysis reported in this paper has opened the possibility for other high temperature dependent hydrogels to be constructed into 3D biological matrices without delay.

Towards complete product development teaching employing combined CAD–CAM–CAE technologies

AbstractProblem based learning and teamwork activities often turn out to be the student's first point of contact with what Industry is really like and becomes a fundamental milestone in their learning throughout their degree course. The complete development of products and machines provides opportunities for active learning projects where students can apply computer aided design, engineering and manufacturing technologies, as well as the most advanced rapid prototyping technologies, so highly valued by Industry. We present complete product developments that have been undertaken by teams of students, as a way to the practical application of design and manufacturing concepts acquired in the subject “Design and Manufacture with Plastic Materials.” This subject is taught in the 5th course at Universidad Politécnica de Madrid—U.P.M. as part of the Mechanical Engineering Degree. The use of the “Rapid Prototyping Technologies” available in the U.P.M.'s Product Development Laboratory, has enabled prototypes to be manufactured, which means the pre‐production stage has been attained. The use of these technologies for teaching purposes constitutes a whole new experience in the U.P.M. Important information for improvements has been obtained from students' surveys and the correspondence between students' dedication and the European Credits assigned to the subject is very satisfactory. © 2009 Wiley Periodicals, Inc. Comput Appl Eng Educ 18: 661–668, 2010; View this article online at wileyonlinelibrary.com; DOI 10.1002/cae.20270

Advances in Rapid Prototyping for Solid State Ionics

Scientists and engineers often need to consider several material or design properties with regard to solid-state ionics. However, most techniques for fabricating devices or scientific samples have several drawbacks. These include, but are not limited to, material incompatibility, lack of fine-line resolution, or expensive/time consuming when considering iterative design processes. This work involves the development of materials for use with a new type of rapid-prototype platform (nScrypt, Inc). The ultimate goal is to produce multiple design schemes for various devices (e.g., fuel cells and gas sensors) which will allow for quick analysis and engineering turnaround for improved performance.

Construction of 3D biological matrices using rapid prototyping technology

PurposeHydrogels with low viscosities tend to be difficult to use in constructing tissue engineering (TE) scaffolds used to replace or restore damaged tissue, due to the length of time it takes for final gelation to take place resulting in the scaffolds collapsing due to their mechanical instability. However, recent advances in rapid prototyping have allowed for a new technology called bioplotting to be developed, which aims to circumvent these inherent problems. This paper aims to present details of the process.Design/methodology/approachThe paper demonstrates how by using the bioplotting technique complex 3D geometrical scaffolds with accurate feature sizes and good pore definition can be fabriated for use as biological matrices. PEG gels containing the cell‐adhesive RGD peptide sequence were patterned using this method to produce layers of directional microchannels which have a functionalised bioactive surface. Seeding these gels with C2C12 myoblasts showed that the cells responded to the topographical features and aligned themselves along the direction of the channels.FindingsThis process allows plotting of various materials into a media bath containing material of similar rheological properties which can be used to both support the structure as it is dispensed and also to initiate cross‐linking of the hydrogel. By controlling concentrations, viscosity and the temperature of both the plotting material and the plotting media, the speed of the hydrogel gelation can be enhanced whilst it is cross‐linking in the media bath. TE scaffolds have been produced using a variety of materials including poly(ethylene glycol) (PEG), gelatin, alginic acid and agarose at various concentrations and viscosities.Originality/valueThis paper describes one of the very few examples of accurate construction of 3D biological microporous matrices using hydrogel material fabricated by the bioplotting technique. This demonstrates that this technique can be used to produce 3D scaffolds which promote tissue regeneration.

Advances in Rapid Prototyping for Solid State Ionics

not Available.

Using RP to promote collaborative design of customised medical implants

PurposeThe last decade has seen major advances in rapid prototyping (RP), with it becoming a multi‐disciplinary technology, crossing various research fields, and connecting continents. Process and material advancements open up new applications and manufacturing (through RP) is serving non‐traditional industries. RP technology is used to support rapid product development (RPD). The purpose of this paper is to describe how the Integrated Product Development research group of the Central University of Technology, Free State, South Africa is applying various CAD/CAM/RP technologies to support a medical team from the Grootte Schuur and Vincent Palotti hospitals in Cape Town, to save limbs – as a last resort at a stage where conventional medical techniques or practices may not apply any longer.Design/methodology/approachThe paper uses action research to justify the proposal of a new method to use CAD/CAM/RP related technologies to substitute lost/damaged bone regions through the use of CT to CAD to.STL manipulation.FindingsA case study where RP related technologies were used to support medical product development for a patient with severe injuries from a road accident is discussed.Originality/valueThe paper considers current available technologies, and discusses new advancements in direct metal freeform fabrication, and its potential to revolutionise the medical industry.

Effect and control of hatch length on material properties in the direct metal laser sintering process

As one of the advanced rapid prototyping and manufacturing processes, the direct metal laser sintering (DMLS) process gives designers the possibility of building parts of almost any complexity in a wide range of metal materials. In DMLS, the sintered material is anisotropic and heterogeneous, affecting the quality and performance of the built parts. This paper presents a study that focuses on these two material characteristics and proposes a method to control them. Firstly, a series of experiments have been designed and conducted to study the influence of material anisotropy and heterogeneity on the built part strength. The heterogeneity was analysed and the microstructural changes due to different hatch line lengths were observed using scanning electron microscopy. The relationship between the hatch line length and the part quality is derived on the basis of experimental data collected and an appropriate statistical analysis applied. A genetic algorithm method is also proposed to optimize the hatch direction for obtaining more homogeneous sintered material properties. The experimental results verify that the negative effect of varying hatch lines in the early sintering process can be controlled effectively.

Rapid prototyping: a key to fast tracking design to manufacture

Describes recent advances in rapid prototyping using a new ink jet style binder fluid that speeds up prototype manufacture by a factor of ten. Also cites numerous application examples and cost benefits.

A comparison between stereolithography and aluminium injection moulding tooling

Advances in rapid prototyping and machining have resulted in reduced lead times for injection moulding tooling. Comparisons between aluminium and stereolithography (SL) tools are made with regard to the ejection forces required to push mouldings from the tools, heat transfer through the tools and the surface roughness of the tools. The results show that ejection forces for both types of tools are increased when a longer cooling time prior to ejection is used. The ejection forces required from a rough aluminium tool are considerably higher than those from a smooth aluminium tool. SL tools do not appear to be subjected to any smoothing as a result of moulding polypropylene parts. The rubber like nature of the tool’s surface is as a direct consequence of the low glass transition temperature and low thermal conductivity of the tool material. Further potential benefits of the low thermal properties of the tool are discussed.

FUSION OF DIGITAL PHOTOELASTICITY RAPID PROTOTYPING AND RAPID TOOLING TECHNOLOGIES

The recent advances in rapid prototyping (RP) [1–5] have made it possible to produce prototypes of very complicated parts directly from three-dimensional computer aided design (CAD) models without using part specific tooling. Application of these techniques for producing prototypes leads to considerable reduction in the total cycle time. There are a number of RP techniques developed so far, such as stereolithography (STL), fused deposition modelling (FDM), solid ground curing (SGC), selective laser sintering (SLS) etc. This technology has emerged in response to the need for reducing the lead-time to produce physical prototypes. These models could be directly used for checking form, fit and function, getting management approval for detailed design and development, conducting market research, submitting for price negotiations and as models for wind tunnel testing.