Digital Fabrication Techniques Research Articles

A scoping review of digital fabrication techniques applied to prosthetics and orthotics: Part 1 of 2-Prosthetics.

Traditionally, the manufacture of prostheses is time-consuming and labor-intensive. One possible route to improving access and quality of these devices is the digitalizing of the fabrication process, which may reduce the burden of manual labor and bring the potential for automation that could help unblock access to assistive technologies globally. To identify where there are gaps in the literature that are creating barriers to decision-making on either appropriate uptake by clinical teams or on the needed next steps in research that mean these technologies can continue on a pathway to maturity. Scoping literature review. A comprehensive search was completed in the following databases: Allied and Complementary Medicine Database, MEDLINE, Embase, Global Health Archive, CINAHL Plus, Cochrane Library, Web of Science, Association for Computing Machinery, Institute of Electrical and Electronics Engineers, and Engineering Village, resulting in 3487 articles to be screened. After screening, 130 lower limb prosthetic articles and 117 upper limb prosthetic articles were included in this review. Multiple limitations in the literature were identified, particularly a lack of long-term, larger-scale studies; research into the training requirements for these technologies and the necessary rectification processes; and a high range of variance of production workflows and materials which makes drawing conclusions difficult. These limitations create a barrier to adequate evidence-based decision-making for clinicians, technology developers, and wider policymakers. Increased collaboration between academia, industry, and clinical teams across more of the pathway to market for new technologies could be a route to addressing these gaps.

Insight into the shear failure mechanism of Wound FRP reinforced concrete beams through numerical simulations considering interface damage and material anisotropy

Utilizing the inherent flexibility of high-strength fibres, Fibre-Reinforced Polymers (FRP) can be engineered as optimized reinforcing cages for concrete structures through the application of advanced digital fabrication techniques. However, existing codified design methods and numerical investigations found in the literature fall short in providing an accurate characterization of the actual performance of FRP reinforcement in concrete structures. This work presents a novel Finite Element (FE) modelling approach for concrete beams reinforced with FRP in non-traditional arrangements, accounting for reinforcement-concrete interface behaviour and FRP material anisotropy. Validation against experimental tests of flexible Wound-FRP (W-FRP) reinforced beams demonstrates accurate predictions of load-displacement curves, crack propagation, and load-strain curves. The study delves into shear failure mechanisms, emphasizing FRP reinforcement behaviour and damage evolution at reinforcement-concrete interfaces. Further parametric analysis explores the impact of W-FRP inclination angle and spacing, revealing their significant influence on beam stiffness and ultimate capacity. Specifically, the horizontal tensile force component in inclined links and increased modulus of links with reduced spacing enhance stiffness. Altered crack propagation due to W-FRP patterns, coupled with resulting damage development at concrete-stirrup interfaces and stress evolution in W-FRP stirrups, are key contributors to varied ultimate capacity. Moreover, higher performance of W-FRP stirrups with smaller spacing and reduced cross-section area further bolsters ultimate capacity. This research advances the modelling of FRP-reinforced concrete, offering potential solutions for optimizing FRP material utilization in concrete structures.

Fracture strength of preformed zirconia crown and CAD-CAM zirconia, ceramic, and hybrid composite crowns for the restoration of primary molars: An invitro study.

Paediatric-preformed zirconia crowns have been associated with several issues, primarily their inability to be crimped and the need for extensive tooth preparation. Additionally, the capacity to adjust the size, shape, and fit of these crowns is very limited. To evaluate and compare the fracture strength of four different types of dental crowns intended for paediatric patients. The fracture resistance of four types of paediatric crowns was evaluated using the universal testing machine; freshly extracted primary molars received one of the following: preformed zirconia crowns, custom-made computer-aided design and computer-aided manufacturing (CAD-CAM) zirconia crowns, custom-made CAD-CAM ceramic crowns, and custom-made CAD-CAM hybrid composite crowns. Data were statistically compared using the Kruskal-Wallis test followed by the Bonferroni test, and the level of significance was set at 5%. Results showed that there was a statistically significant difference among the four groups (p < .001). The highest value of fracture force was observed for the milled zirconia crown and the lowest for the prefabricated zirconia. The implementation of the CAD-CAM digital crown fabrication technique has the potential to address issues associated with preformed crowns in paediatric patients, particularly in terms of fracture resistance.

Unreinforced concrete masonry for circular construction

This paper proposes an effective approach to realise circular construction with concrete, and shows Unreinforced Masonry as a foundational building block for it.The paper outlines the importance of circularity in building structures. It specifically focuses on the impact of circular construction with concrete on improving the sustainability of the built environment in a rapidly urbanising world economy. Subsequently, the relevance of principles of structural design and construction of unreinforced masonry to achieve circularity is articulated. Furthermore, the paper presents and summarises recent developments in the field of Unreinforced Concrete Masonry (URCM) including digital design tools to synthesise structurally efficient shapes, and low-waste digital fabrication techniques using lower-embodied-emission materials to realise the designed shapes. The paper exemplifies these using two physically realised, full-scale URCM footbridge prototypes and a commercially available, mass-customisable building floor element, called the Rippmann Floor System (RFS).The paper also outlines the benefits of mainstream, industrial-scale adoption of the design and construction technologies for URCM, including accelerating the pathway to decarbonise the concrete industry. In summary, the paper argues that URCM provides a solution to significantly mitigate the carbon emissions associated with concrete and reduce the use of virgin resources whilst retaining its benefits such as widespread and cheap availability, endurance, fire safety, low maintenance requirements and recyclability.

Effect of process parameters on mechanical properties and wettability of polylactic acid by fused filament fabrication process

Abstract Fiber-reinforced composites have changed additive manufacturing into a sustainable manufacturing paradigm with the capacity to produce items with outstanding mechanical performance. The fused filament fabrication (FFF) process is the latest in advanced digital fabrication techniques used for fabricating polymer material using additive layer deposition. In this study, the results of mechanical and vibration tests were used to examine the impact of process variables such as layer thickness (0.08 mm, 0.25 mm, and 0.64 mm), infill density (20 %, 40 %, 60 %, and 80 %), and infill pattern (rectilinear, triangular, and hexagonal). The novelty of this work is to correlate the contact angle measurement with the mechanical properties of the 3D-printed specimens. The adhesion behaviour of the 3D printed parts is examined by measuring the contact angle from the wettability test. From the findings, it was observed that the infill density and layer pattern play a significant role in the interlayer adhesion, as evident from the contact angle measurement.

Digital Fabrication in Architecture

Digital fabrication has emerged as a transformative force in the field of architecture, revolutionizing design, and construction processes. The paper begins by providing an overview of digital fabrication and its evolution within the architectural domain. It discusses the integration of advanced technologies such as computer-aided design (CAD), additive manufacturing (3D printing) into architectural processes. The advantages of digital fabrication, including increased design flexibility, enhanced precision, reduced material waste, and accelerated construction timelines, are highlighted. Furthermore, the paper investigates various case studies showcasing the successful implementation of digital fabrication in architecture. Through these examples, the potential of digital fabrication techniques to enable complex geometries and facilitate sustainable design practices is underscored. To conclude, this paper emphasizes the immense potential of digital fabrication as a tool for architectural innovation. It advocates for further research and development in this field to overcome the challenges and maximize the benefits. By embracing digital fabrication, architects can push the boundaries of design, create structures of unparalleled intricacy, and achieve sustainable and efficient built environments.

RECORDING MICHELANGELO'S DAVID: ULTRA-HIGH RESOLUTION 3D SCANNING AND MODELING FOR DIGITAL AND PHYSICAL REPRODUCTION

Abstract. In the twentieth century, the physical reproduction of a work of art was considered only a business activity and a replica would rarely be on display in a museum. In recent decades, however, as high-resolution digital sampling and fabrication techniques have become popular in all fields, the various ways in which they can be applied to cultural heritage are leading to a more articulated approach to their use. They are no longer considered fakes or imitations, but as artefacts specially designed and built to facilitate the dissemination of heritage or perform simulations without damaging the originals. This case study describes the process of creating the replica of Michelangelo's David that has been displayed in the Italian Pavilion at EXPO 2020 in Dubai. Starting with the planning of the survey, the instruments and facilities used, and the fieldwork process are described. The resulting data have been then processed to produce a model optimised for replication on a large format additive manufacturing printer. Finally, the challenges of processing and managing ultra-high-resolution data are outlined.

Assessment of the Effect of two Different Digital Fabrication Techniques on Marginal and Internal Fit of Interim Fixed Dental Prothesis

Assessment of the Effect of two Different Digital Fabrication Techniques on Marginal and Internal Fit of Interim Fixed Dental Prothesis

DEVELOPING A DESIGN FRAMEWORK FOR THE MASS CUSTOMISATION OF HOUSING IN SAUDI ARABIA - A CRITICAL REVIEW

This paper explores the suitability of mass customisation (MC) technologies and techniques in order to provide affordable housing solutions for Saudi Arabia. In particular, the paper analyses ten articles filtered through 1.165 publications searched by using the keywords ‘mass customisation housing or off-site construction’ in the databases Scopus, CumlnCAD, ScienceDirect, and Engineer village and categorised them based on their suitability for the Saudi Arabian context. Our findings include a comparative analysis chart evaluating workflows, tools and technologies on their suitability for the MC design and an MC workflow proposal for including parametric design and digital fabrication tools and techniques.

MOISTURE-HARVESTING LIZARD SKINS AS AN INSPIRATON FOR PERFORMATIVE BUILDING ENVELOPES IN ARID CLIMATES

Research on shape-shifting adaptive architectural skins has recently focused on bio-inspired programmable materials. Only a few studies however examine the microstructure of living organisms, especially in terms of morphological adaptation in harsh climatic conditions. This paper explores the microstructure of moisture-harvesting lizard skins, specifically the Trapelus species of the Agamidae family in North-East Africa, as an inspiration for programmable materials in adaptive building skins in the arid climate of Egypt. The paper investigates the ability to improve the durability and morphological capabilities of programmable materials based on surface formation, utilizing digital fabrication techniques. A series of physical experiments were conducted on different samples of 3D printed wood filament under several humidity conditions, as a single layer, with textured patterns, and with the addition of potassium chloride as a moisture-harvesting chemical composite. The paper concluded that materials composed of textured patterns and moisture-harvesting chemical composites exhibited the highest moisture retention, therefore leading to advantages in its use in adaptive building skins in arid climates, through a wide variety of design possibilities for performative building envelopes.

A comparison of digital and conventional fabrication techniques for an esthetic maxillofacial prosthesis for the cheek and lip

Maxillofacial prostheses have traditionally been manufactured by pouring silicone into molds. However, the development of computer-aided design and computer-aided manufacturing (CAD-CAM) systems allows the virtual planning, design, and manufacture of maxillofacial prostheses through the direct 3-dimensional printing of silicone. This clinical report describes the digital workflow as an alternative to the conventional method of restoring a large midfacial defect in the right cheek and lip. In addition, the approaches were nonblinded evaluated in relation to outcomes and time efficiency, while marginal adaptation and esthetics, including patient satisfaction, were assessed for both prostheses fabricated. The digital prosthesis had acceptable esthetics and fit with improved patient satisfaction, especially in terms of efficiency, comfort, and speed of the digital workflow.

Hands‐on Digital Design Course during the Pandemic: Moulding Design for Fabricating Small Objects

AbstractDue to the pandemic conditions, hands‐on courses in architectural education were conducted remotely and their presentation had to be reconsidered. Hands‐on courses, by their nature, support learning and learner‐instructor interaction in the classroom environment. It was necessary to develop innovative solutions to ensure this interaction in virtual classrooms. This study discusses a method we experienced in the 2021–2022 spring semester of the “Principles of Digital Design and Fabrication in Architecture” course given at Gazi University. To combat potential interaction deficits, “problem‐based learning (PBL)” and “learning by doing (LBD)” teaching methods were applied. While reflecting on foreseen problems in the curriculum on the students, we determined the distance education process causes different reflections on students in terms of digital modelling and fabrication techniques. All constraints and problem determinations obtained by the students were classified and a way to solve these problems developed with the LBD style. By the end of the course, the students, who were expected to design a small 3D object, first designed the mould then realised their fabrication of the object. In this process, while the foreseen problems and curriculum determined at the beginning overlapped, other problem determinations and their reflections formed an important base for the future curriculum.

Digitally Printed Liquid Metal Composite Antenna for Energy Harvesting: Toward Energy‐Autonomous Battery‐Free Wearable Bioelectronics

AbstractRapid progress on wearable bioelectronics holds the promise for remote patient monitoring. However, there are concerns related with the use of batteries, including the need for frequent charging, user safety, and environmental pollution. The development of rapidly deployable battery‐free patches that harvest their energy from external sources is highly desired. Here, untethered battery‐free patches through far‐field energy harvesting are demonstrated. Taking advantage of a stretchable biphasic liquid metal‐based ink and digital fabrication techniques, that is, direct printing, and laser patterning, tailor‐made customized antennas are fabricated over various substrates, including polydimethylsiloxane, Kapton, and wound‐dressing medical‐grade adhesives. Folded dipole and planar inverted‐F antennas (PIFA) are evaluated and they are optimized for an over‐the‐body scenario. Compared to previous works that only show communication of data at &lt;1 Hz, here, battery‐free acquisition and transmission of electrocardiogram (ECG) data at 100 Hz via Bluetooth is demonstrated. It is shown that using 3 parallel PIFA antennas, it is possible to harvest ≈10 mW at 30 cm from the transmitter, which is ≈7× the required power by the ECG circuit. This study proves the feasibility of next generation of battery‐free wearable biomonitoring patches/e‐textiles and demonstrates materials and methods for fabrication of optimized printed antennas.

Removable partial denture - Accuracy in digital workflow

This study aimed to compare the fit and accuracy of metal frameworks for removable partial dentures (RPDs) made with conventional and digital fabrication techniques. On a representative model, maxillary RPD metal frameworks (N=5, n=2 each group) were created. A conventional casting of milled RPD patterns (C-M), and a conventional casting of printed RPD patterns (C-P), were all used to create RPDs. By creating replicas with silicone registration material and measuring under a digital microscope, the fit accuracy of RPD frameworks was examined.For the accuracy measurements (m), a total of 11 sites and 29 areas in the RPD metal frameworks were taken into account. Wilcoxon signed rank and the Friedman test were used in the statistical analysis of the data (p 0.05). Prior to finishing and polishing, the fit accuracy of the C-M approach (118 m) was significantly superior (P .001) when compared to other techniques. After finishing and polishing, the C-M approach demonstrated comparable fit accuracy to the C-P. When RPD precision is taken into account, it was observed that digital techniques were efficient and clinically acceptable.

Streamline Effect Improvement of Additive Manufactured Airfoil Utilizing Dynamic Stream Control Procedure

In the era of fast transport, to create inventive stream flow management solutions that are capable of diminishing the aerodynamic drag of the vehicles, there is a need to modify the flow characteristics over the vehicle by deferring or expelling the position of the flow partition. The objective of this study involves the parameterized design of an airfoil utilizing the Bezier curve technique with the assistance of the simulation program. For flow regulations, synthetic jet modules are ingrained at different percentages of the chord to manage the stall characteristics. The parametrization system, combined with the stream control method, can give a much better insight into flow re-energization and pave some way for the reduction of the wake. Digital fabrication technique (3d printing or Rapid Prototyping method) is used to fabricate the end product for aerodynamic testing. The comparative outcome showed a reduction in drag at certain angles of attack due to the surface finish obtained. By comparing the results, the aerodynamic efficiency showed a significant rise of 13.05% at lower angles of attack when compressed gas was used in the synthetic jet closer to the frontier edge of the airfoil. Near the stall angle of attack, the coefficient of lift (Cl) and coefficient of drag (Cd) values showed no progress.

Digital-enabled Design for Manufacture and Assembly (DfMA) in offsite construction: A modularity perspective for the product and process integration

ABSTRACT This study aims to use modularity to impact various facets of Design for Manufacture and Assembly (DfMA) and explore the relationship between product modularity, process modularity, and DfMA within the context of Offsite Construction (OSC). The study fills this gap through an exploratory single case study by identifying perceptual measures of these three concepts. The study shows the alignment between multi-dimensionality of modularity, such as product modularity and process modularity, enhances the capability of DfMA. From a modularity perspective, the reconfiguration of abstraction, information hiding, and interface is an essential strategy to change the traditional design process. This reconfiguration is to adapt to the new scenarios brought by OSC and digital fabrication technologies and the new design tasks associated with these scenarios. This study has theoretical implications for the modular approach to DfMA and practical implications for those who expect digital fabrication techniques in offsite construction.

A Pedagogy of Digital Materiality: Integrated Design and Robotic Fabrication Projects of the Master of Advanced Studies in Architecture and Digital Fabrication

This paper illustrates the pedagogical approach to teaching computational design and digital fabrication in the Master of Advanced Studies in Architecture and Digital Fabrication. It demonstrates how the introduction of computational design and digital fabrication methods foster a holistic approach to integrate novel material and constructive systems into the design process. Such an integration allows the students to combine digital fabrication techniques with sustainable material processes, taking into account the questions of reversibility, recycling and reuse, and thus designing for a more sustainable construction. In the presented paper, the structure and the curriculum of the MAS programme is introduced and the pedagogical approach of the Integrated Design and Robotic Fabrication Project is demonstrated through four case studies, highlighting their respective teaching strategies in combination with the learning experiences of the students.

Effect of Different CAD/CAM Milling and 3D Printing Digital Fabrication Techniques on the Accuracy of PMMA Working Models and Vertical Marginal Fit of PMMA Provisional Dental Prosthesis: An In Vitro Study.

Background: Minimal evidence exists on the efficacy of different digital manufacturing techniques in the fabrication of precise dental working models and provisional prosthesis. Aim of study: The objective was to evaluate the effect of two digital fabrication techniques (CAD/CAM milling and 3D printing) on the accuracy of PMMA working models and marginal fit of PMMA provisional prosthesis. Materials and methods: Two abutment teeth of modified typodont were prepared. A reference stone model was fabricated, and an optical impression was performed to obtain a CAD reference model. Four CAM milled working models and four printed working models were fabricated. CAD software was used to design the provisional prostheses. Group A tested four milled provisional prosthesis, and group B tested four 3D printed prosthesis. The 3D accuracy of working models was assessed by superimposition of the control reference working model on the CAD test working model. A stereo-optical microscope was used to assess vertical marginal fit of the provisional dental prosthesis. Student’s t and Mann–Whitney U tests were utilized to compare the two groups. Results: Results showed no statistically significant difference between the two tested groups. Conclusion: The two digital working model fabrication techniques recorded comparable accuracy. Similarly, 3D printed provisional prosthesis showed comparable marginal fit to the CAD/CAM milled ones.

Flexural Strength of CAD/CAM Denture Base Materials: Systematic Review and Meta-analysis of In-vitro Studies.

ABSTRACTIntroduction:Digital complete dentures fabrication techniques are expanding. This study aimed to review flexural strength (FS) of milled and 3D-printed denture base materials to answer the study question: is FS of computer-aided designing/computer-aided manufacturing (CAD/CAM) denture base comparable to conventional heat-polymerized materials?Materials and Methods:Search was done within different databases for articles published between January 2010 and June 2021 using specific keywords. Articles of in-vitro studies in English language with methods following International Standards Organization standardization/ADA specifications for flexural testing of conventional and CAD/CAM (milled or printed) polymethyl methacrylate (PMMA) materials were included.Results:Out of the 61 studies, 9 were processed for data extraction and only 7 underwent meta-analysis. Two, six, and one study showed high, moderate, and low risk of bias, respectively. Random-effects model was used for analysis and resulted in the average FS of 120.61 MPa [95% confidence interval (CI): 109.81−131.41] and 92.16 MPa (CI: 75.12−109.19) for CAD/CAM milled and heat-polymerized PMMA, respectively.Conclusion:Subtractive CAD/CAM technique of denture fabrication showed satisfactory FS values, whereas additive CAD/CAM method was comparable to conventional heat-polymerized technique with lower value, requiring further investigations and improvement. The clinical use of milled denture bases is an acceptable substitution to heat-polymerized PMMA, making the denture fabrication an easier and faster process.

A review on 3D printing: An additive manufacturing technology

Additive manufacturing, often known as 3D printing, is a type of digital fabrication technique that builds physical items from a geometrical model through the addition of materials. The field of 3D printing is one that is rapidly expanding. 3D printing has been a common practice around the world in recent years. Mass customization and manufacture of open-source designs are becoming increasingly common uses of 3D printing in the agricultural, healthcare, automotive, and locomotive industries. Using a CAD model as a starting point, 3D printing technology can build a three-dimensional object layer by layer. This paper provides an overview of the different types of 3D printing techniques, Classification, Materials used, & their applications in various sectors.