Digital Fabrication Technologies Research Articles

Developing a circular design framework: Co‐creation and validation of a circular product and service design tool

AbstractSustainable products are at the core of the circular economy, which is gaining momentum in scientific, economic, and policy fields. However, existing research in the field of circular product design remains fragmented. The literature has generally tended to focus on material or resource efficiency, while other complex issues related to product ecosystem also exist, such as the needs of the ecosystem (non‐human) and human user, circular challenge, and circular business model. By using a co‐creation approach, this study aims to create and validate a circular product design framework (CD‐Framework) and a self‐assessment tool for circular product design (CD‐Tool) that facilitates an understanding of how product circularity can be improved from the product ideation. The proposed CD‐Framework consists of 10 interconnected categories: circular challenge; circular business model; production; digital fabrication technologies; materials; branding and communication for circularity; packaging, distribution and logistics; user; usage; and after usage. The CD‐Tool was designed as a tool to aid product developers from various industry sectors in the self‐assessment of the circularity of product design. We contribute to developing tools that accelerate integration of circularity into product design through product‐level and ecosystem‐level considerations.

Unlocking the Potential of 3D Printing in Modern Manufacturing

The process of producing tangible items by layering on materials according to geometric representations is called digital fabrication technology, sometimes referred to as additive manufacturing or 3D printing. This innovative technique has gained popularity. Numerous industries, including healthcare, automotive, locomotive, and aviation, now make extensive use of the quickly expanding area of 3D printing technology. This page discusses the materials utilized in the production process, provides a summary of the many types of 3D printing technology, and illustrates the extensive variety of uses for them With the potential to create intricate structures and personalized patterns straight from computer-aided design (CAD) models, 3D printing technology is a potent instrument that has the potential to completely alter the face of contemporary production.

3D Printing and Additive Manufacturing Technology - The Dawn of a New Era!

This Scientific Paper explores the intricate landscape of the fast emerging and rapidly developing 3D Printing, also known as Digital Fabrication technology, spanning and providing an overview of its initial inception, innovation, historical evolution, present day applications across industries, and the various social and environmental implications of its use. This Study highlights the strengths and limitations of the diverse 3D printing technologies and Materials Science, emphasizing their significance in industrial and consumer contexts. The examination of materials underscores their crucial role in determining the quality and functionality of printed objects, with a focus on emerging materials driving innovation. The Study aims to build upon the rich tapestry of historical developments, fundamental principles, and existing research, providing a comprehensive understanding of diverse and manifold 3D printing technologies, analyzing their transformative impact on industries. Furthermore, it carries out an in-depth exploration of challenges, potential solutions, and future directions, aiming to provide insights into the dynamic and versatile nature of 3D printing and Additive Manufacturing technology.

Influence of SiC Doping on the Mechanical, Electrical, and Optical Properties of 3D-Printed PLA

Additive manufacturing, also known as 3D printing or digital fabrication technology, is emerging as a fast-expanding technology for the fabrication of prototypes and products in a variety of applications. This is mainly due to the advantages of 3D printing including the ease of manufacturing, the use of reduced material quantities minimizing material waste, low-cost mass production as well as energy efficiency. Polylactic acid (PLA) is a natural thermoplastic polyester that is produced from renewable resources and is routinely used to produce 3D-printed structures. One important feature that makes PLA appealing is that its properties can be modulated by the inclusion of nano or microfillers. This is of special importance for 3D-printed triboelectric nanogenerators since it can enhance the performance of the devices. In this work we investigate the influence of SiC micron-sized particles on the mechanical, electrical, and optical properties of a PLA-SiC composite for potential application in triboelectric energy harvesting. Our result show that the ultimate tensile strength of the pure PLA and 1%-doped PLA decreases with the number of fatigue cycles but increases by about 10% when SiC doping increases to 2% and 3%, while the strain at max load was about 3% independent of doping and the effective hardness was increased reaching a plateau at about 2 wt% SiC, about 40% above the value for pure PLA. Our results show that the mechanical properties of PLA can be enhanced by the inclusion of SiC, depending on the concentration of SiC. In addition, the same behavior is observed for the dielectric constant of the composite material increases as the SiC concentration increases, while the optical properties of the resulting composite are strongly dependent on the concentration of SiC.

Advanced Manufacturing for Sustainable Fashion. Developing Interdisciplinary Educational Experiences

As a creative industry with high cultural, social, and environmental impacts, Fashion is crucially demanding a paradigmatic shift through digital transformation toward a positive, sustainable change. Therefore, fashion education needs to nurture professionals able to tackle increasingly complex challenges, delving into technological systems and aiming at meaningful environmental, economic, cultural, and societal transformations. New learning paths, approaches, and tools should prepare future fashion designers with a hybrid set of skills placed halfway between design, technology, science, and arts. This paper presents the lessons learned from the Advanced Manufacturing for Sustainable Fashion (ASMF) module conducted at Politecnico di Milano (Design School) in the course Design for the Fashion System. While exploring digital fabrication and smart wearable technologies, students delve into prototyping activities aiming at reflecting on sustainability and fashion design practices’ impacts. The paper describes the used learning tools and approaches and reports on instructional and pedagogical learning outcomes, problems, and future implementation of interdisciplinary educational experiences toward a systemic design paradigm.

Computational reparations as generative justice: Decolonial transitions to unalienated circular value flow

The Latin roots of the word reparations are “re” (again) plus “parere” which means “to give birth to, bring into being, produce”. Together they mean “to make generative once again”. In this sense, the extraction processes that cause labor injustice, ecological devastation, and social degradation cannot be repaired by simply transferring money. Reparations need to take on the full sense of “restorative”: the transition to a decolonial system that can support value generators in the control of their own systems of production, protect the value they create from extraction, and circulate value in unalienated forms that benefit the human and non-human communities that produced that value. With funding from the National Science Foundation, we have developed a research framework for this process that starts with “artisanal labor”: employee-owned business and worker collectives that have people doing what they love, despite low incomes. Focusing primarily on Detroit's Black-owned urban farms, artisanal textile businesses, Black hair salons, worker collectives, and other community-based production, with additional connections to Indigenous and other communities, we have introduced digital fabrication technologies, sensors, artificial intelligence, server-side apps and other computational support for a transition to unalienated circular value flow. We will report on our investigations with the challenges at multiple scales. At each level, we show how computational supports can act as restorative mechanisms for lost circular value flows, and thus address both past and ongoing disenfranchisement.

Planar-thick panels and 3D-printed gap fillers: A hybrid digital fabrication approach to curved surface approximations

Curved surfaces may be approximated using polygonal panels to simplify complex architectural designs, yet their constructions can be expensive due to single-use moulds producing unique panels. To reduce costs, strategies like planarizing and reducing the number of different panels have been suggested, which are increasingly achievable with advancing digital fabrication technologies. However, current subtractive and additive manufacturing techniques face challenges in producing complex 3D shapes and large volumes, respectively. Combining these two techniques has been attempted, mainly with small 3D-printed nodes, leaving the direct realization of curved surface approximations unexplored. This paper extends the thick-panel origami theory to introduce planar-thick panels and 3D-printed gap fillers for cost-effective constructions. It presents a computational workflow to transform meshes into non-intersecting panels while preserving edge connectivity and frame-like gap fillers with minimized volumes. Physical prototypes demonstrate significant cost savings compared to direct 3D printing. All prototypes are accurate within a 10 mm material thickness due to the guidance of the gap fillers. The finite element analysis shows that structural performance is greatly influenced by the material properties, especially of panels, due to their relatively larger volume. Numerical examples are also presented using the k-means clustering-optimization method to reduce the number of different panels.

Seismic performance of Fe-SMA prestressed segmental bridge columns with 3D printed permanent concrete formwork

The integration of digital fabrication technology with prestressed segmental column construction offers significant potential for accelerated bridge construction with material-efficient design. This study aims to explore this potential by developing a novel prestressed segmental column system that utilizes permanent 3D printed concrete (3DPC) formwork for column segment fabrication. Prestressing is achieved in the proposed system by using partially bonded iron-based shape memory alloy (Fe-SMA) reinforcement. Large-scale experiments were conducted on two columns under combined gravity and lateral loading to evaluate the seismic performance and feasibility of the proposed system. The ratio of steel to Fe-SMA reinforcement in the column design was the variable considered in this study. The experimental results showed that the columns could withstand lateral drifts of up to 5% without collapse and the permanent 3DPC formwork showed no premature failure or delamination. Furthermore, the columns exhibited self-centering characteristics, maintaining a residual drift of 1% up to a target drift of 4% when the reinforcement ratio of steel to Fe-SMA rebars was 0.3. The results highlight the potential of the proposed prefabrication concept in designing material-efficient and seismically resilient bridge columns with low damage characteristics.

Nothing Like Compilation: How Professional Digital Fabrication Workflows Go Beyond Extruding, Milling, and Machines

Understanding how professionals use digital fabrication in production workflows is critical for future research in digital fabrication technologies. We interviewed thirteen professionals who use digital fabrication for the low-volume manufacturing of commercial products. From these interviews, we describe the workflows used for nine products created with a variety of materials and manufacturing methods. We show how digital fabrication professionals use software development to support physical production, how they rely on multiple partial representations in development, how they develop manufacturing processes, and how machine control is its own design space. We build from these findings to argue that future digital fabrication systems should support the exploration of material and machine behavior alongside geometry, that simulation is insufficient for understanding the design space, and that material constraints and resource management are meaningful design dimensions to support. By observing how professionals learn, we suggest ways digital fabrication systems can scaffold the mastery of new fabrication techniques.

Robust optimization for geometrical design of 2D sequential interlocking assemblies

In the realm of sustainable construction within a circular economy, the study of demountable buildings garners significant interest. Achieving the full potential of reusing materials from disassembled structures demands innovative assembly methods surpassing conventional fasteners like nails. Although traditional joinery has addressed this challenge to some extent, it faces design limitations. Modern digital fabrication technologies, such as CNC milling and additive manufacturing, have expanded the horizons for manufacturable assemblies. This paper builds upon prior research to introduce a flexible method for crafting 2D assemblies adaptable to various geometric assumptions. It offers two contributions. Firstly, it provides a versatile numerical model for analyzing the mechanical properties of diverse designs, uncovering novel assemblies with superior mechanical performance compared to traditional configurations. Secondly, it presents an optimization approach enabling precise control over assembly and disassembly of imperfect parts by optimizing joint geometry. By integrating advanced fabrication techniques, adaptable design methods, and mechanical analysis, this research paves the way for the development of sustainable and mechanically efficient demountable buildings.

Out-of-plane shear performance of a novel non-metallic CLT dovetail joint subjected to monotonic and cyclic loading

Timber structures have garnered increasing attention owing to their sustainability and assemblability. Particularly, engineered wood products like cross-laminated timber (CLT) coupled with digital fabrication technologies have promoted the application of traditional mortise-tenon joints in modern mass timber structures. In this paper, a novel non-metallic dovetail joint was proposed to connect the perpendicular CLT wall and lintel. A total of nine specimens were tested under monotonic and cyclic loading to investigate the out-of-plane shear behavior with different widths of the tenon head. The failure modes of the joints were presented, and the mechanical properties including stiffness, strength, ductility and energy dissipation were compared and analyzed. A simplified strength model was developed to evaluate the shear strength of the joint. The experimental results revealed that the specimens mainly failed by timber splitting and crushing under monotonic loading due to the shear force and additional bending moment. The increase in the tenon head width of the dovetail joint from 70 mm to 105 mm resulted in a significant improvement in both stiffness and strength, with enhancements of more than 42 % and 54 %, respectively. All specimens exhibited similar failure modes but more severe timber crushing under cyclic loading. Due to the damage accumulation, the stiffness and strength of the dovetail joint degraded significantly. The specimen with the tenon head width of 84 mm exhibited the highest energy dissipation and relatively low strength degradation under cyclic loading. Additionally, it is recommended to use a ratio of tenon head width to CLT panel thickness at 4/5. The proposed strength model underestimated the load-carrying capacity of the joint generally due to the neglect of the contribution of the bending moment. This study provides base guidelines for the application of dovetail joints in CLT structures.

From Logo Programming to Fab Labs: The Legacy of Constructionist Learning in K−12 Education Technology

Mens et manus, the motto that is embedded in the MIT official seal, is a simple Latin phrase that translates to “mind and hand.” As a continuation of MIT’s pioneering education and research, Seymour Papert, a renowned educator and learning theorist, established the foundation of constructionism, which emphasizes hands-on/minds-on learning. This article explores the evolution of constructionism in K-12 educational technology from the Logo computer language to Scratch block-based programming and the introduction of Fab Labs, which represent the third-generation platform for constructionist teaching and learning. The use of Fab Labs in K-12 education aligns with the Mens et manus philosophy by providing students with opportunities to apply theoretical knowledge to real-world applications through hands-on experiences with digital fabrication technologies. The adoption of the proposed Fab Labs constructionist framework can help prepare students for the demands of a rapidly changing world and aligns with educational standards for science and mathematics.

3D Printer

Digital fabrication technology, also referred to as 3D printing or additive manufacturing, creates physical objects from a geometrical representation by successive addition of materials. 3D printing technology is a fast-emerging technology. Nowadays, 3D printing is widely used in the world. 3D printing technology has been increasingly used for the mass customization, production of any types of open-source designs in the field of agriculture, in healthcare, automotive industry, locomotive industry and aviation industries. 3D printing technology can print an object via layer-by-layer deposition of material directly from Computer Aided Design (CAD) model. This paper presents an overview of the types of 3D printing technologies, the application of 3D printing technology, and the materials used for 3D printing technology in the manufacturing industry.

Digital Fabrication and Reliability Evaluation Method for G-Band TWT Electron Optical System

Terahertz traveling wave tubes (THz-TWTs) electron optical system (EOS) has strict fabrication accuracy requirements. The low reliability of traditional manual assembly always is the direct problem hindering the development of TWT to high frequency, high power, high efficiency, and high reliability. In this article, a digital fabrication and reliability evaluation method for THz-TWTs EOS was presented. First of all, through improving the gun shell structure and sealing molds, developing automatic and semi-automatic assembly methods, writing automatic geometric measure programs, measuring the thermal deformation of cathode and focusing electrode (FE) under working temperature, etc., the implementation of digital fabrication technology was completed, which promoted the fabrication accuracy (1 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\sigma \text{)}$</tex-math> </inline-formula> to 3–10 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu $</tex-math> </inline-formula> m and 0.05 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{\circ}$</tex-math> </inline-formula> –0.1 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{\circ}$</tex-math> </inline-formula> . Then, in order to find the tolerance limit to keep the electronic trajectory stable and the balance between design reliability and fabrication reliability, the CST particle solver single and multi-parameter sweep function was used to analyze the EOS of a 0.22 THz-TWT. Based on the digital fabrication technology process capability, 6 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\sigma $</tex-math> </inline-formula> quality management theory, and equal proportion compress single parameter tolerance limit method, we defined four independent sensitive parameters, and calculated the reliability of THz-TWT EOS digital fabrication was not less than 72.47% by MINITAB software. This method can be used as a quantitative calculation of whether the TWT EOS design and fabrication are matched, and give appropriate tolerance and compensation range in the actual TWT fabrication process.

Wind Turbine Blade-Tip Optimization: A Systemic Computational Approach

Curved bladelets on wind turbine blades play an important role in improving the performance and efficiency of wind turbines. Implementing such features on the tip of wind turbine blades can improve their overall aerodynamic characteristics by reducing turbulence and loading without hindering lift generation and overall efficiency, thus leading to increased energy capture and reduced costs over the life of the turbine. Subjecting the integrated blade tip to optimization procedures can maximize its beneficial contribution to the assembly in general. Within this context, a systemic workflow is proposed for the optimization of a curved bladelet implemented on a wind turbine blade. The approach receives input in the form of an initial tip geometry and performs improvements in two distinct stages. Firstly, shape optimization is performed directly on the outer shape to enhance its aerodynamic properties. Subsequently, the topology of its interior structure is refined to decrease its mass while retaining its improved airflow characteristics. The proposed workflow aims to approach blade tip optimization holistically, both in terms of aerodynamic performance and structural capabilities; is computationally validated via fluid dynamics studies and finite element analysis to evaluate the performance augmentation achieved through it; and is further coupled with additive manufacturing for the production of prototype parts, benefiting from the manufacturing flexibility offered by digital fabrication technologies. The optimized bladelet model presented an approximate 30% improvement in the torque generated on it, while maintaining only 70% of its original mass, effectively contributing to a 0.81% increase to the total torque generated by the blade, consequently confirming the effectiveness of the proposed methodology.

Acceptance of 3D Printing by Occupational Therapists: An Exploratory Survey Study.

Do-it-yourself (DiY) assistive technology gained attention in accessibility literature recently, especially in relation to the rise of digital fabrication technologies, such as 3D printing. Previously, small-scale studies showed that care professionals generally respond positively towards the idea of creating DiY assistive devices for their clients. However, several barriers and concerns may hinder care professionals' actual adoption of digital fabrication technologies. To better understand occupational therapists' willingness to adopt 3D printing, we have conducted an exploratory survey study (N = 119) based on the unified theory of acceptance and use of technology (UTAUT). Confirming previous studies, occupational therapists in this study showed generally positive attitudes towards adopting 3D printing technology. Factors that may affect their intentions to use 3D printing technology include expectations regarding job performance, effort, social influence, and facilitating conditions, as well as one's tendency to adopt novel technologies. Furthermore, occupational therapists will likely experience difficulties when first using 3D printing technology, despite their overall positive expectations of the ease of use. Therefore, we recommend that further research should focus on training, but especially on effective ways to support occupational therapists on the job, for instance, by facilitating collaborations with 3D printing experts.

Digitally fabricated weak interfaces to reduce minimum reinforcement in concrete structures

AbstractCrack initiators in reinforced concrete structures can facilitate fulfilling the serviceability requirements. They can be used as a design parameter to diminish the minimum reinforcement for members subject to imposed deformation and exposed to the environment as they reduce the crack spacing and width when arranged close enough. While crack initiators in conventional concrete construction are cumbersome to provide (e.g., by construction joints or taperings), they are inherent to layered extrusion processes with digital fabrication technologies: the tensile strength is typically reduced locally in interfaces between layers. Rather than trying to avoid these weak interfaces, this paper discusses the potential of taking advantage of them to act as crack initiators reducing the minimum reinforcement content. A tension chord‐based model is developed to (i) account for the local strength reduction and (ii) predict the effect of weak interfaces on the expected crack spacing and width. As a key finding, the model predicts a reduction of the required minimum reinforcement ratio proportional to the locally decreased concrete tensile strength for a specified maximum crack width requirement under imposed deformations. An experimental campaign on five layered and three reference tension ties confirmed the clearly positive impact of weak interfaces on crack spacings and widths.

Employing surface tooling for thermal modulation

Computer Numerical Controlled (CNC) machines, as one of the digital fabrication technologies, can create various textures as milled surfaces. The geometrical properties of these textures depend on various parameters set by the designer. This paper focuses on CNC cutting tools, tool paths, and cut depth to understand their roles in generating different surface textures on a (12.7 × 12.7)cm2 panel surface. 3D Rhinoceros, and other plugins were used to study the texture created by two distinct CNC tools (ball and vee bits), two tool paths (plunge roughing and parallel), and various tool stepovers. The simulation studies focused on the solar radiation received by the panel surfaces and self-shadow cast by the surface texture. The results showed that each tool, tool path, and tool stepover had different effects on the panel surface solar control. Using vee-type bits increased the amount of radiation by 17% compared to the flat panel and using ball-type bits decreased it by 32%.

Digitally fabricated ribbed concrete floor slabs: a sustainable solution for construction

The concrete used in floor slabs accounts for large greenhouse gas emissions in building construction. Solid slabs, often used today, consume much more concrete than ribbed slabs built by pioneer structural engineers like Hennebique, Arcangeli and Nervi. The first part of this paper analyses the evolution of slab systems over the last century and their carbon footprint, highlighting that ribbed slabs have been abandoned mainly for the sake of construction time and cost efficiency. However, highly material-efficient two-way ribbed slabs are essential to reduce the environmental impact of construction. Hence, the second part of this paper discusses how digital fabrication can help to tackle this challenge and presents four concrete floor systems built with digitally fabricated formwork. The digital fabrication technologies employed to produce these slab systems are digital cutting, binder-jetting, polymer extrusion and 3D concrete printing. The presented applications showcase a reduction in concrete use of approximately 50% compared to solid slabs. However, the digitally fabricated complex formworks produced were wasteful and/or labour-intensive. Further developments are required to make the digital processes sustainable and competitive by streamlining the production, using low carbon concrete mixes as well as reusing and recycling the formwork or structurally activating stay-in-place formwork.

3D printing concrete with recycled coarse aggregates: The influence of pore structure on interlayer adhesion

Concrete digital fabrication technology has been rapidly emerging while facing sustainability issues due to the high cement proportion in printed materials, rendering an environmentally friendly material design containing coarse aggregates one way for the concrete 3D printing industry to achieve more sustainable development. Here, 3D printed concrete with recycled coarse aggregate (RCA) was prepared, and its interlayer bonding properties were investigated considering different RCA replacement ratios, interlayer time intervals and layer heights. The results showed that RCA and the printing time interval degraded the interlayer bond strength, whereas no clear correlation was found with the layer height. Although the incorporation of RCA significantly changed the interlayer bonding system and cracking pattern, the interlayer bond strength of 3D printed recycled coarse aggregate concrete was substantially higher than that of 3D printed mortar. Finally, focusing on the pore structure characteristics, the mechanism influencing the interlayer bond performance is discussed.