Conventional manufacturing of aeronautic and aerospace parts requires substantial amount of resources (energy and materials) while generating high quantities of waste and carbon dioxide emissions. ...Metal additive manufacturing (MAM) has the potential to reduce resource consumption, which is particularly important for energy-intensive materials such as titanium. We undertake a systematic literature review of MAM processes for the aerospace/aeronautic sector focusing on energy and material efficiency. Relevant literature was classified and discussed based on the life cycle stages at which resource efficiency strategies for MAM were identified: (1) product design; (2) material development and sourcing; (3) processes development, control, and optimization; (4) end-of-life extension and circular economy. Results highlight the key factors required to optimize MAM and the relevance of assessing its environmental impact compared to conventional manufacturing. Material and energy efficiency vary significantly between different MAM processes due to several factors directly linked to the process but also associated with the supply chain, e.g. electricity mix or material sourcing. Further research could explore new trends in technological development for circularity or multi-material MAM.
•Metal Additive Manufacturing (MAM) as an enabler of resource efficiency in aeronautics.•Efficiency strategies were identified at different levels: design, material, process, and end-of-life.•Key factors affecting MAM overall performance were identified.•Material and energy efficiency vary significantly between different MAM processes.
•3D printed applicators are safe and feasible for nasal vestibule cancer brachytherapy.•Use of 3D printed individual applicators cause less need for interstitial catheters.•Toxicity with 3D printed ...applicators nasal vestibule brachytherapy is very limited.
Brachytherapy is treatment of choice for early stage nasal vestibule cancer. Over the years improvements were achieved by means of image guided target definition, interstitial implant techniques and also individual mold techniques. The aim of this study was to improve the technique of the implant so that the need for interstitial catheters can be limited by making use of patient individualized 3D-printed applicators.
In 19 patients 3D-printed applicators were used to deliver pulse dose rate (PDR) brachytherapy. All patients underwent computed tomography (CT) and magnetic resonance imaging (MRI). A pre-plan with tumor delineation and manually optimized catheter positions to achieve tumor coverage was made. Based on the pre-plan a 3D-printed applicator was manufactured. Dose was evaluated by several indices: Conformity Index, Healthy Tissues Conformity Index, Dose Homogeneity Index, Dose non-uniformity ratio, Conformal index and high dose (HD) index.
A high target coverage was achieved, with a median V100%CTV of 99.1 % (range, 81.8–100 %) and median CI of 0.99 (range, 0.82–1.00), as well as a median V0.7GyGTV of 100 % (range, 93.0–100 %). The median HD was 0.39 (range, 0.20–0.83). Interstitial catheters were needed in 12 patients. None of the patients developed grade ≥ II toxicity within the median follow up of 18 months.
This study shows that using 3D-printed applicators limits the need for interstitial catheters and also limits the high doses in normal tissue.
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•Industrial scale substrate with complex structure was prepared using 3D printing.•The structure significantly influences the turbulence flow regime within the channels.•Conversions ...of CH4, CO and hydrocarbons are higher on the 3D printed structure.•3D printed substrates are promising for emission control in dual-fuel engines.
A full size ceramic substrate was successfully prepared using a robocasting 3D printer and tested as a methane oxidation catalyst in the after treatment system (ATS) of a heavy-duty diesel engine, converted to co-combust (dual fuel) with natural gas (NG). The 3D printed substrate performance exceeded that of a commercially sourced straight-channelled DOC over most working conditions, despite the 3D printed structure having a lower precious group metal (PGM) loading and channels per square inch (CPSI) density. At moderate and high inlet temperatures, where the reaction rate is limited by internal and external mass transfer, the enhanced catalytic activity of the 3D printed substrate is attributed to the generation of internal turbulence, which increases oxidation rates of methane (CH4) and non-methane hydrocarbons (NMHC). In contrast, there is relatively little difference between the catalytic activity of the 3D and straight-channelled substrates at low temperatures (e.g. cold start up), where the reaction is kinetically controlled and the additional turbulence/mass transfer of the 3D printed complex structure did not measurably alter the catalytic converter performance. Computational fluid dynamics (CFD) confirmed the increased turbulence within the channels of the 3D printed structure. We also report the effects of NG substitution on the fuel combustion efficiency under different engine load settings. The findings provide proof of concept evidence that 3D printing is a suitable means of designing a catalytic converter prototype with higher reaction activity than a conventionally extruded structure. This has significant implications for the design and potential mass production of new catalytic converters with enhanced efficiencies.
Fused Deposition Modeling (FDM) is one of the most common polymer 3D printing technologies used in many applications today. However, limited volume capacity for 3D printing large parts or components ...is the usual downside of this technology, especially desktop 3D printers. Hence, to offset this limitation, the 3D-printed parts are often designed in multiple pieces and assembled after printing, which requires post-processing called cold welding. Such welds are also quite strong but not as strong as a single-piece print. Therefore, finding suitable parameters or settings that can provide substantial strength for cold-welded 3D-printed parts will be beneficial. This study aims to determine the failing behavior and shear strength of ABS FDM 3D-printed single-lap joint using ABS glue as adhesive. Specimens were printed with varying raster angles (+45o/-45o and 0o/90o) and layer thickness (290 μm, 190 μm, and 90 μm) to investigate the effects on the adhesion or shear strength and failure mode of the acetone welded 3D-printed joints. Results show that raster angle and layer thickness significantly affected the shear strength of acetone welded materials. Single-lap joint test sample printed with +45o/-45o raster angle reveals higher shear strength than specimens printed with 0o/90o raster angle. Results also indicated that the gaps between the raster and voids between adjacent filaments of 3D-printed parts affects the adhesion and failure mode of a single-lap joint.
Adding nanoparticles (NPs) into surfactant solutions represents a promising strategy for enhancing oil displacement in porous media, with significant implications for various engineering and ...environmental applications, including soil remediation and enhanced oil recovery from underground reservoirs. Recent investigations have focused on the integration of silica and alumina NPs into anionic surfactant solutions to mitigate interfacial tension (IFT) and reduce the contact angle between the surfactant and oil phases. However, the utilization of these injection scenarios in fractured porous media has received limited attention. In this experimental study, we employed a 3D printer to design and fabricate three distinct porous media types: single permeability (S), fractured (F), and dual permeability (D). Subsequently, we prepared the sodium dodecyl sulfate (SDS) solution by adding SDS powder into a brine solution containing 2% NaCl. Nanofluids were then produced through the dispersion of SiO2 and Al2O3 NPs in the SDS solution using a sonicator. The prepared solutions were subsequently injected into each porous medium, while the recovery process was recorded using a camera. Recovery rates for each scenario were calculated utilizing a developed Python image processing code. Furthermore, analysis of the images enabled us to demonstrate the behavior and growth of the displacing phase’s fingers within the oil phase. Findings from this study showed that SDS injection into the S medium resulted in an approximate 60% oil recovery. Adding silica and alumina NPs into the SDS solution led to enhanced total recovery rates of up to 70% and 78%, respectively. The recovery results obtained from tests conducted within the F medium exhibited a pronounced decrease, with the SDS solution sweeping a mere 25% of the medium, while the silica and alumina nanofluids recovered 43% and 47%, of the oil respectively. Notably, the silica nanofluid displayed superior performance to the alumina nanofluid during the breakthrough stage in the F medium. In the D medium, the injection of SDS, silica, and alumina nanofluids achieved total recovery rates of 49%, 53%, and 56%, respectively. These outcomes highlight the diminished effectiveness of nanofluids within the dual permeable medium.
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•Different porous media (single permeability, dual permeability and fractured structure) were fabricated utilizing 3D printing technology. dual permeability (D).•A base solution was prepared by combining NaCl and sodium dodecyl sulfate (SDS), followed by the addition of SiO2 and Al2O3 nanopowders.
Origami has recently emerged as a platform for building functional engineering systems with versatile characteristics that targeted niche applications. One widely utilized origami-based structure is ...known as the Kresling origami spring (KOS), which inspired, among many other things, the design of vibration isolators, fluidic muscles, and mechanical bit memory switches. KOSs are traditionally constructed out of foldable materials (e.g. paper, kapton, fabric, polyethylene terephthalate, and acetate sheets) using conventional fabrication processes which include manual folding and creasing. Such materials and fabrication methods are ideal for conceptual illustrations and laboratory testing, but lack many important aspects necessary for real-world implementation. In addition to the very low durability resulting from the high plastic deformations at the folds; lack of repeatability, and high variation of performance among similar samples are typically inevitable. To circumvent these issues, this paper presents a novel approach for the design and 3D printing of a KOS which mimics the qualitative behavior of a paper-based KOS without compromising on durability, repeatability, and functionality. In the new design, each fundamental triangle in the traditional KOS is replaced by an inner central rigid core and an outer flexible rubber-like frame, which are fabricated out of different visco-elastic materials using advanced 3D printing technologies. The quasi-static behavior of the fabricated springs is assessed under both compressive and tensile loads. It is shown that KOSs with linear, softening, hardening, mono- and bi-stable restoring force behavior can be fabricated using the proposed design by simple changes to the geometric design parameters. The durability of the resulting springs is also assessed with no changes observed in the quasi-static behavior even after 5000 loading cycles.
•Developed novel material for direct 3D printing of ion exchange adsorbers.•3D printed adsorbers showed comparable protein binding capacity to commercial materials.•Designed new adsorber geometry to ...enable continuous protein uptake measurements.•3D printing of complex structures such as the Schoen Gyroid with 500 μm features.
Monolithic adsorbers with anion exchange (AEX) properties have been 3D printed in an easy one-step process, i.e. not requiring post-functionalization to introduce the AEX ligands. The adsorber, 3D printed using a commercial digital light processing (DLP) printer, was obtained by copolymerisation of a bifunctional monomer bearing a positively charged quaternary amine as well as an acrylate group, with the biocompatible crosslinker polyethylene glycol diacrylate (PEGDA). To increase the surface area, polyethylene glycol was introduced into the material formulation as pore forming agent. The influence of photoinitiator (Omnirad 819) and photoabsorber (Reactive Orange 16, RO16) concentration was investigated in order to optimize printing resolution, allowing to reliably 3D print features as small as 200 μm and of highly complex Schoen Gyroids. Protein binding was measured on AEX adsorbers with a range of ligand densities (0.00, 2.03, 2.60 and 3.18 mmol/mL) using bovine serum albumin (BSA) and c-phycocyanin (CPC) as model proteins. The highest equilibrium binding capacity was found for the material presenting the lowest ligand density analysed (2.03 mmol/mL), adsorbing 73.7 ± 5.9 mg/mL and 38.0 ± 2.2 mg/mL of BSA and CPC, respectively. This novel 3D printed material displayed binding capacities in par or even higher than commercially available chromatographic resins. We expect that the herein presented approach of using bifunctional monomers, bearing commonly used chromatography ligands, will help overcome the material limitations currently refraining 3D printing applications in separation sciences.
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•Printability (3D) of beams of two recycled materials was evaluated experimentally.•Flexural (bending) tests showed excellent performance of the composite beams.•Composite beams with ...plastic showed higher loads than beams with timber.•We quantified to what extent and which material can provide flexural strength.•The infill density was found to be effective in bending capacity.
The abundance of the waste materials of wood and plastic inspired the authors to explore the possibility of 3D printing the recycled materials as composite beams. This paper addresses the design, fabrication, and structural testing of 3D printed composite beams under 3-point bending. The authors believe that 3D printing of beams from timber waste and Polylactic Acid (PLA) is a state-of-the-art and has excellent potential to be transformed to state-of-the-practice in the construction industry. Beams with different compositions of materials and printing densities were designed, printed and tested to failure. This paper elaborates details of the design and printing of the beams, which then will be followed by detailed discussions as to how each beam reacts under flexural loading in terms of deformability, stiffness, strength-to-mass ratio, failure, and load-carrying capacity. General deformations of the specimens implied that the design of the specimens was quite successful in avoiding any premature failure. Large deflections of all specimens indicated that the shear strengthening performed effectively as the shear-vulnerable areas were not affected by the shear failure. The infill density affects the flexural capacity, which is obviously due to the amount of material present against loading. The capacity of the specimens with PLA at the top and bottom sections of the beams was higher than the equivalent beams with timber flanges. Overall, very promising results were obtained with a view to extending the idea into more advanced elements and techniques to develop various 3D printed structural elements towards the ongoing discussion on automation in the construction and prefabrication.
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