Three-dimensional Fabrication Research Articles

Particle fabric imaging for understanding the monotonic and cyclic shear response of silts

The findings from geotechnical laboratory testing has shown that, in addition to the well understood influence of void ratio and effective confining stress, the particle fabric has a significant effect on the monotonic and cyclic shear behaviour of silts. There is a need to advance our understanding of these effects through systematic quantification of the particle fabric in a given silt matrix in terms of individual particle parameters (e.g., dimensional sizes, volumes, shapes, orientations) as well as inter-particle contact arrangements. In addressing this need, new methodologies were developed for X-ray micro-computed tomography (μ-CT) imaging of silts with specific attention paid to: sampling and preparing of silt specimens, scanning parameters to obtain the needed image resolutions, and digital processing of images to capture individual particle data. The ability of μ-CT imaging to effectively image and capture individual particle parameters and three-dimensional fabric of silt is demonstrated. The particle fabric in terms of orientation in reconstituted silt specimens is illustrated using the μ-CT images produced using standard-size silica particles. The fabric(s) quantified from the imaging of a natural low plastic silt is also presented, and the findings are in accord with those inferred from the mechanical laboratory element testing of the same silt. The work contributes to systematic accounting for fabric in understanding the macroscopic shear behaviour of natural silts.

Three-dimensional orthogonal woven hybrid fabrics in X band frequency region for electromagnetic shielding effectiveness

The three-dimensional fabric structures with metallic yarns and different fibers offer additional opportunities to enhance the electromagnetic shielding potential. This study involves the manufacturing of a Three-Dimensional Orthogonal Woven (3DOW) hybrid conductive fabric to be potentially used in an electromagnetic shielding field. 3DOW fabric consisting of copper filament-based core-sheath hybrid yarn in the weft direction has been manufactured to obtain maximum shielding effect. Hybrid yarns were produced using the DREF-III spinning technique, having copper filament in the core and sheathing by Polyphenylene Sulfide (PPS) staple fibers. The experiment was designed using Box-Behnken method. The orthogonal fabric samples are tested in an electromagnetic frequency region of 8-12 GHz using Free Space Measurement System (FSMS) to estimate absorbance, reflectance, and transmittance. Hybrid yarn parameters such as PPS fiber diameter, copper filament diameter, and yarn linear density considerably affect electromagnetic shielding. 3DOW fabric’s electromagnetic shielding effect increase with the diameter of the copper core filament, as does PPS yarn’s diameter, showing a promising trend towards shielding. The findings of orthogonal structure can be further extended in other Three-Dimensional structures like multi-layer, angle interlock, draperies, and tops for civilians and soldierly applications.

The through-thickness thermal conductivity and heat transport mechanism of carbon fiber three-dimensional orthogonal woven fabric composite

This paper successfully constructed a high through-thickness thermal conductivity carbon fiber composite with three-dimensional orthogonal woven fabric (3DOWF) by taking advantage of the high conductivity of carbon fiber. The effect of structural parameters and Z-direction bundling yarn (Z-yarn) on thermal conductivity (TC) was investigated, and thermal transport mechanism was analyzed. The results show that the TC in the through-thickness direction of 3DOWFs increase dramatically after adding Z-yarn structure, reaching up to 4.12 W/m/K, which is 116% higher than the laminated sample. A plane heat source was established to record the temperature-time curves of the composites, and results show that the composites with higher TC have faster equilibrium time and higher equilibrium temperature. Infrared thermography demonstrates the difference of thermal response process between 3DOWF and laminated material. To sum up, a large amount of heat energy can be transferred rapidly from hot surface to cold one through these Z-yarn paths in the thermal conductive network of 3DOWF, which has potential application in composite with high thermal conductivity.

Preparation and Thermal Protection Properties of Basalt/Polyimide Three-Dimensional Spacer Woven Fabrics

Preparation and Thermal Protection Properties of Basalt/Polyimide Three-Dimensional Spacer Woven Fabrics

Polymerizable rotaxane hydrogels for three-dimensional printing fabrication of wearable sensors

While hydrogels enable a variety of applications in wearable sensors and electronic skins, they are susceptible to fatigue fracture during cyclic deformations owing to their inefficient fatigue resistance. Herein, acrylated β-cyclodextrin with bile acid is self-assembled into a polymerizable pseudorotaxane via precise host-guest recognition, which is photopolymerized with acrylamide to obtain conductive polymerizable rotaxane hydrogels (PR-Gel). The topological networks of PR-Gel enable all desirable properties in this system due to the large conformational freedom of the mobile junctions, including the excellent stretchability along with superior fatigue resistance. PR-Gel based strain sensor can sensitively detect and distinguish large body motions and subtle muscle movements. The three-dimensional printing fabricated sensors of PR-Gel exhibit high resolution and altitude complexity, and real-time human electrocardiogram signals are detected with high repeating stability. PR-Gel can self-heal in air, and has highly repeatable adhesion to human skin, demonstrating its great potential in wearable sensors.

Study on thermal, mechanical, and wettability properties of three-dimensional weft-knitted spacer fabrics with various silica aerogels coating

This study investigated the thermal, mechanical, and oil absorption-retention properties at various temperatures (20°C, 30°C, 40°C, 50°C, and 60°C) of three-dimensional (3D) weft-knitted spacer fabrics with optimal performance of silica aerogel coating that demands exceptional attention. Silica aerogels and (silica aerogels + poly(vinyl-alcohol)) sols were prepared and coated on 3D weft-knitted spacer fabrics to study and compare the basic properties, i.e. thermal resistance, thermal conductivity, tensile strength, initial modulus, compression, bending rigidity, wettability, oil absorption, and retention capacity. The scanning electron microscopy and Fourier transform infrared spectroscopy studies were completed to understand the influence of both coatings on 3D weft-knitted spacer fabrics such as surface morphology and molecular interaction. The tensile, bending, and compression tests of 3D weft-knitted spacer fabrics were accomplished to check their durability, bendability, and compressibility. All the coated samples (both silica aerogels and (silica aerogels + poly(vinyl-alcohol))) showed greater thermal resistance (0.0971 ± 0.0003 m2 KW−1 and 0.0912 ± 0.0005 m2 KW−1) and lower thermal conductivity (0.0309 ± 0.0001 Wm−1 K−1 and 0.0329 ± 0.0002 Wm−1 K−1) with better thermal stability than the uncoated samples, most specifically coated sample 5. Besides, coated sample 5 exposed higher oil absorption ((7.91 ± 0.06 g/g and 7.88 ± 0.06 g/g) and (7.56 ± 0.04 g/g and 7.53 ± 0.04 g/g)) and retention ((90.10 ± 0.53% and 89.07 ± 0.55%) and (92.47 ± 0.49% and 91.43 ± 0.47%)) capacity for vegetable and engine oil in all conditions, especially at 40°C. The outcomes demonstrated that both coatings played a vital role in the thermal, mechanical, and wettability properties of 3D weft-knitted spacer fabrics with statistically significant performance ( p < 0.05). Moreover, these new types of sorbents (3D weft-knitted spacer fabrics) have better consequences in most cases than conventional knitted, woven, and nonwoven sorbents. Hence, these 3D weft-knitted spacer fabrics could be used for industrial applications as eco-friendly and multifunctional oil sorbent materials.

Geometric Analysis of Three-Dimensional Woven Fabric with in-Plane Auxetic Behavior

Auxetic textiles are emerging as an enticing option for many advanced applications due to their unique deformation behavior under tensile loading. This study reports the geometrical analysis of three-dimensional (3D) auxetic woven structures based on semi-empirical equations. The 3D woven fabric was developed with a special geometrical arrangement of warp (multi-filament polyester), binding (polyester-wrapped polyurethane), and weft yarns (polyester-wrapped polyurethane) to achieve an auxetic effect. The auxetic geometry, the unit cell resembling a re-entrant hexagon, was modeled at the micro-level in terms of the yarn's parameters. The geometrical model was used to establish a relationship between the Poisson's ratio (PR) and the tensile strain when it was stretched along the warp direction. For validation of the model, the experimental results of the developed woven fabrics were correlated with the calculated results from the geometrical analysis. It was found that the calculated results were in good agreement with the experimental results. After experimental validation, the model was used to calculate and discuss critical parameters that affect the auxetic behavior of the structure. Thus, geometrical analysis is believed to be helpful in predicting the auxetic behavior of 3D woven fabrics with different structural parameters.

Nanoscale three-dimensional fabrication based on mechanically guided assembly

The growing demand for complex three-dimensional (3D) micro-/nanostructures has inspired the development of the corresponding manufacturing techniques. Among these techniques, 3D fabrication based on mechanically guided assembly offers the advantages of broad material compatibility, high designability, and structural reversibility under strain but is not applicable for nanoscale device printing because of the bottleneck at nanofabrication and design technique. Herein, a configuration-designable nanoscale 3D fabrication is suggested through a robust nanotransfer methodology and design of substrate’s mechanical characteristics. Covalent bonding–based two-dimensional nanotransfer allowing for nanostructure printing on elastomer substrates is used to address fabrication problems, while the feasibility of configuration design through the modulation of substrate’s mechanical characteristics is examined using analytical calculations and numerical simulations, allowing printing of various 3D nanostructures. The printed nanostructures exhibit strain-independent electrical properties and are therefore used to fabricate stretchable H2 and NO2 sensors with high performances stable under external strains of 30%.

The influence of high molecular weight polyethylene and basalt content on the mechanical risks of protective three-dimensional weft-knitted fabrics designed to wear next to skin

This study examines the resistance of three-dimensional (3D) weft-knitted fabrics to mechanical risks to determine the influence of varying percentage contents of high molecular weight polyethylene and basalt on cut, puncture, abrasion, and tear resistance. The three-dimensional weft-knitted fabrics are designed by separating functional layers: the outer (protective) layer contains varying percentage contents of high molecular weight polyethylene and basalt; the inner layer (suitable for contact with the skin) contains polyester; both layers are connected using polyamide. The strength properties of knits in response to mechanical impact were evaluated by performing cut, puncture, abrasion, and tear resistance tests. Basalt was found to improve the cut resistance of knits significantly, even with its content as low as 5% in the outer layer. The knit with the highest high molecular weight polyethylene content in the outer layer demonstrated the best puncture and tear resistance. No correlation was established between the varying percentage contents of high molecular weight polyethylene and basalt and the maximum number of abrasion cycles, as the three-dimensional weft-knitted fabrics showed no noticeable wear. The test results show that the structure of three-dimensional weft-knitted fabric with the outer layer designed to withstand mechanical impact and the inner layer suitable for direct contact with the skin protects against a wide range of mechanical impacts. This applies even when varying percentage contents of high molecular weight polyethylene and basalt are used only in the outer layer.

Near thermal-electric field controlled electrohydrodynamic 3D printing of high aspect ratio microstructures

Electrohydrodynamic (EHD) printing is an effective method for high-resolution two-dimensional patterning because of its high material compatibility. The latest research on three-dimensional (3D) structure fabrication has been reported for metal nanoparticles, small molecular materials, and phase change materials by process regulation. One of the main challenges in conventional EHD 3D printing of polymers is the low accuracy of filament deposition and stacking at the microscale. It is difficult to achieve a high aspect ratio (AR) for printed structures. This study develops an external field-assisted EHD printing process for polymer materials, where the filament formation can be improved by the near thermal field and the stacking accuracy of filaments is further promoted by applying an alternating voltage between layers. The feasibility of this method is demonstrated by printing polystyrene, a typical polymer material, on the silicon substrate with. The regulatory effect of the process parameters on the filament width is explored. The influence of the external thermal field on filament formation and deposition is discussed, and a promotion mechanism is revealed of alternating voltage for accurate deposition. Based on these combinative effects, micro-scale 3D structures with a high AR are successfully printed on the insulating substrate with three kinds of polymers.

The aryl-boron phenolic resins with super ablation properties for resin-transfer molding process of three-dimensional fabric

Boron phenolic resin (BPR) is one of the most extensively utilized matrix resins in ablative field due to its outstanding heat resistance and ablation performance. However, the existing BPR applications are severely limited since they are unsuited for the resin-transfer molding (RTM) process. This research created and manufactured arylboronic acid (PBA) modified phenolic resins (ABPRs) for RTM techniques. Since ABPRs maintain a low viscosity (0.8 Pa·s) throughout a wide temperature range (65–80°C), they can meet the essential criteria of co-injection RTM techniques. The inclusion of PBA significantly improved the heat and oxidation resistance of ABPRs. The char yield of PR and ABPR-d are 64.5% and 70.4%, respectively (800°C, N2 atmosphere). Three-dimensional woven carbon fiber textiles strengthen the CF/ABPR composites, which possess excellent mechanical and ablation properties. The oxygen-acetylene test revealed the mass ablation rates of CF/PR and CF/ABPR-d were 0.052 and 0.049 mm/s, respectively. Since the ABPRs for RTM developed for this work have excellent processability, thermal characteristics, mechanical properties and ablation capabilities, the resin matrix can offer excellent comprehensive attributes for the nozzle-expanding section of solid rocket motors.

A Stable Porous Aluminum Electrode with High Capacity for Rechargeable Lithium-Ion Batteries

A binder-free aluminum (Al) electrode was fabricated by electrodeposition on a three-dimensional copper foam (3DCu) or carbon fabric (3DCF) from a mixed-halide ionic liquid. The strong adhesion, structural stability and interface compatibility between Al and 3DCu facilitate high electrical conductivity and effectively alleviate large volume change. In a lithium-ion battery, the continuous, dendrite-free Al/3DCu electrode enables stable and reversible reactions, which delivered a first discharge capacity of 981 mAh g−1 in a coin cell at 21 mA g−1. It operates stably for at least 12 cycles with a discharge depth of about 1 mAh per cycle (7 h each) at the rate of 21 mA g−1. The cycled Al/3DCu electrode maintains good interfacial stability and shows no shedding. In contrast to many nanostructured electrodes, the amount of Al can reach 30% of a solid Al electrode with an average conversion to Li0.71Al. The concept of porous 3D electrodes provides a good compromise between diffusion kinetics and the total amount of active metal available in a battery with alloying-type anodes and appears promising for application.

Graphene Nanoplatelets on Multi-Scale Polymer Composites for Potential Ballistic Shielding

Continuous development, improvement and innovation of ballistic material systems with superior energy absorption performance has been the subject of numerous works nowadays. Some research has been carried out with the objective of replacing traditional metallic and ceramic materials and composites with high-performance polymeric composites. Due to their excellent properties, multi-scale polymer composites have been used in the most varied segments of the industry, being recently researched in applications such as ballistic materials. This work promotes the combination of high-strength three-dimensional woven aramid fiber fabrics with vinyl ester resin to produce a panel through the compression molding process. The resin was reinforced with graphene nanoplatelets (0.1, 0.2 and 0.3% wt). The impact, tensile and flexural strength were evaluated, along with dynamic-mechanical analysis by DMA and by Hopkinson split bar test, indicating a trend of better performance for the composite containing 0.1% of graphene nanoplatelets.

A Quantitative Representation of Damage and Failure Response of Three-Dimensional Textile SiC/SiC Ceramics Matrix Composites Subjected to Flexural Loading

Abstract In the present work, the microstructure deformation and synergetic damage evolution of a three-dimensional textile SiC/SiC ceramic-matrix composite under flexural loading are investigated by in situ digital image correlation at ambient temperatures. The correlations between microstructure evolution and macro-mechanical degradation of 3D textile composites under flexural loading are established based on the experimental results. In addition, by establishing continuum damage mechanics and a thermodynamic framework with synergetic effects of microstructures, a flexural loading-induced damage evolution model is developed to reveal the relationship between the energy release rate and elastic modulus degradation. The proposed model can be used to predict the flexural stress–strain curves of 3D textile SiC/SiC composites to further improve the design and assessment of new textile architectures with specific mechanical properties.

Making and selecting the best embryo in the laboratory

Over the past 4 decades our ability to maintain a viable human embryo invitro has improved dramatically, leading to higher implantation rates. This has led to a notable shift to single blastocyst transfer and the ensuing elimination of high order multiple gestations. Future improvements to embryo culture systems will not only come from new improved innovative media formulations (such as the inclusion of antioxidants), but plausibly by moving away from static culture to more dynamic perfusion-based systems now made a reality owing to the breakthroughs in three-dimensional printing technology and micro fabrication. Such an approach has already made it feasible to create high resolution devices for intracytoplasmic sperm injection, culture, and cryopreservation, paving the way not only for improvements in outcomes but also automation of assisted reproductive technology. Although improvements in culture systems can lead to further increases in pregnancy outcomes, the ability to quantitate biomarkers of embryo health and viability will reduce time to pregnancy and decrease pregnancy loss. Currently artificial intelligence is being used to assess embryo development through image analysis, but we predict its power will be realized through the creation of selection algorithms based on the integration of information related to metabolic functions, cell-free DNA, and morphokinetics, thereby using vast amounts of different data types obtained for each embryo to predict outcomes. All of this will not only make assisted reproductive technology more effective, but it will also make it more cost effective, thereby increasing patient access to infertility treatment worldwide.

Micro-macro-capillaries fabric-based evaporator for eliminating salt accumulation and highly efficient solar steam generation

Solar steam generation is considered to be a perspective technology to address water scarcity issues globally. However, its further application is limited by the complicated preparation strategy, poor salt rejection, and durability. In this study, a novel solar steam generation system based on a three-dimensional (3D) hierarchical flax fabric (HFF) is fabricated by carbonizing and coating with polypyrrole (PPy) on the fibers surface. The HFF fabric fabricated by an ordinary loom has a 3D hierarchical structure composed of float layer (FL), basket weave layer (BWL) and plain weave layer (PWL) by an ordinary loom. The hydrophilic carbonized hierarchical flax fabric modified by PPy (CHFF-PPy) shows highly efficient water supply by the continuous water transport channels for water transportation. The formed double-scale capillary water on the surface of CHFF-PPy is composed of micro-capillary water in the yarns for high interfacial water evaporation and macro-capillary water between the yarns for salt-rejection. Therefore, these functions cooperatively to endow the CHFF-PPy with all-in-one function including superior solar-driven water evaporation (1.4 kg m−2 h−1, 91.5 % efficiency for saline), efficient solar desalination, and long-term salt-rejecting property without any post-cleaning treatment. The design principle of the 3D fabric structures is provided for extending the application of salt rejection and the investigation of structure-design-induced double-scale capillaries control in the solar desalination field.

The effect of HydroSpacer implant placement on the wear of opposing and adjacent cartilage.

A HydroSpacer implant, that is,a swelling hydrogel confined by a spacer fabric, was developed to repair focal cartilage defects and to prevent progression into osteoarthritis. The present study evaluated the effect of implant placement height in an osteochondral (OC) plug on wear of the opposing and adjacent cartilage. Three-dimensional warp-knitted spacer fabrics, polycaprolactone with poly(4-hydroxybutyrate) pile yarns, were filled with a hyaluronic acid methacrylate and chondroitin sulfate methacrylate hydrogel. After polymerization of the hydrogel, these HydroSpacers were implanted in OC defects (ø 6 mm) created in bovine OC plugs (ø 10 mm) and allowed to swell to equilibrium. A custom-made pin-on-plate wear apparatus was used to apply simultaneous compression and sliding against bovine cartilage. Cartilage damage, visualized with Indian ink, was only seen for the group in which the HydroSpacer was placed flush with the surrounding cartilage. A significant increase on average surface roughness of the sliding path compared to the adjacent cartilage confirmed surface damage for this group. When the implants were recessed (with and without extra hydrogel layer on top of the implant), this damage was not observed, but the cartilage surrounding the implants was compressed (without damage) indicating substantial load sharing with the implant. Furthermore, it was shown that all defects treated with a HydroSpacer implant resulted in shear forces comparable to intact cartilage.Clinical significance: The present study suggests that placing a HydroSpacer implant recessed into the surrounding cartilage would decrease wear of the opposing cartilage. Altogether, this study supports the development of textile-constraining hydrogels for cartilage replacement.

Fabrication of Flexible Wiring with Intrinsically Conducting Polymers Using Blue-Laser Microstereolithography.

Recently, flexible devices using intrinsically conductive polymers, particularly poly(3,4-ethylenedioxythiophene) (PEDOT), have been extensively investigated. However, most flexible wiring fabrication methods using PEDOT are limited to two-dimensional (2D) fabrication. In this study, we fabricated three-dimensional (3D) wiring using the highly precise 3D printing method of stereolithography. Although several PEDOT fabrication methods using 3D printing systems have been studied, few have simultaneously achieved both high conductivity and precise accuracy. In this study, we review the post-fabrication process, particularly the doping agent. Consequently, we successfully fabricated wiring with a conductivity of 16 S cm-1. Furthermore, flexible wiring was demonstrated by modeling the fabricated wiring on a polyimide film with surface treatment and creating a three-dimensional fabrication object.

A Fully-Encircled Polymerized Microfiber Bragg Grating by 3D Femtosecond Laser Nanofabrication.

Through the merits of the arbitrary three-dimensional (3D) fabrication ability and nanoscale resolution of two-photon polymerization, we demonstrated a fully encircled polymerized microfiber Bragg grating using 3D femtosecond laser nanofabrication. In order to generate strong enough polymer Bragg grating units around the microfiber surface, and to possess a possible smaller unit pitch and structure size, the composition of photoresist and grating dimensions were both experimentally optimized. A fast-curing, high-adhesion, great-heat-resistant acrylate monomer EQ4PETA was chosen as the cross-linking element, and a high-efficiency photoinitiator DETC was used. Along the tapered microfiber with a diameter of 2 microns, dozens of grating units of 300 nm thickness were successively fabricated. The resonance wavelength was approximately 1420 nm, with a unit pitch of 1 μm, slightly different with varying unit pitches. The refractive index sensitivity reached up to ~440 nm/RIU, which is much higher than other microfiber grating sensors. We also measured the temperature and strain sensitivity of this fully encircled microfiber Bragg grating, and this was estimated at 88 pm/°C and 6.3 pm/µε. It is foreseeable that with the continuous progress of fabrication technology, more highly integrated functional optical devices will emerge in the future.

Quantitative analysis of monofilament architecture in three-dimensional mesh fabric using micro X-ray computed tomography

Three-dimensional mesh fabric has been successfully installed in ventilated car seats due to its excellent cushioning and ventilating properties originating from a sandwich monofilament architecture. In this paper, a detailed structural analysis is presented of a 10.3 mm thick three-dimensional mesh fabric to better understand the structural features and mechanical behavior. A continuous monofilament architecture was reconstructed by using a filament centerline tracing technique and micro X-ray computed tomography data. The curvature, torsion, and length of a unit cell extracted from the monofilament architecture were calculated. Inflection points from the curvature and torsion curves were used to divide the continuous monofilament architecture into separate monofilament loops and spacer monofilaments. The monofilament loops are found to have similar maximum curvatures at their intermediate points between 1.5 and 1.8 mm−1, but the spacer monofilaments have discrepant maximum curvatures close to the ends between 0.3 and 0.75 mm−1. The monofilament loops are sinusoidally arranged with a sinusoidal torsion distribution at their ends ranging from 0.2 and 0.9 mm−1 due to the stretching and heat setting process. Spacer monofilament torsions vary nonlinearly from negative to positive and the maximum torsions are between 0.45 and 0.9 mm−1. The monofilament loops have a length of 3.07–3.90 mm, while the spacer monofilaments have a length of 10.94–12.54 mm. Spacer monofilaments within the unit cell differ in curvature, torsion, and length, so their contributions to fabric compression resistance should be different.