Filament Breakage Research Articles

Termoplastik Malzemelerin Neden Olduğu 3B Baskı Hatalarını Ortadan Kaldırmak İçin Gerçek Zamanlı Bir Takip Sistemi Tasarımı

Material-related printing errors are frequently encountered in 3D printers based on the Fused Filament Fabrication (FFF) technology. When the materials used are investigated, materials such as PLA, ABS, and Nylon are generally preferred at affordable prices. However, printing problems may occur due to the mechanical characteristics difference between the materials. Among the main reasons for this are parameters such as material characters, melting temperature, and extrusion speed. These errors cause problems such as filament breaking, nozzle clogging, and filament falling out of the holder. As a result, the filament flow is interrupted, and the printing process continues without extrusion of the filament because the 3D printer cannot detect this flow. 3D printers on the market do not have a system to detect possible printing errors. Therefore, in this study, a system design measures the filament weight via a load sensor and informs the user has been performed. 3D printers could stop the printing process since they can detect possible errors in advance with the developed system and prevent electricity consumption and time loss. In addition, the amount of used and remaining filaments, which are not yet common in 3D printers, can be followed by the user.

Breakup of a low-viscosity liquid thread

We examine the breakup of low-viscosity ($\ensuremath{\mu}$) liquid filaments. When $\ensuremath{\mu}$ is small, the filament initially thins as if it were inviscid and its minimum radius ${h}_{m\phantom{\rule{0}{0ex}}i\phantom{\rule{0}{0ex}}n}$ obeys a universal scaling law. Here, we use simulations to show that for fluids of sufficiently small $\ensuremath{\mu}$, a coefficient value in the scaling law predicted from computations agrees with theory to three decimal places and inviscid power-law behavior can be observed over 2-3 decades in ${h}_{m\phantom{\rule{0}{0ex}}i\phantom{\rule{0}{0ex}}n}$ as ${t}_{b}\ensuremath{-}t\ensuremath{\rightarrow}0$ where ${t}_{b}$ is the filament break up time. Transition from the inviscid regime to a viscous one is also demonstrated from simulations.

Resistive Switching in Biocompatible Glucose Films Doped With Honey for Highly Flexible Nonvolatile Memory Application

A mixture of honey and glucose (GH) as a new natural biomaterial for resistive random access memory (RRAM) switching layer on polyethylene terephthalate (PET) substrate is presented. The flexible substrate allows the devices to be bent and used for a wider range of applications. These devices with the GH film exhibit good reproducibility and reliability over more than 300 cycles. Moreover, the ON/OFF ratio of these devices is over 105, and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$V_{\mathrm {SET}}$ </tex-math></inline-formula> and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$V_{\mathrm {RESET}}$ </tex-math></inline-formula> are lower than that of the device with a pure glucose film. The nonvolatile nature of the devices is confirmed by measuring retention for 104 s. This switching behavior is attributed to ohmic conduction and trap-controlled space charge-limited current (TC-SCLC) mechanisms that confirm filament formation and breakage at high-resistance state (HRS) and low-resistance state (LRS), respectively.

The Role of MreB, MreC and MreD in the Morphology of the Diazotrophic Filament of Anabaena sp. PCC 7120.

The cyanobacterium Anabaena sp. PCC 7120 forms filaments of communicating cells. Under conditions of nitrogen scarcity, some cells differentiate into heterocysts, allowing the oxygen-sensitive N2-reduction system to be expressed and operated in oxic environments. The key to diazotrophic growth is the exchange of molecules with nutritional and signaling functions between the two types of cells of the filament. During heterocyst differentiation, the peptidoglycan sacculus grows to allow cell enlargement, and the intercellular septa are rebuilt to narrow the contact surface with neighboring cells and to hold specific transport systems, including the septal junction complexes for intercellular molecular transfer, which traverse the periplasm between heterocysts and neighboring vegetative cells through peptidoglycan nanopores. Here we have followed the spatiotemporal pattern of peptidoglycan incorporation during heterocyst differentiation by Van-FL labeling and the localization and role of proteins MreB, MreC and MreD. We observed strong transitory incorporation of peptidoglycan in the periphery and septa of proheterocysts and a maintained focal activity in the center of mature septa. During differentiation, MreB, MreC and MreD localized throughout the cell periphery and at the cell poles. In mreB, mreC or mreD mutants, instances of strongly increased peripheral and septal peptidoglycan incorporation were detected, as were also heterocysts with aberrant polar morphology, even producing filament breakage, frequently lacking the septal protein SepJ. These results suggest a role of Mre proteins in the regulation of peptidoglycan growth and the formation of the heterocyst neck during differentiation, as well as in the maintenance of polar structures for intercellular communication in the mature heterocyst. Finally, as previously observed in filaments growing with combined nitrogen, in the vegetative cells of diazotrophic filaments, the lack of MreB, MreC or MreD led to altered localization of septal peptidoglycan-growth bands reproducing an altered localization of FtsZ and ZipN rings during cell division.

Cooperative bundling by fascin generates actin structures with architectures that depend on filament length.

The assembly of actin-based structures with precisely defined architectures supports essential cellular functions, including motility, intracellular transport, and division. The geometric arrangements of the filaments within actin structures are stabilized via the association of crosslinking proteins, which bind two filaments simultaneously. Because actin polymerization and crosslinking occur concurrently within the dynamic environment of the cell, these processes likely play interdependent roles in shaping the architectures of actin-based structures. To dissect the contribution of polymerization to the construction of higher-order actin structures, we investigated how filament elongation affects the formation of simple, polarized actin bundles by the crosslinking protein fascin. Using populations of actin filaments to represent distinct stages of elongation, we found that the rate of bundle assembly increases with filament length. Fascin assembles short filaments into discrete bundles, whereas bundles of long filaments merge with one another to form interconnected networks. Although filament elongation promotes bundle coalescence, many connections formed between elongating bundles are short-lived and are followed by filament breakage. Our data suggest that initiation of crosslinking early in elongation aligns growing filaments, creating a template for continued bundle assembly as elongation proceeds. This initial alignment promotes the assembly of bundles that are resistant to large changes in curvature that are required for coalescence into interconnected networks. As a result, bundles of short filaments remain straighter and more topologically discrete as elongation proceeds than bundles assembled from long filaments. Thus, uncoordinated filament elongation and crosslinking can alter the architecture of bundled actin networks, highlighting the importance of maintaining precise control over filament length during the assembly of specialized actin structures.

Rheological design of thickened alcohol-based hand rubs

The handleability and sensory perception of hand sanitisers by consumers affect the hygiene outcome. Spillage may result in under-dosing and poor sensory properties can lead to under-utilisation. We first propose four principles (low runoff, spreadability, smoothness and non-stickiness) for designing the rheology of thickened alcohol-based hand rubs with acceptable handleability and hand feel. We then evaluate a commercial hand gel and a variety of simplified formulations thickened with microgels (Carbopol 974P, Carbopol Ultrez 20 and Sepimax Zen), or linear polymers (Jaguar HP 120 COS), and evaluate them against these design criteria. All four additives provide acceptable spreadability by shear thinning to eta approx {10^{-1},mathrm{text {Pa}text { s}}} at dot{gamma }sim {10^3,mathrm{text {s}^{-1}}}. Either the finite yield stress conferred by the microgels (sigma _y gtrsim {10,mathrm{text {Pa}}}) or the increase in low-shear viscosity provided by the linear polymer (eta gtrsim {1,mathrm{text {Pa}text { s}}} at dot{gamma }lesssim {0.1,mathrm{text {s}^{-1}}}) give rise to acceptably low runoff. However, the formulation using the linear polymer shows a filament breakage time of tau _mathrm{b} approx {1,mathrm{text {s}}} in capillary rheology, which may result in stickiness and therefore a less than optimal hand feel.

A Proper-Orthogonal-Decomposition (POD) Study of the Wake Characteristics behind a Wind Turbine Model

A comprehensive study was performed to analyze turbine wake characteristics by using a Proper-Orthogonal-Decomposition (POD) method to identify the dominant flow features from a comprehensive experimental database. The wake flow characteristics behind a typical three-bladed horizontal-axis wind turbine (HAWT) were measured in a large-scale wind tunnel with a scaled turbine model placed in a typical offshore Atmospheric Boundary Layer (ABL) wind under a neutral stability condition. A high-resolution Particle Image Velocimetry (PIV) system was used to achieve detailed flow field measurements to characterize the turbulent flows and wake vortex structures behind the turbine model. Statistically averaged measurements revealed the presence of the characteristic helical-tip vortex filament along with a unique secondary vortex filament emanating from 60% of the blade span measured from the hub. Both filaments breakup in the near-wake region (~0.6 rotor diameter downstream) to form shear layers, contrary to previous computational and experimental observations in which vortex filaments break up in the far wake. A Proper-Orthogonal-Decomposition (POD) analysis, based on both velocity and vorticity-based formulations, was used to extract the coherent flow structures, predominantly comprised of tip and midspan vortex elements. The reconstructions showed coherence in the flow field prior to the vortex breakup which subsequently degraded in the turbulent shear layer. The accuracy of the POD reconstructions was validated qualitatively by comparing the prediction results between the velocity and vorticity-based formulations as well as the phase-averaged PIV measurement results. This early vortex breakup was attributed to the reduced pitch between consecutive helical turns, the proximity between midspan filaments and blade tips as well as the turbulence intensity of the incoming boundary layer wind.

Effect of Fatigue Fracture on Resistive Switching of ZnO and NiO Stacking Films

The ZnO and NiO stacking films are prepared by sol–gel spin‐coating method to explore the impact of bending on device resistive switching. Compared with others, the device with NiO/ZnO/NiO/indium tin oxide/PET stacking structure exhibits a higher ON/OFF ratio. After bending 1000 times, the switching performance is reduced by two orders of magnitude due to the branch breakage of the conductive filaments. The finite element studies indicate that stress mutation between the ZnO and NiO functional layers leads to microcrack formation and interfacial delamination, increasing the interfacial barrier and depletion width. The cracks propagate along the grain boundary and thus result in more traps, which may act as electron blocking layers to restrict the carrier transport. The scanning electron microscopy observation shows that when the crack density increases to about 0.03 μm−1, the device is broken down. Under threshold bending cycles as simulated by Comsol Multiphysics, the grain boundary is completely torn leading to fatigue fracture. The proposed work provides some information for improving the flexibility of memory devices.

Tubulation and dispersion of oil by bacterial growth on droplets.

Bacteria on surfaces exhibit collective behaviors, such as active turbulence and active stresses, which result from their motility, growth, and interactions with their local surroundings. However, interfacial deformations on soft surfaces and liquid interfaces caused by active growth, particularly over long time scales, are not well understood. Here, we describe experimental observations on the emergence of tubular structures arising from the growth of rod-shaped bacteria at the interface of oil droplets in water. Using microfluidics and timelapse microscopy, the dimensions and extension rates of individual tubular structures as well as bulk bio-aggregate formation are quantified for hundreds of droplets over 72 hours. Tubular structures are comparable in length to the initial droplet radius and are composed of an outer shell of bacteria that stabilize an inner filament of oil. The oil filament breaks up into smaller microdroplets dispersed within the bacterial shell. This work provides insight into active stresses at deformable interfaces and improves our understanding of microbial oil biodegradation and its potential influence on the transport of droplets in the ocean water column.

Mechanical and Physical Properties of Recycled-Carbon-Fiber-Reinforced Polylactide Fused Deposition Modelling Filament.

Carbon-fiber-reinforced plastic materials have attracted several applications, including the fused deposition modelling (FDM) process. As a cheaper and more environmentally friendly alternative to its virgin counterpart, the use of milled recycled carbon fiber (rCF) has received much attention. The quality of the feed filament is important to avoid filament breakage and clogged nozzles during the FDM printing process. However, information about the effect of material parameters on the mechanical and physical properties of short rCF-reinforced FDM filament is still limited. This paper presents the effect of fiber loading (10 wt%, 20 wt%, and 30 wt%) and fiber size (63 µm, 75 µm, and 150 µm) on the filament’s tensile properties, surface roughness, microstructure, porosity level, density, and water absorptivity. The results show that the addition of 63 µm fibers at 10 wt% loading can enhance filament tensile properties with minimal surface roughness and porosity level. The addition of rCF increased the density and reduced the material’s water intake. This study also indicates a clear trade-off between the optimized properties. Hence, it is recommended that the optimization of rCF should consider the final application of the product. The findings of this study provide a new manufacturing strategy in utilizing milled rCF in potential 3D printing-based applications.

Bubble production by air filament and cavity breakup in plunging breaking wave crests

Air filaments and cavities in plunging breaking waves, generically cylinders, produce bubbles through an interface instability. The effects of gravity, surface tension and surface curvature on cylinder breakup are explored. A generalized dispersion relation is obtained that spans the Rayleigh–Taylor and Plateau–Rayleigh instabilities as cylinder radius varies. The analysis provides insight into the role of surface tension in the formation of bubbles from filaments and cavities. Small filaments break up into bubbles through a Plateau–Rayleigh instability driven through the action of surface tension. Large air cavities produce bubbles through a Rayleigh–Taylor instability driven by gravity and moderated by surface tension, which has a stabilizing effect. Surface tension, interface curvature and gravity are all important for cases between these two extremes. Predicted unstable mode wavenumber and bubble size show good agreement with direct numerical simulations of plunging breaking waves and air cylinders.

In situ infrared temperature sensing for real-time defect detection in additive manufacturing

Melt pool temperature is a critical parameter for the majority of additive manufacturing processes. Monitoring of the melt pool temperature can facilitate the real-time detection of various printing defects such as voids, over-extrusion, filament breakage, clogged nozzle, etc. that occur either naturally or as the result of malicious hacking activity. This study uses an in situ, multi-sensor approach for monitoring melt pool temperature in which non-contact infrared temperature sensors with customized field of view move along with the extruder of a fused deposition modeling-based printer and sense melt pool temperature from a very short working distance regardless of its X-Y translational movements. A statistical method for defect detection is developed and utilized to identify temperature deviations caused by intentionally implemented defects. Effective detection for multiple defect types and sizes is demonstrated using both a simple L-shaped test geometry and a more complex industry standard test article. Strengths and limitations of this approach are presented, and the potential for expansion via more advanced data analysis techniques such as machine learning are discussed.

Process Chain Development for the Fabrication of Three-Dimensional Braided Oxide Ceramic Matrix Composites.

Fiber composites with a three-dimensional braided reinforcement architecture have higher fiber volume content and Z-fiber content compared to a two-dimensional braided reinforcement architecture; as a result, the shear strength increases. Porous oxide fiber composites (OFCs) have the inherent weakness of a low interlaminar shear strength, which can be specifically increased by the use of a three-dimensional fiber reinforcement. In this work, the braiding process chain for processing highly brittle oxide ceramic fibers is modified; as a consequence, a bobbin, which protects the filament, is developed and quantitatively evaluated on a test rig with regard to tension and filament breakage. Subsequently, a braiding process is designed which takes into account fiber-protecting aspects, and a three-dimensional reinforced demonstrator is produced and tested. After impregnation with an Al2O3-ZrO2 slurry, by either a prepreg process or a vacuum-assisted process, as well as subsequent sintering, the three-dimensional braid-reinforced OFC exhibits an interlaminar shear strength (ILSS) which is higher than that of two-dimensional braid- or fabric-reinforced samples by 64–95%. The influence of the manufacturing process on the relative macropore content is investigated and correlated with the mechanical properties.

Deformation and breakup of droplets in a double T-junction microdisperser with double input of the continuous phase

Droplet dynamics at double T-junction microdisperser are usually occurred in multiphase flow and complex fluids within microfluidics and microreactors. However, the mechanism of droplet dynamics in double T-junction microdisperser with the double input of the continuous phase remains unclear. In this article, the deformation and breakup of droplets in double T-junction microdisperser is experimentally studied with the double input of the continuous phase. Various flow patterns are observed for the dynamics of droplets. The droplet deformation is analyzed and discussed, and a prediction formula for the maximum droplet deformation is proposed. In addition, the breakup dynamics of droplets are studied systematically. The breakup of the droplet can be divided into squeezing stage, transition stage and pinch-off stage. The influence of the capillary number and the viscosity ratio of both phases on each stage of the droplet breakup are discussed. Finally, it is found that in the transition zone between the deformation and breakup of droplets, the tail of a droplet is often accompanied by corrugated filaments, and the filament breakage presents either tip streaming or self-similar fractures.

Direct Observation of a Large-scale CME Flux Rope Event Arising from an Unwinding Coronal Jet

Abstract Coronal mass ejections (CMEs) and coronal jets are two types of common solar eruptive phenomena, which often independently happen at different spatial scales. In this work, we present a stereoscopic observation of a large-scale CME flux rope arising from an unwinding blowout jet in a multipolar complex magnetic system. Based on a multiband observational analysis, we find that this whole event starts with a small filament whose eruption occurs at a coronal geyser site after a series of homologous jets. Aided by magnetic field extrapolations, it reveals that the coronal geyser site forms above an elongate opposite-polarity interface, where the emergence-driven photospheric flux cancellation and repetitive reconnection are responsible for those preceding recurrent jets and also contribute to the ultimate filament destabilization. By interacting with overlying fields, the erupting filament breaks one of its legs, and results in an unwinding blowout jet. Our estimation suggests that around 1.4–2.0 turns of twist release in its jet spire. This prominent twist transport in the jet spire rapidly creates a newborn larger-scale flux rope from the jet base to a remote site. Soon after its formation, this large-scale flux rope erupts toward the outer coronae causing an Earth-directed CME. In its source region, two sets of distinct postflare loops form in succession, indicating this eruption involves two stages of flare magnetic reconnection. This work not only reveals a real magnetic coupling process between different eruptive activities but provides a new hint for understanding for the creation of large-scale CME flux ropes during the solar eruption.

Suppression of the critical current degradation under the compressive stress on the internal reinforcement bronze processed Nb3Sn wire using Cu-Sn-In ternary bronze alloy matrix

Typical large current capacity conductors for fusion magnet are often manufactured by the Cable-In-Conduit (CIC) method. The CIC conductor is fabricated by twisting multiple Nb3Sn strands and pure Cu wires, and huge local stress/strain concentration alike the point contact was observed in each twisted Nb3Sn strand applied to transverse compressive load based on the electromagnetic force. These concentrations caused to the Nb3Sn filament breakage and it was also a major factor of the current sharing temperature (Tcs) and critical current density (Jc) degradation on CIC conductor. Mechanical strength improvement of the Nb3Sn strand is required to realize superconducting magnet under higher electromagnetic force for a future DEMO. Recently, we succeeded to fabricate the internal matrix reinforcement bronze processed Nb3Sn multifilamentary wire using a Cu-Sn system ternary alloy matrix containing Indium (In) element.In this study, critical current (Ic) property with the in-situ compressive stress on the internal matrix reinforcement Nb3Sn wire was evaluated. The compressive stress obtained to the Ic deterioration of 5% on the internal matrix reinforcement Nb3Sn wire was confirmed at 150 MPa, and this stress was 3 times higher than Nb3Sn wire without reinforcement. We found that the internal matrix reinforcement was one of the great advantage methods to suppress the Ic degradation by the compressive stress.

Strategies and mechanisms to improve the printability of pharmaceutical polymers Eudragit® EPO and Soluplus®

The poor printability of most pharmaceutical polymers greatly restricts the application of the fused deposition modeling (FDM) technique in the field of personalized pharmaceutical preparations. General strategies to improve printability and provide practical guidelines for the optimization of formulations are lacking. Moreover, the mechanism associated with the smooth printing process of modified printing materials needs to be investigated. In this study, three different strategies were used to improve the FDM printability of typical brittle polymers with poor printability. The relationship among additives, material properties, and printability was explored. The finite element method was used to simulate the radial stress–strain behavior of the filament, while computational fluid dynamics was used to simulate the axial melt flow field in the printing head. It was found that the addition of an inert filler (i.e., talc), a drug with high melting points (i.e., diclofenac sodium), and a polymer with high strength (i.e., plasticized ethylcellulose) effectively improved the printability of plasticized Eudragit® EPO and Soluplus®. In addition, regulating the mechanical properties of filaments improved printability, and it was deduced that printable filaments should have neither very low stiffness nor very low flexibility. The suitable melt viscosity or shear-thinning property of the printing material facilitated smooth extrusion without filament breakage or nozzle blockage. The results of this study also showed that simulation could assist in understanding the stress–strain behavior of filaments and the flow field of melts during FDM printing.

False-twist draw-texturing with water-jet twister/cooler and superheated steam heater: effect of steam temperature on textured yarn properties

The objective of this research work was to investigate the effect of steam temperature on the properties of false-twist draw-textured yarns produced at speeds of 1000 m/min, 1200 m/min, and 1500 m/min using false-twist draw-texturing system with waterjet twister/cooler and superheated steam heater. This method replaces the contact heater of a standard false-twist texturing machine with a ‘super-heated steam heater’ and the normal false-twisting device and cooler replaced with a ‘water-jet twister/cooler’, combined into one unit, so as to reduce the thread-line length and to increase the production speed significantly. The new heating, twisting and cooling unit is only one meter in length. The reduced thread path has significant advantages when the surging speed is considered. The shorter thread path reduces thread instability and so higher texturing speeds can be achieved. Since the water-jet twisting is virtually friction-free, and has no mechanical moving parts, the production speed can be increased, avoiding filament breaks. Polyester POY used in this study was textured at up to 1500 m/min, significantly higher texturing speeds than the standard commercial texturing speeds, while maintaining 40% bulk levels with good process stability. Achieving texturing speed up to 1500 m/min is a significant breakthrough in the false-twist draw-texturing. Therefore, outcome of this study will have a significant impact on false-twist draw-texturing research, particularly application of water-jet twisting as a non-friction medium of false-twisting to achieve higher production speeds.

A numerical study of liquid compound filament contraction

Droplets resulting from liquid filament contraction have been widely used in industrial processes. However, detailed investigations of liquid compound filament contraction processes are lacking in the literature. Therefore, this study provides a numerical investigation of the contraction of a two-layered compound filament. The simulations are based on an axisymmetric front-tracking method. It is found that because of the interfacial tension force, the initially long cylindrical filament contracts to a compound droplet without any breakup or breaks up into smaller droplets during contraction. Unlike simple filaments, the presence of the inner filament inside the compound filament results in a more complicated compound filament breakup process with various droplet types, e.g., simple droplets, single-core compound droplets, and multi-core compound droplets. We find that the inner filament breaks up into droplets, while the outer does not induce breakup. Such a breakup mode produces a multi-core compound droplet after contraction. In some cases, while the inner filament only contracts to a single droplet, its enclosing filament breaks up to produce simple droplets at each end. We also find a breakup mode that combines these two modes, where both the inner and outer filaments perform breakup. In addition, the breakup of the compound filament occurs via one of two mechanisms: end-pinching and necking. These breakup modes and mechanisms are affected by various parameters such as the inner and outer aspect ratios, the Ohnesorge number, the interfacial tension ratio, and the viscosity ratios. Based on these parameters, various regime diagrams of breakup and non-breakup are proposed.

THERMOPHYSICAL MODEL OF A MEMRISTOR-DIODE MICROCHIP

The most popular models of memristor, based on the principle of formation and breakage of conductive filaments in memristive layer, are applied to consideration of a single memristor. However, consideration of a full-fledged microchip with many memristors may be also interesting. In this case, it is very important to determine the thermal mode of work of the device, in particular, to determine if it needs cooling and how the microchip architecture affects on the nature of heat transfer. At the same time, the proposed model should be quite simple, since modeling of conductive filaments in each memristor greatly complicates work with the model and requires large computational resources. In this paper a thermophysical model of the microchip based on a memristor-diode crossbar created at the REC “Nanotechnology” at Tyumen State University is presented. The model takes into account Joule heating and convective heat transfer. A feature of the model is a simplified determination of memristor state by the resistivity value of memristive layer from the data of the current-voltage characteristic of a real memristor sample. Simulation is carried out in the ANSYS software package. Within the framework of the model, self-consistent electrical and thermophysical problems are solved in a non-stationary setting. The temperature fields and graphs of the temperature versus time were obtained for various operating modes. The results obtained are in good agreement with similar data from other studies published in the literature. The model shows itself well in various operating modes, both in modes with memristor state switching process and without it. The presented model can be used at the design stage to take into account the features of the microchip architecture, which can significantly affect the thermal state of microchip operating modes.