Braid Pattern Research Articles

Geomorphological characteristics of Gandak river between Sahibganj and confluence with Ganga river during 1989–2022

The Gandak River originates in Nepal and merges with the Ganga River in India. The Gandak River is experiencing significant geomorphological alterations due to climate change and anthropogenic causes. In this study, an attempt has done to examine river bank erosion & accretion, shifting of the river bank, sinuosity, and braiding index of the Gandak River between Sahibganj and the confluence with the Ganga River, covering a length of 92.4 km from 1989 to 2022 (33 years) using remote sensing and geospatial technologies. The delineation of the river bank line for different periods, along with the quantification of erosion and accretion of the river’s right and left banks, were analysed using GIS, including the sinuosity and braiding patterns. The overall sinuosity value ranged from 1.16 to 1.01 and did not follow any specific pattern in significant reaches. The sinuosity value was almost constant over the most d/s reach of 30.74 km. The braiding index of the River was found to be the maximum between Ismailpur and Baijalpur and the minimum value between Munja and Chakia in 2015 and 1995 respectively. This study revealed that the river is shifting to the right, and bank protection measures were needed. Finally, the proposed investigation revealed the braiding phenomenon, river shifting in the transverse direction, and shifting of the meander bend was primarily responsible for the erosion and accretion of the river banks. This study will benefit local government agencies, concerned authorities, and people residing along the banks of the Gandak River by providing insights into the river’s migration patterns. Further, this knowledge aids in better planning of riverbank protection measures and developing a navigation system.

Monsters in the hollow: counting Naiki braid patterns using de Bruijn's Monster theorem

ABSTRACT The Japanese braids known as Naiki, which are distinguished by their hollow interior, have a simple structure shared by many other fiber arts and crafts. The way in which this structure forms a cylindrical braid imposes a particular set of symmetries on the final product. This paper uses enumerative combinatorics, including de Bruijn's Monster Theorem, to count the number of two-color Naiki braids under equivalence by this natural set of symmetries.

Strong and Flexible Braiding Pattern of Carbon Nanotubes for Composites: Stiff and Robust Structure Active in Composite Materials.

Carbon nanotubes (CNTs) exhibit high strength, Young's modulus, and flexibility and serve as an ideal reinforcement for composite materials. Owing to their toughness against bending and/or twisting, they are typically used as fabric composites. The conventional multiaxial braiding method lacks tension and resultant strength in the thickness direction. Some braiding patterns are proposed; however, they may have shortcomings in flexibility. Thus, this study proposed three types of braiding pattern for fabrics based on natural products such as spider net and honeycomb, in accordance with thickness-direction strength. The spider-net-based structure included wefts with spaces in the center with overlapping warps. At both sides, the warps crossed and contacted the wefts to impart solidness to the structure and enhance its strength as well as flexural stability. In addition, box-type wefts were proposed by unifying the weft and warps into boxes, which enhanced the stability and flexibility of the framework. Finally, we proposed a structure based on rectangular and hexagonal shapes mimicking the honeycomb. Moreover, finite element calculations were performed to investigate the mechanisms through which the proposed structures garnered strength and deformation ability. The average stress in fabrics becomes smaller than half (43%) when four edges are restrained and sliding is inserted. Under three-dimensional forces, our proposed structures underwent mechanisms of wrapping, warping, sliding and doubling, and partial locking to demonstrate their enhanced mechanical properties. Furthermore, we proposed a hierarchical structure specialized for CNTs, which could facilitate applications in structural components of satellites, wind turbines, and ships. The hierarchical structure utilizing discontinuity and sliding benefits the usage for practical mechanical systems.

Observation of Acoustic Non-Hermitian Bloch Braids and Associated Topological Phase Transitions.

Topological features embedded in ancient braiding and knotting arts endow significant impacts on our daily life and even cutting-edge science. Recently, fast growing efforts are invested to the braiding topology of complex Bloch bands in non-Hermitian systems. This new classification of band topology goes far beyond those established in Hermitian counterparts. Here, we present the first acoustic realization of the topological non-Hermitian Bloch braids, based on a two-band model easily accessible for realizing any desired knot structure. The non-Hermitian bands are synthesized by a simple binary cavity-tube system, where the long-range, complex-valued, and momentum-resolved couplings are accomplished by a well-controlled unidirectional coupler. In addition to directly visualizing various two-band braiding patterns, we unambiguously observe the highly elusive topological phase transitions between them. Not only do our results provide a direct demonstration for the non-Hermitian band topology, but also the experimental techniques open new avenues for designing unconventional acoustic metamaterials.

Quasi-equilibrium channel metamorphosis in planform of a subtropical river in India in post-dam period

A basic fluvio-dynamics process in the sediment-energy fluxes is channel meandering and braiding. The construction of dams and barrages has primarily altered the meandering and braiding patterns of the world's large rivers. To this end, the present study aims to analyze post-dam planform characteristics of the Damodar River, a subtropical river in India, based on the analysis of meander geometry, Mueller’s sinuosity index, braiding index, channel count index, and channel length index during the last 50 years (1970–2020) using topographical maps and satellite images. The study also intends to forecast channel meandering and braiding characteristics for 2030 and 2050 using an Artificial Neural Network (ANN) model. The study results show that between 1970 and 2020, the standard sinuosity index (SSI) showed a larger tendency to meander in the middle of the river than the upper and lower courses owing to hydraulic control, while the lower and upper courses were controlled by topographic factors. Similarly, channel braiding indices (BI*, BI, and Pt) exhibit swelling in the upper and middle courses followed by a gradual fall in the lower stretch. The building of dams, the presence of lineaments, faults, and other anthropogenic controls primarily regulate the physical planform characteristics of the river. Regarding allometry, the river's upper segments exhibit both positive and negative allometry in certain combinations, whereas the lower segments primarily exhibit negative allometry. The study demonstrates that over the past 50 years, overall channel meandering has slightly decreased while braiding has slightly increased over time, indicating a quasi-equilibrium channel metamorphosis. However, the prediction with higher accuracy (80–95 %) shows that the river meandering and braiding (BI* and BI) will increase in the short run (2030), and decrease in the long (2050). The study findings may be helpful for the various planners and stakeholders involved in the development of the river basin.

An experimental investigation of the mechanical performance of PLLA wire-braided stents

Much of our current understanding of the performance of self-expanding wire-braided stents is based on mechanical testing of Nitinol-based or polymeric non-bioresorbable (e.g. PET, PP etc.) devices. The small amount of data present for bioresorbable devices characterizes stents with big nominal diameters (D>6mm), with a distinct lack of data describing the mechanical performance of small-diameter wire-braided bioresorbable devices (D≤5mm). This study presents a systematic investigation of the mechanical performance of wire-braided bioresorbable Poly-L-Lactic Acid (PLLA) stents having different braiding angles (α=45° , α=30°, and α=20°), wire diameters (d=100μm, and d=150μm), wire count (n=24 and n=48), braiding patterns (1:1–1, 2:2–1 and 1:1–2) and stent diameters (D=5mm, D=4mm, and D=2.5mm). Mechanical characterisation was carried out by evaluating the radial, longitudinal and bending response of the devices. Our results showed that smaller braid angles, larger wire diameters, higher number of wires and smaller stent diameter led to an increase in the stent mechanical properties across each of the three mechanical tests performed. It was found that geometrical features of a polymeric braided stent could be adapted to achieve a similar performance to the one of a metallic device. In particular, substantial increases in stent mechanical properties were found for a low braiding angle and when the braiding pattern followed a one-over-one-under configuration with two wires in parallel (1:1–2). Finally, it was shown that a mathematical model proposed in literature for metal braided stents can provide reasonable predictions also of polymeric stent performance but just in circumstances where wire friction does not have a dominant role. This study presents a wide range of experimental data that can provide an important reference for further development of wire-braided bioresorbable devices.

Trackability of distal access catheters: an in vitro quantitative evaluation of navigation strategies

BackgroundIn mechanical thrombectomy (MT), distal access catheters (DACs) are tracked through the vascular anatomy to reach the occlusion site. The inability of DACs to reach the occlusion site has been...

GETTING THE RIGHT TO MAKE A NEW SHEPHERD TO USE THE OPPORTUNITIES OF THE MECHANISM OF MODERN CREATIVE TECHNOLOGIES

In the article we have developed a method for creating new patterns and designs of Sarja, Satin (Atlas) T-shirts based on existing theory of welding techniques with the use of modern computerized cordless weaving machines. The peculiarity of this method of obtaining a knitting pattern is that under a certain law, a knitting Sarja, a torn-type Sarja, is chosen as a base. It is possible to obtain a new rotation pattern by placing the base axis in the coordinate arrows and diagonal arrows that are in between them. When creating a new knitting pattern, the base is formed by shifting the direction of movement of the joints, body, rope coatings in the base braiding cells. The base rotation placed in the center of the coordinate axis cannot be changed. The base around the obtissa and the ordinate and the diagonal axes are altered according to a specific law, until the design of the pattern is well polished. The base at the center of the coordinate axis indicates that the base bracket is reinforced once for all axes around the axis.In the second variant of the method, the rotation pattern is adjusted by rotating the rotation sliding or coating clockwise or to the right of the base around the center. It is shown that different patterns can be obtained using the methods mentioned above. There is also a formula for defining the pattern of body and weave braiding patterns in the formation of these joints.

Fiber-level numerical simulation of biaxial braids for mesoscopic morphology prediction validated by X-ray computed tomography scan

This paper proposes a modeling methodology to predict the 3D and internal geometry of biaxial braids. Inspired by the digital element approach, braided yarns are modeled as a bundle of virtual fibers. Here we adopt truss elements to a virtual fiber with actual material properties instead of beam elements that have limitations due to the beam flexural rigidity. The mesoscopic morphology prediction of two common braid patterns of the diamond (1/1) and regular (2/2) are validated by a comprehensive quantitative comparison with X-ray micro-computed tomography (CT) scans of braided carbon fibers. We find that the fiber-level frictional behavior is able to explain the jammed state of braids wherein the frictional dissipation energy quickly grows, while the braid has a stable elongation, diameter, and braid angle. Parametric studies illustrate how the increase in the coefficient of friction affects the yarn cross-sectional shape, whereas it has an insignificant effect on the crimp and jammed state of braids. Models also reveal that changing a wide range of the fiber modulus of elasticity hardly impacts the mesoscopic morphology and crimp of the braids.

Multi-material braids for multifunctional laminates: conductive through-thickness reinforcement

Conventional carbon fibre laminates are known to be moderately electrically conductive in-plane, but have a poor through-thickness conductivity. This poses a problem for functionality aspects that are of increasing importance to industry, such as sensing, current collection, inductive/resistive heating, electromagnetic interference (EMI) shielding, etc. This restriction is of course more pronounced for non-conductive composite reinforcements such as glass, organic or natural fibres. Among various solutions to boost through-thickness electrical conductivity, tufting with hybrid micro-braided metal-carbon fibre yarns is one of the most promising. As a well-characterised method of through thickness reinforcement, tufting is easily implementable in a manufacturing environment. The hybridisation of materials in the braid promotes the resilience and integrity of yarns, while integrating metal wires opens up a wide range of multifunctional applications. Many configurations can be produced by varying braid patterns and the constituting yarns/wires. A predictive design tool is therefore necessary to select the right material configuration for the desired functional and structural performance. This paper suggests a fast and robust method for generating finite-element models of the braids, validates the prediction of micro-architecture and electrical conductivity, and demonstrates successful manufacturing of composites enhanced with braided tufts.

An experimental study on the interaction between braiding structural parameters and their effects on ropes mechanical properties

Braided rope configuration and properties are the main key factors to consider on choosing it for various industrial applications. Rope's structure is characterized by high axial tensile strength combined with flexibility. The mechanical properties of ropes are greatly influenced by braiding process settings which have crucial effects on their functional performance. In this study, 27 types of braided polyester ropes were produced and divided into three groups according to their structural parameters and braiding settings, which include take-up and tension rates, yarn count, braid pattern, number of spindles and carriers' settings. The effects of changing these parameters on braid angle, repeat length, linear density, and mechanical properties such as tensile stress, strain and tensile modulus were investigated. Statistical analysis was conducted to evaluate the results using multiple regression analysis, F-test, surface and contour plots to illustrate the relation and the interaction between variables that have significant effects on the ropes' properties and to assess their performance. The results indicated that increasing the take-up rate leads to increase the ropes' braid angle. Whereas, increasing the tension leads to obtain ropes of low linear density with high stress and modulus. Ropes of lower strain were attained by increasing the take-up and decreasing the tension rates. Furthermore, the rope sample produced with pattern 2/2 using the high take-up and medium tension rate achieved the highest mechanical properties of high stress, modulus with low strain among all rope samples in the three groups.

Following the effect of braid architecture on performance and damage of carbon fibre/epoxy composite tubes during torsional straining

The torsional performance of bi-axially braided carbon fibre reinforced polymer (CFRP) tubes as a function of braid architecture is investigated. It is found that for a given braid pattern, the 45° braided CFRP tubes have higher shear moduli and lower shear strength than the 35° braids. In general, 2/2 (regular) braided CFRP tubes exhibit both higher shear strength and higher shear modulus than 1/1 (diamond) braids. However, beyond the peak load, the shear strength of 2/2 braided CFRPs exhibits sudden and steep drops, resulting in a lower remnant shear strength than 1/1 structures after the shear strain exceeds 4.5%. Moreover, the damage evolution is monitored in-situ by synchrotron X-ray computed tomography during torsional straining. It shows that for a 2/2 structure, inter-tow debonded regions are vertically interconnected allowing rapid crack propagation and strength drops, whereas for the 1/1 braid they are distributed in a chequer board pattern causing a more gradual loss of strength. The fibre/matrix interfacial strength and tow cross-over density play key roles in the torsional failure of 1/1 and 2/2 braided CFRP tubes, as the former controls damage initiation and the latter controls damage propagation.

Valley polarization braiding in strained graphene

Previous works on deformed graphene predict the existence of valley-polarized states, however, optimal conditions for their detection remain challenging. We show that in the quantum Hall regime, edge-like states in strained regions can be isolated in energy within Landau gaps. We identify precise conditions for new conducting edges-like states to be valley polarized, with the flexibility of positioning them at chosen locations in the system. A map of local density of states as a function of energy and position reveals a unique braid pattern that serves as a fingerprint to identify valley polarization.

Enhancement of oxidation resistance of CVD SiC coated Cf/C-SiC hybrid composite tubes processed through Si-infiltration

Carbon fiber reinforced SiC based composites show an excellent combination of physical, mechanical and thermal properties. The combination of these properties makes Cf/SiC composites a material of choice for high-temperature load-bearing applications. However, the high-temperature oxidation has been an issue for structural ceramic composites. The combined effect of passive and active oxidation at a different temperature, influencing the overall oxidation behavior of Cf/SiC composites, which is mainly influenced by the partial pressure of oxygen. Although constant research is ongoing to improve the oxidation resistance of Cf/SiC composites, the literature on the in-depth oxidation mechanism of SiC based composites is scant. In the present study, three different types of Cf/C-SiC hybrid composite tubes were fabricated by the liquid silicon infiltration process (LSI) to study the high temperatures oxidation behavior. The dense carbon nanofibers (CNF) containing silicon carbide composite tubes (SiC(CNF)) braided with long carbon fabric (Cf) of different braiding patterns were used as a base matrix material for LSI. Further, a dense and uniform cubic β-SiC coating was applied on the surface of the above-mentioned hybrid composite tubes by using the chemical vapour deposition (CVD) technique to improve its oxidation resistance property. The oxidation behavior of bare Cf, Cf/C-SiC (LSI) composite and CVD- SiC coated Cf/C-SiC hybrid composite samples were examined separately from room temperature to 1450 °C in the air using thermogravimetric analysis (TGA). The exhibited residual mass of LSI composite and SiC coated hybrid composite samples was found to be 24% and 0.7% respectively. It is evident from the TG analysis that SiC coated hybrid composite samples exhibited the highest oxidation resistance amongst all the composites due to the formation of highly dense uniform coating.

An experimental evaluation of the mechanics of bare and polymer-covered self-expanding wire braided stents

Self-expanding wire braided stents have been used in a wide-range of medical implant applications due to the distinct flexibility offered by the wide-range of tunable design parameters, which includes braid angle, wire diameter and braid pattern. Recently, there has been increasing attention on developing covered stent systems in endovascular repair, whereby the stent frame is wrapped with a graft or textile material, typically made from expanded polytetrafluoroethylene (ePTFE) or polyester (PET, Dacron). However, the addition of a polymeric cover to a wire braided stent fundamentally changes its mechanism(s) of deformation and there is distinct lack of understanding how the functional performance of these systems compares to their bare-metal counterparts. This paper presents the first systematic evaluation of the effect of a polymeric cover on braided stent mechanics using radial compression, axial compression and tension, kink deformation and stent elongation testing. Nitinol wire braided stents were manufactured with braid angles of α = 30°, α = 45°, and α = 60°, and subsequently covered with a polyurethane-silicone composite polymer with cover thicknesses of t = 25 μm and t = 100 μm. Results demonstrate that the response of both bare-metal and covered wire braided stents is heavily influenced by braid angle across all loading regimes. In particular, it was shown that the bare-metal stents exhibited higher stiffness under radial and axial loading when the direction of loading was closer aligned to the orientation of the wires. It was shown that covering stents with a polymeric cover led to a stiffer response across all braid angles and, in some cases, this could be up to two orders of magnitude greater when thicker covering systems were considered (t = 100 μm). Covered wire braided stents with braid angles of α = 30° and α = 45° show excellent potential for use in femoropopliteal applications, where the addition of 25 μm cover increased the radial resistive force but did not have any negative effects in terms of flexibility. The current analysis shows that use of a cover in braided stent mechanics is another variable parameter which can be used to produce optimum stent properties tailored to an application.

Characterizing braided rivers in two nested watersheds in the Source Region of the Yangtze River on the Qinghai-Tibet Plateau

Large and complex braided channels (>1 km wide) in the Source Region of the Yangtze River (SRYR) on the Qinghai-Tibet Plateau, China, are characterized by a unique alpine environment with very high elevations and glacier sources. Yet, little is known about the morphological complexity and changes of large braided channels owing to the scarcity of hydrological and topographical data. In this study, we provided the first insight into these issues using compiled long-term (several decades) climatic and suspended sediment data, and Landsat images of braided channels in two nested headwater watersheds (i.e., Tuotuo and Tongtian river watersheds) in the SRYR. Analysis of annual and monthly mean temperature, precipitation, and water discharges illustrated the nature of the hydrological regime and their response to glacier melting in the two watersheds. Examination of annual mean suspended sediment loads and concentrations (C) led to two sediment rating curves and generally similar C values between the two watersheds. Among a suite of morphological indices for braided rivers, braiding intensity may be quantified using four different ones. After comparing the indices, we showed that they had similar ability of characterizing braiding patterns and adopted branch count index (BIT3) for further analysis. We found that BIT3 was linearly correlated with active valley width (WR) during both flood and dry seasons for the 17 selected braided reaches distributed within the two nested watersheds. In addition, braiding density, defined as the ratio of BIT3 to WR, remained approximately unchanged irrespective of elevations and locations of these reaches, indicating clearly that morphological structures of braided channels are spatially uniform in the SRYR. Along the main channels of the two nested watersheds over the entire study period, BIT3 always reached the maximum as RW, defined as the ratio of water body to exposed active riverbed area, was around 0.43. Furthermore, RW was always positively correlated with the associated water discharge (Q). Variable degrees of braiding adjustment in response to changes of hydrological regime were represented by hysteresis loops between BIT3 and Q. These results revealed relatively homogeneous morphologic properties of braided channels across the two nested watersheds and provided an important benchmark for future morphodynamic research on braided rivers in the SRYR.

Effect of carrier configuration on the 3D four-directional and full five-directional rotary braided fabric structures

3D rotary braiding process has high flexibility to fabricate various fabric structures which lead to different mechanical properties of composites, but the carrier configuration, a key variable, has not been elucidated. This paper reveals its effect on the braided fabric structures. Potential carrier configurations are discussed and topological models are established based on representative braiding patterns. Yarn geometries are derived according to the mechanism of yarn squeezing, then unit cells are identified. Interior unit cells show total different yarn topologies, which demonstrates that either four-step or surface-core braids can be produced by rotary method. The dimension, yarn orientation and fiber volume fraction have close correlations to carrier configurations, which is attributed to the interlacing density in braiding process. However, the addition of axial yarns in full five-directional fabrics leads to same yarn topology as to eliminate the difference.

Discovering privileged topologies of molecular knots with self-assembling models

Despite the several available strategies to build complex supramolecular constructs, only a handful of different molecular knots have been synthesised so far. Here, in response to the quest for further designable topologies, we use Monte Carlo sampling and molecular dynamics simulations, informed by general principles of supramolecular assembly, as a discovery tool for thermodynamically and kinetically accessible knot types made of helical templates. By combining this approach with the exhaustive enumeration of molecular braiding patterns applicable to more general template geometries, we find that only few selected shapes have the closed, symmetric and quasi-planar character typical of synthetic knots. The corresponding collection of admissible topologies is extremely restricted. It covers all known molecular knots but it especially includes a limited set of novel complex ones that have not yet been obtained experimentally, such as 10124 and 15n41185, making them privileged targets for future self-assembling experiments.

Control of Braid Pattern on Every Side of a Braided Composite Part Produced by Asymmetrical Braiding Process

Prediction and control of braid angle in braided composites is of great importance. Especially in producing new braided composite like braided lattice and braided actuator, controlling of braid angle in each point of the part is of great importance. This paper presents a method for controlling the braid angle on every side of a flat mandrel with the help of an elliptical guide ring to be added to the braiding machine. At first applicability of this elliptical guide ring is demonstrated by experiments and numerical simulations. To develop this method, first the theoretical relations are formulated. Once verified with experimental results, these relations are then used to develop a procedure for calculation of guide ring dimensions, take-up speed and mandrel eccentricity that yield the desired braid angles. In the end, these calculations are performed for several arbitrary angles and the results are reproduced by experiment.

Theoretical and experimental study of braid pattern in mandrels with arbitrary cross-sections

Braid angle is a key factor associated with the mechanical properties of braided composites, so accurate prediction of this angle is of vital importance for the design and manufacture of braided preforms. This paper presents a theoretical model for the prediction of braid angle at any point of a mandrel with constant arbitrary cross-section by taking into account the kinematic parameters of circular braiding machine. The proposed theoretical model pays particular attention to two parameters that strongly affect the braid angle, namely the position of fell point on the mandrel’s surface and the yarn length between this point and the carrier. Both of these parameters undergo continuous change during braiding and thus should be calculated on a point-to-point basis. The model was validated by a series of braiding experiments conducted, using a circular braiding machine, on mandrels with circular, elliptical, and oval cross-sections and then determining the resulting braid angles over the mandrel’s surface by an image processing method. The experimental results showed the high accuracy of the proposed theoretical model in predicting the braid angle for mandrels with constant arbitrary cross-section. Thus, the proposed model can contribute to faster and more accurate design and manufacture of braided composite preforms.