Flexible Thread Research Articles

Исследование характеристик стационарных режимов движения подводной привязной системы «ТНПА – кабель – судно»

The efficiency of using uninhabited underwater vehicles of the tethered type is associated with the need for its propulsion and steering complex (PSC) to compensate for the reaction of the communication cable of the device with the support vessel when maneuvering near the work site. The work examines the achievable boundaries of the maneuvering zone of a remotely controlled uninhabited underwater vehicle (ROV) for known values of the length of the communication cable, the submersion depth of the device, the current speed in the work area and the traction characteristics of the PSC. Algorithms for determining the boundaries of the working area and the achievable speed of the apparatus are presented, based on calculating the tension at the ends of the communication cable in a stationary flow, using the equations of a catenary line and the numerical integration of the equations of an inextensible flexible thread. In order to increase the operational reliability of underwater technical work, recommendations have been developed for choosing a cable length that prevents it from sagging below the submersion depth of the apparatus with possible snagging and damage by bottom objects. During the model experiment, the boundaries of the maneuvering zone were assessed relative to the coordinates of the carrier for a promising ROV with known hydrodynamic resistance and traction characteristics of the PSC, as well as the dependence of the achievable speeds of the vehicle within the maneuvering zone on the immersion depth and the speed of the oncoming current.

Determining the shape of a flexible thread in the field of horizontal and vertical forces

In theoretical mechanics, the equilibrium of a flexible, inextensible thread is considered, to which the tension force of its ends and the distributed force of weight along the length of its arc are applied. An unsolved problem is finding the shape of the thread under the action of other distributed forces. This study has considered the equilibrium of a completely flexible thread, to which, in addition to this force, a transverse distributed force is applied. A sail serves as an example. Wind of equal intensity in the plane of the orthogonal section of the sail can be considered a distributed force. The sail can be cut into narrow strips with the same shape of the curves of the cross-section, which are equal to the cross-section of the sail as a whole. The theory of flexible thread is applied in the current study. The task is reduced to finding the curve of the cross-section of the sail. The object of research is the formation of a cylindrical surface from a flexible thread under the action of distributed forces applied to it. An important characteristic of the shape of a flexible thread is its curvature. Its dependence on the length of the arc was found and it was established that the found curve is a chain line (catenary). This is the feature of the current research and its distinguishing characteristics. The significance of the results stems from the derived analytical dependences, according to which the change in the ratio between the distributed forces acting on the flexible thread deforms it, but it retains the shape of the catenary. At the same time, the angle of deviation of its axis of symmetry from the vertical changes. In the absence of a horizontal distributed force and the presence of only a distributed force of weight, the axis of symmetry of the chain line is directed vertically – at an angle of 90° to the horizontal. If they are equal, this angle is 45°. Scope of application includes structures with stretched supporting wires, conveyor belts, flexible suspended ceilings, the shape of which can be calculated by using our results

MIXED SCHEME OF THE FINITE ELEMENT METHOD FOR CALCULATING CABLE SYSTEMS

A methodology for constructing variational formulations and solving geometrically nonlinear mixed problems by the finite element method is considered using the example of equilibrium of a flexible tensile thread. The results of solving the model problem are presented.

Calculation of parameters of the space tethered systems

The work carried out an analytical search for restrictions on the parameters of a space transport tether system for stable operation in orbital conditions. The main function of the considered system is load transportation from the massive “big” satellite to the small spacecraft (counterweight), along a kevlar stretchable tether. Such systems make it possible to move payloads between orbits or spacecraft, and “clean” the operational orbit of space debris without significant fuel costs. The analytical model of the system taking into account wave processes in the tetheris developed. The tether was modeled as a flexible elastic thread using the methods of deformable solid mechanics. Also processes of releasing the transported load in the lower part of the tether and its launching into the Earth atmosphere were considered.

Scalable, flexible carbon fiber electrode thread arrays for three-dimensional probing of neurochemical activity in deep brain structures of rodents

We developed a flexible “electrode-thread” array for recording dopamine neurochemicals from a lateral distribution of subcortical targets (up to 16) transverse to the axis of insertion. Ultrathin (∼10 μm diameter) carbon fiber (CF) electrode-threads (CFETs) are clustered into a tight bundle to introduce them into the brain from a single-entry point. The individual CFETs splay laterally in deep brain tissue during insertion due to their innate flexibility. This spatial redistribution allows navigation of the CFETs towards deep brain targets spreading horizontally from the axis of insertion. Commercial “linear” arrays provide single-entry insertion but only allow measurements along the axis of insertion. Horizontally configured arrays inflict separate penetrations for each individual channel. We tested functional performance of our CFET arrays in vivo for recording dopamine and for providing lateral spread to multiple distributed sites in the rat striatum. Spatial spread was further characterized in agar brain phantoms as a function of insertion depth. We also developed protocols to slice the embedded CFETs within fixed brain tissue using standard histology. This method allowed extraction of the precise spatial coordinates of the implanted CFETs and their recording sites as integrated with immunohistochemical staining for surrounding anatomical, cytological, and protein expression labels. Our CFET array has the potential to unlock a wide range of applications, from uncovering the role of neuromodulators in synaptic plasticity, to addressing critical safety barriers in clinical translation towards diagnostic and adaptive treatment in Parkinson’s disease and major mood disorders.

Application of STEM Technologies on the Example of the Problem of a Thread with a Load

This paper demonstrates the application of STEM technologies using the example of the problem of a thread with a load. As a training problem, parameter finding of a flexible inextensible thread with a load sliding along it, as well as with a fixed load, is considered. A mathematical model of a thread with a load is created without using simplifying assumptions such as a negligibly small mass of the thread, a thread with a small sag or a parabolic approximation of the thread form. When solving the problem, methods of analysis from various branches of mathematics, theoretical mechanics, physics, history of mathematics, as well as various tools of computer mathematical packages (Mathcad), are used. The reasonability of considering such tasks from the perspective of teaching effectiveness for first-year students in engineering as well as in physics and mathematics is proved. Promising educational tasks based on the investigated problem are considered.

A Simplified Method of Flexible Conductors Mechanic Calculation in Switchgears without Restrictions on the Number of Taps

The purpose of the mechanical calculation of flexible conductors of switchgears and power lines is to determine the sag, tensions, and loads on support structures, minimum distances to adjacent live parts and some other parameters. Calculations should be made taking into account distributed and concentrated loads. Distributed loads directed vertically are determined by the weight of the wire, insulator strings, and possible ice deposits on them. Distributed loads in the horizontal plane should be calculated in climatic conditions with lateral wind pressure. Concentrated loads are created by such elements as taps to electrical devices, phase-to-phase insulating spacers, barrier balls, loops, etc. Concentrated loads mainly act in the vertical plane, and in the case of taps, they can have an almost arbitrary spatial direction. The most accurate methods of mechanical calculation of flexible conductors include methods based on the numerical solution of the equation of wires in the form of a flexible elastic thread. Such an algorithm is implemented in the author's computer program MR21. However, in many cases, simplified methods of mechanical calculation are preferable, as they are available to a wider range of users. The simplified method of mechanical calculation of flexible conductors proposed in the article is based on the equation of state of the wire and allows taking into account concentrated and distributed loads. Various climatic regimes and loads are taken into account using the horizontal and vertical load factors in the calculated and initial modes. Expressions are proposed for calculating the above coefficients for any number of taps in a span and with an accurate approach to taking into account their spatial arrangement. Formulas for calculating sag and horizontal deflections of conductors are given, too. The MR21 computer program, tested earlier, has been used in this work as a tool for checking the calculation results using the proposed simplified method.

Mathematical Modeling of the Optimization of the Cables Arrangement on the Width of the Conveyor Belt

The article presents the research work carried out in the field of conveyor transport. The analysis of the calculation scheme for the calculation has been carried out according to the theory of flexible thread. The width of the conveyor rubber-tether belt has been implemented in mathematical modeling of optimization of cable arrangement. The calculation scheme for determining the cross-sectional area has been offered. It is evident from the calculated scheme that the area of the cross area of the belt section falling for one wire is determined as a trapezium area. The total linear load is determined per rope on the belt section. The presented results of theoretical research, have an applied value, and will be interesting for scientific and engineering workers engaged in research in the field of improvement of belt conveyors operation

Исследование конструкции земляного полотна на свайном основании с гибким ростверком

Purpose: To investigate the roadbed in the construction of pile foundation united by flexible grillage made of geosynthetic material. To investigate how geosynthetic material will work in such a grillage. To create analytical model of pile foundation with flexible grillage. To determine the strength of such textile material used in the construction. To analyze the advantages and flaws of existing methods for calculating pile foundation structure united by flexible grillage made of geosynthetic material. Methods: Structure parameters of flexible grillage reinforced with geosynthetic material, were calculated using three methodologies: British standard BS 8006-2010, German EBGEO methods, flexible thread calculating method. Results: Arched effect arising in mound body has been studied. Deflections in geosynthetic material were calculated at different loading levels of the structure by soil. Experimental values of forces in geosynthetic material are obtained. "Critical height" is set - the distance from pile top which within, arched effect is formed. Numerical value of uniform emptying has been established which at, pile foundation different rigidity is not revealed on surface. The strength of geosynthetic material of flexible grillage of highway mound foundation is estimated. Existing calculation methods for compliance with experiment results are analyzed. Practical importance: Technical solutions have been developed for two types of flexible grillage structures, both, combined and flexible ones with the use of one or more layers of high-strength geotextile with sand in the form of geo-confining. The developed technical solutions meet all requirements of existing regulatory documents and obtained calculated indicators as well as the requirements for strength, reliability and structure durability. The proposed constructions can be recommended for practical use.

ANALYTICAL MODELLING OF THREAD TENSION ON A SYSTEM OF SURFACES

The paper deals with the determination of the tension of a flexible thread using numerical methods. The equilibrium of a homogeneous inextensible heavy thread, when statically interacting with a system of surfaces of various shapes, has been simulated. The paper presents the results of analytical modelling of thread tension. The formulas for calculating the tension at any point of thread by characteristic sections and the normal pressure at critical points have been derived. An example of calculation of thread tension on two smooth cylindrical surfaces and a rough surface of a cone simulating some working bodies of textile machines has been given. The normal pressure on the thread sections at the points dangerous, with respect to contact disturbance, has been determined. After solving all the equations and determining their components, a mathematical model of heavy thread tension at static equilibrium has been constructed using the points found.

Mathematical Model of Spatial Motion of the Controlled Parachute-Tether System of the Wind Kite Type

Mathematical modeling is created for the mathematical task of spatial motion of the controlled parachute-tether system of the “wind kite” type. The mathematical model parachute-tether system consists of a model of the main para-chute and a model of the braking parachute. The parachutes are connected by the tether. The model of the main para-chute is supposed to be the solid body. This solid body has two planes of symmetry. The braking parachute is the solid body with axial symmetry. The tether model is an absolutely flexible elastic thread. The tether is connected by ideal hinges with the main parachute and braking parachute. The control of the main parachute is carried out by changing the length of the control slings. Changing the length causes deformation of the dome. This is the reason for the change in its aerodynamics. Maneuvering of the main para-chute occurs in the vertical plane, when the length of the control slings changes simultaneously. Maneuvering of the main parachute in space is carried out when the length of the control slings changes, when the slings are given a travel difference. The system of dynamic and kinematic equations is designed for calculating the controlled spatial movement of the main parachute, braking parachute and tether. The option exists when the mass of the tether and the forces applied to the tether cannot be neglected. The motion of the tether is represented by the equations of motion of an absolutely flexible elastic thread in projections on the axis of a natural trihedron. The mathematical model is represented by a system of ordinary differential equations and par-tial differential equations. The problem is solved using various numerical methods. The solution is possible with the help of an integrated numerical and analytical approach as well.

On the Motion of a Body Suspended on a Thread with Variable Length

In this paper, we consider the motion of a body suspended on a thread of variable length. We obtain expressions for the speed of the flexible thread when it is wound on a drum, the angular velocity of the drum, and the total duration of the process.

Сформулированы основные задачи подвеса тяжелой гибкой нити в «точной» постановке: без исполь- зования «упрощений», характеризующих существующие методы расчета проводов и тросов ВЛ. Дано общее решение по определению фактического положения и тяжения гибкой нити, моделиру- ющей провод ВЛ, на основании результатов натурных геометрических измерений. Показана воз- можность решения «точных» задач с использованием существующего программного обеспечения.

The main tasks of suspension of a heavy flexible thread are formulated in an “exact” formulation: without the use of “simplifications” characterizing the existing methods of calculating overhead wires and cables. A general solution is given to determine the actual position and gravity of the flexible thread modeling the overhead line wire, based on the results of full-scale geometric measurements. The possibility of solving “exact” problems using existing software is shown.

Melt coated flexible stainless-steel thread based co-axial triboelectric yarn nanogenerators

ABSTRACT Textiles that are smart and responsive have become the new norm in recent years. The development of smart textiles has sparked research into self-powered distributed sensors and portable wearable electronics integrated into clothing. One of the main functionalities of smart textiles is the ability to power these electronics by generating electrical energy from body movements. Since fibres, yarns, and filaments are the basic units of textiles, integrating smart functionality into these basic units is a rational approach. Herein, we report on a co-axial yarn-like triboelectric nanogenerator (Y-TENG) by utilising a scaled-up dielectric (i.e. PVDF) melt coating method to coat a flexible stainless steel thread. The average peak open-circuit voltage (Voc), peak Voc, average peak short-circuit current (Isc), and peak Isc were recorded as 3.82 V, 16.1 V, 12.96 nA, and 53.1 nA, respectively, at 700 N force and 2.11 Hz frequency.

Highly flexible and conductive stainless-steel thread based piezoelectric coaxial yarn nanogenerators via solution coating and touch-spun nanofibers coating methods

The concept of nanogenerators (NGs) based on textiles was introduced to impart functional attributes to textiles for developing smart textiles and integrating wearable electronics of various functionalities. The human body can generate sufficient mechanical energy that can be harvested by the piezoelectric NGs (PENGs) and used to power up low power consuming wearable electronics. Two simple and easy approaches for coating a highly conductive weave-able metal electrode with polyvinylidene fluoride (PVDF) piezoelectric polymer to construct two different types of coaxial yarn-based PENGs (Y-PENGs) are presented in this paper. The proposed techniques result in the in-situ formation of the β phase of the PVDF. The Y-PENGs are based on facile solution coating and touchspun nanofibers (TSNFs) coating of the inner electrode. The solution-coated Y-PENG (SC-YPENG) showed 5.12 V of peak open-circuit voltage (V oc) and 41.25 nA of peak short circuit current (I sc). Whereas the TSNFs coated Y-PENG (NFC-YPENG) showed 5.08 V of peak V oc and 29.1 nA of peak I sc. In a series connection, the average peak V oc were synergized by ∼2.53 and ∼2.4 factor respectively for the SC-YPENG and the NFC-YPENG. The Y-PENGs were able to charge capacitors and run LEDs. Additionally, our coated inner electrode shows great flexibility, thereby it could be knitted or woven into smart textiles to run wearable electronics sustainably.

Assessment of the Possibility of Using ROV in the Mode of Joint Traffic with the Support Vessel

The correspondence of the characteristics of the propulsion and steering complex (PSC) to the values required to compensate for the response of the communication cable determines the efficiency of using tethered underwater vehicles. The report assesses the requirements for the thrust characteristics of the PSC, which ensures the maneuvering of the vehicle relative to the carrier or garage in the mode of movement of the complex along an extended bottom object. The assessment is based on the results of calculating the tension of the communication cable in the stream, due to the joint movement of the tethered system “carrier-garage-vehicle”. This tension, together with the hydrodynamic resistance of the apparatus body, determine the requirements for the thrust characteristics of the PSC, as well as for the power supply system of the complex as a whole. An algorithm is proposed for calculating the tension of the communication cable between the vehicle and carrier in a stationary flow, based on the equation of a chain line and numerical integration of the equations of an inextensible flexible thread. An example of using the proposed methodology for calculating the variants of a tethered system is given.

Flexible cotton-AuNP thread electrode for non-enzymatic sensor of uric acid in urine

We report on the development of an electrochemical sensor platform based on modified cotton fibers for the non-enzymatic detection of uric acid (UA), an important biomarker for gout disease. To create the flexible electrode, a cotton thread was coated with carbon ink as a pre-conductive layer prior to direct electrodeposition of AuNPs. Then, differential pulse voltammetry (DPV) was used to evaluate the sensor performances, and a linear detection range between 10 µM and 5.0 mM of uric acid was obtained. The sensor has a detection limit of 0.12 µM, which is sufficient for use in the patients suffering from gout disease which uric acid is higher than 4.46 mM. Furthermore, we found that the detection sensitivity of the platform was not affected by the presence of other physiological compounds present in human urine. The described platform has the potential for integration in a diaper hence enabling rapid detection and screening for gout disease.Graphic abstract

Vibrations of a flexible flat thread under biharmonic influences

Nonlinear biharmonic fluctuations of a flexible thread with the motionless support located at one level are considered. Amplitude and phase and frequency characteristics of fluctuations of a thread at a frequency of total and differential tone are output; there are living conditions of such fluctuations.

ВИЗНАЧЕННЯ ОПТИМАЛЬНОЇ КРИВИЗНИ ПРУЖНО ДЕФОРМОВАНИХ ВАНТ ПОСЕРЕДИНІ ПРОЛЬОТУ У ВИСЯЧОМУ ПОКРИТТІ ЗА ДОПОМОГОЮ КОМП’ЮТЕРНОЇ СИСТЕМИ MATHCAD

Abstract. The paper presents the theoretical results of improving and refining the general methodology for selecting the cross section of a flexible elastic thread for cable-stayed using the capabilities of computer programs. A technique is proposed for finding the optimal curvature of the cable in the middle of the span by compiling the target function of the cable cost and coverage and determining its minimum. The hanging coating of the building is considered, consisting of parallel-located flexible cables. Coating elements are laid on them. It is assumed that the load is evenly distributed over the curved surface of the coating. With this application of load, the sag curve is adopted as a chain line. In the calculation, two states of the thread are considered. In the first state, it is loaded with a linear load uniformly distributed along its length from its own weight. In the second state, the thread is loaded with the total calculated linear load evenly distributed along its length. To select the cross section of the thread, the maximum longitudinal force arising in it in the second state is determined, which depends on the curvature in the middle of the span. This curvature is determined on the basis that the difference between the lengths of the thread in the first and second states is equal to the elastic elongation according to Hooke's law. Using ordinary algebraic methods, solving the problem is quite complicated. Therefore, it was proposed to solve it using the MathCAD computer system. With the found value of the curvature in the middle of the span, the required cross-sectional area of the thread is calculated. After that, the appropriate rope is selected according to the assortment. To optimize the cable-stayed coating, the optimal curvature in the middle of the span is determined in the first state, at which the total cost of cable-stayed and coating will be minimal. For this purpose, the objective function of the cost of the cable and the coverage that lies on this cable has been compiled. To determine the optimal curvature, it is proposed to accept a series of values of this curvature with some step in a certain range. For each curvature, the value of the objective function is calculated. Using the MathCAD computer system, it is proposed to build the graph of the objective function and find the value of the optimal curvature at which this function has a minimum. After that, it is proposed to find the corresponding optimal sagging arrow. The proposed method allows us to determine the optimal parameters of the hanging coating with parallel cables on the basis of the minimum cost, as well as to calculate the necessary cross-sectional parameters of the flexible cable from the strength condition.

Mathematical Model of Spatial Motion of the Controlled Parachute-Tether System of the Wind Kite Type

Mathematical modeling is created for the mathematical task of spatial motion of the controlled parachute-tether system of the “wind kite” type. The mathematical model parachute-tether system consists of a model of the main parachute and a model of the braking parachute. The parachutes are connected by the tether. The model of the main parachute is supposed to be the solid body. This solid body has two planes of symmetry. The braking parachute is the solid body with axial symmetry. The tether model is an absolutely flexible elastic thread. The tether is connected by ideal hinges with the main parachute and braking parachute. The control of the main parachute is carried out by changing the length of the control slings. Changing the length causes deformation of the dome. This is the reason for the change in its aerodynamics. Maneuvering of the main parachute occurs in the vertical plane, when the length of the control slings changes simultaneously. Maneuvering of the main parachute in space is carried out when the length of the control slings changes, when the slings are given a travel difference. The system of dynamic and kinematic equations is designed for calculating the controlled spatial movement of the main parachute, braking parachute and tether. The option exists when the mass of the tether and the forces applied to the tether cannot be neglected. The motion of the tether is represented by the equations of motion of an absolutely flexible elastic thread in projections on the axis of a natural trihedron. The mathematical model is represented by a system of ordinary differential equations and partial differential equations. The problem is solved using various numerical methods. The solution is possible with the help of an integrated numerical and analytical approach as well.