Wire Vibration Research Articles

Numerical Study on Drag Reduction Performance of a New Type of Composite Skin

In order to reduce the surface resistance of underwater vehicles, a new type of composite skin is proposed by combining flexible skin with flexible and miniaturized steel wire vibration isolators. Using ANSYS fluent and transient structure to conduct bidirectional Fluid-structure interaction and drag reduction performance of the skin was studied. The effects of flow velocity and material parameters on its drag reduction performance were discussed. Research results indicate that compared with the steel plate without skin, the resistance of the skin is significantly reduced. Analyzing its mechanism, the wall shear stress after laying the skin is reduced. This study provides a new approach for the design of skin for underwater vehicles.

Self-powered system for environment and aeolian vibration monitoring in the high-voltage transmission system by multi-directional wind-driven triboelectric nanogenerator

The concentration of abundant wind energy on the high-voltage transmission tower with the feature of high height not only provides a promising solution for powering distributed sensors in smart grid, but also enables a potential feasibility for the real-time sensing of the multi-directional wind to evaluate the transmission line aeolian vibration induced by wind excitation. In this paper, the comprehensive strategy appropriately hybridizes the ingenious integration of a rotating-type TENG for efficient wind energy harvesting and a flapping-type TENG for multi-directional wind vector sensing to establish the self-powered multi-directional wind-driven triboelectric nanogenerator (SMW-TENG). The basic D-TENG and F-TENG in terms of structural parameters and response characteristics are systematically optimized to realize an efficient energy harvesting with the peak power of 3.9 mW, a smooth output in the wind speed of 3.7–16.3 m s−1 and sensitive response to eight-direction wind speed ranging from 2.6 to 13.5 m s−1. Hybrid power supply strategy based on collaborative working of UD-TENG as a standby power and LD-TENG as a main power is innovatively proposed to prolong the continues power supply of a Bluetooth temperature and humidity sensor by 70% and 126.7% compared to the single module, respectively. Importantly, the F-TENG equipped with an eight-channel signal acquisition and processing is developed to achieve the multi-directional wind vector information in response to the aeolian vibration. Furthermore, a self-powered ambient weather and multichannel wind vector sensing system based on the SMW-TENG, a hybrid power supply circuit, an eight-channel signal acquisition circuit and a Bluetooth module is developed to comprehensively realize the real-time monitoring of temperature, humidity, wind speed and direction. The abnormal wire vibration alarm can be realized through monitoring the wind direction angle on the transmission line cross-section, thereby exhibiting a great potential for developing self-powered sensing in the field of smart grids.

Effect of a liquid bridge on the dynamic behavior of diamond wires during slicing

Diamond wire sawing with narrower kerf losses and thinner as-cut wafers is a critical technology to further reduce wafering costs in the semiconductor industry. Nevertheless, as the scale of the wire web decreases, the effect of the liquid bridge formed by the capillary condensation of the cutting fluid between the diamond wires becomes significant. Moreover, the transverse wire vibration reduces the wire web gap at certain moments, which makes it easier for the wires to adhere to each other after wetting, thus hindering the slicing process. Therefore, a dynamical model for a double-wire system with liquid bridge action was developed in this study based on the transverse vibration theory of a diamond wire under support excitations to reveal the action mechanism of the liquid bridge between diamond wires. The dynamic adhesion process between the diamond wires moving with the supports is discussed. The effects of the guide wheel manufacturing error and the sawing parameters on the critical gap for spontaneous adhesion between the diamond wires are analyzed. The results show that the static double-wire system does not generate spontaneous adhesion when the surface gap of the wires is between the critical gap for spontaneous adhesion and the maximum adhesion gap. The support excitation causes the transverse wire displacement, which increases the critical gap for spontaneous adhesion to increase the risk of wires adhesion. The critical gap for spontaneous adhesion increases with increases in the guide wheel manufacturing error and the wire span as well as the wire speed and decreases with increases in the wire groove diameter and the wire tension. When the manufacturing error is doubled, the critical gap for spontaneous adhesion will increase more than twice this error increment. Strict control of the guide wheel manufacturing error is the most effective way of reducing the risk of wires adhesion during processing. Increases in the guide wheel diameter and decreases in the wire span and the wire speed within a reasonable range, or enhancing the mechanical properties of the wire to improve its breaking force, also help to reduce the critical gap for spontaneous adhesion.

Experimental Investigation on the Surface Formation Mechanism of NdFeB during Diamond Wire Sawing

Diamond wire sawing is widely used in processing NdFeB rare earth permanent magnets. However, it induces periodic saw marks and fracture chipping pits, which severely affect the flatness and surface quality of the products. In this study, the lateral motion of the diamond wire was monitored to determine the surface formation mechanism. Then, a white light interferometer and an SEM were used to observe the sawed surface profile. Finally, the surface quality was quantitatively studied by identifying the area rate of fracture chipping pits with an image recognition MATLAB script. According to the observation results, the calculation formula of PV which is related to the process parameters was deduced. Additionally, by combining the fracture rate and wire vibration, a novel method was proposed to investigate the optimal process parameters. It can be found that the surface quality sawed at P = 0.21 MPa, vf = 0.2 mm/min, and vs = 1.8 m/s remains better than when sawed at P = 0.15 MPa, vf = 0.1 mm/min, and vs = 1.8 m/s, which means the sawing efficiency can be doubled under such circumstances, i.e., when the surface quality remains the same.

Machine vision-based transverse vibration measurement of diamond wire

Diamond wire sawing is one of the key technologies for wafering in the semiconductor industry. The transverse vibration of the wire during sawing will generate additional displacement that not only reduces the as-cut wafer quality but increases the critical adhesion gap between the wires, which is an important factor limiting the development of diamond wire slicing technology toward narrower kerf loss and thinner as-cut wafer. The vibration measurement of the diamond wire provides an indispensable test basis for its vibration control. Therefore, a machine vision-based transverse vibration measurement method of diamond wire is developed in this paper. The approximate edge position of the wire in the image midline is obtained to crop the region of interest in the image by using the maximum continuous same-directional pixel gradient algorithm and thus reduce the computing time. The wire edges in the image are accurately extracted by an adaptive image segmentation method proposed based on the image histogram. According to the surface topography characteristics of diamond wire, a feature extraction algorithm based on the multiple inward line fitting using the least square method is proposed, which can effectively detect the position of the inner diameter boundary of the diamond wire. Accordingly, the equation of the central axis of the wire in the image is obtained to realize the transverse vibration detection of the diamond wire. To conclude, a diamond wire vibration measurement experiment is conducted and the machine vision detection results are compared with the vibration displacement measured by the accelerometer at the same position of the wire end. The results show that the measurement error of the machine vision vibration inspection is generally small for the different types of diamond wires and the different frequencies of the wire transverse vibration, which means that the measurement method proposed in this paper has good accuracy, and applicability, and robustness.

Review of the Causes of Wire Breakage and Its Mitigation During the Wire Electric Discharge Machining Process

Abstract Wire electric discharge machining (WEDM) is a widely used high-precision machining process. It has the capability of cutting high-strength alloys, namely, tool alloys, Hastelloy, and monel with very tight tolerance. Frequent wire breakage adversely affects the product geometric precision, surface integrity, and productivity of the manufacturing establishments. It is essential to understand the causes of wire breakage and to mitigate the frequency of its occurrence. This paper comprehensively reviews the experimental as well as theoretical research work reported on various aspects of wire electrode erosion such as the effect of heat generated in spark plasma, thermal stresses, wire rupture phenomena, and wire fatigue. It also presents important research findings on the causes of wire failure and advancements to reduce wire erosion and wire vibrations. The paper systematically and carefully examines the measures suggested to improve the wire life and depicts the development of various wire health monitoring and control systems. Overall, it presents useful insights and important guidelines for the efficient utilization of the wire EDM process by mitigating the causes of wire erosion and its failure. It will certainly help for the improvement of the precision machining capability of the WEDM process.

Novel Vision Monitoring Method Based on Multi Light Points for Space-Time Analysis of Overhead Contact Line Displacements.

The article presents an innovative vision monitoring method of overhead contact line (OCL) displacement, which utilizes a set of LED light points installed along it. A light point is an, LED fed from a battery. Displacements of the LED points, recorded by a camera, are interpreted as a change of OCL shape in time and space. The vision system comprises a camera, properly situated with respect to the OCL, which is capable of capturing a dozen light points in its field of view. The monitoring system can be scaled by increasing the number of LED points and video cameras; thus, this method can be used for monitoring the motion of other large-size objects (e.g., several hundred meters). The applied method has made it possible to obtain the following novel results: vibration damping in a contact wire is nonlinear by nature and its intensity depends on the wire vibration amplitude; the natural frequency of contact wire vibration varies, and it is a function of vibration amplitude; the natural frequency of contact wire vibration also depends on the wire temperature. The proposed method can be used to monitor the uplift of contact and messenger wires in laboratory conditions, or for experimental OCL testing, as well as for verifying simulation models of OCL.

Prediction and analysis of material removal rate and white layer thickness during wire electrical discharge turning (WEDT) process

This paper seeks to propose an analytical model for material removal rate (MRR) and white layer thickness (WLT) during wire electrical discharge turning (WEDT) process. This approach considers the predicted crater radius and depth (based on overlapping of craters) for the determination of MRR. The discharge energy (ranging from 4.217 J to 12.228 J) was utilized for the evaluation of the process responses. Besides, a detailed analysis of material removal is visually demonstrated with the aid of a high-speed camera captured at 15,000 fps. The images/videos from the camera help to visualize the material removal process at various discharge energies and input settings. A non-uniform increase in MRR at discharge energy ranging from 4.217 J to 8.475 J was observed, presumably due to the unpredictable wire vibration as confirmed from the high-speed camera. The white layer formation during the process was analyzed using SEM images. Beyond the discharge energy value of 10.276 J (approx.), substantial increase in molten pool formation causes the WLT to shift to a higher incremental slope. The predicted MRR and WLT values are in good agreement with the measured results with an absolute average error of 7.09% and 5.12%, respectively. A detailed EDS analysis confirms the variation in surface elemental composition before and after the WEDT process.

Optimization of Machining Parameters for Corner Accuracy Improvement for WEDM Processing

Corner accuracy occurring in wire electrical discharge machining (WEDM) is influenced by machining parameters such as wire vibration, wire lag, and excessive discharge, etc. This study proposed an optimization method which can improve the corner accuracy of the WEDM process. The parameters of pulse-on time (ON), pulse-off time (OFF), open circuit voltage (OV), servo voltage (SV), wire tension (WT), and flushing pressure (WA) were selected to investigate the influences of the major parameters on the machining accuracy in this study. Three different corner angles of 30°, 60°, and 90° were chosen for the verification experiments. The response surface methodology (RSM) was used to analyze and investigate the effect of each parameter on the corner error. After integrating the response surface value and algorithm, an optimization system with a friendly human–machine interface, which has a procedure guiding function, was developed with use of C# language. The system can predict the corner error and also recommend optimal machining parameters for smaller corner error and faster machining speed based on the original machining parameters. Finally, cutting experiments were conducted to verify the proposed system, and the results showed that the proposed method can effectively improve the corner accuracy by 39%, 20%, and 33%.

Transverse forced vibration of a diamond wire under support excitations

Diamond wire sawing is a key technology for wafer processing in the semiconductor industry. Transverse wire vibration decreases the wire web gap to below the critical adhesion spacing between the wires, which is an important factor that limits the development of diamond wire slicing technology toward narrower kerf losses and thinner as-cut wafers. In fact, the external excitation source that causes the diamond wire vibration comes primarily from the supports at both ends of the wire. Therefore, an analytic model for transverse forced vibration of a diamond wire under support excitations was developed in this study based on the transverse vibration theory of an axially-moving string fixed at both ends. This partial differential equation with non-homogeneous boundary conditions was solved using the superposition principle and the finite element method. To verify the theoretical model, experimental equipment to text the transverse vibration of a diamond wire with support excitations was developed. The support excitation signal and the wire vibration response were obtained using accelerometer measurements and machine vision detection, respectively. The theoretical results agree well with the experimental results, indicating the correctness of this proposed model. The effects of the vibration source and the installation parameters on the transverse vibration displacement of a diamond wire are discussed. The results show that hysteresis in the movement of the center of the wire causes a certain additional high-frequency vibration, which can make this maximum transverse displacement to be greater than the excitation amplitude, thus making the wire transverse vibration change non-linearly with some parameters. The maximum transverse vibration displacement at the center of the diamond wire increases with increases in the guide wheel machining error amplitude and the wire diameter as well as the wire span, while it decreases with increases in the wire groove diameter and the wire tension. This maximum transverse vibration displacement decreases by approximately 100.22 % and 6.17 % when the guide wheel manufacturing error amplitude and the wire groove diameter are reduced by half and doubled, respectively. Improving the manufacturing accuracy of the guide wheel is still the most effective way of reducing the transverse vibration displacement of the wire. In addition, appropriate increases in the groove diameter and the wire tension and decreases in the wire span are also beneficial for suppressing the wire vibration.

Analytical models of movement of wires of air high-voltage power transmission lines

The article PURPOSE with the problem of monitoring the state of high-voltage overhead power lines in order to ensure uninterrupted and reliable supply of consumers with electricity. METHODS. As parameters of the state, the sag, the tensile force and the mass per unit length of the wire hanging in the span are defined. IT IS STRESSED that a complete picture of the state of an overhead line can be established by determining the spectral composition of the wire vibrations using mounted automated multi-parameter sensors with accelerometers as sensors. It is shown that the currently used dynamic models for describing the motion of a wire as a pendulum and as a tightly stretched string are not complete enough to represent the vibrations of the wire in all three spatial coordinates, do not cover vibrations with odd harmonics and symmetrical vibrations. A system of equations has been OBTAINED that makes it possible to describe the spatial oscillations of the wire along all three axes, taking into account the difference in heights of the wire suspension points. IT IS SHOWN that the analysis of the higher harmonics of the spectrum of vibrations of the wire makes it possible to determine all the main mechanical parameters of the wires of overhead power lines.

Integrated numerical simulation of an electromagnetic transmission line galloping excitation test system

PurposeThis paper aims to establish the mathematical model and solve the complex calculation multi-field coupling problem for an electromagnetic overhead transmission line galloping excitation test system.Design/methodology/approachAn electromagnetic excitation test system is introduced. To calculate the vibration response of the transmission line, a transient coupled finite element model containing electromagnetic repulsive mechanism and transmission line system was established. Considering the advantages of Newmark-ß algorithm and fourth-order Runge–Kutta algorithm, the two algorithms are combined to solve the model. Compared with the simulation results of existing commercial finite element software, the accuracy of the calculation model of electromagnetic force and wire vibration response are verified.FindingsComparison results show that the proposed calculation model can accurately obtain the force of electromagnetic mechanism and the vibration response of the overhead power lines, and improve the calculation efficiency. The calculation results show that vibration under electromagnetic excitation presents a double half-wave mode, and the galloping amplitude varies according to the charging voltage.Originality/valueThis paper built the transient simulation model for a galloping test system. The Newmark-ß algorithm and the fourth-order Runge–Kutta algorithm are used to solve the model. The research results are of great significance for the actual galloping test system design.

Optimization of Dielectric Oil Viscosity for High-precision Wire EDM

Deionized water has been conventionally used as dielectric fluid in wire EDM, while oil in die-sinking EDM. The gap distance using dielectric oil is smaller than that using deionized water, since the electrical resistivity of dielectric oil is higher. In addition, EDM in oil can prevent oxidization and anodization of machined surface. For these reasons, dielectric oil has been recently used also in wire EDM for achieving high-precision machining. However, the influence of dielectric oil properties on wire EDM characteristics has not been clarified sufficiently. This study fundamentally investigated the influence of dielectric oil viscosity on wire EDM characteristics. Three types of dielectric oil differing only in viscosity were examined in this study.Linear cutting experiments were carried out using these oils at first. The experiment results showed that the removal rate increases with dielectric oil viscosity. Then, the influence of viscosity on crater removal volume was investigated to discuss the cause of the change in removal rate, and it was found that crater removal volume increases with the viscosity. Next, the difference in machining accuracy with dielectric oil viscosity was investigated. It was found that the corner shape accuracy deteriorates with the increase of dielectric oil viscosity while the machined surface waviness and straightness improve slightly. In addition, CFD analysis of hydrodynamics force distribution on wire surface, structural analysis of wire deflection, and high-speed observation of wire vibration during machining were carried out. The results showed that the wire deflection increases, and the wire vibration decreases in the case of higher viscosity. From these results, it can be considered that the hydrodynamics force acting on the wire increases with dielectric oil viscosity. Then, the wire deflection in the machining direction increases, leading to the deterioration in corner shape accuracy. On the other hand, the wire vibration is somewhat restrained, leading to the improvement in the machined surface accuracy.

Simulation of Wire EDM Combined with Measurements of Discharge Locations and Wire Displacement

This paper describes a development of a wire electrical discharge machining simulation combined with the measurements of the wire displacement and discharge locations. The wire displacement was measured using an optical sensor to obtain the discharge reaction force and damping coefficient of the wire vibration which are variable during machining. The discharge locations were measured to obtain the points where the discharge reaction force is applied. Considering the discharge reaction force and electrostatic force acting on the wire electrode, the wire deflection and vibration were calculated to obtain the machined workpiece geometry to be compared with the experimental results. Most significant advantage of the simulation newly developed is that those parameters can be updated in real time during machining. With the help of the sensor fusion, the parameters were found to change with increasing the depth of cut and the cut geometries could be simulated with higher accuracy.

Разработка программно-аппаратного комплекса поддержки принятия решений по режимам эксплуатации контактной сети с помощью машинного обучения

Рассмотрены особенности работы и функциональная схема программно-аппаратного комплекса поддержки принятия решений по режимам эксплуатации контактной сети с применением технологии машинного обучения. Предлагаемый комплекс осуществляет сбор, накопление и обработку информации о техническом состоянии объектов наблюдения, а также дает рекомендации оперативно-техническому персоналу для принятия продуктивных решений (снижение скорости движения на участке, усиление готовности обслуживающего персонала и т.д.). Работа комплекса представлена на примере определения натяжения проводов контактной сети с помощью диагностических сенсоров и модели дерева решений для классификации цифровых отпечатков. Обучение математической модели классификации проведено в MATLAB Classification Learner на массиве виброускорений проводов контактной сети, смоделированном конечно-элементной моделью при различных вариантах натяжения. Предлагаемый программный комплекс может быть интегрирован в аналогичные системы диагностики и контроля работы электрооборудования с целью поддержки принятия решений персоналом сферы электроэнергетики.

Influence of the Material Properties on Microgrooving u sing Wire Tools Electrodeposited with Diamond Grains

In this study, the main objective is to clarify the relationship between the material properties of the work material and the grooving properties for various work materials from hard and brittle materials to metallic materials. In this paper, in order to investigate the grinding characteristics of diamond electroplated wire tools, including the wear characteristics, we conducted grooving experiments with borosilicate glass (Pyrex), which is a kind of hard and brittle material, and aluminum alloy (A5052), and tough pitch copper (C1100), a kind of metallic material, using diamond electroplated wire tools in a work material rotation method. As a result of the grooving experiments, it was clarified that the grooving characteristics of the work materials were influenced by the hardness and brittle behavior of the materials. The groove depth is influenced by the hardness and brittleness behavior of the material. When machining hard materials, the groove depth increases slowly in the initial stage of machining due to the poor bite of the wire tool, but increases rapidly as the machining progresses. On the other hand, the groove width does not depend on the machining time or speed, but is influenced by the hardness of the material and the ease with which plastic deformation occurs. The wear of the wire tool is also influenced by the hardness and brittleness of the material. In the machining of hard materials, the wear caused by stray wire and vibration in the early stages of machining was significant. The grinding ratio calculated from the ratio of the groove depth to the amount of grinding has a very different trend for hard and brittle materials and metallic materials. In the machining of hard and brittle materials, the amount of machining increased rapidly as machining progressed, so the grinding ratio also increased, but in metallic materials, the amount of machining itself was small and the grinding ratio did not increase. For A5052, the grinding ratio tended to decrease as machining progressed. Future work In the future, it is necessary to clarify the machining conditions to reduce the wear caused by stray wire tools and vibration during the initial machining of hard materials.

The mechanics of sawing granite with diamond wire

Today, wire sawing of natural stone is undergoing widespread commercialization. In addition to rock extraction and processing with single wires, composed of a multitude of diamond-impregnated beads mounted onto a steel rope, this technology is increasingly used for slabbing of granite blocks on multi-wire machines. Evolving sophistication of stone sawing equipment dictates novel tool designs and formulations. For technologists specifying bead compositions, it is a common habit to instinctively follow the circular saw segment design guidelines. A poor tool performance is often an undesirable consequence of such an approach. To meet that challenge, theoretical models of sawing granite by means of a diamond wire saw and a diamond circular saw have been presented and contrasted with respect to diamond loading conditions. The analytical treatments are supported by scarcely available industrial quantitative assessments and qualitative observations. The evaluation of cutting forces and the identification of system characteristics affecting wire vibration and wire rotation are instrumental in both machine design and tool formulation. For practitioners working with granite, the provided knowledge is also essential to diagnose and prevent problems inherent in wire sawing, such as the high incidence of wire breakage, unsatisfactory tool life and cutting capability and eccentric bead wear.Graphical abstract

Adjustment of Wire Vibrations in Order to Improve Geometric Accuracy and Surface Roughness at WEDM

Although WEDM is one of the most precise finishing technologies, deviations from the required geometric shapes and surface roughness occur in the production of parts with rotary surfaces. Even though these shortcomings have only a minimal impact on planar cuts, the production of circular profiles is a different problem. One of the factors causing this poor quality is the vibration of the wire electrode. With appropriate vibration adjustment, it would be possible to achieve significant improvements of the eroded area quality, both in terms of geometric accuracy and in terms of surface roughness. This would significantly increase quality, enabling WEDM technology to compete with other technologies in terms of economic efficiency. Therefore, the proposed solution aims to provide a partial adjustment to the wire tool electrode vibrations, based on their sensing by the means of acoustic emissions or a laser beam, with subsequent dynamic adjustment of the actual technological parameter values. This way, the given solution will increase the production accuracy of circular holes, increase productivity, and ultimately provide an overall increase in the economic efficiency of the WEDM process. The article also presents the scheme of a control algorithm for monitoring and subsequent adjustments of the vibrations of the wire tool electrode during the electroerosion process in order to minimize geometric deviations of circularity, cylindricity and roughness of the machined surface.

Study on surface characteristics in ultrasonic vibration-assisted WEDM-LS based on spatial vibration of electrode wire

The spatial vibration model of the electrode wire in ultrasonic vibration (USV)-assisted low-speed wire electrical discharge machining (WEDM-LS) under continuous discharges is proposed for analyzing its vibration state, and subsequently, a theoretical model of material removal from the TiNi-01 shape memory alloy workpiece is established by means of Gaussian heat source in single-pulse discharge process and the principle of the nearest-point discharge breakdown. Then, the topological matrix of the surface morphology is developed for investigating the surface characteristics and the distribution of discharge points by simulation. Finally, the experiment of photographing the discharge channel position is accomplished to validate the reliability and feasibility of the model. The results show that the discharge channels are more uniformly distributed in the hybrid process, which enhance effectively the success rate of the discharge pulses and decrease the surface roughness. In addition, a mathematical model to evaluate the uniformity of the discharge point distribution is employed as an evaluation index of the burn degree on the workpiece surface. The distribution uniformity coefficient obtained by the compound process is higher than that of the traditional WEDM-LS. This is consistent with the phenomenon of alleviated surface burn under the hybrid machining technology, and the average errors of the simulated and experimental values of the uniformity coefficient of traditional WEDM-LS and the hybrid process are 4.9% and 3.4%, respectively. The maximum errors of surface roughness between simulated value and experimental value about the WEDM-LS and hybrid process are 7.4% and 8.2%, respectively. It is demonstrated that the model can effectively and accurately predict the surface roughness and the surface burn of the workpiece.

Математическая модель модуля дистанционного мониторинга проводов по каналам измерения механических воздействий на провод воздушной линии

This paper focuses on developing a mathematical model of a remote monitoring module by mechanical impact measuring channels on an overhead power line.The mathematical model simulatessag angle monitoring,wire break, wire vibration, and conductor gallopingprovided that one half-wave is forming at one power line span. The proposedmathematical model has been implemented as part of control tools at an electric power supply company.