Wire Strands Research Articles

Carnivore exclosures to protect sheep affect the distribution of a wild cervid

With the recent recovery of large carnivores in Europe, preventive measures to protect livestock are on the rise. Fences that exclude carnivores from grazing areas have been proven as effective, but they can be costly as well as posing a barrier for wildlife. We studied the effect of exclosures of > 10 km2 to protect sheep Ovis aries on the distribution and density of moose Alces alces using fecal pellet group counts in two study areas in southeastern Norway. During the summer grazing season, the fences were powered. Outside of the grazing season, one exclosure remained fenced while the other fence was demounted. This quasi‐experimental setting allowed us to investigate whether fences had a barrier effect for moose, and/or whether moose density was affected by interactions with sheep (competition or facilitation) or large carnivores (refuge hypothesis). During winter, moose pellet group density was about equal inside and outside of the exclosure with demounted wire strands, but less than half inside the permanently fenced exclosure compared to outside, indicating a potential fragmentation effect of the fence. During the grazing season, when wire strands were powered, moose pellet group density was equal or doubled inside as compared to outside both exclosures. Moose may have sought refuge from large carnivores inside the fences. Fecal pellet group densities of moose and sheep inside the fence were neither positively (facilitation) nor negatively (competition) correlated. However, moose used young forest, the most used habitat type by sheep, to a lesser extent inside than outside of the exclosures, maybe due to interference competition. Our study demonstrates that livestock protection fences can have an impact on more than the targeted wildlife species. To understand the mechanisms behind direct and indirect effects of fences, monitoring the movement and survival of individuals by means of GPS and camera traps would be needed.

Experimental study on the flexural behavior of reinforced concrete beam strengthened with novel prefabricated HSSM-UHPC thin plate

Ultra-high performance concrete (UHPC) has been used to strengthen reinforced concrete (RC) structures recently. Although UHPC has high compressive strength, the tensile strength is still low and, the high curing condition on site requirements of UHPC may hinder the further application in complex condition. In this study, a novel prefabricated UHPC thin plate, which is reinforced with high-strength steel wire strand meshes (HSSM), is proposed for rapidly strengthening RC beams. In order to understand the flexural performance of RC beams strengthened with the prefabricated HSSM-UHPC thin plate, four-point bending tests were conducted on three beams including one unstrengthened RC control beam (CB), one cast-in-place HSSM-UHPC strengthened beam (SUB) and one prefabricated HSSM-UHPC strengthened beam (PSUB). The failure modes of the beams were investigated and, the crack development process of the test beams was detailly observed by digital image correlation (DIC). Experiment results showed that compared with CB, the cracking, peak load of SUB and PSUB increased by 25.30%, 28.5% and 19.8%, 26.4%, respectively. However, the deflection ductility of the strengthened beams slightly decreased. Finally, calculation model and theoretical equation for predicting the cracking as well as peak flexural capacity of HSSM-UHPC plate strengthened beams were proposed. Comparison between theoretical and test results showed that the proposed model can accurately predict the cracking and peak capacity of the strengthened beams, and can be used for strengthening design.

Research on the Design of Multi-Rope Friction Hoisting System of Vertical Shaft Gravity Energy Storage System

Renewable energy generation methods such as wind power and photovoltaic power have problems of randomness, intermittency, and volatility. Gravity energy storage technology can realize the stable and controllable conversion of gravity potential energy and electric energy by lifting and lowering heavy loads. The hoisting system is an important component of a gravity energy storage system, and its lifting capacity and speed seriously restrict its energy storage capacity, energy conversion efficiency, and operational safety and reliability. In this paper, a design method for a multi-rope friction hoisting system of a vertical shaft gravity energy storage system is proposed. The parameter design and calculation of the hoisting rope, balance rope, and friction wheel of the friction hoisting system under typical conditions were carried out. The static and dynamic anti-slip capabilities of the friction hoisting system under the typical condition were explored. The results show that the maximum acceleration and deceleration speed of the compacted strand wire rope scheme is the largest, and the lifting and lowering time is the shortest. The maximum acceleration and deceleration speed of the triangular strand wire rope scheme is the lowest, and the lifting and lowering time is the longest. The dynamic tension of the hoisting rope at the heavy-load end is positively correlated with the acceleration, and the maximum value occurs in the accelerated lifting stage and decelerated lowering stage of the heavy load. The static anti-slip safety factor between the hoisting rope and the friction lining and the specific pressure between the hoisting rope and the friction lining comply with the requirements of China’s Safety Regulations for Coal Mines. The dynamic anti-slip safety factor of the hoisting system under different rope selection schemes is greater than the minimum value of 1.25 stipulated in the Safety Regulations for Metal and Nonmetal Mines. The research results are of great significance for the safety, reliability, and stable and efficient energy storage of a gravity energy storage system.

Experimental Investigation of Strain Rate Influence on Anisotropy of Uniaxial Tensile Mechanical Properties of CuFe2P Alloy Sheet.

Wire crimping, a process commonly used in the automotive industry, is a solderless method for establishing electrical and mechanical connections between wire strands and terminals. The complexity of predicting the final shape of a crimped terminal and the imperative to minimize production costs indicate the use of advanced numerical methods. Such an approach requires a reliable phenomenological elasto-plastic constitutive model in which material behavior during the forming process is described. Copper alloy sheets, known for their ductility and strength, are commonly selected as terminal materials. Generally, sheet metals exhibit significant anisotropy in mechanical properties, and this phenomenon has not been sufficiently investigated experimentally for copper alloy sheets. Furthermore, the wire crimping process is conducted at higher velocities; therefore, the influence of the strain rate on the terminal material behavior has to be known. In this paper, the influence of the strain rate on the anisotropic elasto-plastic behavior of the copper alloy sheet CuFe2P is experimentally investigated. Tensile tests with strain rates of 0.0002 s-1, 0.2 s-1, 1 s-1, and 5.65 s-1 were conducted on sheet specimens with orientations of 0°, 45°, and 90° to the rolling direction. The influence of the strain rate on the orientation dependences of the stress-strain curve, elastic modulus, tensile strength, elongation, and Lankford coefficient was determined. Furthermore, the breaking angle at fracture and the inelastic heat fraction were determined for each considered specimen orientation. The considered experimental data were obtained by capturing the loading process using infrared thermography and digital image correlation techniques.

Parametric modeling and finite element analysis of triangular strand wire rope

The triangular strand wire rope exhibits superior performance and holds substantial potential over its round strand counterpart, which is brought by its unique and excellent structural design. However, the investigation of specialized strand components with such distinctive shapes remains limited, and the predominant challenge resides in modeling. This paper introduces a precise vector expression for the spatial trajectory of distinct steel wire types within the triangular strand wire rope structure. Moreover, a comprehensive suite of parametric modeling methodologies tailored for finite element analysis have been established, based on ABAQUS/CAE. The finite element model has been validated by experiments. Furthermore, a series of examples with various boundary conditions and parameters are intended to evaluate the factors affecting the accuracy of the FE model. Employing the established parametric modeling method, triangular strand wire ropes with a range of lay length were established, the differences in their mechanical properties under tensile load were compared, yielding insights that form the basis for proposed design considerations regarding lay length ratios. This model is apt for investigating the macroscopic mechanical response and local force characteristics of triangular strand wire ropes during typical service processes. Moreover, its versatility extends to the realm of other complex rope structures, promising to address the behavioral analysis of intricate strands and rope configurations.

Clinical limitations and its solutions of the digital clear aligner treatment

The digital clear aligner is widely used due to the convenience and efficiency of simultaneously manufacturing the entire aligner used in treatment with a single setup. However, due to the characteristics of clear aligners, which make it difficult to effectively transmit orthodontic force to the teeth compared to traditional brackets, the teeth do not move as planned, resulting in repeated refinements and increased treatment periods. The following measures have been proposed to solve these problems:1. Partial production of Clear aligner: Manufacturing the entire aligner not all at once but in stages, typically 8-10 at a time, allows for more precise management of the individual tooth movement. Additionally, adjustments can be made promptly if treatment does not go as planned.2. Direct 3D printing of clear aligners: Direct 3D printing offers the possibility of creating more efficient aligners that adhere more closely to the teeth than vacuum-formed ones. Moreover, effective tooth movement can be achieved by adjusting the aligner's thickness or designing structures to apply orthodontic forces as required.3. Digital hybrid treatment: Using 3D-printed brackets with two strands of NiTi wire allows for rapid and accurate tooth movement with gentle force. In particular, the ability to manufacture clear aligners and 3D-printed brackets together in a single digital setup enables various clinical applications. This not only shortens the treatment period but also allows for better treatment results.

Design of overhead ground wire repair robot based on unmanned aerial vehicles

AbstractAiming at the problem that it is impossible to accurately transport the aerial ground wire repair robot to the repair point and efficiently repair the ground wire broken strands and scattered strands, this paper designs an aerial ground wire repair robot based on Unmanned Aerial Vehicle (UAV). Firstly, the mechanical structure of the overhead ground wire repair robot is selected and designed, and the information transmission and the cooperative operation of each module are realized. A landing mark based on ArUco code is designed, which uses C++ for visual navigation, and then uses the double closed‐loop Proportional Integral Derivative (PID) control method to control the position and attitude of the UAV, so as to realize the tracking of the robot position by the UAV. At the same time, the mechanical structure and the control method of the UAV hanging device are designed to cooperate with the overhead ground wire repair robot to ensure the accurate completion of the repair operation. Finally, a UAV‐based aerial ground wire repair robot prototype was developed and successfully applied to the repair operation of the broken strand of the aerial ground wire of the 66 to 67 tower of the 500 kV Jiangzi line in Ya'an. It is verified that the UAV‐based aerial ground wire repair robot studied in this paper has a good engineering application value.

Energy dissipation enhancement of wire rope isolators

Wire Rope Isolators (WRIs) are critical in mitigating vibrations in various engineering applications, particularly in seismic isolation. Despite their inherent advantages, the effective damping of WRIs significantly diminishes with increased deformation amplitudes, creating the need to develop improved configurations to enhance their damping capabilities. This paper presents the results of two new experimental approaches to improve energy dissipation in WRIs: applying coatings to wire strands to modify the viscous medium between them and utilizing external confining wires to increase inter-strand frictional forces. Experimental tests were conducted on treated WRIs using sinusoidal displacements across different configurations, including tension-compression, inclined at a 45° angle, shear, and roll. The study evaluated the impact of three coating materials and introduced external confining wires made of steel, copper, aluminum, and solder on the damping properties of WRIs. Among these, steel wires demonstrated a notable increase in damping effectiveness due to their high modulus of elasticity. The results indicate that techniques like confining wires can significantly enhance damping effectiveness at various deformation levels. The findings suggest valuable directions for refining the energy absorption features of WRIs.

Micro-crack localization for steel strands using nonlinear vibro-acoustic modulation based on modified signal bispectrum analysis

Under continuous environmental erosion and long-time high tension, fatigue micro-cracks of bridge cables appear frequently to challenge the reliability of cables. The vibro-acoustic modulation analysis is adopted because of its sensitivity to contact-type defects, especially fatigue cracks. In this paper, using multiple sets of low-frequency vibration and high-frequency ultrasonic excitation, the propagation of the ultrasonic wave in the steel strands is studied. Then, the modulated signal bispectrum is proposed to improve the detection reliability of nonlinear modulation components in the nonlinear vibro-acoustic modulation signal of the contact-type defect. The numerical simulations and laboratory tests of straight wire, helical wire, and multi-wire strands are carried out for micro-crack detection to verify the robustness of the proposed method. Compared with the traditional method, the modulated signal bispectrum can still produce clearer peak detection under high noise conditions. The results show that it provides a promising, dynamic and rapid cable defect detection technique.

Effects of load rate, heating rate, and creep on the ultimate strength and rupture of A416 7-wire strand at elevated temperature

Tensile testing was performed on ASTM A416 cold-drawn 7-wire strands under varying combinations of applied loading and high temperature in three phases: “steady-state” tests, for which increasing load is applied to a specimen at steady-state temperature; “transient” tests, for which the ambient specimen is initially loaded to a constant target tension value and the temperature is then increased until the specimen fractures; and “creep” tests, for which the specimen is subjected to a constant target combination of temperature and tensile loading for a prolonged period of time, during which it accumulates creep strains until fracturing. Temperature-induced decreases in ultimate strength and proportional limit are relatively consistent compared to the existing literature for a wide range of cold-drawn strands fabricated under different governing standards. Steady-state tests produced slightly more thermally induced strength loss compared to transient tests, which suggests that design-basis predictions that are founded on steady-state test results can be used to conservatively predict the thermally induced strength loss in strands that are increasingly heated during fire exposure. Strands loaded to a stress utilization ratio beyond 70 % of their thermally dependent ultimate strength can experience a significant increase in creep strain under prolonged thermal exposure.

Elevated-temperature mechanical property and constitutive model of galvanized parallel wire strands

High-temperature conditions lead to severe degradation of the mechanical properties of steel cables. This study conducted uniaxial tensile tests on 19-wire galvanized parallel wire strands (GPWSs) at elevated temperatures. Using a non-contact measurement system, the failure modes under high-temperature conditions were observed, and stress-strain curves were obtained for 12 temperature levels ranging from 20 °C to 700 °C. The yield strength corresponding to a strain level of 1.5% was determined as the nominal yield strength, which ensures both material strength and sufficient safety. By analyzing the stress-strain curves, reduction factors for the proportional limit, elastic modulus, nominal yield strength, and ultimate strength at various temperatures were obtained for the GPWS. Additionally, a Boltzmann curve was used to fit the reduction factors of the mechanical properties of the GPWS. A constitutive model for the entire process of the GPWSs was established through the segmented fitting of the elastic, plastic hardening, and necking stages. High temperatures severely affect the tensile strength of the GPWS. When the temperature reaches 400 °C, the ultimate tensile strength of the GPWS is only about 50% of that at room temperature. At 700 °C, the ultimate tensile strength of the GPWS is reduced to only 2.5%.

Application of magnetic flux leakage method in the crimping inspection of carbon fiber conductor

Compared with steel core aluminum strand wire, carbon fiber composite core wire has many excellent characteristics such as large flow capacity, good heat resistance, light weight, but its mechanical properties are poor, and the unqualified crimping quality is easy to lead to wire breakage accidents, which greatly affects its popularization. For this reason, a scheme for the detection of crimping defects of carbon fiber composite mandrel based on magnetic leakage method is proposed. Firstly, the finite element analysis model of the clamping fixture was established, and then the magnetic pole distance k and radial air gap n of the magnetic leakage testing device were explored. Based on the signal-to-noise ratio under the two typical defect conditions of fracture and low pressure, the most suitable excitation structure parameters of the magnetic leakage device were obtained. The results show that when k=55mm and n=3.5mm, the signal-to-noise ratio of MFL detection device reaches the best effect. The research results are of great significance to the quality inspection of compacts of carbon fiber composite mandrel.

Mechanical analysis of new-type arc-cone anchor for CFRP strand wires

Conventional anchors tend to produce ‘notch-effect’ at the tensile end due to stress concentration when anchoring prestressed CFRP strand cables. A new-type arc-cone anchor was designed with the purpose of optimizing the stress distribution in the anchor zone in this study. The ‘arc-cone’ model was proposed to represent the mechanical characteristics of the anchor, and the numerical simulation and experiments were carried out. The effect of the design factors on the anchoring performance was discussed, involving the arc-cone radius, the anchoring length, and the end hole wall thickness. The failure mode, the ultimate load, the anchoring efficiency coefficient as well as the stress distribution were ascertained with the consideration of the effect of the abovementioned design factors. The research results show that the extrusion stress on the barrel decreases with respect to both the wall thickness and the anchor length. The larger the radius of the arc-cone is, the larger the slip of the CFRP strand wire is. The proposed anchor configuration inversely changes the stress distribution from the tensile end to the free end, alleviates the ‘notch effect’ existing in the anchoring zone of conventional anchors, and consequently, improves the anchoring efficiency for CFRP strand wires.

Strand wire winding method in a solenoidal coil with limited geometry for good impedance matching

Strand wire winding method in a solenoidal coil with limited geometry for good impedance matching

Finite element modeling for single-twisted Fi(29) strand that reproduces strand stiffness and wire stress

Finite element modeling for single-twisted Fi(29) strand that reproduces strand stiffness and wire stress

Force-Chain Superposition Method for Interface Force Conditions on the Cross Section of Parallel Steel Wire Strands

Force-Chain Superposition Method for Interface Force Conditions on the Cross Section of Parallel Steel Wire Strands

Erection strategy for main cable based on unstrained length of parallel wire strands

This paper presents a construction scheme aimed at achieving one-time erection of strands through precise control of the unstrained length. The scheme entails correcting system errors through the initial strand erection and reducing the influence of random errors by improving manufacturing conditions and increasing field measurements. The key objective is to control cable erection using cable length. A reliability analysis program was developed to assess the accuracy of the main cable installation. A case study of an actual bridge was conducted to verify the feasibility of the scheme. First, an assessment of the distribution characteristics of the random variables was performed. Subsequently, a comparative analysis was performed to evaluate the reliability of the proposed scheme against conventional erection methods. Finally, the new method was validated by on-site installation of several strands. Results revealed that while the reliability of cable formation shape was comparable between the traditional method and the proposed scheme, the latter exhibited superior uniformity of internal force among cable strands after formation. In addition, the average value of the cable length correction for Nos. 2 to 15 strands closely aligns with that of the reference strand, suggesting that the systematic error correction determined by the reference strand exhibits relatively high accuracy. Furthermore, strands erected with cable length as the control objective effectively maintained sag errors within the range of [− 4 mm, 8 mm], demonstrating a high level of precision.

Mechanical properties and bonding strength of twisted wire strands at elevated temperatures

This paper experimentally investigates the mechanical properties of 1860 MPa twisted wire strands and the load capacity of hot casting sockets at elevated temperatures. The stress-strain curves of the strands at the temperature in 20 °C to 600 °C range are reported, and the elastic modulus, yield strength, ultimate strength, ultimate strain and rupture strain are obtained and compared to EC2 and other existing studies. The failure mode, load capacity, failure displacement and critical temperature of the sockets at the temperature in 20 °C to 440 °C range are acquired. The test results show that 1860 MPa twisted wire strands have significantly improved ductility in necking stage after 200 °C, which is underestimated in EC2. The strands with hot casting sockets rupture before 180 °C, and are pulled out from the sockets after 230.5 °C. The load capacity drops after 150 °C, and the failure displacement dropped after 300 °C, indicating significant influence of the sockets on the fire resistance. Based on thick-walled cylinder model, calculation methods are proposed to determine the bonding strength and load capacity of the strand with hot casting sockets. The prediction of the failure modes and load capacity agrees well with test results. The parametrical analysis by the calculation methods shows that the load capacity of the strands with sockets increases as the embedded length or internal diameter of socket increases, or the diameter of the strands decreases in a limited range. For fire protection, it is recommended to keep the socket temperature under the critical temperature in accordance with load ratio.

Formation of columnar grains during diffusional growth of Nb3Sn layer and its suppression

The manufacturing process of multifilamentary Nb3Sn superconducting wire includes annealing for diffusional growth of the Nb3Sn intermetallic compound layer. During the process, the formation of columnar Nb3Sn grains should be suppressed to maximize the flux pinning effect. However, the detailed mechanism underlying the formation of columnar Nb3Sn grains has not been clarified yet, and is an obstacle to finding optimal process conditions. In the present work, we investigated the fundamental reason for the columnar grain formation, using a novel Monte Carlo Potts model which can simultaneously predict grain growth and interfacial reactions. We found that a decrease in thermodynamic driving force due to insufficient Sn at the interface causes the formation of columnar Nb3Sn grains. Accordingly, columnar grain formation is expected to be suppressed when abundant Sn atoms are supplied rapidly to the reaction front. Based on the fundamental understanding of columnar grain formation, possible ways to suppress columnar grain formation are suggested. We especially focused on the difference in the columnar grain fraction depending on the wire strand type (bronze processed wire vs. internal-tin processed wire). Based on simulations and experimental analyses, we suggest a brief guideline for the design of wire strand geometry to avoid columnar grain formation.

Selection of Magnetic Pulse Crimping Process Conditions to Improve Crimped Terminal Quality

The crimping of copper terminals via hand-operated and hydraulic compressors is used to generate a compressive force between a terminal and a wire, generally on a worksite. However, this equipment often causes compression defects because non-uniform pressure is applied to the terminal surface in the radial direction during crimping. When the crimped terminal is connected to electrical parts such as the power transmission system, a low-quality crimped terminal can separate from the wire strands, increasing resistance to current flow through the terminal, energy loss, and the risk of fire due to overheating. For this reason, Magnetic Pulse Crimping (MPC), which can yield highly durable crimped terminals with uniform quality, has recently been developed. This process uses only the magnetic force generated by high electromagnetic interaction between the crimping coil part and the surface of the terminal, without physical contact. The objective of this research was to confirm the superiority of the MPC process over the conventional crimping process and then analyze the effects of the main process parameters, including the crimping length and the charge energy on the crimping part, so that this new process can be applied at worksites. To realize these goals, copper terminals and 35 mm2 copper wire strands were employed, and various types of crimping parts were manufactured under different crimping conditions. In particular, the distribution of electromagnetic force on the crimped parts were analyzed via numerical analysis. The crimping part performance was improved when the MPC process was applied to terminal crimping. In particular, decreasing the crimping length led to increased crimping quality, while increasing the charge energy caused increases in the compression ratio and pullout strength. However, excessively high charge energy caused the edge to break the wire strands; therefore, it is important to select the proper charge energy.