Wire Breakage Research Articles

Corrosion on prestressing wires due to segregation of the injection mortar – Detection of injection defects with Ultrasonic-Echo Technique

Unsuitable granulometry of injection mortar can promote segregation if high hydrostatic pressure impacts on the mortar for longer time during hardening. Endangered for segregation are long perpendicular prestressing tendons e.g. used in high towers due to the high hydrostatic pressure inside. The segregation causes an accumulation of water and solved ions on top of the tendons. In this area an extremely high pH-value and a very low electrochemical potential occurs. This environment is extremely corrosive and can cause wire breaks within only few months. With the Ultrasonic-Echo Technique (Flaw Detectors) it is possible to detect injection defects by using the phase shift technique.

Theory and Numerical Analysis of Extreme Learning Machine and Its Application for Different Degrees of Defect Recognition of Hoisting Wire Rope

An improved classification approach is proposed to solve the hot research problem of some complex multiclassification samples based on extreme learning machine (ELM). ELM was proposed based on the single‐hidden layer feed‐forward neural network (SLFNN). ELM is characterized by the easier parameter selection rules, the faster converge speed, the less human intervention, and so on. In order to further improve the classification precision of ELM, an improved generation method of the network structure of ELM is developed by dynamically adjusting the number of hidden nodes. The number change of the hidden nodes can serve as the computational updated step length of the ELM algorithm. In this paper, the improved algorithm can be called the variable step incremental extreme learning machine (VSI‐ELM). In order to verify the effect of the hidden layer nodes on the performance of ELM, an open‐source machine learning database (University of California, Irvine (UCI)) is provided by the performance test data sets. The regression and classification experiments are used to study the performance of the VSI‐ELM model, respectively. The experimental results show that the VSI‐ELM algorithm is valid. The classification of different degrees of broken wires is now still a problem in the nondestructive testing of hoisting wire rope. The magnetic flux leakage (MFL) method of wire rope is an efficient nondestructive method which plays an important role in safety evaluation. Identifying the proposed VSI‐ELM model is effective and reliable for actually applying data, and it is used to identify the classification problem of different types of samples from MFL signals. The final experimental results show that the VSI‐ELM algorithm is of faster classification speed and higher classification accuracy of different broken wires.

Double whip stitch for free graft femoral fixation in ACL reconstruction: experimental study on porcine model.

Background and aimsUsing free quadriceps tendon graft for anterior cruciate ligament (ACL) reconstruction has become more popular in the last years due to the low morbidity at the harvest site and biomechanical and structural properties similar to other types of graft (hamstring and patellar tendons). As long as the tibial tunnel fixation with interference screws is considered the standard fixation, femoral fixation is still an open subject. Even though the most common type of femoral tunnel fixation are the cortical suspension devices, the type of suture used for tying the graft to the loop is still evaluated and discussed. We aimed to evaluate the resistance and elongation of a double whip stitch used for tying a tendon to the loop of a cortical suspension device.MethodWe used 10 porcine flexor digitorum profundus as free graft for a graft-suture-cortical suspension device construct using the double whip stitch. The total length of the construct and tendon length were recorded before and after the test was performed. Tensioning curves, total construct elongation and maximum tension at breaking point were electronically recorded on the testing device’s software. The mean values and coefficient of variance were assessed.ResultsWe noted the breaking of the suture wire where the wires passed through the loop of the cortical suspension device as final point for all tests. The mean of maximum load was 505.68N (Max=639.38 N; min=358.93 N; SD=82.88078 N) and the mean of total construct elongation was 39.54784mm (Max= 48.60466 mm; min=31.74853 mm; SD=4.85371 mm).ConclusionWith some minor improvement in technique and graft preconditioning and pretensioning, the double whip stitch can be used in connecting a free tendon to a cortical suspension device.

Online Workpiece Height Estimation for Reciprocated Traveling Wire EDM Based on Support Vector Machine

The reciprocated traveling wire EDM is a unique type of wire EDM machine, in which the wire electrode is not discarded after passing the discharge gap but being re-winded on the wire drum instead. It is of specific features such as ultra-thick workpiece cutting and reuse of wire electrode. While cutting variable height workpieces with constant machining parameters, this type of WEDM faces the same challenges as western style WEDM, either the risk of wire breakage or the low cutting speed. Due to the intermittent discharge process and the varying machining characteristics, online estimation of workpiece height becomes even more difficult for this type of WEDM.This paper proposes a method of online workpiece height estimation based on support vector machine (SVM), an effective machine learning method. The inputs of the SVM model are effective discharge frequency, pulse interval, programmed feed rate and actual feed rate and the output is the estimated height. The algorithm is integrated in a newly developed computer numerical control (CNC) system for reciprocated traveling WEDM, with a sampling circuit collecting current and voltage signals from the discharge gap and an adaptive control unit which adjusts the machining parameters according to the workpiece height estimation.The data for training the SVM were produced by cutting stair-shaped workpieces to build the SVM model. Then verification was carried out by cutting through workpieces with variable height cross sections. The results demonstrated the effectiveness of the proposed method. The estimation error was less than 2mm and the machining time was reduced by more than 30%.

Location, Assessment, and Repair of Wire Breaks on a 30- and 42-inch PCCP Force Main Fairfax County Department of Public Works and Environmental Services

Location, Assessment, and Repair of Wire Breaks on a 30- and 42-inch PCCP Force Main Fairfax County Department of Public Works and Environmental Services

Effect of Copper Coating and Reinforcement Orientation on Mechanical Properties of LM6 Aluminium Alloy Composites Reinforced with Steel Mesh by Squeeze Casting

Uncoated and copper coated steel wire mesh reinforcing LM6 aluminium alloy composites have been produced using squeeze casting process by varying reinforcement orientation viz., 0°, 45° and 90° respectively. Microstructure of the castings has been examined and mechanical properties such as hardness, tensile strength and ductility have been investigated. Fracture surface of tensile specimens has been analysed using field emission scanning electron microscope. Microstructure of samples reveals that copper coating on steel wires improves the interface bonding between matrix and reinforcement. Average hardness values of 259 and 90 Hv have been observed in steel wire and matrix respectively. Tensile strength of composites increases with increasing angle of reinforcement orientation from 0° to 90°. Tensile strength increases up to 11% by reinforcing copper coated steel wire mesh at 90° orientation as compared to LM6 aluminium alloy. Fracture surface of composites shows pullout of steel wires in uncoated steel wire mesh composites and broken wires in copper coated steel wire mesh composites respectively. Dimples have been observed on the fracture surface of LM6 aluminium alloy. In general, copper coated steel wire mesh composites offer better hardness and tensile strength compared to uncoated steel wire mesh composites and LM6 aluminium alloy. This may be attributed to the copper coating on steel wires which results better interface bonding between matrix and reinforcement.

A novel technique for slicing SiC ingots by EDM utilizing a running ultra-thin foil tool electrode

Recently, a multi-wire electrical discharge slicing (EDS) process has been proposed for slicing SiC ingots into wafers. A significant reduction in kerf loss is expected with this method compared with the conventional multi-wire saw method. However, this process entails a high risk of wire breakage. Therefore, in the present study, a novel electrical discharge slicing process utilizing a running ultra-thin foil tool electrode is demonstrated for the slicing of SiC ingots. Relative to multi-wire EDS, the risk of tool breakage can be reduced with this new technique by increasing the tool cross-sectional area. A 25-mm (1-inch) SiC ingot was successfully sliced with the proposed method and a kerf loss of about 100μm was achieved by utilizing a foil tool electrode with a thickness of 50μm. This paper summarizes the specific characteristics and results of this process, including the machining stability, machining strategy, selection of foil tool material and multiple simultaneous slicing.

Wire electrical discharge machining characteristics of AA6061/cenosphere as-cast aluminum matrix composites

ABSTRACTMachining of metal matrix composites (MMCs) reinforced with low-density waste byproduct particulates using nonconventional processes is relatively new in the field of material science. However, more attention has been paid for investigations on nontraditional machining of such MMCs currently as the conventional machining may generate additional complexity. This study investigates the wire electro-discharge machining behavior of compo-casted cenosphere-reinforced AA6061 alloys. Cu60Zn40-coated copper wire was used as electrode material. The investigation demonstrates that melting and vaporization are the dominant machining mechanisms. The weight fraction of cenosphere was observed to be the most substantial process variables affecting the cutting rate, on-time, and the wire speed of tool were the next in the order of importance. The presence of nonconductive cenosphere particles along with thermal degradation of the aluminum matrix composites leads to degrading processed machined surface quality. The issues related to wire breakage and poor quality of the machined surface, surface finish, and dimensional accuracy are described in detail.

Новые решения защитных устройств линий электропередач

Objective: Patented and experimentally fulfilled development of supported electric cables and wires’ successful protection from snow build-up, ice covering and possible breakages, caused by strong rushes of wind, was suggested for pilot installing in operation. It is known that, on average, the financial losses of our country from wire breakages amount to about 1 billion rubles. Nevertheless, some districts are left without heat and light, which demands the start of emergency electric power sources and sending the repair squads for power lines’ breakage elimination. Methods: Experimental tests were conducted under conditions close to natural, that is, in winter time and open air. Results: Original and simple implementation solutions of effective damping of possible wire oscillations corroborated the impossibility of resonant swinging of wires formation, which considerably increases the reliability of line functioning. Practical importance: Positive results, indicating a complex fulfillment of the set objective on wires’ protection were obtained, which demonstrate commercial efficiency of the study.

The establishment of a numerical model for structural cables including friction

A friction element is presented in this paper. The element was incorporated into a simplified numerical model of cables, which were established by a beam element. A detailed numerical model was implemented based on general-purpose finite element software. Moreover, a flowchart of a numerical analysis was proposed. The accuracy of the proposed numerical model was validated by comparing the results derived in this work to the analytical results derived from Costello's theory and experimental results. The bending performance of 1×37 semi-parallel wire cables was investigated. Then, the dynamic response of cable caused by wire break was analyzed. Sensitivity analysis was conducted to investigate the influence of several factors on dynamic response. Results indicated that the friction element proposed in this paper can capture the sliding among different wires and thus can be efficiently adopted in dynamic analysis.

Use of Location Probing to Detect Damage to the Wires of High-Voltage Electric Transmission Lines

Experimental data on the detection of short circuits and wire breaks on 35 – 220 kV overhead electric transmission lines acquired over the course of 20 years of research by a location method are summarized. Techniques that may be used to analyze reflectometer patterns in location probing of transmission lines in order to identify the type and location of wire damage are described. Features involved in the detection of short circuits on existing 35, 110, and 220 kV lines are considered separately. Methods for the detection and display of different types of short circuits and line breaks on existing electric transmission lines are discussed.

Treatment of Salter-Harris type II phalangeal fracture in children

Objective To evaluate the clinical outcomes of closed reduction and Kirschner wire fixation in the treatment of Salter-Harris typeⅡphalangeal fracture in children. Methods From January 2014 to March 2016, 12 cases (14 fingers) of pediatric phalangeal fracture were treated by closed reduction and percutaneous Kirschner wire fixation. The preoperative X-ray showed that the fractures were displaced but not comminuted. According to the Salter-Harris classification, all the fractures were typeⅡ. X-ray examination was performed at 2, 4 and 6 weeks after operation to observe fracture healing. Results All the patients were follow-up for 2 to 16 months with an average of 7 months. All the phalangeal fractures were healed with an average healing time of 3.5 weeks. There were no obvious angular or rotational deformities, no kirschner wire breakage or loosening and no pin infection. According to the visual analogue scale (VAS), the pain scores were excellent. According to the functional evaluation standards issued by Hand Surgery Society of the Chinese Medical Association, the results were excellent in 10 cases (11 fingers), good in 2 cases (3 fingers). Conclusion Under the premise of mastering the indications, closed reduction and Kirschner wire fixation for the treatment of Salter-Harris typeⅡphalangeal fracture in children with angular displacement can achieve satisfactory results. Key words: Child; Finger phalanges; Fracture fixation; Salter-Harris typeⅡ

Failure analysis of wire-breaks in aluminum conductor production and investigation of early failure reasons for transmission lines

Abstract In this study, continuous casting process performed using AA1070 and AA6101 feedstock alloys for bare conductor manufacturing. Test samples were provided at breaking time in casting and wire driving processes. Analysis of wire defects and damages were analyzed using Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS) and categorized with respect to fracture mechanism to investigate their possible origin. Seven different failure modes: hole defect, solidification cavities, tear apart of the embedded inclusions, “check” defect, a splinter from the embedded hard oxidized particles, overfill break, metal oxide accumulation zone breaks were detected on wire-break samples. This analysis was done to investigate early failure reasons of transmission lines due to working under several types of vibration phenomena in service life. It has been detected that major cause of the defects is related to the metal purification in the holding furnace. Besides, drawing die angles and guide of the stranding machines were also detected as another source of failure. The two main reasons for wire break were found as machine interaction and the inclusions.

Integration of risk matrix and event tree analysis: a natural stone plant case

Machining has considerably increased with evolving technology and increasing demand in natural stone production facilities. Different types of accidents may occur in natural stone facilities during movement, dimensioning, cutting of blocks and surface processing. These accidents may be due to physical, chemical, ergonomic and mechanical conditions. Therefore, possible work accidents and occupational diseases should be investigated. In this study, an L-matrix analysis is conducted to analyze hazards and forecast risks in natural stone facilities. According to the L-matrix results, three major initiating events are identified. For each of these initiating events, event tree analysis is used to calculate risk scores. These initiating events are hoist rope fatigue and breaking, diamond wire fatigue and breaking, and electrical leakage due to old systems. These events and their results are classified according to the probabilities using event tree analysis.

Comparison of Efficacy of Transalveolar Screws and Conventional Dental Wiring Using Erich Arch Bar for Maxillomandibular Fixation in Mandibular Fractures.

Maxillomandibular fixation is required in nearly all cases of facial fractures which can be achieved by conventional dental wiring techniques or newer methods using transalveolar screws. A prospective randomized clinical study divided into two groups with thirty adult patients each with mandibular fractures was undertaken comparing the Maxillomandibular fixation technique using transalveolar screws and Erichs arch bar. Total time taken, rate of glove perforation, intraoperative and postoperative complications were noted in both the groups. The time taken for maxillomandibular fixation in minutes and rate of glove perforation was found to be statistically significantly less for transalveolar group compared to arch bar group (p<0.05). However, there was no significant difference found in the oral hygiene and gingival status using the Glass index and Gingival index. The rate of screw breakage (04.67%), wire breakage (05.12%), non-vitality due to iatrogenic dental damage (01.66%), soft tissue injury and tooth loss were some of the noted complications during the study. We found that transalveolar group offered advantages like less time taken with a definite decreased risk of percutaneous injury, while the iatrogenic complications like dental damage can be reduced by taking adequate precautions.

(Invited) Using Electrochemical Measurements to Diagnose Neural Interface Electrodes

The sophistication of neuroscience experiments designed to elucidate the functionality of the mammalian central and peripheral nervous system is rapidly increasing, and so must the use of more complex electrodes that are used to interrogate the behavior of neural networks. Despite the rapid rise of optical techniques, the metal microelectrode remains the workhorse of experimental neuroscience, and implantable electrode arrays continue to be an important experimental tool. Unfortunately, the reliability of multielectrode arrays remains marginal. While some researchers have been able to record neural activity for many months, or years, more commonly the neuroscientist is hampered by short-term degradation in electrode insulation, increasing array electrical leakage, breakage of wires, and failure of percutaneous connectors. Often these failures obscure the neuroscience experimental goals, and the neuroscientist is left to guess whether changes in data are due to array deficiencies or biological effects. Initiated by a DARPA grant, our group has developed a microelectrode array analytic and diagnostic instrument that can assess the “health” of implanted electrode arrays. Using a combination of CV, EIS, and pulsed-current measurements, the multiple electrode array analyzer uses 16 parallel potentiostatic modules to perform these measurement modalities in parallel, rather than multiplexing a single instrument. This parallel measurement capability is important because the duration of sessions with experimental animals is often very limited, and the researcher is unable to dedicate a significant portion to merely determining the status of the implanted electrodes. Parallel measurement of 16 electrodes dramatically reduces the time required to diagnose the condition of implanted electrodes at the onset of an experimental session. However, performing parallel measurements of CV and EIS for multiple electrodes pose unique instrumentation challenges that have been addressed in our design. The performance of this instrument has been evaluated in experiments performed on Macaque with electrode arrays implanted in the brain in a location that is particularly vulnerable to cable breakage. Diagnoses of the electrodes, and connection system, have been performed that clearly show increased electrical leakage as differentiated from biological encapsulation of the electrode tips. The presentation will describe these experiments, the electrochemical data, and the functional diagnoses. Our long-term goal is the development and distribution of a diagnostic software module which permits frequent and rapid collection of in-vivo electrode electrochemical data, with the option of upload to a central database for sharing among researchers. Using this diagnostic means, the researcher can anticipate electrode array failures, and make appropriate experimental decisions.

Influence of Nozzle Jet Flushing on Wire Breakage in 1st-Cut Wire EDM from Start Hole

In wire EDM process, it is important to smoothly exclude debris and bubbles generated in the working gap for keeping stable performance. Much debris stagnation in the gap would cause frequent occurrence of discharge concentration and secondary discharge, which results in unstable machining performance, such as frequent wire breakage, low removal rate, and low shape accuracy. Therefore, a jet flushing of working fluid using upper and lower jet nozzles has been conventionally applied for excluding the debris and bubbles from the machined kerf. Nevertheless, it is well known that the wire often breaks when the machined kerf length is a few mm from the start hole in 1st-cut wire EDM. The influence of machined kerf length on the flow field, the debris exclusion, and the wire behavier caused with hydrodyanamic force by the jet flushing should be made clear.In this study, variations of flow field in the kerf, the debris accumulation state and the wire deflection caused jet flushing with machined length were analytically investigated by CFD (computational fluid dynamics) and structural analysis when 1st-cut wire EDM was done from a small start hole. Moreover, the effects of machined kerf length on the wire deflection and wire breakage were discussed. Wire breakage frequency experiments showed that wire tended to frequently break at a certain machined kerf length, where the wire deflection rapidly increased and the debris particle residence time in the gap became long.

Experimental study on surface topography and fracture strength of worn saw wire in multi-wire sawing

In multi-wire sawing, reducing the wire wear loss and increasing wire consumption are the common means to avoid the risk of saw wire breakage because the worn saw wire experiences a complex process with strength degradation and surface damage. So, it is urgent and necessary to give a reliable wire wear loss in theory. This paper focused on the surface topography and fracture strength of worn wire with different wire wear loss. Furthermore, the saw wire maximum safety wear loss model was presented based on the experimental results. By observing the surface topography of the worn saw wire, the dented traces were distributed on the whole surface and a few grooves with large depth were shown in the local zone. The cross-sections of the worn saw wires with different wear loss were circular. In addition, its fracture strength of the wore saw wires was not reduced with the increasing of the saw wire wear loss. On the contrary, the fracture strength of the wire with large wear loss was improved by hardening in comparison with fresh saw wire. This phenomenon suggested that surface damages did not affect the fracture strength of saw wire under the experimental condition. Furthermore, fracture photograph of the fracture test samples was divided into the crack propagation zone and final fracture zone. By analyzing these fracture topography, almost all the crack propagation zones were circular and its diameter was about 48.27 μm. It is not correlated with the amount of wear loss. However, the shape became non-circular in some samples with large depth damage on the surface. By summarizing these results, the model and calculation method of the maximum safety wear loss of saw wire were established, which could provide the theoretical basis for the determining the maximum safety wear loss.

Dynamic breaking of a single gold bond

While one might assume that the force to break a chemical bond gives a measure of the bond strength, this intuition is misleading. If the force is loaded slowly, thermal fluctuations may break the bond before it is maximally stretched, and the breaking force will be less than the bond can sustain. Conversely, if the force is loaded rapidly it is more likely that the maximum breaking force is measured. Paradoxically, no clear differences in breaking force were observed in experiments on gold nanowires, despite being conducted under very different conditions. Here we explore the breaking behaviour of a single Au–Au bond and show that the breaking force is dependent on the loading rate. We probe the temperature and structural dependencies of breaking and suggest that the paradox can be explained by fast breaking of atomic wires and slow breaking of point contacts giving very similar breaking forces.

Effectiveness of cerclage and a figure-of-eight tension band by a single titanium wire in treatment of patellar fracture

To estimate the outcome of cerclage followed by a figure-of-eight tension band with a single titanium wire for the treatment of patellar fracture. A retrospective analysis was made on the clinical data of 46 patients with patellar fractures treated between June 2012 and November 2014. There were 30 males and 16 females, aged 20-86 years (mean, 54 years). The fracture causes included falling in 27 cases, traffic accident in 16 cases, and knock in 3 cases. There were 41 cases of closed fractures and 5 cases of open fracture. The injury located at the left side in 24 cases and the right side in 22 cases. According to AO classification, fracture was rated as type 34-A in 3 cases, as type 34-B in 1 case, as type 34-C1 in 7 cases, as type 34-C2 in 13 cases, and as type 34-C3 in 22 cases. The time between injury and operation ranged 1-12 days (mean, 3.7 days). During operations, a single titanium wire was used to pass around the patellar, followed a figure-of-eight wrapping, to tight and fix at the tension of 35 kg. All incisions healed primarily. The patients were followed up 20.6 months on average (range, 6-24 months). Partial wire loosening was found in 2 cases, irritation of skin or soft tissue in 1 case. The X-ray examination showed bony healing at 3 months after operation, without breakage of titanium wire. The internal fixation was removed in 38 cases at 12 months after operation. According to the Böstman rating score, the mean score was 28.34 (range, 24-30) at 12 months after ope-ration; the results were excellent in 42 cases and good in 4 cases, with an excellent and good rate of 100%. For patellar fracture, cerclage followed by a figure-of-eight tension band with a single titanium wire is able to achieve an effective stability and to allow early motion for patient with less complication.