Wire Failure Research Articles

Behavior of Fully Encapsulated Cable Bolt in Various Double-Shear Methods and the Sequence of Wire Failure in the Newly Developed Shear Apparatus

The use of long-tendon ground support elements (cable bolts) is now a common practice in modern underground coal mines, hard rock mines, tunnels, and other underground structures. The paper briefly introduces the development of test methods for rock and cable bolts, including single- and double-shear methods, in the last 30 years and focuses on the novel development of the fourth generation of cylindrically shaped shear test apparatus (MK-IV Double Shear Box) for assessing tendon performance in shear based on the experience gained from the development of previous versions of shear experiment apparatus. The results were compared with similar test findings using a rectangular-shaped double-shear apparatus with and without friction across joint faces. The sequence of wire failure was studied by using the newly developed double-shear test apparatus, and the performance of abnormal phenomena in the double-shear tests was analyzed. The sequence of wire failure can be inferred based on the positive and negative values of strain gauge readings, and the wire of cable bolt under shearing may be broken in the joint area. The failure possibly occurred from one side to the other instead of from top to bottom. The modified double-shear test apparatus with a long section of concrete cylinder was proposed to conduct further research on cable bolt debonding.

Multi-Chip IGBT Module Failure Monitoring Based on Module Transconductance with Temperature Calibration

The Insulated Gate Bipolar Transistor (IGBT) is the component with the highest failure rate in power converters, and its reliability is a critical issue in power electronics. IGBT module failure is largely caused by solder layer fatigue or bond wires fall-off. This paper proposes a multi-chip IGBT module failure monitoring method based on the module transconductance, which can accurately monitor IGBT module chip failures and bond wire failures. The paper first introduces the failure mechanism and module structure of the multi-chip IGBT module; then, it proposes a reliability model based on the module transconductance and analyzes the relationship between chip failure, bond wire failure, and the transmission characteristic curve of the IGBT module. Finally, the module transconductance under chip failure and bond wire failure is measured and calculated through simulation, and the temperature is calibrated, which can eliminate the influence of temperature on health monitoring. The results show that the method has a high sensitivity to chip failures and bond wire failures, can realize the failure monitoring of multi-chip IGBT modules, and is of great significance for improving the reliability of power converters.

Explosive electrical wire failures behave differently depending on the voltage applied

High-speed imaging of electrical wire failure reveals regions of fluid instability, bubble growth and rapid change from fluid breakup to phase explosion.

Experimental Study on Corrosion-Fretting Fatigue Behavior of Bridge Cable Wires

Abstract Bridge cables are often subjected to tensile stress variation, interior contact stress, and corrosion environment, resulting in premature failure of wires. This paper experimentally invest...

High-speed imaging of transition from fluid breakup to phase explosion in electric explosion of tungsten wires in air

High-speed visible imaging of sub-microsecond electric explosion of wires at the low specific energy deposition threshold reveals three distinct modes of wire failure as capacitor charge voltage and energy deposition are increased. For 100 μm diameter gold-plated tungsten wires of 2 cm length, deposited energies of 1.9 eV/atom produce a liquid column that undergoes hydrodynamic breakup into droplets with radii of the order of wire diameter on timescales of 200 μs. Instability growth, column breakup, and droplet coalescence follow classical Rayleigh–Plateau predictions for instability of the viscous fluid column. Above a deposited energy of 3.2 eV/atom, wires are seen to abruptly transition to an expanding mixture of micrometer scale liquid-droplets and vapor within one frame (less than 3.33 μs), which has been termed “phase explosion” in the literature. Between these two limits, at a deposited energy of 2.5 eV/atom, the wire radius remains unchanged for the first 10 μs before the onset of a rapid expansion and disintegration that resembles homogenous nucleation of mechanically unstable bubbles. Thermodynamic calculations are presented, which separate cases by temperature obtained during heating: below the boiling point, near the boiling point, and exceeding the boiling point.

Metallurgical investigation of welding wire rod grade during processing

The research work provides an intensive analysis of premature failure of the wires during cold drawing operations. The steel wires are made of WR3M grade, which contains low carbon (0.06–0.08 wt%) with high ‘Mn’ (1.40–1.50 wt%) and ‘Si’ (0.80–1.00 wt%). It is a premium low carbon electrode grade, which can produce superior quality welds and trouble-free performance during different continuous welding process. This welding grade is manufactured from continuous cast billet of dimension 150 mm × 150 mm and then hot rolled through successive rolls to achieve desired dimension. Present work includes microstructural and different thermo-mechanical study to determine the origin of premature failures of wires. Investigation suggested that wire breakage took place due to the presence of light brown hard phase (martensite) which makes the material brittle and initiate chevron cracks during drawing operations. X-ray mapping doesn’t provide any segregation along or near the light brown hard phase. From different plant trials and thermo-mechanical study, it reveals that the light brown hard phase formed due to incomplete transformation of wire rods during retarded cooling process at hot rolling stage.

Wire-Bonding Reliability Evaluationa

Abstract In microelectronic devices, wire bonding is the most common first-level interconnection method between die and lead. Failure of wire bonding causes component failure. Component failure may lead to system or sub-system failures, which often have very expensive consequences. Such failures are even more severe in the harsh operating conditions of the Oil and Gas industry, where services such as rig charge are extremely expensive. We have developed a robustness-evaluation method for microelectronic components using construction analysis.

The Impact of Connection Failure of Bonding Wire on Signal Transmission in Radio Frequency Circuits

Bonding wires are widely used in microwave circuits and chip packaging. The exposure to harsh environments may lead to connection failure in these wires. In this article, the impact of such failures on signal transmission was studied using model analysis and experimental testing. The effects of gold bonding wire failure on both the dc and high frequency characteristics were analyzed. Signal reflection and loss caused by failed gold bonding wire at different positions and a number of failed gold bonding wire were also investigated. Based on computational electromagnetics and transmission line theory, a 3-D electromagnetic field numerical calculation model and a distributed parameter circuit model were developed. The electromagnetic field model results are in good agreements with those obtained from the distributed parameter circuit model. The results obtained by the model simulation are validated using experimental tests. The results of this investigation provide a better understanding of the influence of the position and the number of failed bonding wires on the signal integrity of the circuit and theoretical support for identifying failure features in fault diagnosis.

Enhanced saltwater stability of CNT wires under electrical bias

Wires formed of densified as-received and purified commercially available Carbon Nanotube (CNT) sheet material as well as a laid CNT wire were tested for long-term stability in a saltwater environment under an applied electrical bias. Tafel electrochemical measurements showed increased chemical stability for the CNT samples over copper, with the corrosion resistance of CNT samples showing further improvement after purification. Under constant DC voltage biases of 2.50 V, CNT materials show improvements in failure time by as much as 108 times over comparable diameter copper wires, with further improvement over copper at lower applied voltages due to material stability and an absence of gas evolution. Shear forces resulting from gas formation was found to significantly contribute to the failure of CNT wires at elevated voltages compared to chemical corrosion typical in copper wires.

Manual of Wiring Techniques for Orthopedic Surgery

Cerclage and tension band wiring techniques can be inexpensively and effectively utilized in orthopedic surgical procedures, many of which are enumerated in this article. The following cerclage wiring configurations are described and demonstrated in accompanying videos: wrapped around once and wrapped around twice patterns locked with a symmetric twist, knot twist, eyelet bend-back, or crimped double barrel sleeve; doubled symmetric twist; hairpin loop; and Mittelmeier’s double loop bend-back with twist. Tension band wiring variations are also described and illustrated. Modes of wire failure are discussed and displayed in videos. Results of previously unreported experiments measuring compression capability of a variety of wire tightening devices and cerclage configurations support the superiority of the wrapped around twice pattern over wrapped around once, symmetric twist over eyelet bend-back and knot twist, and the importance of using a finishing twist when tensioning and locking wire with a symmetric twist or doubled symmetric twist.

Electrical Performance Retention of Chemically Doped Carbon Nanotube Wires

Carbon nanotube (CNT) wires are light-weight and robust alternatives to conventional metal conductors. The weight savings, increased flexure tolerance, and corrosion resistance of CNT conductors make them a viable solution for a variety of space, defense, and power transmission applications. An individual CNT has orders of magnitude greater electrical conductivity than conventional metal conductors, but this has not been realized in bulk CNT networks. Recently, the use of chemical dopants has resulted in bulk CNT wire conductivities approaching 10 MS/m. As the electrical conductivity of CNT wires continues to approach that of conventional metals, deployment of these CNT conductors will require an understanding of how these CNT conductors and chemical dopants behave during practical operation.In the present work, commercially scaled CNT wires are physically densified through radial drawing dies and chemically doped with KAuBr4 resulting in an improvement in electrical conductivity to greater than 1 MS/m, a 6x improvement compared to the as-received CNT wire. The current density at failure of CNT wires increases with KAuBr4 doping and densification by 67% to 35 MA/m2. The electrical performance retention is determined by applying increasing current densities with intermittent rest steps and low current I-V sweeps. The low current I-V sweeps allow for changes in electrical conductivity due to permanent material degradation caused by previous high current density exposure to be determined. The instantaneous electrical conductivity averaged over the last 5 seconds of each current “on” step is used to determine the temperature dependent effects on electrical conductivity caused by Joule heat during high current application. The KAuBr4 doped and densified samples experience no permanent change in initial electrical conductivity at current densities up to ~32 MA/m2, 4x greater than the as-received CNT wires.The enhanced electrical conductivity retention of KAuBr4 doped and densified CNT wires at high current density was further probed though an analysis of the thermal stability of these doped CNT conductors. Thermogravimetric analysis indicated that minimal degradation of the KAuBr4 dopant occurs prior to thermal oxidation of the CNT materials at 400 °C. A variety of KAuBr4 doping and 400 °C thermal oxidation procedures were performed on CNT wires to understand how thermal degradation of the dopant relates to changes in the electrical conductivity and high current density stability. Energy dispersive X-ray (EDX) spectroscopy further related the changes in electrical conductivity to the elemental spatial analysis of gold and bromine in the KAuBr4-doped CNT samples before and after 400 °C thermal oxidation. This work concludes that the thermal stability of KAuBr4 results in improved electrical conductivity and stability at high current densities. Trace bromine and gold nanoparticles are maintained at temperatures below the onset of CNT degradation, thus providing residual doping until ultimate CNT wire failure.Recently chemical dopants such as I2 and IBr have also emerged as premiere dopants to improve the electrical conductivity of bulk CNT networks. These dopants will be used to further explore the effect doping procedures and the presence of excess dopant have on the electrical conductivity and high current stability of doped CNT wires. Developing a relationship between dopant thermal stability and electrical conductivity retention will allow for the development of a mechanism explaining dopant degradation at high current densities.

Corrosion fatigue failure analysis and service life prediction of high strength steel wire

In this paper, corrosion fatigue failure of high-strength steel wire was studied based on the actual cable or sling in the bridge, and the service life prediction formula considering the corrosion effect was put forward, which provides a force basis for future research. Firstly, six groups of steel wires with different corrosion degrees were analyzed by a 3D scanner, and the corrosion characteristics of different specimens were given. Secondly, S-N curves of different corrosion degrees and S-N-φ surface were given by fatigue tests of six groups of steel wires with different corrosion degrees. The results show that the S-N curve becomes steeper with the increase of steel wire corrosion. Fatigue life considering the corrosion is much lower than that without considering corrosion. Finally, a fatigue life prediction model considering the corrosion fatigue coupling effect was proposed. The calculation results show that the fatigue life prediction model considering the corrosion fatigue coupling effect can reflect the effect of the corrosion fatigue coupling effect to some extent.

Failure analysis of the low-pressure blade lacing wire in steam turbine

The failure analysis of the low-pressure last stage blade lacing wire in steam turbine made of 0Cr17Ni4Cu4Nb(S17400) is presented. The failure of the low-pressure last stage blade occurred at 7 operating years. Several examinations were carried out to identify the blade lacing wire failure’s root cause: macroscopic inspection, chemical composition analysis, hardness test, metallographic analysis, microscopic examination and inspection of maintenance records. It is found that there is local displacement of the roots of the low-pressure rotor, and the collision between the lacing and the lacing holes is the direct cause and external mechanical incentive of the lacing fracture.the high content of P element and the high hardness reduce the plasticity and toughness of the material which is the intrinsic factor of this tensile fracture, without obvious plastic deformation, the low-pressure last stage blade lacing wire breaks rapidly. It is suggested to find out the local displacement of blade root and fix it in a reliable way, check the strength after eliminating the harmful defects such as cracks, and replace the blade if necessary, strictly according to DL/T438-2016 and the manufacturer’s standard requirements for the inspection of the lacing wire before use.

Lifetime prediction for carbon fiber composite core wire based on accelerated degradation test

To reduce the huge loss caused by the failure of long-term transmission wire, proper method for the life time prediction is imminent. In this paper, to accomplish long-term service time prediction of carbon fiber composite core (CFCC) wire, an accelerated degradation test is conducted, where 15 samples are allocated to three temperature levels and the degradation data sets under different condition are obtained. Based on the test results, an accelerated degradation model is constructed where Arrhenius function is incorporated to characterize the relationship of degradation rate and temperature. Finally, the median service life and 95% reliable service life of CFCC wire for several conditions is predicted based on the test results and the accelerated degradation model.

Failure of copper wires in a railway Motor Operation Contact

Many engineering alloys can fail by environmentally assisted cracking (EAC). The risk of failure is dependent on the specific combination of material, the environment and the stress. Identification of the stresses (applied and residual) can be difficult because of the retrospective nature of failure investigation and the commonly complex character of stresses in real engineering applications. A routine inspection of a Motor operation contact installed aside a railway line in the British countryside found that the copper wire contact had failed. Standard failure investigation techniques combined with fractography were applied to identify an intergranular failure mode. Experimental observations combined with a review of the relevant literature allowed the root cause to be assigned to environmental assisted cracking in the presence of gaseous ammonia in the local environment.

A Health Monitoring Method for Bond Wires in IGBT Modules Based on Voltage Ringing Characteristics

Bond wire failure is a common failure that seriously affects the reliability of insulated-gate bipolar transistor (IGBT) modules. Real-time health monitoring for bond wires is very important to avoid catastrophic failures. In this article, we introduce a new health monitoring method for bond wires in IGBT modules based on the voltage ringing characteristics. We applied a double pulse circuit to generate voltage ringing in IGBTs and freewheeling diodes (FWDs) during turn off and reverse recovery phases. To monitor bond wire failure, we theoretically and experimentally validated the overshoot and oscillation frequency as indicators. In particular, we investigated the effects of the junction temperature and operating conditions on the overshoot and proposed their influence functions. We designed a measurement circuit to identify small changes in the overshoot. Finally, the health baselines for the overshoot under different conditions were experimentally verified. The novelty of the research lies in the accurate online monitoring for bond wire failure in IGBT modules without any external injection; the measurement circuit adopts the interrupt mode to save the controller resources. Our experimental results showed that after half the bond wire of the IGBT and the FWD failed, their voltage overshoot increased by nearly 5%.

Nondestructive wire fault diagnosis using resistance spectroscopy analysis

Wires in field applications, such as aircraft, are often exposed to stress conditions, including overheating, moisture ingress, or inherent defects, which may result in electrical discontinuity, wire insulation breakdown, and system failure. This study proposed a nondestructive and real-time wire fault diagnosis method through resistance spectroscopy to diagnose the health of wires under stress conditions. Wire abrasion tests were conducted by applying cyclic mechanical stress to produce gradual damage to a wire under test. During abrasion testing, a lock-in amplifier generated high-frequency signals and monitored the signals transmitted through the wire to diagnose the wire failure under test. Differences in signal amplitude, and phase shift spectra during wire degradation exhibited specific and distinguishable behavior based on the physical damage progression of the tested wire. Test results implied that resistance spectroscopy analysis could serve as a nondestructive wire fault diagnosis method, providing damage progression in real time.

Description and outcome of prosthetic ligament placement for stabilization of medial or dorsomedial tarsometatarsal joint luxation in dogs and cats: 16 cases (2004-2017).

To describe prosthetic ligament placement for reduction and stabilization of medial or dorsomedial tarsometatarsal joint luxation in dogs and cats and to report complications and postoperative outcomes for patients that underwent that procedure. 14 dogs and 2 cats with medial or dorsomedial tarsometatarsal joint luxation. The electronic database of a referral surgery practice was searched to identify records of dogs and cats with tarsometatarsal joint luxation that underwent prosthetic ligament placement between January 2004 and March 2017. For each study subject, information extracted from the medical record included signalment, a description of the tarsometatarsal joint injury, durations of anesthesia and surgery, and intraoperative and postoperative care and complications. Radiographic images were also reviewed. The long-term outcome for study subjects was assessed by administration of a standardized questionnaire to owners. Prosthetic ligament placement successfully stabilized the luxated tarsometatarsal joint in all 16 patients. Six patients developed minor postoperative complications, which included bandage-associated dermatitis or ulceration (n = 5) and orthopedic wire failure (1). No major or catastrophic complications were reported. All 13 owners who completed the questionnaire perceived that the described technique resulted in satisfactory long-term function for their pets. Results suggested that prosthetic ligament placement was a technically simple procedure that achieved satisfactory long-term stabilization of the tarsometatarsal joint in small animal patients with medial or dorsomedial luxation of the joint. Prosthetic ligament placement may be an alternative to arthrodesis for tarsometatarsal joint stabilization in appropriate patients.

Life prediction of copper wire bonds in commercial devices using principal component analysis (PCA)

Copper has been widely adopted as a viable alternative to gold for wire bonding, due to its lower cost, better electrical and thermal conductivity, lower tendency for wire sweep due to a higher modulus and slower intermetallic compound (IMC) formation with aluminum bond-pad. However, these IMCs can cause an increase in resistance and separation between bonding interface which causes an open circuit. Wire bond and component reliability must consider all factors in combination with the change of wire bond materials and processes. How can users of off-the-shelf components determine the effects of wire bond material changes on the reliability of the components in their systems? How will these changes affect high reliability applications such as automotive, military and harsh environments?Although physics-of-failure based models can represent the failure mechanisms individually, the complex nature of the mixed failure mechanism has inhibited development of an analytical equation to represent it. In addition, geometrical and material characteristics of the entire package along with bonding process parameters play a crucial role in magnitude of stress experienced by these bonds, portraying difficulty in developing one such equation for use to all copper wire bonded devices. This study has aimed to develop a data-based predictive method based on the principal component analysis technique to provide an estimate of the wire bond time to failure for plastic encapsulate components. Extensive thermal cycling experiments have been performed on multiple commercial devices to obtain training data for the model. This method of wire bond fatigue and failure prediction is an adaptive technique which can achieve greater accuracy as more data is added. This method aims to provide a life-time estimate of copper wire bonded component with inputs such as initial geometrical, material properties, and wire bond related attributes for a specific package.

Modified PDMS packaging of sensory e-textile circuit microsystems for improved robustness with washing

Electronic Textiles (e-textiles) should ideally be handled and cleaned like traditional textiles. Therefore, we can expect e-textiles to be machine washed or hand washed. As e-textiles enhance traditional fabrics with electronic functionality, any embedded microsystem i.e., flexible electronic circuits, will be expected to survive and show functionality after the e-textile has been washed multiple times to ensure the garment is practical. Therefore, the choice of encapsulation material for microsystems in a textile must be hydrophobic and offer minimal expansion when washed and ensure the electronics are undetectable when the textile is handled or cleaned. This paper evaluates five different base/curing agent mixing ratios—5:1, 7:1, 10:1, 15:1, and 20:1—of commercial polydimethylsiloxane (PDMS) as an electronic packaging encapsulation. Contact angle and aqueous permeability experiments were conducted to tailor the PDMS mixture specifically for washable e-textile applications. The experimental results show that 20:1 PDMS is the most suitable as it is sufficiently hydrophobic with minimal swelling in commercial washing machine trials. Following this, a 40.3 µm-thick 20:1 conformal encapsulation of PDMS upon an touch and proximity flexible circuit that can be integrated into textiles via knitting and/or weaving, was examined. Results show the washing spin speed is a crucial factor with washing cycle duration having minimal impact when determining circuit functionality survival. Overall, the e-textiles in this work survived between 10 and 15 washes with microscopic inspection of the circuits revealing failure of the external wires but not the PDMS encapsulation—suggesting its sufficient robustness and durability as a suitable encapsulation material for washable electronic textiles.