Electrical Damage Research Articles

Evaluation of potential electric vehicles load-induced damage on flexible pavements

The adoption of Electric Vehicles (EVs), driven by policies like the Zero Emission Vehicle (ZEV) mandate, is rapidly transforming transportation infrastructure. In 2021, over 1.25-million light-duty EVs were registered in the United States, signaling a shift that extends to heavy vehicle categories. This study evaluates the implications of this transition on road networks, focusing on the increased gross weight of EVs compared to traditional Internal Combustion Engine (ICE) vehicles and its impact on flexible pavement structures. The study investigates the deterioration patterns and potential damage to road infrastructures resulting from integrating EVs into the traffic mix, utilizing both the AASHTO 1993 and Mechanistic-Empirical (ME) pavement evaluation methodologies. The analyses reveal a significant acceleration in road degradation, necessitating urgent consideration of EV-induced stresses by transportation authorities. Recommendations for future research and practical strategies for mitigating these impacts are provided to guide policymakers and engineers in adapting to this evolving vehicular landscape.

Effect of electrical current on sliding friction and wear mechanisms in a-C and ta-C amorphous Carbon coatings

This study investigated the sliding wear behaviour of amorphous carbon (a-C) and tetrahedral amorphous carbon (ta-C) coatings, two forms of diamond-like carbon (DLC) coatings, against SAE 52100 steel using a modified ball-on-disk tribometer with applied electrical currents ranging from 100 mA to 1800 mA. It focused on the variations in sliding friction and wear characteristics of these coatings as electrical currents increased under constant load and speed conditions. The a-C coatings exhibited lower coefficient of friction (COF) values and reduced volumetric wear losses up to 1500 mA, while ta-C coatings studied displayed higher wear, similar to uncoated M2 steel, at 300 mA with degradation occurring at low currents, resulting in failure due to severe oxidational wear. The a-C coatings showed no significant electrical damage at these currents. Raman spectroscopy revealed structural changes on the wear tracks of sp2-rich a-C coatings, specifically the formation of graphene layers. In comparison, the wear tracks of sp3-rich ta-C coatings did not display such transformation under the conditions studied. The graphene coverage on the surfaces of the a-C coatings increased with the increase in the current as revealed by the Raman intensity maps of 2D peaks and this increase was accompanied by a higher defect density in the graphene. The low COF of graphene-covered a-C surfaces was consistent with the proposed mechanisms of moisture adsorption. However, at currents exceeding 900 mA, surface temperatures of a-C coatings exceeded 100 °C, impairing graphene's ability to maintain low friction, resulting in an increased COF.

Electrical damage mechanism analysis of traction motor bearings on high-speed trains considering overvoltage impulse

ABSTRACT As the critical rotating knuckle, traction motor bearings play a vital role in transmitting torque from motors to wheels for high-speed trains, while some electrochemical corrosion signs appear in traction motor bearings. To maintain the safety of the traction system, it is essential to explore the electrical damage mechanism of traction motor bearings considering the impact brought from current or overvoltage impulses. Herein, via analysing the electrochemical corrosion evolutionary process of bearings, main influencing factors are determined that both transient overvoltage impulse and long-term grounding current bring dramatic impact on bearings. To assess overvoltage distribution on different carriages, a ‘catenary-train-substation’ traction power supply model is launched based on practically collected impedances. A ‘carriage-bogie-motor’ circuit model is built to evaluate the overvoltage propagation path, meanwhile, the 3D finite element geometry of the bogie with bearings is launched to observe the overvoltage distribution in the bearings for evaluating breakdown risk.

Current-carrying friction behavior of CrN coatings under the influence of DC electric current discharge

CrN coatings are renowned for their low friction coefficients, high chemical inertness, excellent corrosion resistance, and substantial hardness, making them ideal for the tribological demands of bearings and gears in electric vehicles. This study investigated the current-carrying friction behavior of CrN coatings when sliding against steel balls under both non-electrified and electrified conditions. The friction coefficient (CoF), wear volume, wear type, and mechanism of the coating were reported by adjusting the direct current (DC) intensity and lubrication status. The findings indicate that while the current significantly exacerbates substrate wear during dry friction, its impact on the CrN coating is minimal. Even at a maximum DC current of 1.5 A, the wear rate of CrN coating during dry friction is only 1.9 × 10−4 mm3·(N·m)−1, representing a reduction by 79.1 % compared to the steel substrate. This effect is further pronounced when lubricated with PAO oil. The wear of CrN coating shows minimal change even as the current increased, and surface wear remains very slight. At a current of 1.5 A, the wear rate of CrN coating decreases to as low as 9.7 × 10−6 mm3·(N·m)−1, indicating a reduction by 98.7 % compared to its substrate. It is observed that under electrified conditions, the oxidation and degradation of CrN coating are accelerated, thereby resulting in the formation of a loose and low-hardness Cr2O3 oxide layer on the surface. The oxide layer is primarily attributable to the deterioration in frictional properties of the CrN coating under electrified conditions. Finally, CrN coatings exhibit minimal changes in tribological behavior under electrified conditions, thereby offering effective protection for substrates against electrical damage. Therefore, CrN coatings are ideal for applications involving electrical contacts.

Novel recyclable epoxy resin with releasable residual stress and synergistically enhanced dielectric properties and healing ability

It has been a challenge to improve the performance of epoxy insulation in the whole life cycle by achieving the reduction of residual stress during manufacturing, the healing of damages during application, and the recycling after decommissioning. In this paper, a novel recyclable epoxy resin (SEP) with releasable residual stress and synergistically enhanced dielectric properties and healing ability was successfully developed by introducing dynamic thiocarbamate bonds (DTBs). A reduction in residual stresses by 45 % was detected after SEP was annealed at 30 °C below the glassy transition temperature (Tg) for 8 h, during which the mechanical properties remained unchanged. Synergistically improved dielectric properties and damage-healing ability were also observed in SEP. A high healing efficiency of 94.4 % for electrical breakdown damage was found in SEP, meanwhile its dielectric properties were superior to commercial epoxy resin. Additionally, SEP featured good recyclability, including reprocessability and degradability. All those excellent properties were ascribed to the dissociation and recombination of DTBs triggered by thermal stimulation. This work provides an effective solution to a series of issues throughout the full lifecycle of epoxy materials.

3D Soft Architectures for Stretchable Thermoelectric Wearables with Electrical Self-Healing and Damage Tolerance.

Flexible thermoelectric devices (TEDs) exhibit adaptability to curved surfaces, holding significant potential for small-scale power generation and thermal management. However, they often compromise stretchability, energy conversion, or robustness, thus limiting their applications. Here, the implementation of 3D soft architectures, multifunctional composites, self-healing liquid metal conductors, and rigid semiconductors is introduced to overcome these challenges. These TEDs are extremely stretchable, functioning at strain levels as high as 230%. Their unique design, verified through multiphysics simulations, results in a considerably high power density of 115.4µWcm⁻2 at a low-temperature gradient of 10°C. This is achieved through 3D printing multifunctional elastomers and examining the effects of three distinct thermal insulation infill ratios (0%, 12%, and 100%) on thermoelectric energy conversion and structural integrity. The engineered structure is lighter and effectively maintains the temperature gradient across the thermoelectric semiconductors, thereby resulting in higher output voltage and improved heating and cooling performance. Furthermore, these thermoelectric generators show remarkable damage tolerance, remaining fully functional even after multiple punctures and 2000 stretching cycles at 50% strain. When integrated with a 3D-printed heatsink, they can power wearable sensors, charge batteries, and illuminate LEDs by scavenging body heat at room temperature, demonstrating their application as self-sustainable electronics.

Effect of shaft voltage on electric damage of GCr15 bearing material

Electrical erosion pit is a fundamental manifestation of electrical bearing damage. As the shaft voltage increased, the degree of electrical damage became more severe, and the residual compressive stress and hardness of bearing surface decreased. The transition of martensite into ferrite induced by high discharge temperature was found at the edge of the erosion pit using a transmission electron microscopy. This phenomenon has not been observed below the mechanically rolled surface under the same conditions. Electrical penetration harmed the bearing through surface erosion, lubrication deterioration and martensite decomposition. The electrical pit could be observed when current density exceeded 0.95 A/mm2. The results can help understand bearing failure in the fields of railways, wind turbines, and new-energy vehicles.

Elastic-plastic conductor damage evaluation at over 0.4% strain using a high-stress REBCO coil

Recent reports on screening current stress simulations of high-field REBCO magnets frequently present peak stresses over 1 GPa. However, this result is probably an unrealistic artifact of purely elastic calculations, considering the macroscopic yield and fracture stresses of approximately 900 MPa and less than 1.1 GPa for Hastelloy substrate-coated conductors. Here, we evaluate elastic-plastic conductor damage at over 0.4% strain using a high-stress REBCO coil exposed to a high field to explore this elastic-plastic regime. The coil was located off-center in a low-temperature superconductor magnet so as to induce a significant screening current in the enhanced radial field. Voltage taps, a Hall sensor, and two strain gauges were used for the instrumentation. We obtained strains exceeding 0.4% near the outward edge during the coil current charge from 350 A to 390 A, where the coil was exposed to external axial and radial magnetic fields of 13 T and 0.5 T. Post mortem results showed wavy plastic deformation, electrical damage, and REBCO defects. An elastic-plastic simulation reproduced the measured strains and predicted that ∼1 GPa stress is sufficient to induce ∼0.9% strain, thus validating our initial concerns with purely elastic models. This paper provides our experimental and simulation results.

Effect of the contact load and rotation speed on the formation of rolling current-carrying arc and the corresponding material damage

The current-carrying arc is a critical factor that affects the electrical contact performance and material damage of contact pairs. In this study, a copper disk–copper disk pair was used to simulate the rolling electrical joint in a conductive rotating joint. Under operating conditions with a current of 2 A, rotation speeds from 4 to 600 r/min, and loads from 40 to 180 N, the dynamic behavior of the current-carrying arc and the surface damage mechanism were investigated. The movement characteristics of the arc at the friction interface were observed, and the arc generation difficulty and intensity were statistically analyzed based on the arc burning rate and arc energy. With increasing load and rotation speed, the generation of current-carrying tribological arcs became easier, and both the arc burning rate and arc energy increased. After the arc was generated, the arc root position was randomly distributed at the contact interface, exhibiting dynamic phenomena such as splitting and merging. Following the generation of the arc, the dominant damage mechanism at the current-carrying friction interface transitioned from mechanical damage to electrical damage. The manifestations of electrical damage included burning, oxidation, and roughening, with the degree of electrical damage positively correlated with the arc burning rate and arc energy. Surface oxidation could reduce the adhesion between metal contact pairs, contributing to a decrease in the current-carrying friction coefficient. Simultaneously, the film resistance caused by oxidation and the contraction resistance caused by roughening could lead to an increase in the average contact resistance.

Experimental and numerical simulation research on shock wave rock-breaking by high voltage electric pulse

High-voltage electric pulse(HVEP) drilling technology has the advantages of high rock-breaking efficiency, green and non-polluting. Aiming at the importance of HVEP drilling technology in generating plasma channels, plasma shock waves, and rock-breaking pits, this paper carries out multi-physics field numerical simulations and indoor electric pulse breakdown experiments. This paper first constructs a two-dimensional numerical model of rock electric breakdown. The simulation of HVEP rock breaking, plasma channel and plasma shock wave is realized from the five-field coupling and combined with the wave control equations. The effects of different electrode shapes on the plasma channel, breakdown channel and shock wave are analyzed. Then, this paper designed an indoor HVEP rock-breaking experiment to investigate the influence of different electrode shapes on rock breakdown and plasma shock waves. The simulation and experimental results show that the indoor electric pulse breakdown experiment results are consistent with the simulation results; The plasma channels are formed by the ‘electrical damage’ through each other, and the secondary plasma channel is often generated inside the rock. The generation of the secondary plasma channel means that the rock fragmentation depth and the fragmentation area will be increased; The larger the contact area of the electrode bit with the rock, the larger the radius (volume) of the plasma channel and the smaller the amplitude of the plasma shock wave; The quadrangular electrode bits have the best rock-breaking effect and are recommended; The conical electrode bit has the most excellent dispersion in the statistical analysis of the electric pulse rock-breaking effect, and the stability of the rock-breaking effect is poor, so it is recommended to use it together with the composite drill bit; The cylindrical electrode bit has the best aggregation degree of electric pulse rock-breaking and the most stable rock-breaking effect.

A smart insulation material achieving self-reporting and autonomous repairing against electrical and mechanical damages based on targeted controllable microcapsules

Under the long-term action of electrical and mechanical stresses, irreversible micro-damages, such as electrical trees and cracks tend to occur inside solid insulation materials, leading to insulation failures, which have no effective countermeasures. This study develops a multi-responsive, target-controlled microcapsule to endow the epoxy resin with dual functions of self-reporting and autonomous repair against internal damage even under strong electric fields without human intervention. A turn-on mechanism for self-reporting signals is designed, to be applicable to electrical tree damage inside an epoxy matrix. In situ UV emissions generated by the partial discharge during electrical treeing are employed to automatically cure the microcapsule core material released into the damaged channel. This triggers aggregation-induced emission (AIE) signals and simultaneously repairs the damaged matrix. The polyurethane hybrid shell filled with magnetic particles endows the microcapsules with magnetic response characteristics. Under the control of a directional magnetic field, the microcapsule is concentrated around the vulnerable areas, obtaining high fluorescence emission intensity under low doping content without affecting the matrix performance. This method enables the autonomous inspection and maintenance of electric equipment and electronic devices under live working and provides new insight into the bionic intelligence of electrical and electronic insulation materials.

NeurostimML: a machine learning model for predicting neurostimulation-induced tissue damage

Objective. The safe delivery of electrical current to neural tissue depends on many factors, yet previous methods for predicting tissue damage rely on only a few stimulation parameters. Here, we report the development of a machine learning approach that could lead to a more reliable method for predicting electrical stimulation-induced tissue damage by incorporating additional stimulation parameters. Approach. A literature search was conducted to build an initial database of tissue response information after electrical stimulation, categorized as either damaging or non-damaging. Subsequently, we used ordinal encoding and random forest for feature selection, and investigated four machine learning models for classification: Logistic Regression, K-nearest Neighbor, Random Forest, and Multilayer Perceptron. Finally, we compared the results of these models against the accuracy of the Shannon equation. Main Results. We compiled a database with 387 unique stimulation parameter combinations collected from 58 independent studies conducted over a period of 47 years, with 195 (51%) categorized as non-damaging and 190 (49%) categorized as damaging. The features selected for building our model with a Random Forest algorithm were: waveform shape, geometric surface area, pulse width, frequency, pulse amplitude, charge per phase, charge density, current density, duty cycle, daily stimulation duration, daily number of pulses delivered, and daily accumulated charge. The Shannon equation yielded an accuracy of 63.9% using a k value of 1.79. In contrast, the Random Forest algorithm was able to robustly predict whether a set of stimulation parameters was classified as damaging or non-damaging with an accuracy of 88.3%. Significance. This novel Random Forest model can facilitate more informed decision making in the selection of neuromodulation parameters for both research studies and clinical practice. This study represents the first approach to use machine learning in the prediction of stimulation-induced neural tissue damage, and lays the groundwork for neurostimulation driven by machine learning models.

Advancing infrastructure resilience: A polymeric composite reinforcement grid with self-sensing and self-heating capabilities

In this study, a novel multifunctional grid-shaped polymeric composite (MGPC) with reinforcing, autonomous strain, stress, and damage sensing and localizing in addition to targeted heating capabilities, has been developed. Distinct from preceding composites, this grid synthesizes these features collectively for the first time and concurrently addresses current challenges in multifunctional composites, such as environmental impact, data reliability, complexity, and production costs. The fabrication process entails 3D printing an electrical circuit with conductive filaments within a polylactic acid (PLA) host polymer. The conductive filament was composed of a thermoplastic polymer (TPU) infused with carbon nanotubes (CNT)-grafted carbon fibres (CFs) produced via chemical vapour deposition. The mechanical, microstructural, and electrical properties of the grid elements and cementitious slabs reinforced with MGPC were comprehensively examined. The MGPC's performance in traffic flow monitoring, mechanical behaviour prediction, and damage localization was assessed through wheel tracking, asymmetric punch tests, piezoresistivity response evaluation, and digital image correlation techniques. Furthermore, the self-warming ability of the MGPC in cementitious composites was investigated using different voltages. The extruded TPU containing CNT-grafted CFs exhibited an electrical percolation threshold of approximately 5.0 wt%, resulting in a conductivity of around 70 S/m for the filaments. Incorporating MGPC as reinforcement within cementitious composite slabs led to notable enhancements, with flexural strength increasing by approximately 15 % and failure strain by up to 350 %. Wheel tracking tests revealed changes in the electrical: 5.8 % for 520 N and 7.8 % for 700 N wheel loads, with roughly 5.0 % average error in velocity detection. Transverse elements precisely detected wheel locations demonstrating the MGPC capabilities in accurately detecting wheel speed weight, and location. The study established strong correlations between electrical resistance changes, mechanical behaviour, and damage detection, affirming the MGPC's reliability and efficacy for damage monitoring and localization. The cementitious slab reinforced with MGPC reached around 52°C through a 20 V direct current, with a heating rate of 0.25°C/s and a power density of 142 W/m², showing its potential for practical applications such as self-healing and de-icing. However, design parameters such as mesh and conductive circuit configuration, long-term performance, as well as Life Cycle Assessment need further investigation.

Mechanism of lightning damage to glass fiber composite wind turbine blades

Wind turbine blades (WTBs) are susceptible to lightning damage, resulting in significant costs for repair and replacement, which poses a considerable economic burden on wind farms. Therefore, this study investigates the mechanism of lightning damage of glass fiber composite (GFC)-WTBs to reduce the risk of such damage. The damage of GFC-WTBs caused by lightning strikes was analyzed using a numerical simulation method. The lightning pilot was simulated using high-voltage rod electrodes, and subsequently, the electric field strength and damage area on the blade surface under different conditions were measured. Additionally, a simulation model based on finite element analysis was developed to further predict and validate the experimental findings. The results reveal that the maximum electric field intensity was observed in the blade tip. Notably, the electric field intensity was found to be over 798,000 V/m when the rod electrode was positioned at a 0-degree angle with the blade tip. Further investigation revealed a non-linear and positive correlation between the damage area of GFC and lightning current amplitude, charge, and specific energy. In conclusion, the study provides a comprehensive examination of the relationship between lightning current and the damage to GFC-WTBs, as well as elucidates the mechanism of lightning damage to GFC-WTBs.

Fault diagnosis of accelerometer servo circuit output saturation based on feature electrical parameters extraction

The servo circuit of quartz flexible accelerometer is an extremely vital microelectronic device in inertial system. The paper introduces the traditional analysis process about output saturation fault of accelerometer servo circuit. For the shortcomings of traditional analysis methods, a fault diagnosis method based on feature electrical parameters extraction is proposed. According to the fault phenomenon, combined with the modular characteristics of hybrid integrated circuits, the feature electrical parameters of fault modes are extracted, and the fault modes' judgment basis is set. By the judgment results of the feature electrical parameters of the fault circuit, the circuit with output saturation fault caused by the electrical damage to the differential capacitance detector and other faults can be located quickly and accurately, and it is verified by the analysis of faulty circuit samples. Targeted for these faults, the improvement measures are put forward. This analysis method improves the fault diagnosis efficiency and reliability about the accelerometer servo circuit, and has guiding significance for enhancing the success rate of the failure analysis in the hybrid integrated circuits.

Behavior of Lubricated Bearings in Electric Circuits

In recent years, electrical damage phenomena in rolling and plain bearings have become increasingly important due to the growing electrification of individual mobility and renewable energy technologies [...]

Determining mammalian cells state by fractal micromotion

We applied four fractal dimension estimation algorithms on the temporal electrical impedance signal of normal MDCK type II cell cultures monitored by ECIS technique and showed that the fractal dimension due to micromotion allows discriminating processes not sensed by the spectral impedance of the culture. In this work we subjected cell cultures to electric current damage and drug exposure to analyze the changes in the fractal structure of the temporal signal. Among the changes presented and detected are the differentiation between a healthy monolayer and one exposed to a drug, as well as the distinction between a seeding process and a wound-healing process performed by electric current. The four algorithms used were validated by applying them on topological functions of known fractal dimension, a study that determined the necessary conditions for a correct estimation.

Degradation of electrical performance and radiation damage mechanism of cascode GaN HEMT with 80 MeV proton

In this paper, proton irradiations on Cascode GaN HEMT power device with an energy of 80 MeV and fluences of 2 × 1011 p/cm2 and 6 × 1011 p/cm2 have been carried out, where the threshold voltages drifted negatively by 20.55% and 28.17%, respectively. After two months of room temperature annealing, the threshold voltages recovered 0.22 V and 0.27 V, respectively. The ionizing deposition energy (IEL) was simulated by using Monte Carlo software and TCAD, it the results showed that the value of IEL in Si MOSFET is 5 ∼ 6 orders higher than that in GaN HEMT, while the value of the non-ionizing energy loss (NIEL) is one order higher than that in GaN HEMT. It means that the proton irradiation on the Cascode depleted GaN HEMT is more prone to produce displacement damage. As a large number of electrons and holes pairs were existed on the incident path of Si MOSFET under the proton irradiation, the produced electron will be captured by the gate oxide traps at the SiO2/Si interface, and the holes be captured by the defects generated in displacement damage, resulting in the accumulation of oxide trapped charges. Then, the electrical performance of Si MOSFET degrades seriously, thereby affecting the performance of the entire device. The studies will be helpful for the radiation hardening of Cascode GaN HEMT.

Rapid Self-Healing Hydrogel with Ultralow Electrical Hysteresis for Wearable Sensing.

Self-healing hydrogels are in high demand for wearable sensing applications due to their remarkable deformability, high ionic and electrical conductivity, self-adhesiveness to human skin, as well as resilience to both mechanical and electrical damage. However, these hydrogels face challenges such as delayed healing times and unavoidable electrical hysteresis, which limit their practical effectiveness. Here, we introduce a self-healing hydrogel that exhibits exceptionally rapid healing with a recovery time of less than 0.12 s and an ultralow electrical hysteresis of less than 0.64% under cyclic strains of up to 500%. This hydrogel strikes an ideal balance, without notable trade-offs, between properties such as softness, deformability, ionic and electrical conductivity, self-adhesiveness, response and recovery times, durability, overshoot behavior, and resistance to nonaxial deformations such as twisting, bending, and pressing. Owing to this unique combination of features, the hydrogel is highly suitable for long-term, durable use in wearable sensing applications, including monitoring body movements and electrophysiological activities on the skin.

Excellent angular and electrical performance damage tolerance of wave-absorbing laminate via gradient A-T-A design

Besides broadband electromagnetic wave absorption, electrical performance damage tolerance should be designed and evaluated to compete with advanced detection technologies. In this work, an A-T-A (absorption-transmission-absorption) design strategy with gradient electromagnetic parameters is proposed to enhance angular and electrical performance damage tolerance of wave-absorbing laminated structure in 6–18 GHz frequency band. The quartz fiber cloth with 700 μm periodic inter-bundle pores served as a transmission layer and was embedded into Fe3Co7/epoxy resin magnetic absorption film to improve the maneuverability of input impedance. Meanwhile, Fe3Co7 with a particle size between 10 and 30 μm can easily enter the inter-bundle pore to form periodic pattern, enriching the electromagnetic loss mechanisms. Two significant electromagnetic resonance peaks for the designed 5.3 mm thick gradient A-T-A laminated structure occur in the vicinity of 7 GHz and 15 GHz, realizing reflection loss less than −10 dB at an incidence angle of 0–40° in TE mode. When the penetrating damage area accounts for 20 %, effective absorption bandwidth almost covers 6–18 GHz. Therefore, gradient A-T-A structure provides an insight for realizing excellent angular and electrical performance damage tolerance.