Damage Width Research Articles

Minimal lateral damage fabrication of high-temperature superconducting nanowires via focused helium ion beam irradiation

Abstract Low-temperature superconducting nanowire single-photon detectors have become a key infrared photon counting technology in communication and astronomy applications. However, the constrained physical space of devices demands high-performance superconducting detectors capable of operation at higher temperatures. To date, high-temperature superconductor nanowires still face seriously uneven lateral damage in the ion etching process during fabrication. In this work, we report a promising fabrication method for high-temperature superconducting YBa2Cu3O7−x (YBCO) nanowires, using a focused helium ion beam to minimize the lateral damage of the cut. Based on simulations, we designed tangent circles and adjacent isosceles triangles to replace lines in cutting nanowires to reduce the superimposed damage by He+ ions. The lateral damage of a single helium ion cut has been reduced with a decrease in superimposed damage width from 58.8 nm to 29.7 nm. This work provides a platform for boosting YBCO nanowires to achieve single photon detection.

Steel Wire Rope Damage Width Identification Method Based on Residual Networks and Multi-Channel Feature Fusion

In order to ensure the safety of steel wire rope in various application scenarios, it is particularly important to quantitatively detect the defects of wire rope. Complex detection conditions affect the detection efficiency of wire rope. Therefore, based on the magnetic flux leakage method, this study proposes a method to identify the damage width of steel wire rope for multi-channel fusion of a Hall sensor array. Firstly, the Hall sensor array is used to capture the magnetic flux leakage data of steel wire rope; then, continuous wavelet transform is used to decompose the original data, and moving average filtering is used to denoise each component; the denoised components are merged and converted into a time spectrum, and the time spectrum is classified by ResNet50 image classification model to realize the detection of wire rope damage width. According to the dataset used in this study, the results show that the proposed method performs best in the mainstream noise reduction model; detection accuracy for the width of damage in steel wire ropes is 97%, which proves that the proposed method is effective and feasible.

Fracture properties and acoustic emission characteristics of manufactured sand recycled fine aggregate concrete

To promote the application of recycled fine aggregates, fracture characteristics of concrete beams containing manufactured sand (MS) and recycled fine aggregate (RFA) were investigated. The fracture properties and acoustic emission (AE) characteristics of manufactured sand recycled fine aggregate concrete (MSRFAC) with 0 %, 25 %, 50 %, 75 % and 100 % RFA replacement rates were evaluated by three-point bending test of single-sided notched beams. The fracture mechanisms of MSRFAC beams were explored using AE and digital image correlation (DIC) techniques, and fracture process zone (FPZ) was qualitatively and quantitatively analyzed. The results indicated that the critical nominal stiffness, initial fracture toughness, fracture energy and characteristic length of MSRFAC decreased significantly with the increase of RFA replacement rate, up to 20.2 %, 37.7 %, 22.8 %, and 26.6 %, respectively, while the unstable fracture toughness was insensitive to the variation of RFA. Moreover, the AE activity, the tensile crack, large-scale crack, high amplitude, and high peak frequency in MSRFAC increased with increasing RFA replacement rate. According to the FPZ characteristics of MSRFAC, its FPZ length increased with the increase of RFA replacement rate, while the FPZ width decreased with the increase of RFA replacement rate. The critical FPZ lengths of MSRFAC with different RFA replacement rates were about 20.2–30.0 mm, and the maximum FPZ widths were about 26.0–36.7 mm. The RFA weakened the friction mechanism and interlocking effect between aggregates of MSRFAC, resulting in a faster FPZ propagation rate and smaller damage width of MSRFAC than normal manufactured sand concrete.

Mechanical behavior and thermal damage characterization of granite after flame jet-water cooling treatment

Flame jet-assisted mechanical rock drilling is expected to solve the hard-rock crushing challenges in underground engineering such as mining, tunneling, and drilling. Therefore, it is important to investigate mechanical behavior of the rock after flame jet-water cooling treatment. In this paper, granite blocks were subjected to flame jet-water cooling treatment, which means the rapid heating of the granite using a flame with a temperature of 1564 °C, followed by water cooling. Then, physico-mechanical behaviors of samples at different distances (all the distances mentioned later mean the vertical distance between the sample axis and the flame jet-water cooling path) were measured. Results showed physico-mechanical parameters of the sample increased as the distance increased. The Vp (P-wave velocity), UCS (uniaxial compressive strength) and BTS (Brazilian tensile strength) of the samples increased from 3171.7 m/s, 84.84 MPa and 5.01 MPa at 0 mm to 3619.3 m/s, 145.86 MPa and 7.30 MPa at 70 mm, respectively. Meanwhile, physico-mechanical parameters of samples at 70 mm all reached more than 95 % of those of untreated samples. As the distance increased, cumulative AE counts at peak stress gradually enhanced, and failure modes of uniaxial samples shifted from shear to tensile splitting failure. The SEM (scanning electron microscope) images illustrated that the closer to the flame jet-water cooling path, the more thermal cracks produced in the sample. Meanwhile, the damage factor can well characterize the thermal damage degree of granite. According to the variation of physico-mechanical parameters and SEM images of samples with distances, it can be assumed that the thermal damage width of granite after flame jet-water cooling was about 140 mm. It was much greater than the 50 mm width of spalling pits, which greatly increased the feasibility of thermal-assisted mechanical rock drilling. The tensile stress induced by the temperature gradient below the spalling pit is the fundamental cause of thermal damage to the rock, which is further aggravated by water cooling. The findings can provide some guidance for flame jet-assisted mechanical rock drilling.

Molecular dynamics simulation of the scratching process of GaAs with different crystal orientations.

In order to further improve the manufacturing technology of resonator facet of GaAs (gallium arsenide)-based laser, the scratching process of GaAs was simulated by molecular dynamics. Models of GaAs crystals with different orientations, including GaAs [100], GaAs [110], and GaAs [111], were generated, followed by scratch simulations on these models. The surface characteristics of scratches, damage width, subsurface damage, stack height, and the distribution and activity characteristics of dislocations were analyzed based on the simulation results. The results show that there are obvious anisotropy in the deformation of different crystal orientation during the scratching process of GaAs. Surface features, damage width, subsurface damage, and dislocation dynamics during scraping in GaAs crystals strongly depend on crystal orientation. It was also observed that GaAs exhibits distinct characteristics of dislocation activity during the scratching process, depending on its crystal orientation. In addition, GaAs [110] crystal direction has the smallest maximum damage width and subsurface damage depth. The maximum of maximum damage width is in GaAs [100] crystal direction, and the maximum subsurface damage depth is in GaAs [111] crystal direction. In addition, the stacking height is maximum when GaAs [100] is scraped and minimum when GaAs [110] is scraped. The engraving quality of GaAs materials was investigated utilizing the LAMMPS software through molecular dynamics simulations, while observations were facilitated using the OVITO software. The MD simulation was conducted employing the NPT ensemble, with the temperature fixed at 300 K. A time step of 2 fs was utilized, and the total duration of the MD simulation spanned 600 ps.

Tribocorrosion Characteristics of Hard Anodized Al Alloys on Hydrogen Valve Application for Fuel Cell Electric Vehicles

In this study, the electrochemical and mechanical characteristics of 6061‐T6 aluminum alloy and hard anodized specimens are investigated after tribocorrosion experiments with rotational speed in dry, distilled water, and sulfuric acid solution. The tribocorrosion experiments indicate that the corrosion potential of aluminum alloys and hard anodized specimens decrease with the initiation of friction/wear. In particular, the increase in the wear track width of an aluminum alloy and the exposure of the base material by completely destroying the anodized layers of the hard anodized specimens dramatically decrease the corrosion potential. Compared to the dry conditions, both the width and depth of damage in the distilled water and sulfuric acid solution increase dramatically. However, damage in the distilled water and sulfuric acid solutions do not present a significant difference. The results are attributed to the fact that the presence of fluid has a greater impact on damage degree in a material than corrosion. In particular, the brittleness and porosity of a hard anodized layer facilitates the impingement and penetration of fluid, making it relatively easy to generate and propagate cracks. These cracks accelerate the degradation and damage to the material by synergistic effects of wear and corrosion.

Coastal Vulnerability at Tanjung Pakis and Samudra Baru Beaches in Karawang District West Java Province

Coastal tourism is well renowned for the beaches of Tanjung Pakis and Samudra Baru in the Karawang District of West Java Province. Based on the idea of sustainable coastal tourism in Karawang, Samudra Baru Beach is a beach resort that is more sustainable than Tanjung Pakis Beach. One of the key strategies and concepts for developing sustainable coastal tourism is coastal management. One of the things that must be considered in managing coastal areas to maintain ecosystem sustainability is disaster mitigation by paying attention to the level of vulnerability. The substantial objectives are to examine coastal alterations and assess how susceptible the shoreline is in Samudra Baru and Tanjung Pakis coasts, Karawang District, West Java Province. Coastal vulnerability is influenced by six variables: visual observation, land use, wave height, coastline changes, visual observation, damage length and damage width. Tanjung Pakis’s beach area experienced relatively minor damage. The coastline of Tanjung Pakis has been selected for the construction of a soft or hard coastal protection technique. However, Samudra Baru’s coastal regions have only suffered little damage. This result also showed that Samudra Baru Beach is more sustainable coastal tourism than Tanjung Pakis Beach.

Morphological study of cortical bone damage caused by high-pressure water jet erosion based on SPH-FEM coupling algorithm

Currently, traditional processing methods such as drilling, sawing, and milling are primarily utilized in orthopedic surgery, generating a significant amount of heat during the cutting process, leading to irreversible damage to bone and surrounding tissues. High-pressure water jet technology has demonstrated the capability to effectively reduce cutting temperatures and prevent thermal damage during the cutting process. It holds promising potential as an alternative approach to traditional surgical techniques in orthopedic surgery. This study selected the SPH-FEM (Smoothed particle hydrodynamics-Finite element method) coupling algorithm and LS-DYNA software to simulate the effects of high-pressure water jet erosion on cortical bone. The study analyzed the impact of jet pressure on damage morphology and the degree of cortical bone breakage. The simulation results indicate that the concave section of cortical bone damaged by high-pressure water jet is “U” shape. The maximum damage depth of cortical bone increases with the increase in jet pressure. Specifically, as jet pressure increases from 80 MPa to 245 MPa, the increase rate of the average cortical bone damage depth increased from about 0.01 mm/s to more than 0.45 mm/s. The beginning of the concave section of cortical bone damage presents a “funnel” shape, and the width of cortical bone damage reaches its maximum. When the jet pressure is below 180 MPa, there is a significant fluctuation in the width of cortical bone damage. However, with increasing jet pressure, the fluctuation lessens. Physical experiments were carried out under identical technological parameters to verify the numerical results. The experimental results are basically consistent with the numerical results, which can provide a theoretical basis for improving the surface quality of jet erosion of cortical bone.

Coastal vulnerability level and beach handling priorities in Serang District Banten Province

Coastal erosion and accretion have altered the shorelines of various Indonesian coastal areas, endangering the lives and livelihoods of coastal populations. Damage to beaches in coastal areas affects the community’s daily activities, the transportation system, industry, and trade, as well as the environment and public health. Based on this occurrence, the initial stage of disaster management study resulting from coastal damage is to identify the coast’s vulnerability to threatening harm. To assess coastal vulnerability, field observations and measurement from the research location were carried out to obtain visual damage observation, land use, lithology, tidal range, and beach slope. Coastline data from satellite imagery and wind data from the government agencies were carried out to obtain the rate of shoreline change, width of damage, length of damage, and wave height. The purpose of this research is to look at changes in the coastline of Serang, Banten Province, and analyse the amount of beach damage to set priorities for coastal management. The beaches explored were Karangantu Beach, Domas Beach, Lontar Beach, and Tengkurak Beach. Karangantu Beach’s level of vulnerability is classified as very high, so dealing with it is a top priority. Domas and Lontar Beaches are extremely vulnerable, so dealing with them is a key priority. Tengkurak Beach has a moderate level of vulnerability, hence the priority for managing is rather high. This can be utilized as a model for overcoming coastal damage in Serang District, Banten Province, by constructing coastal protection buildings based on the shore’s vulnerability and management priority.

Exploring Uncertainties for Crashed Vehicle Travelling Velocity Tolerance in One-Dimensional Crash Configuration

Evidence suggests that measurement uncertainty is among the most important factors for reliability assessment. Uncertainty plays a vital role in maximising velocity calculation accuracy in crash reconstruction works. It serves as a reliable calculation tolerance, whereby its contribution becomes more significant when the calculated initial velocity is nearly approaching the posted speed limit. The results suggested that damage width and midpoint offset have a low sensitivity of Delta-V from 0.5 km/h to 0.75 km/h for up to 80 cm and 60 cm measurement errors, respectively. For the crush profile variable, a lesser measurement error of 8 cm results in 0.9 km/h deviation in Delta-V. Meanwhile, vehicle mass, drag factor and post-impact displacement have a higher sensitivity of Delta-V, as compared to the two previous variables. The calculation results may deviate from the actual figure for 1 km/h with a missing 75 kg adult occupant. Deviation of almost 2 km/h initial velocity was observed for as low as 0.5 drag factor determination fault. Moreover, with 1 m displacement measurement inaccuracy is also giving rise to the resulting initial speed of 2 km/h. Overall, the principle direction of force recorded the greatest velocity sensitivity among the investigated variables. Within 20o and 45o of inaccurate principle direction of force, the Delta-V deviation increases exponentially, up to 4.25 km/h. The presented findings are beneficial in terms of crash investigator judgment for the thoroughness measurement while conducting the assessment of the crashed vehicle and the crash scene. This investigation will also contribute to enhancing our understanding of tolerance determination for more accurate velocity estimation.

Guided wave resonance identification of interface delamination in bimaterial composites

Laminate composites are widely used in industrial applications due to their high material strength and efficiency. In such materials, impact loads can cause internal delaminations at the bonding interfaces between sublayers, which further growth during operation could lead to structural failure. Guided wave based non-destructive testing allows detecting such hidden delamination, which manifests itself in the wavefield disturbance at the obstacle vicinity. However, their sizing requires sophisticated post-processing of the acquired wave signals. In our previous studies, a method for sizing an internal strip-like crack in a homogeneous elastic plate has been developed and experimentally approved. The method is based on the numerical evaluation of the scattering resonance frequencies depending on the crack size, and their comparison with the experimentally obtained ones. In the present paper, we extend this approach to the case of dissimilar-material laminates. Numerical simulation and laser Doppler vibrometry measurements were carried out for bi-layer samples composed of various combinations of glued steel, aluminium, and glass sublayers with artificial strip-like delamination. The results obtained confirm the possibility of damage width estimation using the values of scattering resonance frequencies extracted from the signals acquired at the sample surface.

Numerical research on rock cutting by abrasive jet under confining pressure based on SPH-FEM method

On the basis of experimental verification, the methods of smooth particle hydrodynamics (SPH) and finite element methods (FEM) were used to study the process of abrasive jets cutting rock under confining pressure conditions. The results show that the failure of rock was mainly due to compressive and shear stresses, while the propagation of cracks was dominated by tensile stress. Under confining pressure, the cracks in rocks were mainly horizontal. The damage depth significantly decreased with increasing confining pressure, while the damage width first decreased and then increased. The critical distance between two slits without penetration is four times the diameter of the abrasive jet. When the cutting direction of the abrasive jet was perpendicular to the maximum stress, the relief range of the confining pressure formed was larger. The results have certain guiding values for revealing the mechanism of abrasive jet impact rock breaking and engineering applications.

Quantifying bark-stripping damages to address the relationship between external and internal wood defects

The detachment of tree bark (i.e. bark-stripping) by wild ungulate species can be observed in many European forests and it can lead to significant damages to the wood. In our study, bark-stripping of different intensity and age was recorded for 110 European beech (Fagus sylvatica L.) trees growing in the Harz Mountains, Germany. Our goal was to compare the performance of a conventional and a structure-from-motion approach to quantify the external damage and to evaluate whether bark-stripping damages on the outside may accurately reflect internal wood defects. Also, we wanted to know whether potential relationships between inner and outer damages are affected by the condition of the wound. Surprisingly, despite large difference between the two approaches (mean absolute error: 46%) the wood surface on the sawn boards (internal damage) could not be predicted more accurately using structure-from-motion, for the assessment of the external damage when compared to the conventional measurements based on damage height and damage width (rhombus formula). The internally damaged area was smaller than the externally damaged area across all wound categories. In contrast though, and most notably, the length of the stem section negatively affected by the damage was always greater inside than outside. We conclude that sophisticated measurements of the outside wound area do not allow for a better estimation of the internal wound area. Foresters may continue to rely on simple measures of damage extension on the outside of the tree to estimate internal damages. They should however consider the wound status as an additional information for a better prediction of internal damages.

An Approach for Assessing Misclassification of Tornado Characteristics Using Damage

Abstract Tornado characteristics (e.g., frequency and intensity) are challenging to capture. Assessment of tornado characteristics typically requires damage as a proxy. The lack of validation in the enhanced Fujita (EF) scale and the likelihood of rural tornadoes suggests that tornado characteristics are not accurately captured. This paper presents an approach to quantify the potential misclassification of tornado characteristics using Monte Carlo simulation for residential structures in rural areas. An analytical tornado wind field model coupled with fragility curves generates degrees of damage (i.e., DOD) from the EF scale in a wind speed–to-damage approach. The simulated DODs are then used to derive damage-to–wind speed relationships built from the National Weather Service Damage Assessment Toolkit (NWS DAT). Comparisons are then made between the simulated tornado characteristics and those derived from damage. Results from the simulations show a substantial proportion of tornadoes were “missed” and path width and pathlength on average are underestimated. An EF4 rating based on damage is favored for EF3–EF5 simulated tornadoes. A linear regression was utilized and determined damage-based wind speeds of different percentiles, damage length, damage width, and the number of structures rated at a particular DOD were important for prediction. The distribution of DODs was also used to predict wind speed and the associated intensity rating. These methods were tested on actual tornado cases. Tornadoes that have the same damage-based peak wind speed can be objectively assessed to determine differences in overall intensity. The results also raise questions about the level of confidence when assessing wind speed based on damage.

Exploring the potential of the fabrication of large-size mirror facet for semiconductor laser bar utilizing mechanical cleavage

While mechanical cleavage technology is an ideal alternative approach to fabricate large-size mirror facets for high-power laser bar, there has been little scientific understanding of mechanical cleavage mechanisms. To fill this gap, cleavage experiments were designed according to the Taguchi method for analyzing the main effects of three parameters. Surface and subsurface cracks and cleavage plane morphology are analyzed as well. The results show that scribing load has significant impact on the scratch morphology as compared with other parameters, and quadratic polynomial models are formulated to predict kerf width and maximum damage width values. For scribing along the [0−1−1] direction on the (100) GaAs wafer, the subsurface cracks are TLC and LC which propagate along [0-11] direction and MC which propagates along [100] direction. The achieved optimal combination of parameters are scribing load of 10 g, scribing speed of 20 mm/s and scribing length of 0.6 mm. The undamaged length of cleaved planes can reach 11.77 mm. Our results demonstrate that mechanical cleavage is a powerful technique which could guide actual production and manufacturing field of high-power GaAs-based laser bars.

Experimental modeling of various osteotomy modes during navigation trepan biopsy of the jaws

In surgical dentistry, the sampling of the biomaterial of the jaws is usually carried out with the help of dental trepans. As a result of osteotomy, a friction force inevitably arises during trepan biopsy, which can lead to local hyperthermia and, as a consequence, coagulation necrosis of both the bone tissue of the jaw itself and damage to the resulting biopsy. Local overheating can lead to complicated healing of a bone wound in the area of a trepan biopsy, lead to difficulties in verifying the morphological picture of the disease and, as a consequence, further treatment of the patient. When conducting a navigational trepan biopsy using a surgical template, the risk of hyperthermic exposure increases, and the question of choosing the rotation speed becomes obvious. The literature presents limited data on osteotomy regimes using a trepan cutter during jaw bone biopsy, including using a navigational surgical template, which determined the relevance of the study. The purpose of the study: to determine the permissible speed of rotation of the trepan cutter during the navigation trepan biopsy of the jaw bones. Materials and methods: 20 (5) micro-preparations were made from trepan biopsies of the femur of cattle, obtained at speeds of 800 rpm, 500 rpm, 250 rpm, 50 rpm in the classical way; 15 (5) micro-preparations were also made from trepan biopsies obtained at speeds of 350 rpm, 200 rpm, 50 rpm using a surgical navigation template. The width of pathological changes in the tectorial properties of ostein due to coagulation damage of the bone matrix in microns was measured using SlideViewer (3DHISTECH), a built-in tool for measuring linear parameters in microns. The statistical significance of the obtained values was determined using the Kraskel – Wallis H-test. Results: with osteotomy at a speed of 50 rpm, the width of the bone matrix damage reached up to 10 microns. As the rotation speed increased, the width of the damage also increased: at 200 rpm – Me = 36.8 microns, 350 rpm – Me = 98.6 microns. Conclusion: when conducting a navigational trepan biopsy using a surgical template, the recommended rotation speed of the instrument is up to 350 rpm.

Fractal analysis for the blast-induced damage in rock masses with one free boundary

The research on blasting damage of medium has important engineering significance, wherein one of the main factors affecting the blasting effect of the medium is the free boundary of the medium. In this article, the blasting damage of media with one free boundary is studied and the damage evaluation based on fractal theory is carried out. Firstly, an experimental device is designed to simulate the state of the medium’s one free boundary. The distance between blasthole and the free boundary is the only variable considered in the experimental investigation. The fractal theory is used to analyze the fractal damage of the medium caused by the explosion, and MATLAB is used to extract three characteristic parameters (damage depth, damage width, and damage zone) of the binary image after the explosion. Finally, LS-DYNA is used to build a 2D plane strain model with the same size and boundary conditions, which simulates the damage evolution process of medium under a single free boundary blasting pattern. The fractal theory is then used to evaluate the fractal damage observed in the numerical simulation results. The experimental results and numerical simulation results of blasting fractal damage of one free boundary medium are in good agreement. The blasting fractal damage grows initially and subsequently decreases as the distance between the blasthole and the free boundary increases. Thus, the distance between blasthole and free boundary affects the efficiency of blasting energy destroying medium and the blasting failure pattern.

Study on Critical Damage Width of Parallel Double-Free Surface Blasting

Reserved rock wall is usually used in blasting operation when one side has an important protection object. Rock wall demolition blasting was essentially a parallel double-free surface blasting; blasting is the ideal effect of casting a side fully broken rock mass, throwing, on the other side (protection) of rock mass at the injury status of “broken and do not come loose”; the minimum thickness of the rock wall last could hole to protect the width of side of the free surface, called the critical damage width. First, based on the theory of multi-boundary blasting, the relationship among the throwing effect, boundary condition, and charge quantity of parallel double-free surface blasting is expounded in this article. The model of equivalent sub-charge package was established to deduce the relationship of bilateral resistance lines, and the theoretical value of critical damage width was 2.05 W (minimum resistance line). Second, according to the rock wall demolition and blasting of the Yangtou station renovation project in the second line of Yuhuai, the critical damage width of 2.5 W was measured through a single row and hole-by-hole detonation field test. The results of study on critical damage width of parallel double-free surface blasting can provide theoretical guidance for similar projects.

Total Flavonoids of Rhizoma Drynariae Ameliorate Bone Growth in Experimentally Induced Tibial Dyschondroplasia in Chickens via Regulation of OPG/RANKL Axis

Background: Rhizoma Drynariae, traditional Chinese herb, is widely used to treat and prevent bone disorders. However, experimental evidence on the use of Rhizoma Drynariae extract, total flavonoids of Rhizoma Drynariae (TFRD) to treat tibial dyschondroplasia (TD) in chickens and its underlying mechanisms have not been investigated. Purpose: To evaluate the therapeutic effect of TFRD on leg disease caused by TD and elucidate its mechanisms in modulating the bone status. Methods: Thiram-induced chicken TD model has been established. The tibia status was evaluated by analyzing tibia-related parameters including tibial weight, tibial length and its growth plate width and by performing histopathological examination. The expression of tibial bone development-related genes and proteins was confirmed by western blotting and qRT-PCR. Results: The results showed that administration of TFRD mitigated lameness, increased body weight, recuperated growth plate width in broilers affected by TD and the increase of tibia weight and tibia length is significantly positively correlated with body weight. Compared with the TD group broilers, 500 mg/kg TFRD evidently reduced the damage width of the growth plate and improved its blood vessel distribution by elevating the gene expression levels of BMP-2 and Runx2 and OPG/RANKL ratio. Furthermore, correlation analysis found that the damage width of the growth plate was negatively correlated with the expression levels of BMP-2 and OPG. Conclusion: The present study revealed that TFRD could promote the bone growth via upregulating OPG/RANKL ratio, suggesting that TFRD might be a potential novel drug in the treatment of TD in chickens.

Experimental study on electric corrosion damage of bearing and solution

During the operation of the bearing in the motor, the induced current will inevitably be generated. The bearing raceway will be damaged by current. In this paper, the oil film thickness and capacitance in the bearing are analyzed in detail, and the relationship between oil film thickness, rotational speed, and load is obtained. The oil film thickness increases with the increase of bearing rotation speed and decreases slightly with the increase of load. The minimum oil film thickness of the bearing is between 0.4 μm and 2.9 μm. The capacitance of bearing is influenced by Hertz contact area, oil film thickness, and lubricant quality. It is between 1.9 pF and 34.7 pF. A shaft current test rig was developed. Based on the analysis results, orthogonal tests are set up to study the influence of voltage, rotation speed, and load on bearing operation. By using range analysis and variance analysis, the same conclusion is obtained: the most dominant factors affecting the raceway damage width, surface roughness, and vibration amplitude are voltage, load, and rotation speed, respectively. The mixed ceramic bearing and full-ceramic bearing are used instead of steel bearing to solve the problem of shaft current. Add conductive grease and non-conductive grease, respectively, and analyze and compare the advantages and disadvantages of different combinations from the perspective of temperature and friction and wear. The order from inferior to superior is steel bearing, hybrid ceramic bearing with ceramic outer ring, hybrid ceramic bearing with ceramic inner ring, hybrid ceramic bearing with ceramic ball and full-ceramic bearing. By using non-conductive grease, the damage is reduced by 16%–29%, surface roughness is reduced by 90%–122%, and vibration is reduced by 23%–176%. Under the same conditions, the bearings using non-conductive grease are better than those using conductive grease.