Surface Of Bushing Research Articles

Numerical simulation of friction characteristics of bionic flexible contact surface of front axle rocker arm sleeve of car

Based on the finite element software ABAQUS, the friction process of the flexible friction pair of the front axle rocker bushing of a car with a convex structure similar to the mantis head is established.The finite element model of the process is constructed and its friction characteristics are verified. By selecting a suitable hyperelastic constitutive model and changing the size of the convex structure on the surface of the sleeve,The simulation analysis of the mechanical characteristics of the flexible friction pair in radial and torsional directions shows that the bionic convex hull design changes the maximum stress of the bushing when it is subjected to force.The force and strain position are adjusted to reduce the possibility of cracking of the rubber bushing; the contact friction force and friction coefficient of the bionic bushing surface are significantly reduced, and the type 2 modelThe drag reduction and wear resistance of the profiled surface are the best.

Failure analysis of eccentric bushings in large gyratory crusher

Shortly after the start-up of the loaded gyratory crusher, a severe failure issue occurred in the eccentric bushing of the crusher. Based on the analysis of working conditions and force, the failure mechanism of the eccentric bushing is studied in detail by combining macroscopic analysis, finite element analysis, scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The macroscopic analysis results indicate that the failure of the eccentric bushing occurs at the contact position with the mantle shaft, where strong oxidation takes place. The finite element analysis results show that stress concentration occurs at the contact position between the eccentric bushing and the mantle shaft. Nevertheless, the maximum von Mises stress in the eccentric bushing remains significantly below the material's yield strength. Furthermore, the maximum deformation of the eccentric bushing is minor. Therefore, the failure of eccentric bushings is not caused by insufficient material strength or large deformation. It should be noted that the finite element analysis results show that the minimum clearance δ between the beam bushing and the mantle bushing has a great influence on the contact position between the eccentric bushing and the mantle shaft. SEM and EDS analysis of the undamaged samples indicate the presence of numerous micro-pits on the surface of the eccentric bushing. Meanwhile, a large amount of sulfur and oxygen elements and their chemical compounds are found on the fracture surface, exhibiting local enrichment phenomena. The SEM and EDS analyses conducted on samples around the crack reveal pronounced corrosion and spalling phenomena on the surface of the lead-tin bronze alloy. The comprehensive analysis shows that the failure of the eccentric bushing is mainly due to sulfur contamination, which leads to sulfidation and oxidation under elevated temperature conditions, thus promoting corrosion and corrosion-induced cracking.

Triboactive coatings for wear and friction reduction in chain drives

Using hard triboactive (Cr,Al,X)N coatings (X = Mo, Cu) on chain pins is promising to increase the energy efficiency and sustainability of chain drives. (Cr,Al,X)N coatings, when interacting with lubricants, can build a tribofilm in the contact zone which has wear- and friction-reducing properties. These tribofilms can also be transferred to the surface of the chain bush, protecting it from wear. In this study, these coatings were tribologically investigated via pin-on-disc tribometer and a chain-joint tribometer under grease lubrication. The results showed that the (Cr,Al,Mo)N coating achieved the lowest total wear volume and lowest friction coefficient. The tribofilms showed a comparable composition on chain pins and bushes after the tests indicating a transfer of the tribofilm.

Research and Experiment Verification of the Shielding Effect of a 1000 kV Equipotential Shielding Capacitor Voltage Transformer in Consideration of Surface Leakage Current

The non-uniform distribution of the surface contamination on insulation bushings of a traditional capacitor voltage transformer (Tra-CVT) will impact the electric potential distribution along the axis of the capacitor voltage divider (CVD), and causes variation of voltage dividing ratio of the CVT. An increased phase angel difference between primary and secondary voltage will be another consequence. The equipotential shielding CVT (EPS-CVT), with its unique double layer structure, is able to significantly reduce the additional measurement error (AME) caused by surface leakage current (SLC) flowing on the bushing surface. In this work the AME caused by SLC for both types of CVTs are evaluated by an implementation of newly developed equivalent simulation circuit models of both CVTs accounting SLC. A shielding effect evaluation test method is proposed and successfully demonstrated on an UHV EPS-CVT prototype to verify the effectiveness of the AME shielding function of an EPS-CVT.

A thermal EHL investigation for finite line contact under starved condition on bush-pin hinge pairs in industrial chains

During the operation of the industrial chains, serious starvation may happen so that the oil film is often too thin to effectively separate the bush-pin surfaces, resulting in surface damage of the pin since the bush surface is harder. In this paper, the effects of oil supply and equivalent radius of curvature on the variations of pressure, film thickness and temperature in the contact area are studied based on the thermal elastohydrodynamic lubrication (EHL) theory and a finite line contact lubrication model under oil starvation condition is employed. It is found that oil starvation and the increase of equivalent curvature radius will aggravate the stress concentration at the end of the contact area, and more oil supply is required in the contact area if the thermal rise is considered. An oil starvation mechanism of finite line contact EHL is proposed, in which in addition to the direct influence of oil supply, the interaction of film thickness, pressure and temperature in the contact area also play important roles. The reduction of minimum film thickness is proposed to measure the degree of oil starvation at the ends of the contact area. The oil starvation process of finite line contact is divided into four typical stages.

An advanced pressure pulsation model for external gear pump

Pressure pulsation is the inherent characteristic of external gear pump. This paper presents a new pressure pulsation model by considering the lateral clearance and manufacturing error. Firstly, inspired by the Archard model, the maximum roughness peak of lateral bushing surface with or without wear are measured by laser confocal microscope, which is to obtain the change law of lateral clearance indirectly and construct the lateral clearance model. Then, the manufacturing error model is constructed based on the long and short period errors of the master-slave gear acquired by the gear measuring center. Meanwhile, according to the boundary constraints, the lateral clearance model and the manufacturing error model are embedded into the lumped parametric model of the pressure pulsation to realize updating. Finally, the robustness of the new pressure pulsation model under different working conditions is verified, and the nature of the influence of the lateral clearance model and manufacturing error model on pressure pulsation is revealed. Experimental results on an external gear pump validate the merits of the new model in both time domain and frequency domain. The results can provide helpful guidance to understand the mechanism of external gear pump pressure pulsation.

Simulative investigation of the influence of surface texturing on the elastohydrodynamic lubrication in chain joints

In timing chain drives, the chain is the critical component regarding the wear. Relative movements take place at the chain joint between pin and bush, which lead to wear of the chain joint due to friction and so to chain elongation. The chain joint is generally lubricated with oils, through which elastohydrodynamic processes can occur in the gap between the pin and the bush of the chain joint. A simulation model is developed here to examine these elastohydrodynamic processes considering a mass conserving cavitation model, the Newtonian flow behaviour of the lubricant and the structuring of the bush surface, whereby the real form of the bush is considered. MBS simulations are used to obtain realistic loads on the chain joint.

ПОВЫШЕНИЕ ЭФФЕКТИВНОСТИ ДИАГНОСТИРОВАНИЯ ИЗОЛЯЦИИ ВЫСОКОВОЛЬТНЫХ ВВОДОВ ТРЕХФАЗНЫХ ТРАНСФОРМАТОРОВ

The paper considers technical means of methods for diagnostics of insulation of high-voltage bushing for power transformers. It also points out advantages and disadvantages of existing methods and proposes a new solution for contactless diagnostics on the basis of measurement of electric field parameters near the surface of bushing. For control of technical condition of power transformers bushing the authors have developed a scheme for placement of elements of portable diagnostics device. A defect in the insulator leads to redistribution of electric potentials on capacitive elements of the high-voltage bushing and to change of electric field intensity around the fault bushing. The proposed design allows fast mounting of device on the power transformer body without its shutdown and revealing of fault bushing according to change of field intensity (sensors of electric field are located near bushing). The developed method for diagnostics of condition of power transformers bushing based on analysis of data of electric field distribution allows determining technical condition of bushing in operation conditions.

COMBINED TECHNOLOGY FOR RESTORATION AND HARDENING OF BUSHINGS OF GEAR HYDRO MOTORS USING GAS-DYNAMIC SPRAYING

Over the past 10-15 years, the use of aluminum alloy parts in the structures of hydraulic systems of agricultural machinery has increased significantly. A large proportion of such parts account for sliding bearings (bushings), the working surfaces of which are subjected to significant wear during operation. Micro-arc oxidation is a modern method of hardening aluminum alloy parts, but it does not allow to restore parts with wear greater than 0.15 millimeters. For the restoration of parts made of aluminum alloys with significant wear, the method of supersonic gas dynamic spraying is promising. (Research purpose) The research purpose is analyzing the technical condition of worn bushings REXROTH of gear hydraulic motors and develop a combined technology for restoring their working surfaces by gas-dynamic spraying with subsequent hardening by micro-arc oxidation. (Materials and methods) Sixty bushings were chosen for the study. A digital micrometer MCC-25-0.001 GOST 6507 was used to measure wear. Powders A-80-13 and A-20-11 by Obninsk Powder Spraying Center were used. A silicate-alkaline electrolyte KOH-Na2SiO3 was used for microarc oxidation. (Results and discussion) Based on the information on wear, authors have developed a combined recovery technology with hardening of the end surfaces of gear motor bushings, which includes: cleaning of bushings; fault detection; pre-machining; supersonic gas dynamic spraying of worn surfaces; hardening by micro-arc oxidation; finishing mechanical treatment of the coating and final control. (Conclusions) The developed combined technology of bushings will allow to increase their wear resistance up to 2.2-2.3 times and significantly increase the service life of hydraulic motors. The technology is universal, and the possibility of restoring the bushings of foreign hydraulic motors using the proposed technology is especially relevant due to the need for large-scale import substitution.

Evaluation of a boxwood topiary trimming robot

This paper describes a new robot specifically developed for topiary trimming and evaluates its performance through a novel evaluation method. Experiments were carried out in a real garden letting the robot trim spherical-, cylindrical- and cuboid-shaped boxwood topiaries. The robot's performance was evaluated using a quantitative evaluation method, which made accurate 3D point clouds of the bush before and after trimming using photogrammetry. For each point in these point clouds, the Euclidean distance to the ground-truth shape was calculated and classified as correctly trimmed (CT) when the distance was within 2 cm of the ground-truth shape. Using this information the percentage of CT points before and after trimming were compared. Results show a reasonable robot accuracy when trimming spherical topiaries, reporting a 24 percentage point increase of CT points, going from 27% (before) to 51% (after) trimming of the bush surface. Cylinders and cuboids had a lower performance, which reported an increase of CT between −0.2 and 6 percentage point. The performance of the robot was also qualitatively assessed by human observers by scoring topiaries. The highest score of a single bush is a 3.1 out of 5. These results, combined with the quantitative evaluation show that the robot can trim autonomously, but it does not reach the required accuracy for practical application. Despite this, the evaluation method was able to reveal main bottlenecks of the robot in real-world experiments. Together with the robot description, this paper can be used as a guideline for the development and evaluation of gardening robots.

Using the principles of axiomatic design in the development of bushing manufacturing technology

There are different types of bushings used in mechanical equipment and they can be used for different purposes. In the case of bronze bushings used to ensure rotation conditions of shaft-type parts, there are some difficulties in addressing the problem of their manufacture. In essence, in order to meet the machining accuracy requirements specific to the outer and inner revolution surfaces, appropriate manufacturing technologies must be established. Some distinct technological paths can be considered for machining and checking the outer and inner cylindrical surfaces of bushings. In solving certain problems specific to the development of bushing manufacturing technologies, the principles of axiomatic design were used. Thus, the axiom of the independence of the functional requirements was used preferentially in establishing the machining operations to be applied to the workpieceto obtain a bushing. The second axiom was applied to identify the best solutions for the machining of the inner revolution surface. In this way, more convenient manufacturing technology for bronze bushings was identified.

Research on the hydroformed metal stator bushing based on full restraint at both ends

The rubber bushing of the positive displacement motor is easy to age, and the metal bushing stator is proposed. We designed and carried out an experiment of hydroforming of metal stator bushing with equal wall thickness. After the experiment, we found that the metal stator bushing was wrinkled. We applied the finite element method to study the cause of wrinkles in the metal stator bushing. The research results show that the main reason why the metal stator bushing is wrinkled is that the inner diameter of the tube blank is larger. Therefore, We use the finite element method to study the influence of the inner diameter of the tube blank on the quality of the metal stator bushing. From the research results, we found that the suitable inner diameter of the tube blank is 86.5 mm. The surface of the metal stator bushing is smooth, the inner surface of the metal stator bushing is close to the mold, and the maximum gap is 0.15 mm. The metal stator bushing formed by tube blank III has a larger minimum wall thickness, a smaller maximum wall thickness, and the smallest wall thickness variance, which is 2.6 mm, 3.22 mm, and 0.028, respectively. The smallest plastic strain, the largest plastic strain, and the largest displacement of the metal stator bushing formed from the tube blank III are 0.2, 0.7, and 14 mm, respectively. When L2/L1 = 0.9577, the quality of the metal stator bushing is better.

Numerical Modeling on the Compliance and Load Capacity of a Two-Row Aerostatic Journal Bearing with Longitudinal Microgrooves in the Inter-Row Zone

Aerostatic bearings are attractive, with minimal friction losses, high durability, and environmental friendliness. However, such designs have a number of disadvantages, including low load-bearing capacity and high compliance due to high air compressibility and limited injection pressure. The article proposes a double-row aerostatic journal bearing with an external combined throttling system and longitudinal microgrooves in the inter-row zone. It is hypothesized that the use of microgrooves will reduce the circumferential flows of compressed air, as a result of which the compliance should decrease and the bearing capacity should increase. To test the hypothesis, we carried out the mathematical modeling, calculations, and theoretical study of stationary operation modes of the bearing for small shaft eccentricities in the vicinity of the central equilibrium position of the shaft and bearing capacity for arbitrary eccentricities. Formulas were obtained for the numerical evaluation of compliance for bearings with a smooth bushing surface and with longitudinal microgrooves. Iterative finite-difference methods for evaluating the fields of the squared pressure are proposed, on the basis of which the load capacity of the bearings is calculated. Experimental verification of the bearing’s theoretical characteristics was carried out, which showed satisfactory agreement between the compared data. The study of the compliance and load capacity of a microgroove bearing yielded impressive results. We show that the positive effect from the application of the improvement begins to manifest itself already at four microgrooves; the effect becomes significant at six microgrooves, and at twelve or more microgrooves, the circumferential flows in the bearing gap practically disappear; therefore, the bearing characteristics can be calculated on the basis of one-dimensional models of air lubrication longitudinal flow. Calculations have shown that for a length of L = 1, the maximum load capacity of a bearing with microgrooves is 1.5 times higher than that of a conventional bearing; for L ≥ 1.5, the bearing capacity increases twice or more. The result obtained allows us to recommend the proposed improvement for practical use in order to increase the load capacity of aerostatic journal bearings significantly.

The Analysis Chemical Composition and Microstructure of Bolt Anchor Bushing in Cessna Caravan Type 208B

Bolt Anchor Bushing is a component contained in an aircraft in the form of a cylindrical iron tube in which there is rubber. Bolt Anchor bushing functions as a bearing between moving and immovable components. This is done so that aircraft components can carry out their functions properly and safely. Bolt Anchor Bushing must be sturdy and strong for the shaft elements and the machine to work properly. If the Bolt Anchor bushing does not work properly, it will affect how the component system works. The methods in this research were observation, interviews, quotes with journals, and testing of chemical composition and microstructure. The results of characteristics Bolt Anchor bushing include medium carbon steel with 0.42% Carbon and 93.98% Fe mixture of Nickel 1.91% Ni. Bolt Anchor Bushing has the characteristics of being resilient and corrosion resistant. The results of the microstructure on the outer, middle and inner surface of the bolt anchor bushing consist of ferrite and pearlite phases. The colour of ferrite phase is light and the dark is colour of pearlite phase. The ferrite phase is stable at low temperatures, solubility is limited and can be with Fe3C or cementite. The pearlite phase is in ferrite and Fe3C. In this study, the bushing consisted of Fe-Ni. It has the properties of high hardness, ductility, corrosion resistance and high temperature resistance.

Mathematical model of a journal bearing with low-melting and porous coating in its structure on different contacting surfaces with incomplete filling of operating clearance

The authors consider the development of a mathematical design model of an infinite journal bearing lubricated with a lubricant with Newtonian rheological properties and a melt of a low-melting metal alloy covering the surface of the bearing bush, as well as a porous coating on the surface of the shaft, taking into consideration the dependence of the viscosity characteristics of the lubricant, the melt and the permeability of the porous coatings on the pressure with incomplete filling of the operating clearance. The authors found asymptotic solution of the system of differential equations with respect to the parameter K due to the melt and the rate of dissipation of mechanical energy and the exact self-similar solution for the zero approximation without regard for the melt and the first approximation taking into consideration the melt. This solution was found according to the equation of motion of a viscous incompressible fluid for a thin layer, the equations of continuity, Darcy equation and the equation determining, taking into account the expression for the rate of dissipation of mechanical energy, the profile of the molten contour of the bearing bush with regard to the dependence of the permeability of the porous coating, the viscosity of the lubricant depending on pressure. As a result, the fields of velocities and pressures in the lubricating and porous layers were determined taking into consideration the dependence of the lubricant viscosity and the permeability of the porous coating on pressure, as well as the function Φ1(θ), reasoned by the melt of the bearing bush surface. In addition, the main performance characteristics were determined: load-bearing capacity and friction force.

The pre-hot dipping effects on the bimetal casting of nitriding steel sleeve into the Al-Si matrix

Steel-aluminum composite material combine the excellent mechanical properties of steel such as high strength and good wear resistance with the advantages of lightweight aluminum for widely using in automobile engine block, gearbox and other car body structures. In this paper, a new process is used to cast the alloy steel sleeve into Al-Si alloy matrix for preparing aluminum engine block with steel cylinder liner. The process consists of three parts: the surface pre-treatment of steel, the hot-dipping melt and solid-liquid casting of steel with aluminum. Generally, the hot dipping melt should have lower melting point than the melting point of aluminum alloy, good temperature oxidation resistance and amount of solid solubility both with steel and aluminum. Giving consideration of such condition and cost, Zn´ Al and its alloys are used in present paper for learning the effect of hot dip coating melts on the interface properties of steel/aluminum at different times. After hot dipping, a coating formed on the surface of the steel bushing, which improves its wettability in the aluminum melt and the metallurgical bonding effect of the steel-aluminum interface. The microstructure, phase composition, growth kinetics and hardness distribution of the interface were analyzed by metallographic microscopy, scanning electron microscopy with EDS. The results show that the metallurgical bonding interface of steel/aluminum bimetal casting can be obtained by hot dipping. Hard-brittle diffusion layer produced by dipping pure Al is thicker than that produced by ZL101. Dipping pure zinc produces a dense intermetallic layer of 3-5 um and a large amount of dispersed phase of Al3FeZnx, and the bonding performance of such interface is better than the other two. The interface hardness of steel-aluminum bimetal casting obtained by hot dipping pure Al melt, ZL101 melt and pure Zn melt can reach 563.5HV, 528.3HV and 632.3HV, respectively.

Influence of Congruency Design on the Contact Stress of a Novel Hinged Knee Prosthesis Using Finite Element Analysis.

ObjectivesTo investigate the contact stress and the contact area o tibial inserts and bushings with respect to different congruency designs in a spherical center axis and rotating bearing hinge knee prosthesis under gait cycle loading conditions using finite element analysis.MethodsNine prostheses with different congruency (different degrees of tibiofemoral conformity and different distances between the spherical center and the bushing) designs were developed with the same femoral and tibial components. The models were transferred to finite element software. The peak contact stresses and contact areas on tibial inserts and bushings under the gait cycle loading conditions were investigated and compared.ResultsFor tibial insert, the peak contact stress was the highest in the low conformity‐long group (61.4486 MPa), and it was 1.88 times higher than that in the group with the lowest stress (moderate conformity‐short group, 32.754 MPa). The contact area was the largest in the low conformity‐long group (420.485 mm2), and it was 1.19 times larger than that in the group with the smallest area (moderate conformity‐middle group, 352.332 mm2). For bushing, the peak contact stress was the highest in the high conformity‐long group (72.8093 MPa), and it was 3.21 times higher than that in the group with the lowest stress (high conformity‐short group, 22.6928 MPa). The contact area was the largest in the low conformity‐short group (2.41 mm2), and it was 2.27 times larger than that in the group with the smallest area (high conformity‐middle group, 1.063 mm2).ConclusionThe results of our study showed that the congruency of the tibiofemoral surface and bushing surface should be considered carefully in the design of the spherical center axis and rotating bearing hinge knee prosthesis. Different levels of contact performance were observed with different congruency designs. In addition, the influence of contact stress and contact area on the polyethylene wear of rotating hinge knee prostheses should be confirmed with additional laboratory tests.

Study on Surface Rainwater and Arc Characteristics of High-Voltage Bushing With Booster Sheds Under Heavy Rainfall

The flashover performance of insulators can be improved by BS (booster sheds) in the rain, which is mainly attributed to the reasons that BS break up long cascades of water and block connections of arcs. However, surface rainwater characteristics and arc characteristics of bushing have not been quantitatively studied under heavy rainfall. In this article, the artificial rain tests were conducted on a 500 kV transformer high-voltage bushing equipped with and without BS under the rainfall intensity of 10 mm/min. X (the total length of water column) and L arc (the critical length of arc) on the bushing surface were taken as the feature parameters of surface rainwater characteristics and arc characteristics, respectively. The effects of BS on E h (the rain flashover voltage gradient along the insulation height), X and L arc were investigated, respectively. Furtherly, the relationships were studied among Eh, X and L arc . Results indicate that E h has a sharp rise as the number of BS (NBS) is from one to two, however the rise of E h gradually decreases when NBS exceeds two. X decreases while L arc increases with the rise of NBS, however both the change ranges of them continually fall. Furthermore, L arc presents remarkable negative correlation to X because of the effect of the electric field. E h rises nonlinearly with the decrease of X, which is due to the change of the wetting uniformity on the bushing surface and the potential redistribution along air gaps in the presence of the local arc.

Effects of double parabolic profiles with groove textures on the hydrodynamic lubrication performance of journal bearing under steady operating conditions

The textures on the bushing surface have important effects on the performance of journal bearing. In this study, the effects of double parabolic profiles with groove textures on the hydrodynamic lubrication performance of journal bearing under steady operating conditions are investigated theoretically. The journal misalignment, asperity contact and thermal effects are considered, while the profile modifications due to running-in are neglected. The Winkler/Column model is used to calculate the elastic deformation of bushing surface and the adiabatic flow hypothesis is adopted to obtain the effective temperature of lubricating oil. The numerical solution is established by using finite difference and overrelaxation iterative methods, and the rupture zone of oil film is determined by Reynolds boundary conditions. The numerical results reveal that the double parabolic profiles with groove textures with proper location and geometric sizes can increase load carrying capacity and reduce friction loss under steady operating conditions, which effectively overcome the drawbacks of double parabolic profiles. This novel bushing profile may help to reduce the bushing edge wear and enhance the lubrication performance of journal bearing.

Monitoring of hole quality in friction drilling using different machine learning techniques

The present investigation deals with monitoring the bush and collar formation during the friction drilling (FD) process of Be-Cu alloy. During the FD process, the alloys are often prone to structural damages as well as irregular bush formation. Hence, monitoring the quality of the hole during the process becomes inevitable. The quality of the drilled hole was monitored using different machine learning (ML) techniques. The vibration signals were captured using an accelerometer sensor. The change in amplitude of the measurement data concerning each process parameter and the measured bush surface roughness values were used to validate the effectiveness of the proposed method. The results inferred that the rigidity of the hole could be differentiated between the formation of a proper and improper bush. The study opines that the decision tree method is faster and more accurate compared to the other two methods for identifying the quality of the drilled hole.