Search Results (64)

This article analyzes statistics on the failure of technological equipment, assemblies, and mechanisms of agricultural (and other) machines associated with the breakdown or failure of gear pumps. It was found that the leading causes of gear pump failures are the opening of gear teeth contact during pump operation, poor assembly, wear of bushings, thrust washers, and gear teeth. It has also been found that there is a problem related to the restoration, repair, and manufacture of parts in the conditions of enterprises serving the agro-industrial complex of the Republic of Kazakhstan (AIC RK). This is due to the lack of necessary technological equipment, tools, and instruments, as well as centralized repair and restoration bases equipped with the required equipment. This work proposes to solve this problem by applying AM technologies to the repair and manufacture of parts for agricultural machinery and equipment. The study results on the stress–strain state of support bushings under various pressures are presented, showing that a fully filled bushing has the lowest stresses and strains. It was also found that bushings with 50% filling and fully filled bushings have similar stress and strain values under the same pressure. The difference between them is insignificant, especially when compared to bushings with lower filling. This means that filling the bushing by more than 50% does not provide a significant additional reduction in stresses. In terms of material and printing time savings, 50% filling may also be the optimal option. Full article

The new mineral achyrophanite (K,Na)₃(Fe³⁺,Ti,Al,Mg)₅O₂(AsO₄)₅ was found in high-temperature sublimates of the Arsenatnaya fumarole at the Second scoria cone of the Northern Breakthrough of the Great Tolbachik Fissure Eruption, Tolbachik volcano, Kamchatka, Russia. It is associated with aphthitalite-group sulfates, hematite, alluaudite-group arsenates (badalovite, calciojohillerite, johillerite, nickenichite, hatertite, and khrenovite), ozerovaite, pansnerite, arsenatrotitanite, yurmarinite, svabite, tilasite, katiarsite, yurgensonite, As-bearing sanidine, anhydrite, rutile, cassiterite, and pseudobrookite. Achyrophanite occurs as long-prismatic to acicular or, rarer, tabular crystals up to 0.02 × 0.2 × 1.5 mm, which form parallel, radiating, bush-like, or chaotic aggregates up to 3 mm across. It is transparent, straw-yellow to golden yellow, with strong vitreous luster. The mineral is brittle, with (001) perfect cleavage. D_calc is 3.814 g cm^–3. Achyrophanite is optically biaxial (+), α = 1.823(7), β = 1.840(7), γ = 1.895(7) (589 nm), 2V (meas.) = 60(10)°. Chemical composition (wt.%, electron microprobe) is: Na₂O 3.68, K₂O 9.32, CaO 0.38, MgO 1.37, MnO 0.08, CuO 0.82, ZnO 0.48, Al₂O₃ 2.09, Fe₂O₃ 20.42, SiO₂ 0.12, TiO₂ 7.35, P₂O₅ 0.14, V₂O₅ 0.33, As₂O₅ 51.88, SO₃ 1.04, and total 99.40. The empirical formula calculated based on 22 O apfu is Na_1.29K_2.15Ca_0.07Mg_0.34Mn_0.01Cu_0.11Zn_0.06Al_0.44Fe³⁺_2.77Ti_1.00Si_0.02P_0.02S_0.14V_0.04As_4.90O₂₂. Achyrophanite is orthorhombic, space group P222₁, a = 6.5824(2), b = 13.2488(4), c = 10.7613(3) Å, V = 938.48(5) ų and Z = 2. The strongest reflections of the PXRD pattern [d,Å(I)(hkl)] are 5.615(59)(101), 4.174(42)(022), 3.669(31)(130), 3.148(33)(103), 2.852(43)(141), 2.814(100)(042, 202), 2.689(29)(004), and 2.237(28)(152). The crystal structure of achyrophanite (solved from single-crystal XRD data, R = 4.47%) is unique. It is based on the octahedral-tetrahedral M-T-O pseudo-framework (M = Fe³⁺ with admixed Ti, Al, Mg, Na; T = As⁵⁺). Large-cation A sites (A = K, Na) are located in the channels of the pseudo-framework. The achyrophanite structure can be described as stuffed, with the defect heteropolyhedral pseudo-framework derivative of the orthorhombic Fe³⁺AsO₄ archetype. The mineral is named from the Greek άχυρον, straw, and φαίνομαι, to appear, in allusion to its typical straw-yellow color and long prismatic habit of crystals. Full article

A novel closed-form solution representing the fluid motion within a porous bushing was created to develop a recently patented bearing configuration with a self-contained lubrication system. The configuration has a lubricant reservoir surrounding the porous bushing that continuously supplies lubricant without an external pump. In regions of low pressure, the lubricant moves into the bearing clearance; where clearance pressure is high, the lubricant is transferred to the porous bushing and refills the supply reservoir. The porous bushing’s pressure distribution was used within Darcy’s law to determine the injection velocity into the bearing clearance. Selected cases were compared with previously published work for approach validation. The validity of assuming a linear distribution within the porous media was investigated, as was the variance of the attitude angle for eccentricity and the effects of porous medium thickness and bearing parameter on bearing load capacity. It was concluded that increasing the feeding parameter increased the bearing load capacity. The porous bearing’s pressure distribution, commonly assumed to be linear, was discovered to be increasingly nonlinear near the bearing’s axial ends. The effect of nonlinearity on the bearing load capacity depended on the thickness of the porous bushing and the eccentricity of the bearing. Full article

In this paper, the calculation model and method of the lubrication performance of the thrust bearing, which considers the thermal bomb deformation, are constructed based on the working characteristics of the main pump thrust of the nuclear power plant. The key design parameters of the tile package Angle θ are analyzed by taking the design parameters of the thrust-bearing tile as the variable. The circumferential fulcrum coefficient of tile, the influence of tile thickness B, and tile elastic modulus E on the lubrication performance of thrust bearing are analyzed to obtain improved design parameters. The lubrication performance of the thrust bearing includes the minimum oil film thickness h_min, the maximum temperature of oil film T_max, total flow Q_x, total power consumption W, maximum thermal deformation of axial bush δT_max, and the maximum elastic deformation of the axial bush δF_max. The scale test of the designed thrust bearing is carried out. The take-off speed of the bearing is tested and compared with the results of the theoretical analysis. The study results show that the influence is becoming more obvious from θo to h_min. Moreover, the impact becomes more obvious from T_max to Q_x, B to hmin, and Q_x to δT_max and δF_max. Lastly, the impact is also obvious from E to Q_x and δF_max. Full article

This study investigates the influence of geometric parameters on wear of journal bearings within a multibody system framework. While extensive research has explored the impact of wear on journal bearing performance, limited attention has been given to the role of geometric parameters in wear progression. To address this gap, this study examines the effects of bushing depth, internal and external bushing diameters, and bushing rim thickness on wear in a non-lubricated journal bearing joint within a slider–crank mechanism. The joint consists of a 347 stainless steel journal and a PTFE bushing operating under moderate loading conditions (0.25 MPa to 5 MPa) and low sliding velocities (1 mm/s to 10 mm/s). Wear predictions are conducted using the elastic foundation model (EFM) and finite element method (FEM), with multibody dynamics analysis providing joint force estimations. The results from both approaches reveal that (1) increasing bushing depth reduces both wear volume and maximum wear depth, (2) bushing outer diameter has little to no effect on wear volume and maximum wear depth, (3) smaller bushing rim thicknesses lead to greater wear volume, and (4) larger bushing depths reduce both wear volume and maximum wear depth. Consequently, it is recommended that journal bearings designed to minimize wear should have smaller inner diameters, with attention to the stress effects on the journal due to the reduced diameter. Additionally, small bushing rim thicknesses should be avoided, and larger bushing depths should be considered to reduce wear. These insights contribute to the optimization of journal bearing design for improved durability and performance in mechanical systems. Full article

The marine water-lubricated bearing’s (WLBs) dynamic properties are essential for ensuring the shaft system’s operational dependability. The coupled model of mixed lubrication and turbulence under the impact of bidirectional misalignment is proposed in this research, and the perturbation equations of marine WLBs with 32 coefficients are derived. The finite difference method (FDM) is used to solve the steady-state and perturbation equations, and the impacts of turbulence, bearing bush deformation, surface roughness, and bidirectional shaft misalignment on the dynamic characteristics of the WLBs are systematically investigated. The results reveal that under mixed lubrication, surface roughness and the turbulence effect can both greatly improve the stiffness and damping of the bearings, but that there is a threshold phenomenon for the turbulence effect’s influence on these properties. Neglecting the elastic deformation of the bush may lead to an overestimation of the bearings’ stiffness and damping, causing substantial inaccuracies in conditions of heavy load or declined Young’s modulus. The 32 coefficients of the WLB exhibit considerable variation with the misalignment angle; hence, a more comprehensive dynamic model should be developed for misaligned marine WLBs. The study’s findings provide valuable insights for rotor dynamics research and optimal design of lubrication performance in marine WLBs. Full article

In light of the issues associated with the laying process of transmission line cables, including concealed security risks and contact collisions between pulleys and cables, which primarily stem from reliance on drawings, this paper introduces a simulation methodology for the cable laying construction process utilizing Building Information Modeling (BIM) technology. Initially, two-dimensional DWG graphic data are employed to develop a model of the target equipment and construction environment using BIM software (Solid works 2020). Subsequently, the cable is accurately modeled by applying ADAMS virtual prototype technology, the bushing force connection method, and the macro command language. This allows for the construction of a three-dimensional real cable laying system for transmission lines, enabling the simulation of the dynamic cable laying process in the field. Subsequently, an error analysis is conducted to compare the axial tension and laying speed of the cable with theoretical calculation values. The study then proceeds to analyze tension fluctuations during the cable laying process and assess the load-bearing capacity of the pulleys, thus facilitating effective control of the construction process and enhancing safety measures. The findings indicate that the proposed method can accurately and efficiently simulate the on-site cable laying construction process, with numerical errors maintained below 5%, thereby validating the integrity of the model. Furthermore, the traction overload safety protection amplification coefficient is determined to be α = 1.5. It is highlighted that the bearing capacity of the block must exceed 60% of the load carried by the conductor at constant speed. This research provides a theoretical foundation for addressing safety hazards in cable laying engineering and holds certain engineering value. Full article

Carbon Fiber Reinforced Polymers (CFRPs) are extensively utilized in civil engineering and other domains due to their exceptional mechanical properties. Integrating CFRPs with steel presents an approach to structural design, characterized by enhanced load-bearing capabilities and extended service life. Static tensile and hysteretic tests were employed to examine the influence of the bolt diameter and steel plate thickness on the shear resistance of component. The results indicate that under monotonic loading, the load–displacement curves for each component undergo three distinct phases: the linear stage, damage evolution stage, and failure stage, ultimately leading to a bolt pull-off failure in all six groups of components. Under cyclic loading, the component with a 1.5 mm thick steel plate and a 4.6 mm diameter bushing bolt experienced bolt shear failure, primarily caused by the increased steel plate thickness, which enhanced the component’s load-carrying capacity, ultimately leading to the overloading and failure of the M4 bolt. The other five groups of components experienced pull-off failures. The hysteresis curve analysis revealed that enhancements in steel plate thickness and bolt diameter improve the hysteresis behaviour of the connections. However, there was a significant reduction in the strength degradation coefficient and hoop stiffness, which decreased to approximately 55% and 40% of their initial values, respectively. Full article

Predictive assessments of the performance characteristics of metal-polymer (MP) plain bearings at the design stage are necessary and important for engineering practice. They include assessments of bearing capacity, linear wear of the bushing, and bearing life. However, no method for their calculation has been developed. The authors created a generalized analytical method for the mathematical modeling of MP sliding bearings as a classical science-based method to study the contact mechanics of conformal cylindrical bodies with consideration of polymer bushing wear. The contact problem of the theory of elasticity takes into account the significant difference in the elasticity characteristics of polymeric materials from those of steel: their Young’s modulus is 60–250 times smaller, and Poisson’s ratio is 1.27–1.37 times larger. The method was used to study MP bearings with bushings made from several common groups of tribopolymers: polyamides (PAs), polytetrafluoroethylenes (PTFEs), polyethylene terephthalates (PETs), and polyetheretherketones (PEEKs). The maximum contact pressures and durability of the dry friction bearings were calculated while taking into account the load; radial clearance; bushing thickness; the tribopolymers’ elasticity characteristics and wear resistance; the sliding friction coefficient; and the type of tribopolymer material. The Young’s modulus of a polymer material had a significant impact on the level of maximum contact pressures. Polymer fillers, depending on their type and the type of polymer, had very different effects on pressure changes (increase, no change, or decrease). An increase in pressure caused an increase in contact pressures. The durability of a mechanical bearing depended not only on the contact pressure but also on the polymer’s wear resistance, Young’s modulus, and friction coefficient. This study determined the quantitative and qualitative effects of these factors on the maximum contact pressures and bearing durability. The presented analytical method provides an effective and reasonable assessment of the specified service characteristics of sliding bearings with consideration of the multifactorial influence of the above factors. Full article

Tin-based Babbitt alloys are a widely used bearing bushing material which have good comprehensive properties. However, problems such as high-temperature softening and insufficient bearing capacity occur during their use, so the optimization of tin-based Babbitt alloys has become a research hotspot. In this paper, ZChSnSb11-6 alloy was mainly prepared by the gravity casting method, and different amounts of Zn were added to the alloy (the mass fraction values were 0 wt.%, 0.05 wt.%, 0.1 wt.%, 0.15 wt.%, and 0.2 wt.%, respectively). Through the hardness test, the tensile test, the friction and wear test, and the microstructure observation of the prepared alloy, the influence of Zn on the organization and properties of the ZChSnSb11-6 alloy was analyzed. The results show that the size of the SnSb hard phase changed with the increasing content of Zn. The size of the hard phase of the SnSb tended to increase first and then decrease, and the number of phase particles increased first and then decreased, resulting in changes in performance. Through comparison, it was learned that the addition of Zn can effectively improve the hardness, tensile strength, yield strength, and wear resistance of the alloy, but the elongation rate was reduced. When the Zn content was 0.1 wt.%, the hardness value of the alloy reached the maximum value, 25.82 HB, which increased by 7.3% when compared with the sample without Zn. The hardness of the Zn, 0.15 wt.%, is close to that of the Zn, 0.1 wt.%. Compared to the sample without Zn, the tensile strength and elongation of the alloy were maximized at a Zn content of 0.15 wt.%. Compared to the sample without the Zn, the tensile strength was increased by 21.29%, and the elongation rate was increased by 46%. An analysis showed that the alloy has good comprehensive mechanical properties when the Zn content is 0.15 wt.%. Full article

Firmly, the bearing capacity test of 1:1 equal ratio pillar under different constraint forms and different filling medium conditions was carried out. The results show that the binding pillar-forming effect is relatively good. The constraint ability of unconstrained, metal mesh, polyester mesh, hooked iron flat-hoop bushing, bellows, and spiral iron pipe is enhanced, in turn, and the carrying capacity is improved successfully. The homogeneity of high-water materials is better than concrete, and they have better compressibility, but their carrying capacity is relatively weak. The carrying capacity of concrete pillars is generously higher than that of high-water materials, but the compressibility is poor. Second, the migration characteristics of the surrounding rock structure of the gob-side entry retaining and the rule of side support are analyzed, the requirements of the side support are pointed out, and the side-support technology of the binding pillar is proposed. Taking Hijiata Mine’s 50108 working face gob-side entry retaining as an example, the bellows pump-filled concrete pillar is used as the side support body, supplemented by handling steel mesh and air-duct cloth, and toughness material is sprayed between the pillars to seal the goaf, meeting the requirements of side support and road stability. The pillar has the characteristics of high early strength, strong final consolidation carrying capacity, good crimping effect, high mechanism degree, fast construction speed, less concrete consumption, low comprehensive cost, etc., and it has a good application prospect in the gob-side entry retaining or rapid advanced working face. Full article

Lead-Bismuth Eutectic (LBE) is an interesting candidate as a coolant for Generation IV nuclear power plants. Lead-bismuth lubricated radial guide bearing is the key component of the mechanical pump in a lead-bismuth coolant system. In this paper, the transient calculation model of multiphase lubrication flow field of journal bearing is established by using Singhal full cavitation model and structured dynamic grid technique. Due to the saturated vapors of LBE being very low, the effects of different Non-Condensable Gas (NCG) contents on the characteristics of lead-bismuth lubricated journal bearing systems were analyzed. The results show that the NCG content has an obvious influence on the working state of the bearing. With the increase in NCG content, the bearing load capacity decreases. Under the same load, with the increase in NCG content, the eccentricity of the static equilibrium position will be larger, which will increase the risk of bearing contact with the bearing bush. Moreover, the increase of NCG content will lead to the increase of tangential oil film force work, which is helpful to improve rotor stability. Full article

A spatial problem of elasticity theory is solved for a layer located on two bearings embedded in it. The bearings are represented as thick-walled pipes embedded in the layer parallel to its boundaries. The pipes are rigidly connected to the layer, and contact-type conditions (normal displacements and tangential stresses) are specified on the insides of the pipes. Stresses are set on the flat surfaces of the layer. The objective of this study is to obtain the stress–strain state of the body of the layer under different geometric characteristics of the model. The solution to the problem is presented in the form of the Lamé equation, whose terms are written in different coordinate systems. The generalized Fourier method is used to transfer the basic solutions between coordinate systems. By satisfying the boundary and conjugation conditions, the problem is reduced to a system of infinite linear algebraic equations of the second kind, to which the reduction method is applied. After finding the unknowns, using the generalized Fourier method, it is possible to find the stress–strain state at any point of the body. The numerical study of the stress state showed high convergence of the approximate solutions to the exact one. The stress–strain state of the composite body was analyzed for different geometric parameters and different pipe materials. The results obtained can be used for the preliminary determination of the geometric parameters of the model and the materials of the joints. The proposed solution method can be used not only to calculate the stress state of bearing joints, but also of bushings (under specified conditions of rigid contact without friction on the internal surfaces). Full article

Poly Ether Ether Ketone (PEEK) is a kind of special engineering plastic with excellent properties such as high-temperature resistance, self-lubrication, wear resistance, and high mechanical strength. However, its blending or composite modification applications still face numerous challenges. The primary objective of this research was to evaluate the friction and wear performance of a three-layer self-lubricating bearing bush, which was made from a modified material containing short carbon fiber and Poly Ether Ether Ketone (SCF/PEEK). The bearing bush is used as a surface contact layer on the pistons of a hydraulic motor in the interface with the cam roller. The bearing bush was processed using a 15% SCF-modified PEEK material, and the friction and wear test was conducted using a self-built friction test machine. This study aimed to assess the frictional and wear characteristics of the SCF/PEEK-modified material in the bearing bush. The results show that as the experimental pressure rises from 15 MPa to 25 MPa, the friction coefficient of the SCF-modified bearing bush experiences a significant decrease from 0.420 to 0.296. Furthermore, the stability of the frictional morphology of carbon fibers indicates its effective adaptability to low speed and high load conditions. Full article

CuAl8Fe5Ni4Zn4Sn1 (OF 2238) is a new lead-free copper alloy for plain-bearing applications that was first officially presented in a scientific journal in 2020. Soon after its invention, the use of the alloy for connecting rod bushings in heavy-duty internal combustion engines was promoted and validated with customers. The aim of this article is to describe the material properties of the new alloy in more detail than previously and explain how the advantageous properties of CuAl8Fe5Ni4Zn4Sn1 are generated. At the beginning of this article, the general development trends in the field of copper alloys for sliding applications are presented, into which the new alloy from this publication can be classified. In the main part of this publication, the authors go through the production chain of CuAl8Fe5Ni4Zn4Sn and show how the entire manufacturing process contributes to obtaining a material with a combination of high strength, ductility and sufficient toughness. This starts with fine microstructures after casting, followed by homogenisation and refinement during hot extrusion and work hardening chiefly during cold drawing. What is most surprising, however, is the finding that a strong hardening effect can be achieved in the new alloy by precipitation of fine κ-phase at temperatures of about 400 °C and air cooling without prior solution treatment. These results make it clear that there is great potential for further material developments to support material efficiency and even to expand the application limits. Full article