Journal articles: 'Rolling contact loads'

1

Zhou, R. S., H. S. Cheng, and T. Mura. "Micropitting in Rolling and Sliding Contact Under Mixed Lubrication." Journal of Tribology 111, no. 4 (October 1, 1989): 605–13. http://dx.doi.org/10.1115/1.3261984.

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Based on morphological tests in rolling and sliding contact, the effect of surface film, the subsurface heavily dislocated layer, crack initiation, crack propagation, and micropitting have been investigated by using a two-disk rig. A micro-macro contact model is presented for surface pitting in rolling and sliding contacts. In this model the pressures related to asperity interaction and the subsurface stress map along whole contact area have been analyzed by superimposing the asperity contacting loads on the Hertzian load for a given specimen surface. Compared to the experimental results, this model is capable of predicting the onset of micropits for given mechanical and lubrication conditions. Cracking is assumed to occur when the accumulated strain energy of the dislocation reaches a critical value. A three-dimensional crack propagating model has also been used for pitting life prediction in rolling and sliding contact.

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Choi, Dong Chul, and Tae Wan Kim. "Contact Analysis for the Critical Shoulder Height in Angular Contact Ball Bearing." Advanced Materials Research 433-440 (January 2012): 538–43. http://dx.doi.org/10.4028/www.scientific.net/amr.433-440.538.

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A numerical method to determine the shoulder height in the angular contact ball bearing using 3D contact analysis is proposed. The load analysis of a ball bearing was performed to calculate the distributions of internal loads and contact angles of each rolling element. From the results of bearing load analysis and the contact geometry between ball and inner/outer raceway, 3D contact analyses are conducted. The developed algorithm is applied to an angular contact ball bearing for the automotive wheel. The critical axial loads which are not affected by edge in the present shoulder height are calculated. The critical shoulder heights are also determined when the bearing is subjected to a practical load.

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Sadeghi, Farshid, and Kyung-Hoon Kim. "Effects of a Single Bump or Dent in Time Dependent Thermal Line EHD Lubrication." Journal of Tribology 116, no. 1 (January 1, 1994): 9–20. http://dx.doi.org/10.1115/1.2927055.

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A time-dependent thermal compressible elastohydrodynamic lubrication of line contact model has been developed to investigate the effects of a single bump or dent in heavily loaded rolling/sliding contacts. The results illustrate the transient behavior of the film thickness, pressure and temperature distributions as a bump or a dent travels through the contact. The multigrid multilevel technique was used to simultaneously solve the discretized time dependent Reynolds, elasticity and energy equations. The effects of various loads and speeds have been investigated. Results are presented for the nondimensional loads of W = 1.3 × 10−4, 2.3 × 10−4 and nondimensional speeds ranging from U = 1 × 10−11 to U = 10−10 under pure rolling and rolling/sliding conditions.

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Wirsching, Sven, and Marcel Bartz. "Using exact macroscopic geometry in elastohydrodynamic simulations of point and elliptical contacts." Tribologie und Schmierungstechnik 69, no. 5-6 (February 15, 2023): 54–61. http://dx.doi.org/10.24053/tus-2022-0045.

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In rib-guided roller bearings, there are a large number of different tribological contact forms. These include not only line contacts on the raceways, the cage and the rolling elements, but also point and elliptical contacts between the rolling element end face and the ring rib. Load is transmitted via these lubricated, concentrated rolling and rolling-sliding contacts. Depending on the load situation, these contacts contribute differently to the operating behavior of the roller bearing. Axial loads on rib-guided roller bearings are mainly transmitted via the point and elliptical contacts between the roller end and the ring rib. These oil-lubricated point and elliptical contacts can be calculated and designed using thermos-elastohydrodynamic (TEHD) simulations. In existing methods for the TEHD calculation of point and elliptical contacts, the macroscopic geometries of the contact partners are described in a simplified manner, similar to the theory according to HERTZ, using ellipsoids. However, contacts of real, complex geometry pairings of rolling elements and ribs, as used to optimize the axial load capacity or the frictional torque of roller bearings, can only be determined inaccurately with this method. Compared to the exact consideration of the macroscopic geometry, larger discrepancies in the lubricant film height, contact pressure and friction can be observed. For this reason, this paper presents a TEHD simulation that considers the exact macroscopic geometry of point or elliptical contacts. The macroscopic geometry is generated using mathematical functions and a ray-tracing method is used to generate the equivalent body for the TEHD simulation. Different geometry pairings of sphere, plane, cone and torus are investigated. The results for lubricant film height, contact pressure and friction are compared with the results from conventional TEHD simulations, which use a geometry description via ellipsoids. By comparing the calculated geometry pairings, the possibilities and limitations of the modified geometry description are assessed.

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Sun, Wei, Xiangxi Kong, Bo Wang, and Xingzhan Li. "Statics modeling and analysis of linear rolling guideway considering rolling balls contact." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 229, no. 1 (April 17, 2014): 168–79. http://dx.doi.org/10.1177/0954406214531943.

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The linear rolling guideway is composed of rail, carriage, rolling balls, and other accessories and contains a large number of rolling interfaces between the rolling balls and the grooves. For such a complex nonlinear mechanical system, it is very significant to obtain the statics deformation and vertical stiffness under different loads for the structural design of guideway and mechanical analysis of Computer Numerical Control (CNC) machine tool. Therefore, the focus of this study is on the development of statics modeling techniques of the linear rolling guideway by analytical and finite element methods, considering the rolling balls contact. First, an accurate statics analytical modeling method was proposed by using the Hertz contact theory and revision of experiment results. Then, on the basis of considering contacts between rolling balls and grooves, the precise finite element modeling was studied. To improve the efficiency of analysis, the full finite element model of guideway was replaced by the component finite element model. At last, the created analytical and component finite element models were applied to analyze the effects of load and preload on the statics characteristics of single ball and the whole guideway system. The proposal of current study may provide a reference to create the precise dynamics model of linear rolling guideway.

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Kumar, S., and S. P. Singh. "Threshold Stress Criterion in New Wheel/Rail Interaction for Limiting Rail Damage Under Heavy Axle Loads." Journal of Engineering for Industry 114, no. 3 (August 1, 1992): 284–88. http://dx.doi.org/10.1115/1.2899793.

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This paper presents a qualitative discussion of the effects of increasing new (initial) wheel-rail contact stresses on the degree of damage to the rail due to heavy axle loads. The importance and need of heavy axle loads and its relationship to rail damage as a result of the increasing wheel-rail contact stresses is discussed. Various mechanisms of energy absorption/losses due to free rolling and modes of rail damage are presented. These modes include surface and internal damage due to wear, contact shear, plasticity, fatigue, shelling, crack formation, etc. The concept of threshold stress observed in free rolling friction much earlier by Drutowski is discussed and analyzed. It is believed by the authors that the threshold stress is s material property. This concept of threshold stress, based on sharply increased rates of wear in free rolling contact, is then presented and analyzed. Considerations of increased plasticity-region development, due to increasing contact stresses and their relationship to increased rates of wear seen in experiments, is utilized to determine an upper bound of contact stresses for new wheel and rail under heavy axle load conditions. It is indicated that new wheel-rail profiles, which will achieve contact stresses below the threshold stress, will enable the U.S. railroads to carry heavy axle loads without serious future damage to the rails. It is concluded that a satisfactory solution for maintaining rail integrity under heavy axle loads is possible with proper design accompanied with laboratory experimentation for the new steels as they may be used in the rails.

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Houpert, L. "Piezoviscous-Rigid Rolling and Sliding Traction Forces, Application: The Rolling Element–Cage Pocket Contact." Journal of Tribology 109, no. 2 (April 1, 1987): 363–70. http://dx.doi.org/10.1115/1.3261367.

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Piezoviscous Rigid (PVR) film thicknesses, rolling and sliding traction forces formulas for the line and point contact case have been derived. They have been used to study the Rolling Element (R.E.)–cage pocket contact mechanism. As the R.E. gets closer to the cage web, the lubrication regime change gradually from the PVR regime to Piezoviscous Elastic (PVE or EHD) regime when steel cages are used. If plastic cages are used, the lubrication regime moves from the Isoviscous Elastic (IVE) regime to EHD regime. For the conditions simulated herein, the transition occurs at typical film thickness values of the order of 0.5 micrometers and substantially large loads can be calculated in the R.E.–steel cage contact. They can be of the order of 100 N at the transition. In many circumstances, the PVR regime prevails and the braking moment due to hydrodynamic traction in the contact can be easily calculated. A tight osculation between the R.E. and the cage pocket will increase significantly the load and braking moment on the R.E. Starvation effects are also estimated and cause a reduction of the load, but not of the braking moment.

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Ghalme, Sachin G. "Probabilistic Life Models in Rolling Contact Fatigue." Advanced Materials Research 433-440 (January 2012): 58–62. http://dx.doi.org/10.4028/www.scientific.net/amr.433-440.58.

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Rolling contact fatigue (RCF) is the name given to crack growth and material damage generated as a result of high loads transmitted between two surfaces which are rolling with relative to each other. An understanding of rolling contact fatigue failure mechanism and a prediction of lifetimes are of interest to both manufacturer and researcher. Subsurface originated cracks have been recognized as one of the main modes of failure for rolling contact fatigue (RCF) of bearings. Numbers of investigators have attempted to determine the physical mechanism involved in rolling contact fatigue of bearings and proposed models to predict their fatigue lives. This paper attempts to cover the most widely used probabilistic life models used in RCF.

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Li, Junning, Jiafan Xue, Ka Han, Qian Wang, and Wuge Chen. "Experimental Analysis on Skid Damage of Roller Bearing with the Time-Varying Slip and Temperature Distribution." Applied Sciences 10, no. 1 (December 18, 2019): 9. http://dx.doi.org/10.3390/app10010009.

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Skid damage affects the performance of aviation bearing, which covers different disciplines in tribology, thermology, materials science, dynamics, et al. In this manuscript, a novel horizontal skid damage test rig of a rolling bearing with higher rotation accuracy and better linear contact was built, which can simulate the rolling/sliding contact between the roller and inner ring. Combining with temperature, load, speed, slip, and surface microscopy, the skid damage mechanism of roller bearings was analyzed from a multi-information perspective. Meanwhile, the dynamic lubrication failure process of the contact pair in rolling bearings with the time-varying slip and temperature distribution was revealed. The effect of different radial loads, inner ring speeds, lubricating oil quantities, and states of cleanliness on the time-varying characteristics of the temperature and the slip of the rolling bearing were obtained. Among them, the radial load has the greatest influence on the slip rate of rolling bearing. In addition, the test results show that the skid damage under extremely light load is the comprehensive effect of adhesive wear and thermal failure.

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Li, Zhi, Jian Chen, Jiazhu Li, and Kun Liu. "Effect of textured surface on the frictional noise under line contact and sliding–rolling conditions." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 232, no. 9 (April 29, 2017): 1679–89. http://dx.doi.org/10.1177/0954406217706721.

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Line contact and sliding–rolling movements exist widely in gears and bearings. In order to investigate the influence of surface microstructure on the frictional noise, a numerical study on the frictional noise generated by textured surfaces under line contact and sliding–rolling conditions by the use of finite element method is presented. The finite element model is established based on real surface topography. To improve the analysis reliability, friction coefficients used in the simulation are measured for different textured surfaces under various loads and speeds. The relationship between the 3D surface topography parameters and the frictional noise are analyzed. Results show that the frictional noise under line contact sliding–rolling conditions increases with load and speed, which can be explained from an energy dissipation perspective. Moreover, the 3D surface topography parameters of mean peak curvature and peak density influence the frictional noise during sliding–rolling under line contact significantly.

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Zhang, Yongbin. "Prevention of interfacial slippage in isothermal pure rolling line contact elastohydrodynamic lubrication under heavy loads." Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology 217, no. 4 (April 1, 2003): 323–32. http://dx.doi.org/10.1243/135065003768618669.

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The contact-lubricant interfacial slippage, near and in the inlet zone, significantly reduces the load-carrying capacity of elastohydrodynamic lubrication (EHL) in isothermal pure rolling line contacts under heavy loads. The EHL load-carrying capacity can be significantly improved by the prevention of this interfacial slippage. Equations are derived for predicting the critical interfacial limiting shear stress, which is the least for preventing this interfacial slippage. These equations can be used for designing the EHL system of which the load-carrying capacity is not reduced by this slippage.

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Mizozoe, Syunsuke, Takahiro Matsueda, Katsuyuki Kida, and Yuji Kashima. "Observation of Surface and Subsurface Crack Propagation in PPS Thrust Bearings under Rolling Contact Fatigue in Water." Materials Science Forum 1020 (February 2021): 120–25. http://dx.doi.org/10.4028/www.scientific.net/msf.1020.120.

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In this study, crack propagation in PPS thrust bearings under rolling contact fatigue (RCF) in water was observed in order to investigate the relation between cracks and flakings. RCF tests in water under loads of 700 N and 900 N were performed. The semi-circular cracks propagated in a direction perpendicular to the rolling direction were observed under a load of 700 N. The line cracks propagated in a direction parallel to the rolling direction at periphery of contact area and the semi-circular cracks were observed under a load of 900 N. To study the subsurface cracks, full section of rolling contact area was observed. It is concluded that the flaking mechanism in PPS thrust bearing has three features as follows: Initiation and propagation of surface cracks depend on the load; When load is 700N, the semi-circular cracks growing from the surface and the cracks branching from the main subsurface cracks join to form the flaking; When load is 900N the line cracks and the semi-circular cracks growing from the surface join to form the flaking.

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Guo, Minrui, and Pan Zhu. "Triaxial Contact Stresses of the Green Bus Tire Including Complex Rubber Materials and Rim." Science of Advanced Materials 14, no. 8 (August 1, 2022): 1401–9. http://dx.doi.org/10.1166/sam.2022.4334.

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The primary purpose of the research is to explore triaxial contact stresses of the green bus tire including complex rubber materials and rim. An accurate finite element model of the bus tire is constructed using ABAQUS software after verification. The measured and calculated values have good consistency under different tire loads and inflation pressures. The finite element model is applied for quantitative research by changing tire loads, inflation pressures, and rolling conditions. The analysis results show that higher inflation pressure increases vertical contact stress, which requires a reasonable balance between high load and high inflation pressure. When the inflation pressure increases, the position of the maximum longitudinal contact stress shifts forward, and the maximum transverse contact stress shifts inboard in the transverse direction. When the tire load becomes larger at the free rolling condition, the position of the maximum vertical contact stress moves forward, and the position at the full braking condition is more advanced under the same load conditions. Overload not only causes great damage to the tire during the braking condition but also accelerates the appearance of the rutting and shoving of the road.

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Королев, Альберт, Albert Korolev, Михаил Захарченко, Mihail Zakharchenko, Кристина Мищенко, and Kristina Mishchenko. "Technological increase of static load carrying capacity of local raceways in ball bearings through ball rolling-off." Science intensive technologies in mechanical engineering 2018, no. 12 (December 8, 2018): 28–32. http://dx.doi.org/10.30987/article_5bf70416c07a10.01524769.

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The paper reports the consideration of the ball rolling-off mechanism of ball bearing rings. The regularities of the distribution of external combined load between balls are defined. There is offered a simulator of a rolling-ff process allowing the ratio definition between a load upon balls and acting factor including the angle of balls contact with a race and a correlation of a radial and axial external loads.

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Ando, M., and Jacob Sukumaran. "Tribological behavior of composite-steel on rolling/sliding contacts for various loads." International Journal Sustainable Construction & Design 2, no. 1 (November 6, 2011): 29–34. http://dx.doi.org/10.21825/scad.v2i1.20432.

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Composites have replaced metals in the bearing industry for the exclusive performances from itsproperties were it can accommodate resins, fabrics and additives. Roll-slip is common behaviors inapplication were non-conformal contact exhibits like bearings, rollers and cams. Two elements control thetribological behavior of the material which is the rolling and the sliding element. Composite-steel contactswere tested using a twin-disc setup with open tribo-system to study the influence of load on the frictionalbehavior of the polymer composites. The contacts were tested with four different loads under 20% slip ratiofor a regular interval of time. The curves from the friction force with respect to different loads follows atendency of linear increase in friction force were the rolling resistance is the dominating mechanism. For thegiven condition the macro level investigations shows the absence of transfer layer on the steelcounterparts. The tendency of the friction curve and the micrograph explicitly deliberates the involvement ofabrasion and adhesion in the harder polymer from metal counterpart. The temperature variable is isolatedin case of the above research. The examination of the contact surface reveals the formation of craters onthe junction of polymer and textile.

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Kossov, V. S., A. V. Savin, and O. G. Krasnov. "On the Issue of Determining Relative Rail Rolling Contact Fatigue Damageability." World of Transport and Transportation 19, no. 1 (September 8, 2021): 6–17. http://dx.doi.org/10.30932/1992-3252-2021-19-1-06-17.

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Adoption of heavy haul traffic on many railroads, comprising Russian railways, has highlighted the relevance of assessing the effect of increased axial loads on the contact fatigue life of rails.The article describes a set of theoretical studies carried out to create a scientifically substantiated method for predicting the contact fatigue life of rails depending on the values of axial loads. The stress-strain state of the contact area has been determined using the finite element model of wheel rolling on a rail. It has been found that the wheel-rail rolling contact area undergoes complex multiaxial loading with the simultaneous action of normal and shear strains. Based on the analysis of models describing multiaxial fatigue damage, the Brown–Miller model was chosen, which considers the simultaneous action of normal strains at the contact area and of maximum shear strains, which most fully describes the stress-strain state of the wheel-rail rolling contact area. To apply the Brown–Miller model, fatigue stress-strain curves for rail steel have been identified. Based on the analysis of methods for determining the parameters of stress-strain curves carried out by V. A. Troschenko, a modified Roessle– Fatemi hardness method has been applied. Based on the experimentally determined values of hardness on the rolling surface, the parameters of the curves of elastic and plastic fatigue have been revealed by calculation and experiment. To establish the damaging effect of the load from wheel rolling on a rail, the concept of relative damage per rolling cycle had been assumed which is the value inverse to the number of cycles preceding formation of a contact-fatigue crack at a given value of the axial load.Calculations of the relative damage rate of the rolling surface of rails caused by contact fatigue defects were carried out with the Fatigue software package considering mean values of the indicators of the degree of fatigue strength and plasticity of rail steel and the calculated stresses in the wheel-rail contact area, as well as the plasticity correction using Neuber method. The polynomial dependence of relative damageability of the rolling surface of rails is obtained. The established functional dependence of relative damageability of the rolling surface of rails on the values of vertical forces can be used as the basis for the developed methodology for predicting the contact fatigue life of rails.

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Shahani, A. R., R. Davachi, and M. Babaei. "The crack propagation path under multiple moving contact loads in rolling contact fatigue." Theoretical and Applied Fracture Mechanics 100 (April 2019): 200–207. http://dx.doi.org/10.1016/j.tafmec.2019.01.015.

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Zamă, A., and A. Tufescu. "A simple method to introduce the centrifugal effects in an angular contact ball bearing." IOP Conference Series: Materials Science and Engineering 1262, no. 1 (October 1, 2022): 012016. http://dx.doi.org/10.1088/1757-899x/1262/1/012016.

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An analytical model was developed for angular contact ball bearings running at high speeds. The model presented in this paper was designed for the 7206 C angular contact ball bearings and considers the geometrical parameters as well as the interactions between the raceways and the rolling elements involved while bearings are in operation. Using an original methodology, the effects of centrifugal forces generated by the rolling elements have been evidenced both on the normal contact load distribution and contact angles between balls and the two races. The effect of centrifugal forces was considered as a “supplementary clearance” included in a general model developed by Houpert for static conditions. Some simulations for various axial and radial loads and high rotational speeds have been presented. The results confirm important deviations of the static contact angle and the load distribution on both races.

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Mutton, P. J., C. J. Epp, and J. Dudek. "Rolling contact fatigue in railway wheels under high axle loads." Wear 144, no. 1-2 (April 1991): 139–52. http://dx.doi.org/10.1016/0043-1648(91)90011-i.

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Axinte, Tiberiu. "Finite Elements Analysis of the Rail-Wheel Rolling Contact." Advanced Materials Research 1036 (October 2014): 559–63. http://dx.doi.org/10.4028/www.scientific.net/amr.1036.559.

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The railway transportation system is nowadays one of the most important systems for land transport because its increased load carrying capacity, high speed, low costs, connectivity and ecologic features. As a result, the railways are subjected to additional loads which produce a higher level of strains and stresses. The rolling contact of a wheel on a rail is the basis of many rail-wheel related problems including the rail corrugation, wear, plastic deformation, rotating interaction fatigue, thermo-elastic-plastic behavior in contact, fracture, creep, and vehicle dynamics vibration. Therefore, this topic became the research subject for many researchers worldwide. Practical experience shows that the stress distribution is an important factor at the rail-wheel contact interfaces, that is, two materials in contact at rolling interfaces which are highly influenced by the geometry of the contacting surfaces, material constants, loads and boundary conditions. Three different procedures have conventionally been utilized to inspect rail-wheel contacts including Hertzs theory and Kalkers analytical method. The calculation of these stresses becomes much more complicated in three dimensional real size geometries. For this reason, many scientists have simplified the problem mainly by means of theoretical or numerical approaches based on the Hertzs theory, which can be considered the starting point of all subsequent researches. Both static and dynamic contact stresses have been carefully examined. Accurate theories, as well as computer software have been developed to evaluate all the parameters which influence the rail-wheel interaction. The analytical equations were employed to calculate the Hertzian stresses using the Octave software. For these elements, the simplifying hypothesis was to consider only the elastic properties of materials and, consequently, to neglect the elastic-plastic characteristics. Besides, many models generally neglected the friction coefficient between the rail and wheel, which is one of the most critical factors in determining the precise amount of stresses and distribution of contact pressure in rail-wheel contact area. On the other hand, some practical methods have also been introduced to solve traditional problems related to rail-wheel interaction. Other original contribution of this research is to create a precise finite element model of a 3D rail-wheel, axle and pads in order to evaluate stresses, strains, and contact forces in this complex interaction system. However, unlike many previous works, this study focuses on the real conditions of the problem including exact boundary and loading conditions, using real-size complete model of various components with precise shapes.

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Oyama, Shunsuke, Katsuyuki Kida, Edson Costa Santos, Hitonobu Koike, and Yuji Kashima. "Surface Profile Observation of PTFE Radial Bearings under Rolling-Contact-Fatigue in Water." Applied Mechanics and Materials 307 (February 2013): 337–41. http://dx.doi.org/10.4028/www.scientific.net/amm.307.337.

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Groove shape effect on wear behavior in PTFE radial bearings under rolling contact fatigue (RCF) was investigated. RCF tests in water-lubricated conditions were carried out at different loads and rotation speeds. The groove surfaces after testing were observed by using a laser confocal microscope and a two-dimensional shape measurement sensor. It was found that PTFE bearings under RCF generate wear debris, however no cracking or flaking failure could be observed. It is concluded that groove deformation depend on load rather than rotation speed. The biggest changes in groove profiles occurred when tested at loads close to 400N.

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Tolcha, Mesay, and Holm Altenbach. "Numerical Modeling Rolling Contact Problem and Elasticity Deformation of Rolling Die under Hot Milling." Metals 9, no. 2 (February 13, 2019): 226. http://dx.doi.org/10.3390/met9020226.

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In metalworking, rolling is a metal-forming process in which slab is passed through one or more pairs of the rolling dies to reduce the thickness and to make the thickness uniform. Modeling of rolling die contact with the slab primarily needs to describe the Tribology of contact phenomena. The central concern of numerical modeling is used in this work to indicate a set of equations, derived from the contact principle, that transfer the physical event into the mathematical equations. Continuum rolling contact phenomena is considered to explain how a contact region is formed between rolling die and slab and how the tangential force is distributed over the contact area with coefficient of friction. At the end, elasticity stress behavior of rolling die contact with the slab for a number of cyclic loads is modeled. The model includes new proposed constitutive equations for discontinuity of the velocity–pressure distribution in rolling contact from the entry side to exit side of the neutral point. To verify the model, finite element simulation and experimental data from the literature are considered. The results show good agreement with finite element simulation and experimental data.

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Tan, Rulong, Bingkui Chen, and Changyan Peng. "General mathematical model of spiral bevel gears of continuous pure-rolling contact." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 229, no. 15 (December 10, 2014): 2810–26. http://dx.doi.org/10.1177/0954406214563964.

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Sliding contact has negative influence for the performance of gears in most situations, such as frictional loss, pitting, micro-pitting, etc. To avoid sliding contact, this paper discusses the fundamental geometrical characteristics of spiral bevel gears of continuous pure-rolling contact. Differential geometry, gearing kinematics, and conjugate curve meshing method are used to derive the general mathematical model of spiral bevel gears of continuous pure-rolling contact. Simplified equations that continuous pure-rolling contact bevel gears must satisfy are derived. An example is represented to explain and verify this model. The theoretical results benefit further studies on design and manufacturing of spiral bevel gears of heavy loads and high efficiency.

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Wei, Yan Gang, Yan Tao Wang, and Chang Tao Han. "FEA on the Roller System of Rolling Mill." Advanced Materials Research 479-481 (February 2012): 1759–62. http://dx.doi.org/10.4028/www.scientific.net/amr.479-481.1759.

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According to contact mechanics, the contact regions between the rollers and the steel plate, and then the boundary conditions and FEA model of the roller system of rolling mill are determined reasonably considering the characteristic of the structure and loads. The simulations of the system under different values of loads have been done using FEA and main results are introduced in the paper. The work of this paper offers a reference to calculate the strength or work life of parts in the system and a basis to analyze the roller bearings in the system with 3D FEA in detail.

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Yang, Lei, Lei Wang, and Wanhua Zhao. "Hybrid modeling and analysis of multidirectional variable stiffness of the linear rolling guideway under combined loads." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 234, no. 13 (February 23, 2020): 2716–27. http://dx.doi.org/10.1177/0954406220908894.

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In the working process of high-speed multiaxis machine tools, inertial loads due to high feed acceleration and time-varying gravity loads due to changing configuration of multiaxis structure result in time-varying complex loads applied to linear rolling guideway. Existing models cannot efficiently represent the effect of complex loads on multidirectional stiffness variation of linear rolling guideway. In this paper, a hybrid model of multidirectional stiffness of linear rolling guideway and the solving algorithm are proposed. The complex loading conditions of linear rolling guideway in high-speed multiaxis machine tool structure are considered. And contact flexibilities between rolling balls and grooves are modeled with the effect of elastic deformations of runner block and rail. The proposed model can calculate the multidirectional stiffness with high accuracy. Meanwhile the differences between the stiffness characteristics in different directions are represented correctly. The variations of multidirectional stiffness of linear rolling guideway under time-varying combined loads are analyzed. This study provides an effective way to comprehensively evaluate the stiffness characteristics of linear rolling guideway which can contribute to the dynamic analysis and active design of high-speed machine tool structure.

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Kang, Young S., Farshid Sadeghi, and Xiaolan Ai. "Debris Effects on EHL Contact." Journal of Tribology 122, no. 4 (June 16, 2000): 711–20. http://dx.doi.org/10.1115/1.1314606.

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A model was developed to study the effects of a rigid debris on elastohydrodynamic lubrication of rolling/sliding contacts. In order to achieve the objectives the time dependent Reynolds equation was modified to include the effects of an ellipsoidal shaped debris. The modified time dependent Reynolds and elasticity equations were simultaneously solved to determine the pressure and film thickness in EHL contacts. The debris force balance equation was solved to determine the debris velocity. The model was then used to obtain results for a variety of loads, speeds, and debris sizes. The results indicate that the debris has a significant effect on the pressure distribution and causes a dent on the rolling/sliding bounding surfaces. Depending on the size and location of the debris the pressure generated within the contact can be high enough to plastically deform the bounding surfaces. Debris smaller than the minimum film thickness do not enter the contact and only large and more spherical debris move toward the contact. [S0742-4787(11)00501-7]

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Romanowicz, Paweł, and Bogdan Szybiński. "Analytical Estimation of Maximal Fatigue Loads in Cylindrical Roller Bearings." Applied Mechanics and Materials 477-478 (December 2013): 54–57. http://dx.doi.org/10.4028/www.scientific.net/amm.477-478.54.

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The limited time of usage and damage of rolling bearings is mainly attributed to the cyclic loads appearing during their work. As it is well-known these loads are distributed over the small contact area, which leads to the relatively high values of contact loads and stresses in the vicinity of the contact zone. This work is a proposal of the application of analytical formulas describing the stress distributions in the contact region and well-established multi-axial fatigue hypothesis in the estimation of fatigue loads of certain roller bearings. Additionally, the analytically calculated stresses are verified by means of the numerical results obtained with the use of finite element approximation.

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Li, Jianyao, Juke Liang, Gubo Chen, and Yan Yang. "Research on Key Control Technology of Intelligent Rolling Contact Fatigue Test Facility." Journal of Control Science and Engineering 2020 (March 16, 2020): 1–11. http://dx.doi.org/10.1155/2020/2045634.

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An intelligent rolling contact fatigue test equipment is developed, and the control methods are presented. For obtaining the slip accurately, the control method based on master-slave synchronization is proposed. For controlling the loads in high precision, the control method took into consideration the influence by two factors, displacement and the load. The nonlinear interference and excess torque in load control are effectively suppressed. Based on the SIMOTION D425 which is the Siemens integrated motion control system, the control system architecture of the intelligent rolling contact fatigue test equipment is constructed. The solutions of slip ratio and the experimental load controlled by these methods are satisfactory with the requirement of design precision. In the validation experiment, the load control accuracy is ±3%, the average error of load control is 1.77%, and the average error of slip control is 0.26%. The experiment results show the proposed control methods are feasible and effective.

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Eberhardt, A. W., and B. S. Kim. "Stress Intensity Factors for a Vertical Surface Crack in Polyethylene Subject to Rolling and Sliding Contact." Journal of Biomechanical Engineering 120, no. 6 (December 1, 1998): 778–83. http://dx.doi.org/10.1115/1.2834893.

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Pitting wear is a dominant form of polyethylene surface damage in total knee replacements, and may originate from surface cracks that propagate under repeated tribological contact. In the present study, stress intensity factors, KI, and KII, were calculated for a surface crack in a polyethylene-CoCr-bone system in the presence of rolling or sliding contact pressures. Variations in crack length and load location were studied to determine probable crack propagation mechanisms and modes. The crack tip experienced a wide range of mixed-mode conditions that varied as a function of crack length, load location, and sliding friction. Positive KI values were observed for shorter cracks in rolling contact and for all crack lengths when the sliding load moved away from the crack. KII was greatest when the load was directly adjacent to the crack (g/a = ±1), where coincidental Mode I stresses were predominantly compressive. Sliding friction substantially increased both KImax and KIImax. The effective Mode I stress intensity factors, Keff, were greatest at g/a = ±1, illustrating the significance of high shear stresses generated by loads adjacent to surface cracks. Keff trends suggest mechanisms for surface pitting by which surface cracks propagate along their original plane under repeated reciprocating rolling or sliding, and turn in the direction of sliding under unidirectional sliding contact.

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30

Guo, Minrui, Xiangwen Li, Maoping Ran, Xinglin Zhou, and Yuan Yan. "Analysis of Contact Stresses and Rolling Resistance of Truck-Bus Tyres under Different Working Conditions." Sustainability 12, no. 24 (December 18, 2020): 10603. http://dx.doi.org/10.3390/su122410603.

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In this work, to analyse the changing characteristics of contact stresses in the tyre–pavement interface and the functional relationship between rolling resistance and the working conditions of truck-bus tyres, a three-dimensional tyre–pavement model is established and used to predict the distribution of contact stresses and rolling resistance under different working conditions of the tyre, comprising various tyre loads, inflation pressures, and velocities. Results show that the magnitude relationship between transverse and longitudinal contact stresses is related to rolling conditions, and overload and low tyre pressure are important contributors to the wear of the tyre shoulder. In addition, the proposed exponential equation presents a method that can be used to forecast rolling resistance related to the working conditions of the truck-bus tyre, and a similar method can be used to predict the rolling resistances of other types of tyres.

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31

Aiyedun, P. O., and S. A. Aliu. "Rolling Temperature for Steel Hot Flat Rolled at Low Strain Rates." Advanced Materials Research 62-64 (February 2009): 317–23. http://dx.doi.org/10.4028/www.scientific.net/amr.62-64.317.

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Different methods of obtaining averages have been used to determine mean rolling temperatures from measured temperatures of various specimens during roll contact in hot flat rolling. The obtained mean rolling temperatures were used in turn in hot rolling simulation programs based on Sims, and Bland and Ford’s theories for calculating rolling loads and torque during hot flat rolling of steels at low strain rates (0.08 – 1.5 s-1). The hot rolling Bland and Ford’s (HRBF) Theory and Sim’s Theory gave similar results when any of the averaging methods of temperature is used to calculate rolling load and torque at high strain rates (1.5 –500s-1). However at low strain rates HRBF gave closer approximations to experimental results. Comparing the results with experimental values, the harmonic mean was found to give the best mean rolling temperature for hot flat rolling simulation at low strain rates compared to geometric mean, arithmetic mean and root mean square.

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32

Kim, Kyung Hoon, and Farshid Sadeghi. "Non-Newtonian Elastohydrodynamic Lubrication of Point Contact." Journal of Tribology 113, no. 4 (October 1, 1991): 703–11. http://dx.doi.org/10.1115/1.2920682.

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A numerical solution to the problem of isothermal non-Newtonian elastohydrodynamic lubrication of rolling/sliding point contacts has been obtained. The multigrid technique is used to solve the simultaneous system of two-dimensional modified Reynolds and elasticity equations. The effects of various loads, speeds, and slide to roll ratios on the pressure distribution, film thickness, and friction force have been investigated. Results for the dimensionless load W = 4.6 × 10−6 and 1.1 × 10−6, and the dimensionless velocity U = 3 × 10−10 and 3 × 10−11 are presented. The results indicate that slide to roll ratio has negligible effect on the minimum film thickness, however, it significantly reduces the pressure spike.

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33

Ricci, Mário César. "Internal Loading Distribution in Statically Loaded Ball Bearings Subjected to an Eccentric Thrust Load." Mathematical Problems in Engineering 2009 (2009): 1–36. http://dx.doi.org/10.1155/2009/471804.

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Rolling-element bearings are simple machine elements of great utility used both in simple commercial devices as in complex engineering mechanisms. Because of being a very popular machine element, there is a lot of literature on the subject. With regard to the behavior of internal loading distribution, elastic deformations at point or line contacts, and geometric parameters under loading, although there are many works describing the parameters variation models, few works show such variations in practice, even under simple static loadings. In an attempt to cover this gap some studies are being developed in parallel. Particularly in this work, anew, iterative computational procedure is introduced which calculates internal normal ball loads in statically loaded single-row, angular-contact ball bearings, subjected to a known thrust load which is applied to a variable distance (lever arm or eccentricity) from the geometric bearing center line. Numerical examples results for a 218 angular-contact ball bearing have been compared with those from the literature. Fifty figures are presented showing geometrical features and the following parameters variations as functions of the thrust load and eccentricity: contact angle, contact ellipse parameters, normal ball loads, distances between groove curvature centers, normal and axial deflections, and loading zones.

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34

Yu, Jianghong, Ran Zhang, Wen Yang, and Qishui Yao. "Dynamic Contact Characteristics of Elastic Composite Cylindrical Roller Bearing." Open Mechanical Engineering Journal 9, no. 1 (September 17, 2015): 703–8. http://dx.doi.org/10.2174/1874155x01509010703.

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Elastic composite cylindrical roller bearing is a kind of new bearing. In view of its structural particularity, explicit dynamics finite element model of elastic composite cylindrical roller bearing is established by utilizing ABAQUS/EXPLICIT. Dynamic responses of elastic composite cylindrical roller bearing are analyzed and response analysis is compared under different radial loads and rotation speeds. Dynamic responses of elastic composite cylindrical roller bearing are analyzed and response analysis is compared under different radial loads and rotation speeds. Results show that rolling and holder lag in rotation is as being compared to inner ring. The motion processes of all the holder, inner ring and roller have certain periodicity. Fluctuation amplitude of inner ring displacement increases with load. Response increases with rotation speed when amplification decreases. Analysis results can offer beneficial reference for further research on dynamic characteristics of elastic composite cylindrical roller bearing.

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35

Singh, S. P., and S. Kumar. "A Laboratory Investigation of Threshold Stress in Wheel/Rail Interaction for Heavy Axle Loads." Journal of Engineering for Industry 114, no. 1 (February 1, 1992): 109–15. http://dx.doi.org/10.1115/1.2899747.

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This study is a continuation of earlier investigations to determine acceptable upper bound of contact stresses (threshold stress) for new wheel and rail under heavy axle load conditions. Using sharply increased wear rate (as initial maximum contact stress increases) under free rolling conditions as an indicator of threshold stress, laboratory investigations of wheel-rail rolling contact wear, simulating the 125-ton car wheel load, were conducted. Tangent track conditions with clean and dry surfaces were tested on two facilities; one of one-quarter scale and the other of one-fifteenth scale wheel-rail simulation. The earlier experiments conducted in the IIT Railroad Engineering Laboratory to investigate threshold stress used a varying load with the same wheel-rail profiles, the present study used constant load with varying wheel-rail profiles to determine whether the above increase in wear rate phenomenon will still be observed. While the results of the small (1/15th) scale facility were not considered quantitatively conclusive because of small size, qualitatively they indicated the presence of threshold stress phenomenon. The results of the one-quarter scale test facility very clearly confirmed that there is indeed a threshold stress above which the rolling contact wear rates increased sharply. The value of this stress, found to be approximately the same as reported in the earlier study, was nearly 200 ksi (for standard carbon steel rail). From the earlier and the present investigations of threshold stress, it is clearly concluded that the increased wear rates are primarily due to the increased initial contact stresses and 200 ksi is the value of threshold stress for standard carbon steel rail. Initial wheel-rail contact stresses for new wheel-rail should not be allowed to exceed this value to reduce damage to rail for heavy axle loads. It is recommended that new wheel-rail profiles should be developed to achieve stresses at or below this threshold stress level. Benefits of improved rail life with this approach are also discussed.

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36

Fröhling, Robert, Ulrich Spangenberg, and Georg Hettasch. "Wheel/rail contact geometry assessment to limit rolling contact fatigue initiation at high axle loads." Vehicle System Dynamics 50, sup1 (January 2012): 319–34. http://dx.doi.org/10.1080/00423114.2012.665163.

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37

Guliyev, Sedir. "ASSESSMENT OF ROLLING BEARINGS OPERATING CONDITIONS." Technical Sciences and Technologies, no. 4(26) (2021): 50–57. http://dx.doi.org/10.25140/2411-5363-2021-4(26)-50-57.

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The article examines the possibilities of ensuring the reliability of the rolling bearingsof the equipment used in the process of painting aluminum sheets. It was noted that the fully mechanized production line at the enterprise ensures the pro-duction of high quality aluminum sheets. However, the productivity of the technological equipment usedin the dyeing process and the rejection of the bearings have a negative impact on the efficiency of production. Technological machines and equipment work in Azeraluminum OJSC in particularly difficult conditions, and therefore there is a need to increasethe reliability and longevity of the used roller bearings. The operating conditions of the bearingss, the distribution of loads between the rolling elements, as well as the contact stresses in the bearings details were assessed.

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38

Zhang, Lu, Lu Chen, and Wen Wang. "Study on the film-forming ability of water in oil emulsion with water concentration." Journal of Physics: Conference Series 2029, no. 1 (September 1, 2021): 012156. http://dx.doi.org/10.1088/1742-6596/2029/1/012156.

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Abstract This paper mainly explores the influence of different loads on the lubrication performance of point contact under pure rolling conditions and the abrasion phenomenon of water-containing emulsion on the contact area under pure sliding condition. The laboratory apparatus is point contact lubrication friction test equipment and the lubricant is water-containing emulsion.

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39

Tan, Yu Long, Qiang Wang, Shuang Hui Han, and Fang He. "Analysis on Structure of Radial-Axial Ring Rolling Experimental Equipment by FEM." Advanced Materials Research 690-693 (May 2013): 2201–4. http://dx.doi.org/10.4028/www.scientific.net/amr.690-693.2201.

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The FEM model of radial-axial ring rolling experimental equipment was established by using ANSYS through processing contact, constraints and loads. The structure stiffness and strength of both radial rolling system and axial rolling system were analyzed based on the analyses of distributions of Von Misese stress, equivalent strain and deformation. It is shown that both the two systems will be within the safe range without any plastic deformation during ring rolling process, and their stiffness is also satisfied with design requirement, which proves the successful design of the radial-axial ring rolling experimental equipment.

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40

Xu, Tengfei, Lihua Yang, and Kai Wang. "Characteristics of Duplex Angular Contact Ball Bearing with Combined External Loads and Angular Misalignment." Applied Sciences 10, no. 17 (August 20, 2020): 5756. http://dx.doi.org/10.3390/app10175756.

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As a kind of common phenomenon in practical engineering, misalignment error considerably changes the working performance of bearing. However, it has rarely attracted attention in the study of duplex angular contact ball bearings (DACBBs). To evaluate the influence of misalignment on DACBB, an analytical model of DACBB considering combined loads and angular misalignment is established for back-to-back, face-to-face, and tandem configurations. According to the geometrical relationship inside the bearing, the deformations caused by external load and angular misalignment are systematically analyzed. On this basis, the effects of external load, axial preload, and angular misalignment on the displacement, maximum contact load, contact load distribution, contact angle, and fatigue life of DACBB are analyzed. The results demonstrate the high dependence of the contact load and contact angle on the above factors. Angular misalignment causes the fluctuation of contact load and contact angle distributions along the azimuth angle of a rolling ball. Nonlinear relationships between fatigue life of DACBB, angular misalignment, and axial preload are obtained. The occurrence of angular misalignment considerably decreases the fatigue life of DACBB. The results suggest the necessity of angular misalignment analysis for DACBB.

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41

Liu, Yongzhen, and Yimin Zhang. "A research on the time-varying stiffness of the ball bearing considering the time-varying number of laden balls and load distribution." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 233, no. 12 (November 21, 2018): 4381–96. http://dx.doi.org/10.1177/0954406218811869.

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In response to the fact that not all rolling balls are laden when the angular contact ball bearing working under the condition with certain combined loads especially when the axial preload is not large enough, an analytical method for the determination of the time-varying stiffness of angular contact ball bearing considering the effect of time-varying number of laden balls and load distribution is proposed in this paper. According to the definition of the stiffness, the time-varying stiffness under different sets of combined loads is obtained by the implicit function derivation method. Only the principal diagonal elements of the stiffness matrix are studied for the sake of simplicity. Several numerical examples are simulated and the simulation results indicate that the time-varying number of laden balls and load distribution have a significant effect on the stiffness. The period of the time-varying stiffness is consistent with the time required for the cage to rotate the angle between the adjacent rolling balls. The calculation of the ball bearing quasi-static model and the analytical method for the determination of the stiffness is verified by the existing references.

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42

Mokhtar, M. O. A., and A. A. Abdel Ghany. "Elastohydrodynamic Behavior of Elliptical Contacts Under Pure Rolling Situations." Journal of Tribology 109, no. 4 (October 1, 1987): 659–63. http://dx.doi.org/10.1115/1.3261531.

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This part is a complimentary work to a previously published work on EHD lubrication behavior under pure sliding and combined rolling and sliding situations. In order to cover all aspects of EHD lubrication, the experimental work has been herein extended to present the results attained when two disks describe a pure rolling motion. A wide range of loads and speeds has been applied to the contacting disks under EHD regimes. The recorded pressure values and distribution confirm the existence of a second peak (spike) near the exit of the contact zone also under pure rolling situation. The spike has a value higher than maximum Hertzian pressure. A local constriction of oil film profile to identify the minimum EHD film thickness at trailing (exit) end of the film is observed to be nearby the location of the pressure spike. The results, compared to theoretical predictions, concluded that under pure rolling conditions, any increase in the applied load results in a corresponding increase in the developed pressure while a noticeable reduction in the minimum film thickness is recorded with decreasing rolling speeds.

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43

Itakura, Kiyoto, Takashi Honda, Shunsuke Oyama, Katsuyuki Kida, Shintaro Hazeyama, and Yuji Kashima. "Surface Profile Observation of PTFE Thrust Bearings under Rolling Contact Fatigue in Water." Advanced Materials Research 683 (April 2013): 391–95. http://dx.doi.org/10.4028/www.scientific.net/amr.683.391.

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The life of the PTFE thrust bearing under rolling contact fatigue (RCF) was investigated. The different conditions of axial loads and the rotating speeds under water were applied. The shapes of the bearing race before and after the tests were measured by a two-dimensional shape measurement sensor. The wear loss of PTFE bearing was rarely generated and the shape of the bearing changed slightly in the test. However, it was found that the lifetime of PTFE bearing depended on the temperature generated in the contact surface. In our testing machine condition, the bearing was collapsed over a load of 1600 N.

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44

Reina, S., D. A. Hills, and D. Dini. "Incipient Slip Conditions in the Rolling Contact of Tyred Wheels." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 224, no. 10 (April 22, 2010): 2049–54. http://dx.doi.org/10.1243/09544062jmes2075.

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The contact problem of a driving tyred wheel, pressed and rolling over an elastically similar half-plane, is considered. Although applicable to a wide range of shrink-fitted assemblies, the simplified model is solved to study the practical case of an elastically similar steel tyre mounted on a locomotive steel wheel subjected to tractive rolling. The behaviour of the system at the tyre—substrate interface is studied using closed-form solutions to calculate the state of stress within the tyre. Conditions leading to incipient slip and/or plasticity are identified and mapped for different loads and geometries.

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45

Rathore, S. K., and N. N. Kishore. "Finite Element Analysis of Rolling Contact Problems Using Minimum Dissipation of Energy Principle." Journal of Applied Mechanics 65, no. 1 (March 1, 1998): 271–73. http://dx.doi.org/10.1115/1.2789038.

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In steady rolling motion, the loads and the fields of strain, stress, and deformations do not change with time at the contact region, as the contact region is continuously being formed by a new rolling surface. The principle of minimum dissipation of energy and the concept of traveling finite elements are made use of in solving such problems and the determination of micro-slips. The conditions of contact are discovered by use of the kinematic constraints and the Coulomb’s law of friction. A two-dimensional plane-strain finite element method along with the iterative procedure is used. The results obtained are in good agreement with expected behavior.

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46

WARDA, Bogdan, and Henryk DUDA. "A METHOD FOR DETERMINING THE DISTRIBUTION OF LOADS IN ROLLING PAIRS IN CYCLOIDAL PLANETARY GEAR." Tribologia 271, no. 1 (February 28, 2018): 105–11. http://dx.doi.org/10.5604/01.3001.0010.6370.

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The power transmission system in the cycloidal planetary gear is created by a serial connection of three rolling pairs: central cylindrical roller bearings, a set of rolling pins in the straight-line mechanism, and cycloidal meshing. The paper presents the numerical method for determining the distribution of forces acting on each rolling pair of this gear. Unlike analytical methods, numerical methods allow one to find that distribution in corrected meshing. Geometrical dimensions used in the equations of balance for the planetary gear transmission Palmgren`s dependences for the deformation line contact were used to calculate forces between co-operating elements. Once the distribution of load is known, one can predict the fatigue life of Cyclo’s gears in rolling pairs. The fatigue of rolling pairs is a very good criterion to optimize geometrical parameters of the power transmission system.

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47

Kossov, V. S., G. M. Volokhov, O. G. Krasnov, M. N. Ovechnikov, A. L. Protopopov, and V. V. Oguenko. "Influence of the axial loads of rolling stock on the contact-fatigue life of rails." Vestnik of the Railway Research Institute 77, no. 3 (June 28, 2018): 149–56. http://dx.doi.org/10.21780/2223-9731-2018-77-3-149-156.

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Analysis of operational data for defective and highly defective rails showed that up to 25 % is the contact-fatigue defects. In connection with the development of heavy haul traffic on the Russian railways, it is relevant to determine the influence of cars with increased axial loads of 25 and 27 tf on the contact fatigue life of rails. The solution of this problem is set forth in this article. The Brown-Miller model of multi-axial fatigue was used in the calculation. This model is integrated into the Fatigue software system, which is tied to the Marc calculation system through Pat-ran. Since under operating conditions the wheel moves (rolls) along the rail on meandering trajectory, in computer modeling weight coefficients were taken into account that characterize the percentage of wheels in the cross-sectional areas of the rail. Calculations of contact fatigue life took into account the variability of vertical loads from the impact on the track of trains formed from innovative open cars with axial loads of 23.5, 25 and 27 tf under operating conditions, loaded with real loading blocks. According to the analysis of calculated data with an increase in axial loads from 23.5 to 25 tf, it is necessary to expect a decrease in the service life of rails in contact fatigue resistance by 19 %, with a further increase in axle loads of up to 27 tf per 32 %. Considering that the share of freight cars with axial loads of 25 tf does not exceed 15...20 %, then on the routes of its use the service life of rails should be expected to decrease by 3...4 %. The method proposed by the authors for predicting the contact fatigue life of rails with increasing axial loads is advisable to improve in part of the experimental determination of the fatigue and strength characteristics of rail steel from the degree of hardening of the rolling surface, its probabilistic properties and the use of the integral distribution law for vertical forces, taking into account the structure of the freight traffic passing through the section. The work was carried out according to the RFBR project 17-20 01088.

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48

Salehizadeh, H., and N. Saka. "Thermal Non-Newtonian Elastohydrodynamic Lubrication of Rolling Line Contacts." Journal of Tribology 113, no. 3 (July 1, 1991): 481–91. http://dx.doi.org/10.1115/1.2920649.

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The two-dimensional thermal elastohydrodynamic equations were numerically solved for a Ree-Eyring type lubricant under pure rolling conditions. Profiles of lubricant pressure, film thickness, and temperature were obtained for medium to heavy loads and moderate to high rolling speeds. The pressure results generally show a small secondary peak near the outlet, but at the highest load considered no pressure spike is obtained and the pressure profile is almost Hertzian. The film thickness results show an increase in minimum film thickness with increasing rolling speeds, but at a lesser rate than those predicted for a Newtonian fluid under isothermal conditions. It is found that unless the lubricant becomes non-Newtonian in the inlet region, the reduction in minimum film thickness at high rolling speeds is completely due to thermal effect. The lubricant temperature profile and the amount of heat generated and dissipated in the contact region were also calculated. The lubricant temperature reaches a maximum just before the entrance to the Hertz contact region. Both shear and compression heating are found to be important in raising the lubricant temperature in the inlet. As the lubricant enters the Hertz contact zone, the temperature first drops rapidly, because of the rapid heat conduction to the rollers, and then remains almost constant for most of the Hertz contact. Near the exit where the pressure gradients are large, the lubricant temperature drops rapidly below the ambient because of lubricant expansion. The lubricant then heats up rapidly before leaving the contact area as a result of heat generated by shear stresses.

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49

Mokhtar, M. O. A., and A. A. Abdel Ghany. "Elastohydrodynamic Behavior of Rolling Elliptical Contacts: Part I: Pressure and Temperature Distributions." Journal of Tribology 107, no. 3 (July 1, 1985): 343–48. http://dx.doi.org/10.1115/1.3261071.

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A two disk machine with a spherical disk mating a plain cylindrical one has been constructed to operate at different elliptical contact situations under various loads and rolling to sliding speeds. The disks axes can skew relative to each other so that various elliptical contacts could be tested. By the aid of specially modified evaporated transducers (Manganin band for pressure measurements and platinum band for temperature measurements), the elastohydrodynamic (EHD) pressure and temperature distributions could be accurately traced. Results, herein presented, confirmed that within the contact zone, the pressure distribution exhibits an almost Hertzian shape but with a second pressure peak (spike) near the trailing (exit) end of the oil film. The temperature has proven to display a distribution analogous to that described by the generated EHD pressure.

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50

Sverdlik, Mikhail, Alexander Pesin, and D. O. Pustovoytov. "Theoretical Basis and Technology Development of the Combined Process of Asymmetric Rolling and Plastic Bending." Advanced Materials Research 586 (November 2012): 259–64. http://dx.doi.org/10.4028/www.scientific.net/amr.586.259.

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The article focuses at technology development of the vertical asymmetric rolling and combined process of vertical asymmetric rolling and plastic bending. It has been shown that vertical asymmetric rolling peculiarity relates to the presence of a mixed zone, in which friction forces on contact roll surfaces are directed are differently. Experimental research showed serious drawbacks in the rolling technology caused by the growth of dynamic loads arising at the moment of plate contact with the bending roller. For solving the problem it was proposed to make the roller position motile to allow its movement along the required trajectory. The application of the motile roller helps to reduce dangerous torque differentiation at working rolls by the value of 1,5-2,5 compared with the rigidly fixed roller. The most effective bending roller trajectory is a second-order curve that is convex parabola.

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Journal articles on the topic 'Rolling contact loads'

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