Rolling-sliding Friction Research Articles

Study on multi-level progressive optimization of planetary roller screw mechanism

This paper establishes a multi-level progressive optimization model of planetary roller screw mechanism (PRSM) to achieve a more uniform load distribution, lower contact stress considering rolling-sliding friction and reduced axial clearance. By integrating the Halton sequence and Kriging model into the design of experiment (DOE), the sensitivity of various parameters to the optimization objectives is studied, thereby determining the optimization flow. Based on the proposed geometric constraints, a combination strategy employing the AMGA2 and Hooke-Jeeves algorithm is implemented to efficiently obtain optimization results, with the optimized parameters from previous levels serving as design constants for the subsequent level of optimization. Further comparisons demonstrate a notable enhancement in the comprehensive performance of the optimized PRSM, which is ultimately validated through FEM.

Experimental study of the effects of temperature and humidity on the wear and damage behavior of U71Mn rail steel

Wheel-rail interfaces operating in open systems are constantly affected by environmental factors, such as water, relative humidity, temperature, leaves, and sand. In this study, a twin-disc rolling-sliding friction and wear test device with a controlled environmental chamber was used to conduct experiments to study the influence of high temperature and humidity on the wear and damage behavior of U71Mn rail steel. The results showed that surface oxidation of rails increased with increasing temperature and humidity. The surface oxides and very humid air provided lubrication that could reduce wear. With increasing temperature and humidity, the trend of the friction coefficient of the rail samples was basically consistent with that of the plastic deformation layer. The wear of rail samples first decreased and then increased with increasing humidity. However, with increasing temperature, the wear of the rail samples first increased and then decreased. With increasing temperature and humidity, the crack length on the rail surface gradually increased and extended to the center of the material, which made the competition between wear and rolling contact fatigue more intense. When the wear was less than rolling fatigue, rail surfaces underwent severe cracking and peeling, which resulted in the loss of a large amount of surface material.

Development of accelerated comparative assessment of contact fatigue strength based on the analysis of acoustic emission of friction units

The article presents the results of theoretical and experimental research of acoustic emission of friction units during rolling-sliding friction contact. The purpose of this study is the development of a method of accelerated assessment of contact fatigue strength with the application of acoustic emission during friction contact. The application of acoustic emission method reveals periods of energy state of the material: the activation, the damage accumulation, the transition to the initial fatigue damage. Pulse loading up to the maximum possible value was used for activation of damage accumulation process on the friction surfaces. Specific destructive energy for one load cycle was used as the fatigue strength assessment criterion. The developed technique allows to quantify the fatigue strength in analogy with the methods of such evaluation with the help of fatigue machines for testing at cyclic loads.

Surface particle lubrication and wearing mechanism for asphalt pavement with aeolian sand in deserts

• Wear and lubrication mechanism of aeolian sand on asphalt pavement was studied. • Rolling-sliding friction exists between tire/road surface with particulate contaminants. • Angularity of the sand accelerates the wear of the asphalt membrane on pavement. • The wearing rate is proposed to evaluate the third body wear effect of aeolian sand. Particulate pollutants have a significant lubricating and abrasive effect on asphalt pavements. In this research, an experimental evaluation using an indoor accelerated wearing apparatus was used to simulate the wearing of Aeolian sand on asphalt pavements in a desert area. The British Pendulum Tester and a 3D scanner have also been used to examine the changes in skid resistance and texture morphology over time. Then, to evaluate the wearing process of sand particles on pavements, the wearing rate was proposed, and ultimately, a prediction model for the pavement with aeolian sand was constructed. The results shows that the wear rates of clean pavement, 50%Ψ and 100%Ψ of sand are 25.6%, 28.6% and 33.8% respectively. In terms of particle lubrication, the pavement is in a mixed lubrication state at 50%Ψ of sand; and in a fluid lubrication state when aeolian sand completely covers asperities of the pavement. From the wearing point of view, tire wearing on clean road is two-body wear; when there is aeolian sand between the tire/road contact interface, it is abrasive wear. The skid resistance prediction model developed by integrating the Pearson Correlation and Ridge Regression methods to identify-five texture indexes (ZMPD, Z Ra , λ q , Z Rs , S dr ) and the British Pendulum Number (BPN) can effectively predict the lubricating and wearing effects of aeolian sand on the pavement.

Slippage effects on the crack behavior of pearlitic steel induced via rolling-sliding friction

The effect of slippage on the crack behavior of pearlitic steel induced by rolling-sliding friction has been investigated to elucidate the wear damage. The results show that the crack-initiated site occurred at sub-surface sites of the severely deformed phase structure — which is due to the exhausted ferrite ductility — and was accompanied by a series of adjacent connected voids. As the slippage increased, more cracks were observed with the dissolved cementite structure, ranging from lamellae to fragments and particles. The slippage effect on the wear and fatigue competition was demonstrated by comparing the crack propagation rate and wear loss of the material during the rolling-sliding friction process. The length and depth of initiated cracks were key parameters in evaluating the wear damage.

Third-body and crack behavior in white etching layer induced by sliding–rolling friction

Abstract The tribologically transformed structure of the white etching layer (WEL) always appears with some cracks accompanying microstructural evolution under friction. This work investigated crack behavior with the existence of WEL on pearlitic steel after rolling-sliding friction tests. The WEL microstructure was characterized using scanning electron microscopy, nano-indentation, focused ion beam, and transmission electron microscopy. According optical images, the WEL zone could be divided into white and yellowish zones; cracks existed at the boundary separating these two zones. The deformation degree of the cementite structure caused color differences in optical images and inhomogeneous chemical composition distributions in the same WEL zone. For cracks initiated and propagated at the WEL colony boundary, crack holes remained unconnected along the plastic deformation line.

Effect of load on tribological properties of silicon nitride/steel under rolling-sliding contact condition

Abstract The tribological behaviors of Si3N4/GCr15 tribo-pair under dry rolling-sliding friction condition at different loads were investigated by using a modified rolling-sliding contact device. The pure sliding friction under the same condition was executed as a comparison test. The results showed the friction coefficient and the wear rate at rolling-sliding contact condition were below that at pure sliding contact condition. For the rolling-sliding contact condition, when the loads were 10 N and 20 N, the wear mechanisms of Si3N4/GCr15 tribo-pair were adhesive wear and abrasive wear. Hence, the friction coefficients were higher (0.58 and 0.4 respectively). With the load continuously increased from 30 N to 100 N, the dominant wear mechanisms were the combination of adhesive wear, delamination wear and contact fatigue, and the friction coefficient decreased with an increase in the load. In addition, it also can be seen that the rotational number of the ball showed an increasing trend with the increase of the load with the aid of high-speed camera. At the loads of 30 N and 50 N, a discontinuous tribofilm was formed on the worn surface and the friction coefficients were 032 and 0.23 respectively. At the loads of 70 N and 100 N, the friction coefficients were as low as 0.14 and 0.08, the wear rates of both ball and disk were the order of magnitude of 10−7 mm3N−1m−1, and the worn surfaces were quite smooth with a handful of spalling zone, which can be attributed to the tribo-chemical reaction products. For the pure sliding contact condition, the wear mechanisms of Si3N4/GCr15 tribo-pair were mainly dominated by mechanical wear at the loads of 10 N, 20 N and 30 N, and when the load was 50 N the dominating wear mechanism was tribo-oxidation reaction.

The influence of bearing grease composition on friction in rolling/sliding concentrated contacts

This paper presents new results examining the relationship between bearing grease composition and rolling-sliding friction in lubricated contacts. Friction coefficient and lubricating film thickness of a series of commercially available bearing greases and their bled oils were measured in laboratory tribometers. Test greases were selected to cover a wide spectrum of thickener and base oil types, and base oil viscosities. The trends in measured friction coefficients were analysed in relation to grease composition in an attempt to establish the relative influence of individual grease components on friction. Two distinct operating regions with markedly different friction behaviour are identified for each grease. At relatively high speeds the greases behave approximately as their bled/base oils, while in the low speed region the frictional response is very dependent on their thickener type and properties of the lubricating film. Low viscosity, synthetic base oil seems to offer efficiency advantages in the high speed region regardless of thickener used, while the choice of thickener type is significant under low speed conditions.

Effect of Microstructure on Rolling Contact Fatigue of Bearings

There has been proposed an innovative thermal treatment of bearing steel 100CrMnSi6-4, where the existing standard heat treatment has been replaced by austempering. The structure of low-temperature tempered martensite has been replaced by a microstructure composed of martensite and lower bainite with midrib. The kinetics of bainitic transformation and isothermal martensitic transition at selected austempering temperatures was controlled by acoustic emission. The research on contact strength was made under the conditions of rolling-sliding friction. The microstructure was revealed with the use of a light microscope and the forms of pitting wear were displayed by a scanning electron microscope. It was found that the optimum microstructure providing the best used contact strength of the tested steel is conditioned by the formation of a lower bainite with midrib at the temperatures near MS. A plausible cause of the increased resistance to pitting is bifurcation of fatigue cracks on dispersion bainitic carbides in combination with primary carbides, in bainitic-martensitic matrix.

Film Formation Property of Mineral Particles as Grease Lubricant Additives at Different Friction States

The characteristics of the 1045 steel pairs using superfine mineral powder as grease lubricant additive were investigated by an AMSLER friction and wear tester at different wear states. The surface topographies and composition of the worn surface of 1045 steel rings were identified by SEM and EDAX. The surface roughness of the samples was investigated by a profilometer. The results show that the additives can form a self-repairing film on the worn metal surface at Sliding state and there no film formed on the worn metal surface at Rolling-Sliding state. The reason is that the friction heat and friction energy produced by Sliding friction higher than the friction heat and friction energy produced by Rolling-Sliding friction.

トライボロジー関連研究の最近の進歩 ゴムのすべりの視覚的研究

The visualization of the rubber slip in the contact area during rolling-sliding friction was reviewed. The contact area between the rotating rubber wheel and the mating glass was observed simultaneously to understand how the sliding region and the adhesion region related to the μ-S characteristics during the rolling-sliding friction. Small markers with equal intervals were observed to measure the movement rates of the rubber surface in the contact area. As the results, the adhesion region and the sliding region in the rolling-sliding contact area were measured during sliding. The adhesion region, however, decreased to zero as the slip ratio attained to 15%. There was only the sliding region in the contact area at the slip ratio more than 15%.

110 転がり滑り接触するゴム摩擦面の固着/滑り域の測定

110 転がり滑り接触するゴム摩擦面の固着/滑り域の測定

Tribological characteristics of bonded MoS 2 films evaluated in rolling-sliding contact in a vacuum

Tribological characteristics of bonded MoS 2 films have been evaluated in air, nitrogen and vacuum using a two-roller type rolling-sliding friction apparatus. Two conventional space-proven films, polyamideimide-bonded and sodium silicate-bonded, designated as film A and film B respectively, were tested at a speed of 998 rev min -1 under a load of 100 N at slip ratios of 1–100%, the slip ratio being defined as ( V 1 - V 2)/ V 1 × 100%, in which V 1 and V 2 was rotational speed of each roller. The wear life of the film A was more slip ratio dependent than that of the film B. The wear life of the film A tested in a vacuum was the longest at 10% slip ratio but it reduced significantly at 1%. On the contrary, the best durability of the film B was obtained at 100% slip ratio (pure sliding). The wear life of the film A shortened considerably in air and nitrogen. In general, a solid lubricant film applied to spur gears is subjected to rolling-sliding friction of 0-10% slip ratios. To improve the endurance life of the film A at 1% slip ratio, films prepared by changing content of pigments (MoS 2 and Sb 20 3) were evaluated. The films with a pigment content of 5-15% showed a marked improvement in wear life at a slip ratio of 1%, while maintaining excellent durability at 10%. The wear process of an improved film was monitored using a gap sensor. It appears to be dominated by fatigue.

Laboratory tests for wear of rail and wheel steels

The extreme diversity of railway working conditions necessitates a variety of experimental methods for testing the wear of rail and wheel steels. This paper aims to develop some relations between the wear and hardness of rail and wheel steels by four test methods: rolling-sliding friction with longitudinal slippage; rolling-sliding friction with constant friction force; rolling-sliding friction with lateral slippage; pure sliding friction. None of the methods can simulate railway performance alone, but their joint consideration allows one to determine the trend of the change in wear resistance due to changes in working conditions.

Properties of Rolling-Sliding Friction on Carbon-Fiber-Reinforced Polyphenylene Sulfide(PPS) Composites.

An investigation was performed on properties of rolling-sliding friction on carbon-fiber-reinforced PPS composites. These tests were conducted with different fiber weight contents (15, 30, 45, 55%) against steel (SUJ2) without lubrication. Discussions were presented on the effects of the rolling-sliding friction on the fiber content and the surface roughness of the test pieces. As a result, the coefficient of rolling-sliding friction showed a minimum value at the fiber content of 30-45 wt. %. The experimental coefficient of friction under rolling-sliding contact between two cylinders was similar to the theoretical value evaluated by the law of mixture on friction. Properties of rolling-sliding friction depended on the fiber contact ratio under a contact area, but were not influenced by the surface roughness.

Investigation of tribological characteristics of rolling-sliding friction systems by means of systematic wear experiments under well-defined conditions

Systematic experimental investigation of wear due to rolling-sliding friction shows that well-defined test conditions enable clear trends in stationary wear rates to be detected. Even slight trend deviations in measured wear rates may be ascribed to the effects of small changes in test conditions.

Studies on the Scoring by Using a Crossed Cylinders Friction Machine : 1st Report, On the Initial Situation of Scoring

By using a crossed cylinder friction machine, the rolling-sliding friction tests under a lubricating condition were carried out, and the scoring marks which had been induced by single friction were studied. Then the initial situation of scoring can be decided by using a drawing method from the scoring marks on upper and lower cylindrical specimens. The features of scoring marks on the normalized steel, the hardened and tempered steel and the surface-hardened steel were also clarified by the observation with a microscope. And then the surface flash temperature at the initial situation of scoring was investigated on the basis of calculating results of frictional surface temperature in the elliptical contact area.