Study on the transient temperature distribution of new conical friction plate under sliding friction

Conical friction surface is a novel configuration for friction plate in transmission. Numerical FEA models for transient heat transfer and distribution of conically grooved friction plate have been established to investigate the thermal behavior of the conical surface with different configurations. The finite element method is used to obtain the numerical solution, the temperature test data of conical surface are obtained by the friction test rig. In order to study and compare the temperature behavior of conically grooved friction plate, several three-dimensional transient temperature models are established. The heat generated on the friction interface during the continuous sliding process is calculated. Two different pressure conditions were defined to evaluate the influence of different load conditions on temperature rise and the effects of conical configuration parameters on surface temperature distribution are investigated. The results show that the radial temperature gradient on conical friction surface is obvious. The uniform pressure condition could be used when evaluating the temperature rise of conically grooved friction plate. The increase of the cone height could improve the radial temperature gradient of the conically grooved friction plate.

Formation of a surfactant adsorption layer on microroughnesses of friction surfaces

Formation of an adsorption surface layer on microneralities of friction surfaces. The model of interaction of the molecule of surface-active substance with the microasperity of friction surface has been given. It has been found that the distance of interaction and the thickness of an adsorbed layer of surface-active substances depend on value of a field of an adsorbing surface and energy of thermal oscillations of molecules of surface-active. It has been shown that the distance of interaction and the thickness of an adsorbed layer of surface-active substances decrease at magnification of temperature of working liquid.

Application of Multifractal Analysis for Research of Structural Materials

Application of multifractal analysis for qualitative and quantitative description of structural materials is demonstrated. This makes it possible to evaluate the system’s characteristics of structures and to characterize the processes of self-organization in the materials. Formation of friction surface structures for aluminum alloys with Al2O3 and SiC additives in the scuffing mode is considered under comparable thermodynamic conditions. The addition of SiC, in comparison with Al2O3 , is less conducive to fragmentation and increase in the frequency of seizure and rupture processes. The addition of graphite into a composite material reinforced with SiC leads to increase in the degree of non-equilibrium of the thermodynamic conditions for the formation of the structures. Additional introduction of graphite further enhances the difference between materials with additions of Al2O3 and SiC, and this leads to the formation of the least ordered structures of the friction surface.

Polymeric Composite Materials of Tribotechnical Purpose with a High Level of Physical, Mechanical and Thermal Properties

Polymeric composites (PC) of tribological applications with a high level of physical, mechanical and thermal properties based on aromatic polyamide and silica gel have been developed. Regularities have been obtained that describe the effect of the filler content in PC on the friction coefficient, temperature on the friction surface and the intensity of linear wear rate of the studied PC-steel friction pair. It was found that the optimal silica gel content in the polymer matrix is 10 wt %. The morphology of the steel surface of friction after friction interaction with PC based on aromatic polyamide and silica gel was studied. The formation of an antifriction film on the steel surface of friction was discovered, which contributes to a decrease in the friction coefficient, temperature on the friction surface, and the linear wear intensity of the studied PC. The influence of the load and sliding speed on the main tribotechnical characteristics of the PC-steel friction pair has been studied. Mathematical laws were derived that describe the influence of the main external factors (load and sliding speed) on the friction coefficient and intensity of linear wear rate of the studied friction pair. Physical, mechanical and thermal investigations of the developed PC were carried out and it was found that the introduction of 10 wt % silica gel contributes to their 5–10 % increase.

Evaluation of the tribological properties of two PEEKs sliding against Al2O3, WC and DLC coatings under dry friction and water lubrication

The tribology performance of two carbon fibre-reinforced polyether-ether-ketones (450FC30 and WG101) sliding against stainless steel 3Cr13 and 3Cr13 coated with aluminium oxide (Al2O3), tungsten carbide (WC) and diamond-like carbon (DLC) under dry friction and water lubrication were studied to reduce the coefficient of friction and improve the wear resistance of water-lubricated bearings. The friction and wear mechanism of different tribopairs were determined via pin-on-disc sliding tests. Experimental results showed that the WG101/Al2O3 tribopair exhibited excellent wear resistance under dry friction and water lubrication. Carbon fibres were exposed on the friction surface of WG101 when WG101 slid against Al2O3. These carbon fibres bore most of the load to reduce wear. This work provides a practical basis for selecting the optimal tribopair for water-lubricated bearings.

Determination of Friction Performance of High Friction Surface Treatment Based on Alternative Macrotexture Metric

Surface friction is currently the most common metric for evaluating the performance of high friction surface treatment (HFST). However, friction test methods such as the locked wheel skid tester (LWST) commonly provide a spot measurement. Large variations may arise in the LWST testing on curves. Based on 21 actual HFST projects, a study was performed to use a macrotexture metric, i.e., the mean profile depth (MPD) to evaluate HFST’s performance and improve its quality control (QC)/quality assurance (QA) procedures. The material properties were presented to understand the aspects of HFST. The method for calculating MPD was modified to account for the variations of macrotexture measurements. A vehicle-based test system was utilized to measure MPD periodically over an 18-month period since HFST installation. Statistical analysis was performed on the MPD measurements to identify the effects of influencing factors. Compared with the friction from LWST, MPD was equally effective in evaluating HFST performance. However, the use of MPD eliminated the errors as arisen in LWST testing and made it possible to detect surface distresses, including aggregate loss, delamination, and cracking. The expected overall MPD may be calculated by combining the MPD measurements made three months after installation at different HFST sites and used as a metric for evaluating HFST performance and QC/QA.

Friction surface modifiers of carbon-containing material for high-temperature operation

The results of high-temperature tribological tests of carbon-containing material in friction on heat-resistant stainless steel 40X13 in the temperature range from 20 to 700 °C under atmospheric conditions are presented. Friction surface modifiers “Argolon-2D” material improve antifriction properties and decrease friction coefficient value. Friction coefficient when using Ni-Se-PTFE modifier at load of 0.67 MPa and speed of 0.16 m/s is less by 5% than at speed of 0.05 m/s, and at speed of 0.25 m/s friction coefficient is less by 13% than at speed of 0.05 m/s. At 500 °C and a load of 0.67 MPa the friction coefficient when using Ni-Se-PTFE modifier is 30% higher than when using InSb-PTFE modifier, and the friction coefficient when using CuO-PTFE modifier is 1.2 times higher than when using InSb-PTFE modifier.

Performance comparisons of triple friction pendulum bearings with different sliding surface properties

In this study the time history analyses are carried out three dimensionally for a simple five-story concrete structure seismically isolated incorporating triple friction pendulum bearings with different sliding surface properties with the help of the ABAQUS finite element program. The altering friction surface properties are friction coefficient and radius of curvature. The performances of the various isolators are compared with each other as well as with those of a fixed based structure. For this purpose, maximum relative story displacements, story accelerations and column base shear forces are investigated as seismic reactions. According to the analysis results it can be stated that the seismic reactions of isolated structures are significantly reduced when compared to those of the fixed supported structure. Additionally, when triple friction pendulum bearing isolators with different friction coefficients and friction surface radii are compared, it can be observed that increasing the friction coefficient increases the reactions of the structure while increasing the friction surface radii decreases the reactions