In this work, the influences of flexibility and surface texture on the performances of a finite-long journal bearing have been investigated theoretically. Reynolds equation has been solved by using finite difference method. In this study, Winkler foundation model has been used to calculate the elastic deformation of the bearing bush or housing. The steady-state characteristics of a lubricated finite-long journal bearing are studied in the textured and untextured bearing surface, respectively. The simulation results of the present study indicate that the surface texture can appreciably change the shaft center-line locus and oil film pressure distribution comparatively to the smooth case. The texture arrangements on the bearing surface, the texture number in the circumferential or axial directions, and the texture depth in the radial direction, all of them have significant influences on the static characteristics of a flexible journal bearing.
The wear of multiple joints with clearance is one of the main impacts on the life of mechanical systems while very limited study has been done on this subject. To be different with many existed researches focused on the dynamic analysis of multibody systems with multiple clearance joints, the wear of two revolute joints with clearance in multibody systems is analyzed in this paper by coupling dynamics with tribology. Based on a planar slider crank mechanism with two clearance joints, it is observed that the clearance sizes nonlinearly influence the wear depths of the two joints with clearance. Meanwhile, an appropriate relationship between the two joints' clearance sizes can significantly decrease the wear of the joints, which would greatly improve the system life. Both the independent and interactive influences of the two joints with clearances on the wear are investigated in this paper. The relation equations of the two clearances obtained in this work will significantly decrease the wear of the two clearance joints.
Purpose – This paper aims to study the impact of surface texture on grease-lubricated journal bearing, load-carrying capacity, friction and friction coefficient. Design/methodology/approach – The paper opted for a basic application research using the commercial CFD software FLUENT 14.0. Findings – The load-carrying capacity can be enhanced if the surface texture is introduced from a suitable position. The textural shape has a more significant effect on the friction and load-carrying capacity than the friction coefficient. The rheological parameters of grease affect the load-carrying capacity in the same way, i.e. the load increases with the increase in the rheological parameters. With the decrease in the value of cavitation pressure, the cavitation area reduces but the dynamic pressure area gets enlarged. Research limitations/implications – Because of the chosen research method, the research results may lack the analysis of experiments. Practical implications – The research results can be applied to the domain in the high-speed spindle and lubricated multibody system. Originality/value – The investigation on the performances of grease-lubricated journal bearing with surface texture would be significant.
Abstract:The regular grooves, dimples or bulges with certain size and distribution can be made on the object surface by employing the machining technology called surface texturing. This technology has attracted much attention of fellow scholars at home and abroad since its emergence. Of course, there are still some controversies and differences between theoretical and experimental studies.For example, if the theoretical results can be applied in the real engineering fully and successfully? And how the phenomenon happened in reality or model experiment can be explained reasonably based on the theoretical knowledge. In this manuscript, the studies on surface texturing have been collected and analyzed both in the theoretical and experimental aspects. Furthermore, the main problems and the development tendency in the future also have been pointed out accordingly. Key words:surface
Purpose This paper aims to propose a semi-analytical model to investigate the elastic-plastic contact between fractal rough surfaces. Parametric studies have been performed to analyze the dependencies between the contact properties and the scale-independent fractal parameters. Design/methodology/approach A modified two-variable Weierstrass-Mandelbrot function has been used to build the geometrical model of rough surfaces. The computation program was developed using software MATLAB R2015a. The results have been qualitatively validated by the existing theoretical and experimental results in the literature. Findings In most cases, a nonlinear relation between the load and the displacement of the rigid plane is found. Only under the condition of larger loads, an approximate linear relation can be seen for great D and small G values. (D: fractal dimension and G: fractal roughness). Originality/value The contact model of the cylindrical joints (conformal contact) with radial clearance is constructed by using the fractal theory and the Kogut-Etsion elastic-plastic contact model, which includes purely elastic, elastic-plastic and fully plastic contacts. The present method can generate a more reliable calculation result as compared with the Hertz contact model and a higher calculation efficiency as compared with the finite element method for the conformal contact problem.
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