Abstract
Silicon nitride ceramic bearings are widely used for their excellent performance. However, due to their special manufacturing method, cracks will occur on ceramic ball surface, and this initial surface crack will propagate under the action of cyclic stress, which will lead to material spalling. This will greatly limit its service life in practical applications, especially under heavy load at high speed. Therefore, it is necessary to study the surface crack propagation of silicon nitride ceramic bearings. In this paper, the effect of initial crack angle and contact load on crack growth is analysed by the finite element method (FEM). A three-dimensional finite element model of a silicon nitride bearing ball containing an initial crack is created by the FEM. The cracks are initially classified based on the angle between the crack and the bearing ball surface, and the location of the most dangerous load for each type of crack is known by theoretical analysis. The stress intensity factors (SIFs) are calculated for the crack front to investigate the effect of load position on crack growth. Subsequently, the SIFs are calculated for each type of crack angle subdivided again to investigate the effect of crack angle on crack propagation.
Highlights
Due to the advancement of modern technology and the development of industrial production, silicon nitride ceramic bearings have been used widely because of their wear resistance and corrosion resistance, and it can work at high speed
Because of the special sintering process of making ceramics, cracks will occur on the surface of ceramic balls with different shapes and random locations, and cracks will propagate as the bearing works, leading to spalling and rolling contact fatigue failure
There has been a lot of work done by related scholars, the failure mechanism of silicon nitride ceramic bearing balls with surface cracks has not been well understood, so it is necessary to study the propagation mechanism of surface cracks to understand ceramic bearing rolling contact fatigue failure
Summary
Due to the advancement of modern technology and the development of industrial production, silicon nitride ceramic bearings have been used widely because of their wear resistance and corrosion resistance, and it can work at high speed. Zhou et al [9] have conducted research on the failure of silicon nitride ceramic balls, including the mechanism of fatigue dynamic failure, influencing factors of fatigue failure, and failure probability model; they proposed that the subsurface cracks are mainly caused by material volume defects, and the critical stress for bearing ball failure is the maximum principal tensile stress in the process of spalling formation. Deng et al [13] investigated the role of material defects on the crack initiation under rolling contact fatigue and considered the effects of the moment,the radical load ,and other factors on SIFs,crack growth rates and crack initiation They proposed a simulated model to study the effect of the crack inclined angle and the hardness of inclusions on fatigue damage in bearings. Cracks of different initial angles are inserted into the ceramic bearing ball model to calculate the SIFs of the crack front. e results are helpful for better understanding the effect of surface cracks on rolling contact fatigue of the silicon nitride ceramic bearings
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