Contact Simulation And Experimental Study Of The Wire Race Ball Bearing Based On The Nonlocal Friction

The wire race ball bearing is a new non-standard bearing. It has a unique structural characteristics, which attracts the attentions of scientists and engineers from all of the world. In recent 10 years, the wire race ball bearing has been widely used in the fields of construction machinery, medical equipment, aircraft simulator and other fields because of its strong anti-overturning and flexible design features. However, the wire race ball bearing has to work in the cyclic alternating contact load frequently, contact fatigue and wear often occur because of that, which would seriously affect the performance of shaft. In order to explore the reason why the contact fatigue and wear occurs, this paper treat it as contact problems, what's more, it will research this problem using the finite element numerical simulation method and destructive contact experiment synthetically.At the micro scale, the nonlocal friction theory accounts that the friction of one point is not only related to the friction state of itself, but also related to the friction state of the points nearby. Therefore, this paper would consider the nonlocal friction effect caused by the asperity on the contact surface, statistical methods are used to get the role of nonlocal friction effect on the contact surface of the wire race ball bearing, set up the contact model between three-dimensional rough surface, and the finite element numerical simulation method was develop in ANSYS, in order to research the contact problem between the ball and the wire race. The numerical simulation results of the three-dimensional contact model of rough surface are more authentic than the three-dimensional contact model of smooth surface, due to the rough contact model can describe the stress and strain distribution, the friction stress distribution, shear stress distribution, stress concentration more closer to the acrual situationg than the smooth contact model.The wire race ball bearing often works in the tangential friction stress and normal cyclic alternating contact stress frequently, thence, the contact surfaces between the ball and the wire race are often prone to contact fatigue and wear. During the destructive contact experimental study, we can achieve accurate contact load by changing the thickness of the shim adjustment. In order to observe the morphology damage using the laser scanning confocal microscope and the scanning electron microscopy, we not only need to gather every group of sheddings that fall off from the contact surfaces under every group of contact load, but also need to collect the sample of the ball and the wire race which are the final destructions in the contact. Compare the destructive contact experimental with the numerical simulation results, summary the characteristics and rules of contact fatigue and wear of the ball and the wire race. Durning the contact process between the ball and the wire race, the conves structure on the contact surface first become contacting with eachother, and emerge stress concertration and plastic deformation. As we can know from the numerical simulation results in the fourth chapter, the maximum shear stress exists in a certain depth below the contact surface, the contact fatigue cracks are often formed here owing to the cyclic alternating stress, and then extend to both sides or to the surface, eventually fall off the contact surfaces forming the pittings, at the same time, it would increase the wear between the contact bodies.The resrarch methods for the wire race ball bearing in this paper provide the theoretical support and experimental evidence for a wider range of application of it. Meanwhile, it also provides a reference for the MEMS, the ultra-precision machining and other micro-contact problems.