Xiao Yang Chen

Research on Commercial Vehicle Clutch Release Bearing Fatigue Life Prediction Model

Commercial vehicle clutch release bearings working at high speed, strong vibration,high temperature, damp and easy pollution conditions. Fatigue life analysis is based on the release bearing rings or rolling body began to appear fatigue spalling, in which this kind of phenomenon is under cyclic stress. The contact stress distribution is not uniform, the contact stress is mainly concentrated near the surface; influenced by the geometry and physical properties and lubrication of the surface significantly. Contact between the two types of fatigue crack extension methods: fatigue crack surface under expansion and surface fatigue crack propagation. The surface crack growth mainly originated from two kinds of cases: crack caused by surface pre crack and contact between the two surface asperity each other. New life prediction model for the release bearing based on L-P theory and Tallian model ,in which influence factors of fatigue life is introduced on the smelting process, surface defect, surface roughness, residual stress, elastohydrodynamic lubrication oil film,environmental cleanliness, temperature, the effect of varying load characteristics and other factors of fatigue life. The results show that: the clutch release bearing life prediction model of new and more close to the real conditions of automobile clutch, provide the theory basis for the development of a new generation high-speed heavy-duty clutch release bearing of the commercial vehicle.

Crown Drop Effects on the Needle Roller Bearing Life in Oscillatory

In this paper, the effects of chamfer dimension at the Lundbergs profile needle roller end and the grinding undercut of raceway on the pressure distribution, which are used in the oscillatory applications, are discussed. The frame of numerical method for the crown drop evaluation considered these two effects is presented, which makes it possible to profile the needle rollers axially until the longitudinal pressure distribution is neither any edge effects nor high-pressure concentration at the center part of contacts. And the crown drop designed by this method is larger than that by Lundbergs theory. The comparison results of accelerated rolling contact fatigue experiment show that the width of grinding undercut and radius of the chamfer must be considered in determining the crown drop of the needle rollers.

Study of Biaxial Rotational Oscillating Sphere-Block Wear Test

Based on the motion characteristics of mechanical oscillating parts, a wear test machine is developed with single drive biaxial rotational oscillating, which can effectively simulate multiaxial rotational oscillation of mechanical oscillating parts and take different kinds of friction couplings wear test. Based on this design, the tribological property of easy wearing material in mechanical oscillating parts is studied and corresponding sphere-block test method is established. Pilot test and demonstration are taken to evaluate the sphere-block test method from feasibility, practicality, reliability and economy aspects. The results are meeting test requirements of tribological property under the condition of composite motion.

The Electrostatic Tangential Resistance of the MEMS Moving Plate Considering the Edge Effects

Friction force is present in most microelectromechanical systems (MEMS), since they have a large ratio of surface area to their volume. To improve the performance and reliability of MEMS devices, it is necessary to full understand the effect of friction which exists in the majority of MEMS. The model of electrostatic tangential force for MEMS’s moving plates is established based on the rule of energy conservation, further it is revised considering the edge effects by the conformal mapping method for smooth and opening holes plates. Three types of the electrostatic tangential resistance, which are the unrevised theoretical value and revised theoretical value and simulation value, were compared. The effects of microscale and applied voltage and holes are investigated, and the electrostatic tangential resistance between two charged moving plates with respect to each other is analyzed. It is found that the three types of the electrostatic tangential resistance will be increased with the rate of the plate width over the gap of two plates or the applied voltage increasing. And the opening holes did not significantly reduce the value of the electrostatic tangential resistance because of the presence of edge effects. The revised analytic results are larger than the ones not revised, and the former are close to results of ANSYS simulation.

Study on Web-Based Collaborative Design for the Vehicle Clutch Release Bearings

Clutch release bearings are an important vehicle powertrain components. Web-based collaborative design automotive clutch release bearings, making the regional formation of enterprises dynamic virtual design team, through a combination of scattered in various technological advantage, the talent to play all engineers, technicians can not subject to geographical restrictions, by computer supported collaborative design (CSCD), is a collaborative model of human and computer technology convergence of new technologies. By numerical calculation and the C# language on the separation of the axial load bearing capacity of the design process is developed. It is established on separate static analysis of the proposed bearing model.

Explore the Dynamic Characteristics of the Off-Road Vehicle Clutch on Release Bearing Life

This article describes the clutch release bearings research on the separation of research methods and characteristics of the bearings described in detail. the off-road vehicle Clutch release bearings often speed, strong vibration, high temperature, humid workability pollution conditions work require release bearings good strength and toughness, resistant to impact wear and excellent contact fatigue performance. Release bearing vibration characteristics and on life affect important theoretical significance and socioeconomic value.

Analysis of Heating Performances for Ultra-High Speed Electric Spindle Bearings Based on the Energy Theory of TEHL in Point Contact State

To analyze the lubricating state and the heating performances of the spindle bearings in ultra-high speed electric spindles, taken the characteristics of oil-air lubrication into account and based on the theories about rolling bearing dynamics and thermal elasto-hydrodynamic lubrication in point contact state, a model was built with the energy method for analyzing the heating performances the ball elements on both raceways in spindle bearings. An equation was derived for calculating the total quality of heat produced in a bearing. The influences of some basic factors such as the running speed, the axial preload, the oil viscidity, the design contact angle of bearing, and the ball materials and so on are analyzed on the heating performances in a bearing. The results show that it is easy to come into being elasto-hydrodynamic lubrication state for a bearing running in an ultra high-speed and lubricated by oil-air. It is also shown that the higher speed is, the more the quality of heat produced inside the oil films in the elasto-hydrodynamic lubrication state will be, which will bring the bearings working conditions worse.

Fatigue Failure of Silicon Nitride Ceramic Balls

Silicon nitride ceramic ball surface is examined after failure with scanning electron microscopy. The profile of the fatigue spalling takes the shape of an ellipse. The failure cause, fatigue phenomenon and mechanics are analyzed. The research shows that subsurface cracks play a dominant role in the formation of spalling failure. These cracks originated from volume defects of the material, and propagate, to form fatigue spalls under the action of principal tensile stresses. The contours of equal tensile stress of Oxy plane underneath surface are elliptical. Subsurface cracks are shape of ellipses and spall is also of the elliptic shape. The principal tensile stress increases with increasing contact load, causing spall formation and reduction of rolling contact life.

Vibration Analysis of Composite Plate Embedded with SMA Fibers

Shape Memory Alloy(SMA)has advantages of great recovery stress and elastic modulus varied with the temperature, so it can be embedded in composite structure to active control structure deformation and vibration. In this paper, we have deducted the recovery stress at different temperature by modifying the phase-change coefficient Ω of Liang Constitutive Model[1], then base on = /E equation, the recovery stress is translated into recovery strain. By using finite element software ANSYS, the natural frequency of composite plate at influence of recovery stress can be obtained under both ends of fixed conditions at three configurations. The steady-state vibration response of the composite plate embedded SMA fibers is also simulated. The results show that recovery stress of SMA can increase the natural frequency and can suppress vibration effectively.

Simulation of Closed-Loop Control of the Landing Position of the Water Jet out from Water Fire Monitors

Ordinarily, water fire monitor extinguishing systems are applied to protect large space places from fire. To intellectualize them and improve the water usability and extinguishing efficiency, it is necessary to realize the closed-loop control of the landing position of the water jet out from the monitors in order to let the water jet reach the fire point as fast as possible. According to the characteristics of the adjusting mechanism of fire monitors, combing with the new theoretical model for their water jet track, the closed-loop control procedure is simulated. The results show that the water jet can reach the ignition point after only several adjustments. The effective control procedure simulation paves a sound basis for the closed-loop control of the landing position of the water jet out from water fire monitors.