An optical interference test rig with spinning elastohydrodynamic lubrication (EHL) was established to investigate the spinning lubrication performance under different oil-supply conditions. Variations in the shape and thickness of the film versus the velocity, the load, and the spinning factor under fully flooded lubrication were discussed, and the effects of the inlet-starvation position and oil-supply quantity were analyzed. The results show that the symmetry for the classical horseshoe shape does not exist under both spinning–rolling and spinning–sliding EHL conditions. Different from spinning–rolling, a dimple is generated more easily under the spinning–sliding condition. The dimple is related to the load and the speed. The effects of the inlet-starvation position on spinning EHL are different. When the inlet starvation is on the low-speed side of the contact, that is, proximal to the center of rotation, the inlet-starvation position extends from the proximal side to the center of rotation to the distal side to the center of rotation, i.e., the high-speed side of the contact, which is starved easily. When the starvation happens on the high-speed side, i.e., distal to the center of rotation, the starvation at this position becomes much more severe, and lubrication failure and a risk of wear will occur. In addition, the effects of oil-supply quantity on spinning EHL are important.

A new method for solving the shear stress and the effective viscosity of Eyring shear-thinning fluid in thermal elastohydrodynamic lubrication (EHL) was proposed and applied to two models. Model 1 is the thermal EHL model with one-direction velocity, and model 2 is the spinning thermal EHL model in which the velocity varies with coordinates. Comparisons between the new and the existing method were carried out. Results show that only replacing the shear strain rate of model 1 with that of model 2, the shear stress and the effective viscosity of model 2 for Eyring shear-thinning fluid can be obtained. For model 1, results obtained with the two methods are the same. The new method can be qualified and applied into model 2. It is proved that the new method has higher efficiency for shear-thinning fluid than the existing method. Therefore, the new method is more efficient and can be used for spinning Eyring shear-thinning thermal EHL.

In order to investigate the performance of elastohydrodynamic lubrication (EHL) in angle-contact ball bearings with spinning,the EHL model considering spinning was built for angle-contact ball bearings.With the numerical technique,the effects of the coefficient of inner groove curvature radius,the inner ring and outer ring contact angle,the number of rolling elements and the speed the EHL performance of angle-contact ball bearings were investigated.The main factors influencing the spinning speed and spinning-roll ratio were analyzed.Results show that,with the increasing of the innegroove curvature radius,the film thickness is decreased slightly,while the pressure is increased significantly because of the decreasing of the contact radius.With the increasing of inner ring contact angle,the asymmetry of the oil film becomes obvious.With the increasing of the outer ring contact angle,the spinning speed is decreased between 0° and 70°,and increased between 70° and 90°,whereas the oil pressure changes little.The more the number of rolling elements,the lighter the load of a single rolling element,the larger the oil film thickness,and the smaller the center pressure.The main factors affecting the spinning speed of angular contact ball bearings are the inner ring speed,and the inner and outer ring contact angle,while the main factors affecting the spinning-roll ratio are the inner and outer ring contact angle.

为讨论自旋运动及表面缺陷对点接触热弹流润滑性能的影响,采用Eyring非牛顿流体,建立了考虑自旋运动存在表面缺陷的点接触热弹流润滑模型.应用多重网格技术和逐列扫描技术进行了数值仿真.从而得出自旋及表面缺陷对润滑油膜厚度、压力及温度分布的影响,为轴承在恶劣条件下工作时提供一些失效的判断依据.

In order to reduce the edge effect,the tilting and skew effect of the roller.Using the Eyring Non-Newtonian fluid model,the parabolic modification function is applied to a finite line contact thermal EHL model.The pressure is solved with multilevel method and the temperature is calculated with sequential column sweeping technique.A special coordinate transformation technology is used for the solving of cylindrical roller skew.For the tilting rollers,the initial value of a dimensionless load offset distance Ew is given,and then the oil film pressure,the film thickness,and the dimensionless momem M are obtained.Moreover,the relative error of torque ErrM is calculated,and a new value of the load is obtained simultaneously.when the roller is at the ideal,the tilting,the skew or the tilting coupled with the skew status,the profile modification for the roller generatrix can reduce the edge effect and the tilting or the skew effect.In addition,an optimum value of the profile modification for the roller generatrix exists at the four kinds of status.The optimum value is 9,11,14 and 16 mm at the four status.The method which a profile modification function is added on the straight roller generatrix is simple and feasible.A new idea for the engineering application of the roller profile modification is provided.

考虑磨损对润滑状态的影响,构建带有磨损带的非牛顿流体圆接触热弹流润滑模型,分析磨损半宽对油膜压力、厚度、温度和摩擦因数的影响,并与牛顿流体的热弹流解进行比较.结果表明,随着磨损半宽的增大,最小油膜厚度明显减小,且总是处于磨损带边缘附近,并向入口处移动;而中心膜厚随磨损半宽的增大线性增大;卷吸速度、载荷及滑滚比对膜厚随磨损半宽改变的影响不大;非牛顿效应对温度和摩擦因数有较大影响.

In order to effectively assess the thermal characteristics of lubrication film,using the Eyring non-Newtonian fluid,the thermal elastohydrodynamic lubrication model considering spinning was built,and numerical simulation was car-ried out with multi-grid method and column by column sweeping technique.The effects of the slid-roll ratio and speed,the characteristics of shearing stress,the maximum Hertzian pressure and the spinning factor on the elastohydrodynamic lubri-cation performances were discussed.Results show that,the main difference between non-Newtonian and Newtonian fluid is that the oil film temperature for the non-Newtonian fluid is significantly lower than that of Newtonian fluid for the moderate or high load considering spinning.The symmetry of distribution of the film thickness and temperature disappears because of spinning.For the non-Newtonian fluid with lower characteristic shearing stress,the irregularity of the temperature distribu-tion is more obvious due to the spinning.With the increase of load,the friction coefficient is firstly increased linearly,while the thermal effect is also gradually strengthened with the load increasing,so the friction coefficient has a decreasing trend after reaching the maximum value.With the increase of spinning factor,the asymmetry of film thickness and temperature distribution are increased,the highest temperature goes up and moves towards one side.

Poly(ester-amine salt)(PEAS) precursor powders were synthesized via esterification process with aromatic dianhydride and diamine as monomers in the mixed solvent consisting of methanol and tetrahydrofuran.Polyimide foams with uniform cells were prepared from PEAS with powder process.The structure and heat-resistant property of the polyimide foams were characterized by scanning electron microscopy(SEM),Fourier transform infrared spectroscopy(FTIR) and thermogravimetry(TG).The influences of initial heating temperature and particle size of the powders on foam density were studied.The results show that the higher the initial heating temperature,the lower the foam density,the lesser the influence of the particle size of the powders on the foam density.