Papers by Author: Yu Tao Yan

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Authors: Yu Tao Yan, Mai Yang, Zhi Li Sun, Li Fang Liu
Abstract: The formation and lubrication mechanism of boundary lubricating film were discussed. The boundary lubricating film includes adsorption film and chemical reaction film, and has respective temperature operating range. The adsorption film adsorbed in metal surface by Van-der Wads, and the parenchyma is the external friction between adsorption molecule layers. The chemical reaction film is made by the reaction between metal and extreme pressure additive in base oil, and the anti-wear capability is realized by the low-melting point eutectic alloy. The temperature is regarded as a judge criterion for failure of boundary lubrication. The failure model for boundary lubricating film is established. According to the failure model, the failure criterion proposed is effective by analysis of the spiral bevel gear using the finite element method. These results provide a basis for the application of boundary lubrication.
Authors: Yu Tao Yan, Zhi Li Sun, Guang Wei Hu
Abstract: The wear experimental project on main influencing factor with load, sliding speed, surface hardness and lubrication was instituted by the uniform design, the wear properties were investigated on a MMW-1 friction and wear tester. The predication formula for wear rate was defined. The wear rate predication model was established by the partial least squares based on the test data, the influencing degree on the main influencing factors was analyzed, the results show the influence on wear rate from big to small is in turn load, lubrication, surface hardness and sliding speed. The lubrication property improved is a handy valid path to decrease the wear rate. The check results show that it is a valid method by partial least squares to establish wear predication model based on test data.
Authors: Yu Tao Yan, Xiao Lin Qian, Guang Yang Hu, Li Sheng Zheng
Abstract: Utilizing ANSYS to analyze the performance of the circumferential seal ring under the condition of different temperatures and different rotational speeds and get the rings value of the maximum stress, the maximum strain, the maximum contact pressure on main sealing surface respectively. By analyzing the change of these values to reveal the change rule of the seal ring, thus provide the basis for designing and selecting the circumferential seal ring.
Authors: Zhi Li Sun, Yun Feng Zhang, Yu Tao Yan
Abstract: The wear volume is obtained by means of experiment and the wear random process model is established according to the result. The Carbon steel material is used and the samples are grouped five after surface treatment, each group tests six times under the same condition. The wear volume under each wear time shows big dispersion. The additional study indicates that the sample has the large wear volume is in the serious wear state from the beginning, and the wear of running-in phase is inflected by the work velocity and the state condition of the surface of the samples. The wear process which the mean value is a constant and the standard deviation is different is a normal process generally, it is a stationary normal process if the standard deviation has no relation to the start of the wear time, or a Wiener process if the standard deviation is liner with the wear time, it is valuable to forecast the wear reliability.
Authors: Qiang Yang, Zhi Li Sun, Yan Yan Shi, Dan Dan Jia, Yu Tao Yan
Abstract: Five-axis CNC machine tool is the top product of numerically controlled machine tool. Kinmatic accuracy is an important index to evaluate the quality of mechanism. Kinematic accuracy analysis of the Five-axis machine tool in previous study ignores the randomness of each input error component, so the conclusions are imprecise. Using the homogeneous transformation, inverse kinematics of VMC650 Five-axis machine tool is calculated. Based on Multi-body System Theory, error model of the machine tool is presented. Considering the randomness of every input error components, applying the Monte Carlo method, math model of kinematic reliability of the mechanism is deduced. The calculation method of kinematics reliability are put forward applying point evaluation and track evaluation. Kinematic reliability analysis provides some theoretical reference for improving the machining accuracy and operation life of machine tool.
Authors: Yu Tao Yan, Zhi Li Sun, Qiang Yang, Yan Zhong Wang
Abstract: The spiral bevel gears of attack helicopter transmission systems are taken as an object in this paper. The numerical analysis model for starved elastohydrodynamic lubrication (SEHL) of spiral bevel gears is established on the basis of the analysis of load tooth contacts analysis and SEHL in elliptical contacts. The SEHL characteristics of spiral bevel gears are also analyzed. The results are as follows: during the course of a gear-tooth meshing cycle of the spiral bevel gear, the extremum of minimal film thickness and maximal film pressure occurs near midpoint of the path of contact, and leans to dedendum. The minimal value of the minimal film thickness is 0.39 um, and the maximal value of the maximal film pressure is 0.69 GPa. The value of minimal film thickness gradually increases with the increasing of meshing point velocity. When the velocity of meshing point exceeds 110 m/s, the increase became tardiness. As the load of meshing point increases, the value of minimal film thickness gently diminishes.
Authors: Yu Tao Yan, Yu Qiu Huo, Zhi Li Sun, Zhen Xing Xu
Abstract: The Ni-P composite coatings onto 4043 aluminum alloy were prepared by electroless plating with nickel sulfate and sodium hypoposphite as raw material. The Ni-P composite coatings were heat-treated for 1 hour at 200°C, 300°C, 400°C, 500°C and 600°C, respectively. The tribological behaviour of the coatings was investigated on a vertical universal friction/wear tester under dry friction. The morphology and phase structure of the composite coatings were characterized by scanning electron microscope (SEM) and transmission electron microscope (TEM), and the microhardness of the composite coatings were measured by Vickers diamond indenter. The results showed that the as-deposited coatings had smooth cellular pattern and amorphous structure, and the microhardness of the coatings reached the maximum at 400°C heat treatment, the reason is the formation of Ni3P alloy phase with increasing of the heat treatment temperature. The friction coefficient of coatings annealed at 400°C is the lowest. The wear loss was found to increase with corresponding increase in load and sliding speed. It was found that the wear mechanism of the as-deposited Ni-P composite coatings was dominated by adhesive wear and scuffing under the experimental conditions, but the wear mechanism of the coatings annealed at 400°C was scuffing.
Authors: Yu Tao Yan, Zhi Li Sun, Xin Ren, Qiang Yang
Abstract: The some five-axis machining center was investigated, and it divided ten subsystems. Based on analysis of fault data, the distribution of fault time submits to Weibull distribution, the distribution function and reliability function of each subsystem were confirmed. The reliability allocation model with the constraints of cost is established based on reliability prediction to get optimal reliability allocation results of the complicated mechano-electronic system. The most growth potential of the reliability of subsystem and growth situation of reliability of each subsystem could be got by using this method. The reliability allocation is an important part of reliability design, because its result influences system design directly. This provides reference for design improving of this series of new products.
Authors: Yu Tao Yan, Zhi Li Sun, Guang Yang Hu, Tian Qi Hu
Abstract: For increasing the experimental efficiency and shortening the experimental time, the uniform design method was used to establish the wear experiment scheme on the tribological properties of the sealing material CrMo cast iron. The experiments were investigated on a vertical universal friction and wear tester, the worn surfaces of specimens were observed by scanning electron microscope (SEM). The results showed that the experiment points chosen by the uniform design is reasonable and effective, and the wear rate distribution rule of the CrMo cast iron was established and was divided three regions, the effect on wear rate in the I region and the III region was more serious than the II region, and the variation of the friction coefficient is bigger under experimental conditions, the main wear mechanism of the CrMo cast iron is desquamation wear and adhesive wear. The load and sliding speed coupling effect on wear of the CrMo cast iron must be thought over.
Authors: Yu Tao Yan, Rui Wang, Wan Li Song
Abstract: Solid phase method was adopted to prepare the graphite fluoride solid lubricant. The friction and wear properties of graphite fluoride were tested with MMW-1 vertical universal friction and wear testing machine. The phase of graphite fluoride was analyzed with infrared spectrometer. The morphology of friction surface was analyzed with the scanning electron microscope. The results show that graphite fluoride has an excellent antifriction wear-resisting property, to compare with molybdenum sulfide, the anti-friction property increased by 35%, wear resistance increased by 49%. The main wear mechanism of the test specimens are fatigue wear and adhesive wear. The solid lubrication film for graphite fluoride was formed in the friction surface.
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