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Table of Content

    28 May 2018, Volume 52 Issue 5 Previous Issue    Next Issue
    Effect of Low Viscosity Oil and Surface Texture on Friction Characteristics of Piston Ring-Liner
    LIU Jun,ZHANG Zhinan,XIE Youbai
    2018, 52 (5):  505-510.  doi: 10.16183/j.cnki.jsjtu.2018.05.001
    Abstract ( 1008 )   Save
    The paper built a numerical model for analyzing friction of piston ring-liner system, which considered the influence of cavitation and mixed lubrication. To investigate the synergistic effect of low viscosity and surface texture, two types of low viscosity oils, i.e. SAE0W20 and SAE5W20, were selected. Besides, the friction of piston ring with spherical texture, which was with a radius of 30μm and a depth of 3μm, was compared to the friction of piston ring without surface texture. The results show that the impact of surface texture is closely related to the viscosity of lubricating oil. Under condition of lubricating oil SAE0W20, the spherical texture helps to reduce friction, while under condition of lubricating oil SAE 5W20, the spherical texture increases friction power loss and friction mean effective pressure.
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    Piston Skirt Mixed Lubrication Analysis Considering the Effects of Lubricant Shear-Thinning
    NING Lipu1,NING Xin2,MENG Xianghui3
    2018, 52 (5):  511-517.  doi: 10.16183/j.cnki.jsjtu.2018.05.002
    Abstract ( 935 )   Save
    A mixed lubrication of the piston skirt-liner system is presented, considering the effects of lubricant shear-thinning, to investigate the friction characteristics of the piston skirt for both monograde and multigrade lubricants, and the validity of the model and the effect of the lubricating oil shear-thinning are verified by the experiment. The results show that the multistage lubricating oil has a significant shear-thinning effect, and a decrease in the lubricant viscosity is an effective way to reduce the friction loss of piston skirt, although it may increase the boundary friction, especially at the expansion stroke. The effect of shear-thinning on the piston secondary motion is not obvious, and the measured value of the experiment is in good agreement with the predicted value of the mixed lubrication model.
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    A Multi-Objective Preventive Maintenance Decision-Making Model for Imperfect Repair Process
    HAO Hongfei1,GUO Wei1,GUI Lin2,WANG Lei1
    2018, 52 (5):  518-524.  doi: 10.16183/j.cnki.jsjtu.2018.05.003
    Abstract ( 950 )   Save
    The preventive maintenance (PM) decision-optimization problem of complex equipment is studied under imperfect repair context aiming at the deficiencies of residual life prediction and cost estimation. Based on the virtual age theory, we built the relationship between maintenance efficiency and equipment age. Furthermore, three different methods are put forward to calculate the relation between checking intervals and maintenance period. The quality fluctuation and variable maintenance cost caused by fault are considered to build a more concise overall cost estimation model. A multi-objective decision-making model for preventive maintenance is established to ensure high availability of equipment and low total cost. Numerical verification is performed using the production and maintenance history data of a machining center. The verification intends to compare the different overall cost rate and equipment availability under static, dynamic and failure limits calculation methods and various maintenance levels. In the same way, the applicability of the three methods is discussed. The influence of the quality cost on the optimal strategy is analyzed to prove the advanced nature of the method.
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    A Mixed EHL Model of Finite-Length Line Contact Considering Asperity Elasto-Plastic Deformation and the Lubricant Properties
    WANG Zhijian,CHEN Xiaoyang,SHEN Xuejin
    2018, 52 (5):  525-532.  doi: 10.16183/j.cnki.jsjtu.2018.05.004
    Abstract ( 923 )   Save
    The thermal mixed lubrication model of finite-length line contacts is established, which takes account of the elasto-plastic deformation of the asperities and boundary-film tribo-chemistry properties.The model is verified by comparing the infinite-length theoretical model, the elastohydrodynamic lubrication (EHL) test rig and double-disk experimental data.Then the effect of surface roughness and the lubricant properties on the lubrication and friction are preliminarily discussed. The results show that reducing the surfuce roughness can effectively improve the scuffing resistance under the current operating conditions.
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    Characteristics of Lubrication Film in Slider-on-Disc Contact Under Limited Lubricant Supply
    ZANG Shuyan,GUO Feng,LI Chao,LI Xinming
    2018, 52 (5):  533-537.  doi: 10.16183/j.cnki.jsjtu.2018.05.005
    Abstract ( 898 )   Save
    Using an optical slider-bearing test rig, the characteristics of lubrication film were studied under condition of limited lubricant supply. A relative film thickness, that is the ratio between the measured film thickness with limited lubricant supply and that with full lubricant supply, was defined to assess the reduction of load-carrying capacity by limited lubricant supply. It was found that when a small quantity of lubricant is supplied, the film thickness increases at first and then remains nearly unchanged with increasing speeds due to development of starvation. Results show that the lubricant viscosity and the reflow time between two slide-overs can markedly affect the film building due to the inadequate lubricant replenishment on the lubrication track. The inlet starvation area may bear some load only when the starvation becomes severe.
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    Data-Driven Performance Degradation Condition Monitoring for Rolling Bearings
    WU Jun a,b,LI Guoqiang a,WU Chaoyong a,CHENG Yiwei c,DENG Chao c
    2018, 52 (5):  538-544.  doi: 10.16183/j.cnki.jsjtu.2018.05.006
    Abstract ( 811 )   Save
    A degradation condition monitoring method based on complete ensemble empirical mode decomposition with adaptive noise (CEEMDAN) and principal component analysis (PCA) for rolling bearings is proposed, which considers the problems of weak fault signals and diverse fault modes. In this paper, intrinsic energy features and failure frequency features are respectively extracted from the preprocessed original vibration signals of rolling bearings using CEEMDAN algorithm and Hilbert-Huang transform. Then, a health index of the rolling bearings is obtained through the feature fusion using spearman rank correlation coefficient and PCA. Finally, the degradation condition of the rolling bearings is identified by the analysis of the monotonicity, robustness and correlation of the health index. The conclusion is drawn by a case study that the proposed method can be applied to accurately and timely identifying the degradation condition of the rolling bearings.
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    Effects of Assembly Temperature on Thermal Reological Lubricating Performance with Load Impact in Ball Bearings
    LIU Xiaoling,YANG Yubing,YANG Peiran
    2018, 52 (5):  545-553.  doi: 10.16183/j.cnki.jsjtu.2018.05.007
    Abstract ( 883 )   Save
    In order to investigate effects of assembly temperature on thermal reological lubricating performance with load impact in ball bearings, by using the Eyring shear-thinning fluid, a thermal reological elastohydrodynamic lubrication (EHL) model with a load impact in ball bearings was established. The model considered differences of the temperature between the assembly and the supplied oil. Multi-grid method and the numerical technique for time-dependent, reology and temperature field were used. Effects of the assembly temperature on the thermal reological lubricating performance of the dynamic oil film were investigated, and phenomena of thermal failure at extreme cases were analyzed as well. Results show that, differring from the convertional solution, the assembly temperature has much more influence on thermal EHL performance of the dynamic oil film. The higher the temperature of the ball, the less the film thickness and the frictional coefficient. At extreme cases, phenomena of high pressure, high temperature, and thin film appear for a bearing inner race-rolling element contact. Moreover, the temperature of the bearing inner race is up to the first critical temperature of desorption for the boundary film. In addition, the bearing inner race-ball contact is in a state of mixed lubrication. Therefore, effects of the temperature field in ball bearings should be considered in analysis of non-steady state thermal reological EHL.
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    Edge-Profiling Effect on the Tribological Properties of Protrusion Textured N-Si-DLC Films in Air
    WU Xingyang,GE Zhou,RUAN Jingjie,YANG Yi,NIU Haozhi,CHEN Teng,ZHANG Jianhua
    2018, 52 (5):  554-560.  doi: 10.16183/j.cnki.jsjtu.2018.05.008
    Abstract ( 912 )   Save
    Normal and edge-profiled textured nitrogen and silicon co-incorporated diamond-like carbon (N-Si-DLC) films with protrusion area densities of 35%, 44% and 58% were prepared by laser ablation, polishing and sputter, RF-CVD methods. The tribological properties of the textured films against the 316L stainless steel ball in air environments under RH 15%, 45% and 75% were investigated by a ball-on-disk type reciprocating tribometer. The finite element method was used to analyze the stress distribution at the contact surfaces in the steady state of sliding. The results show that the edge-profiled textured N-Si-DLC films possess lower friction and wear compared to the normal textured films. The friction and wear showed positive relation to the maximum contact stress appeared at the edge of protrusions. By edge-profiling, the maximum contact stress and sequential friction and wear could be reduced markedly. The reduction effect of edge-profiling is closely related to the protrusion area density and the best effect was obtained for the films with a protrusion area density of 44%.
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    Effect of Tribological Behavior of Nitriding Treatment on the Texturing Titanium Surface in Lunar Soil
    LI Xingliang1,2,YUE Wen1,3,PANG Changtao2,XU Changyu2,KANG Jiajie1,3,TIAN Bin1,4
    2018, 52 (5):  561-567.  doi: 10.16183/j.cnki.jsjtu.2018.05.009
    Abstract ( 1110 )   Save
    In order to improve anti-friction and anti-wear performance of the titanium alloy in aerospace and aircraft area, dimple textures were prepared on TA2 titanium surface by means of laser surface texturing (LST). Then the texturing surface was nitrided by low temperature ion nitriding technology. Tribological behaviors of the texturing surfaces were investigated under lubrication with simulated lunar soil in dry sliding contact on an MS-T3000 friction and wear tester. The micro-morphologies and element content on the worn surfaces were analyzed by scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS), respectively. The result shows that surface nitriding treatment can greatly improve the anti-friciton and anti-wear properties of testured titanium surface by 47.1% and 79.3%, respectively. Dimple diameter and dimple density have great effect on the average friction coefficient on the untreated surface, and the influence of dimple diameter is greater. The texture parameters have no effect on the anti-wear properties. After nitriding, dimple density has greater effect on anti-friciton and anti-wear properties than dimple diameter and dimple depth.
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    Effect of Sand Particle Size on the Damage Behavior of TC4 Alloy Impact Inter Face
    WU Songbo,CAI Zhenbing,LIN Yu,WANG Zhang,LIU Xinlong,ZHU Minhao
    2018, 52 (5):  568-574.  doi: 10.16183/j.cnki.jsjtu.2018.05.010
    Abstract ( 938 )   Save
    Experiments with different particle sizes (120—380 μm) were carried out using a new type of impact wear test machine. The impact wear mechanism and interface response of TC4 alloy in sand and dust environment during impact were studied. The results showed that smalls and particle could significantly affect the impact wear behavior of TC4 alloy, and the sand particle will be broken and deposited on the surface during impact. The worn surface is relatively rough and significantly higher than the original surface of the specimen. As the particle size increased, the peak of impact force decreased significantly, the impact contact time got longer, the energy absorption increased, and the wear area became larger obviously. With the increase of impact cycles, the peak of impact force decreased, the energy absorption rate increased, and the volume of material accumulation tended to increase. The damage mechanism of TC4 alloy under particle impact wear is mainly manifested as the cutting and debris accumulation.
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    Influence of Grinding Parameters on Workpiece Surface Morphology and Friction Performance
    CHEN Shi1,ZHANG Zhinan1,CAI Xiaojiang2,WEI Xinsheng2
    2018, 52 (5):  575-581.  doi: 10.16183/j.cnki.jsjtu.2018.05.011
    Abstract ( 1160 )   Save
    An approach for predicting the friction performance of workpieces with grinding parameters was proposed to reduce the costs of surface profile measurement and development of friction and wear experiments. Considering the movement interference between the cutting edge of the grinding wheel and the workpiece, a model of the workpiece surface topography with the given parameters was established by combining the single-point diamond dressing; then the pressure distribution and friction coefficient of the grinding morphology were obtained by combining with the Reynolds equation under mixing lubrication. Simultaneously, taking machine guideway as an example, the model established above was validated. The analysis shows that the maximum friction coefficient can be obtained when the angles of the upper and lower surface textures are all 0°.
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    Synergy Effect of Nonionic Surfactant and Ultrasonic on the Post-Cleaning of Aluminium Alloy Chemical Mechanical Polishing
    WANG Yongguang1, WU Zhonghua2,ZHAO Yongwu2,CHEN Yao1,LIU Ping2,LU Xiaolong1,ZHU Yuguang1
    2018, 52 (5):  582-586.  doi: 10.16183/j.cnki.jsjtu.2018.05.012
    Abstract ( 1122 )   Save
    This paper studied two cleaning methods comprising of dipping and ultrasonic for 7003 aluminium alloy after chemical mechanical polishing (CMP). A series of experiments were carried out to investigate the effect of octyl phenyl polyoxyethylene ether (TX-100) on the removal of SiO2 particles in post CMP cleaning process of Al alloy. The surface morphology and roughness after cleaning were characterized by atomic force microscope (AFM). It was found that the increase in TX-100 concentration leads to the initially decrease in abrasive particle diameter, Zeta potential and contact angle, followed by an increase trend with the further increase in TX-100 concentration. Combining with ultrasonic and TX-100, the removal ratio of SiO2 particles could be enhanced from 57% to 90%, and the surface roughness decreases to 2.16 nm after cleaning.
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    Oxygen Free Copper Dynamic Mechanical Property in High Speed Machining Process
    YU Jianchao,LIN Youxi
    2018, 52 (5):  587-592.  doi: 10.16183/j.cnki.jsjtu.2018.05.013
    Abstract ( 1055 )   Save
    Hopkinson pressure bar experiments of oxygen free copper in high speed machining process were carried out with temperature ranging from 20℃ to 900℃ and strain rate ranging from 1.0×103 to 1.5×104s-1. The true stress-true strain curves obtained from experiments showed that the mechanical property of oxygen free copper showed obvious strain rate and temperature sensitivity. The flow stress increased significantly with the increase of strain rate and decreased with the increase of deformed temperature. The empirical Johnson-Cook constitutive model had a large error in describing the dynamic mechanical property. Based on the analysis of dynamic mechanical property, a modified Johnson-Cook constitutive model was proposed. It can predicte experimental results well, and then can be used to simulate dynamic mechanical property of oxygen free copper in high speed machining process.
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    Corrosion Resistance and Hemocompatibility of Passivated 316L Stainless Steel
    WANG Jun1,LIU Ying1,2
    2018, 52 (5):  593-598.  doi: 10.16183/j.cnki.jsjtu.2018.05.014
    Abstract ( 1478 )   Save
    In order to improve the corrosion resistance and hemocompatibility of 316L stainless steel, mechanical polished 316L stainless steel was modified in situ by mixed acid (2%HF+10%HNO3, volume fraction) immersion and high-temperature treatment. The surface morphologies of 316L stainless steel and modified 316L stainless steel were characterized by X-ray diffraction (XRD), atom force microscopy (AFM) and scanning electron microscope with energy dispersion spectrometer (SEM-EDS). The corrosion resistance and wettability of 316L stainless steel and modified 316L stainless steel were analyzed by electrochemical and contact angle measurement respectively. The results indicated that Cr-O oxidation films were formed on 316L stainless steel after mixed acid immersion. Fe2O3 and Cr-O mixed oxidation films were grown on the high-temperature treatment 316L stainless steel. The corrosion resistance of modified 316L stainless steel was improved in simulated body fluid. The surface of 316L stainless steel modified by the two methods was hydrophilic. The surface energy polarization component of mixed acid immersion and high-temperature treatment 316L stainless steel were all increased. While, the interfacial tension between the materials and blood was decreased. Mixed acid passivation and high-temperature treated can improve the corrosion resistance and hemocompatibility properties of 316L stainless steel.
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    Molecular Dynamics Simulation of Polishing Process of Silicon Carbide Under Ultrasonic Vibration Conditions
    ZHAI Wenjie,YANG Dezhong,GONG Na
    2018, 52 (5):  599-603.  doi: 10.16183/j.cnki.jsjtu.2018.05.015
    Abstract ( 1307 )   Save
    To deeply understand the material removal mechanisms at the atomic level in the process of chemical mechanical polishing (CMP) of silicon carbide (SiC) under ultrasonic vibration conditions, molecular dynamics (MD) method was employed to establish an atomic model of SiC scratched by a diamond abrasive, and the crystal structure, temperature, normal and tangential forces of SiC during the scratching process were investigated. The effects of ultrasonic vibration frequency on the scratched surface quality and material removal rate of SiC in the scratching process were also analyzed. Simulation results indicate that during the cutting process, amorphization appears in the local area of processed SiC surface. The introduction of ultrasonic vibration to the SiC scratching process can alleviate the average tangential force and the average normal force of the imposed abrasive, which is beneficial to the scratching process and the improvement of scratched surface quality. For the given simulation parameters, the best ultrasonic vibration frequency which can lead to a better polished surface quality and higher material removal rate is 80GHz, above which the surface quality and material removal rate are less affected by the ultrasonic vibration.
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    Fretting Wear Characteristics of Carbon Fiber Reinforced Epoxy Resin Matrix Composites in Low Temperature
    1. Institute of Bio-Inspired Structure and Surface Engineering of College of Astronautics,
    2018, 52 (5):  604-611.  doi: 10.16183/j.cnki.jsjtu.2018.05.016
    Abstract ( 937 )   Save
    The FTM200 friction and wear tester was used and the PH13-8Mo stainless steel was taken as the friction couple and an orthogonal experiment was applied to studying the influences of normal load, fretting frequency, fretting amplitude and test time on the tribological property of carbon fiber reinforced epoxy resin matrix composites at -45 ℃, -20 ℃ and room temperature. The results showed that normal load, fretting frequency, fretting amplitude, test time and temperature affected the friction coefficient very significantly. Friction coefficients of the samples at -45 ℃ were higher than that at room temperature, for the matrix was friable under low temperature and the components were peeled off more easily in the wear process, resulting in increase of wear rate. The influence of normal load and temperature on the wear of composite was more obvious. Under the same temperature, the wear volume of composite increased with the increase of the load. Under the same load, the wear volume of composite at -45 ℃ was larger than that at room temperature, indicating that the fretting and the spalling fatigue occurred more easily. At room temperature, the surface scratching of the composite and some cracks were mainly characterized. The fretting wear mechanism of the carbon fiber reinforced epoxy resin-based composites was abrasive wear and fatigue wear, while the wear mechanism of the material at low temperature mainly focused on fatigue wear.
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    Vibration Reduction Characteristics of Metal Damper in Journal Bearing-Rotor System
    LI Zhaolun,WANG Xiaojing,SHEN Yifan,CHEN Chao,DONG Jian
    2018, 52 (5):  612-619.  doi: 10.16183/j.cnki.jsjtu.2018.05.017
    Abstract ( 896 )   Save
    In order to investigate the influence of metal damper (MD) on the damping performance of journal bearing-rotor system, three kinds of journal bearings (general journal bearings, journal bearings supported on circular MD, journal bearings supported on radial MD) were designed and manufactured. Experiments were carried out to investigate vibration characteristics and stability of the bearing-rotor system with the above bearings. Half speed vortex and vibration reduction characteristics of the system were analyzed. Results show that there is a significant decrease in acceleration amplitude of the bearings embedded with MD compared to general journal bearings. The journal bearings supported on radial MD have better vibration damping effect than journal bearings supported on circular MD, for there is no obvious half speed vortex and asynchronous vibration. Vibration energy dissipated by MD contributes to improving dynamics stability of the bearing-rotor system.
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    Molecular Dynamics Simulation of Frictional Properties at Gradient of Graphene
    YIN Nian, ZHANG Zhinan
    2018, 52 (5):  620-623.  doi: 10.16183/j.cnki.jsjtu.2018.05.018
    Abstract ( 857 )   Save
    In order to further investigate the frictional force characteristics of the silicon probing at the edge of graphene and its microscopic friction mechanism, a model was established by using molecular dynamics method, focusing on the variation of frictional force under different levels and positive pressure. The friction characteristics were also analyzed by using the strain cloud in the x and z directions. The results show that the positive pressure has little effect on the frictional characteristics of the graded edge of graphene, but the change of the number of steps will have a great influence on the frictional characteristics. In the process of pressing on the step, the phenomenon of compressive stress accumulation is accompanied by the release of compressive stress in the process of multi-step climbing. The compressive strain in the x direction and the integrity of the center of the crater in the z direction are important indexes to measure the friction force.
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    Effect of Friction Heat on Interfacial Wear and Brake System Stability
    MO Jiliang,WANG Dongwei,LI Jianxi,LI Zhen,ZHU Minhao,ZHOU Zhongrong
    2018, 52 (5):  624-630.  doi: 10.16183/j.cnki.jsjtu.2018.05.019
    Abstract ( 1113 )   Save
    Based on the working principle of vehicle disc brake system, a reduced disc brake dynamometer test bench was developed. An experimental study of brake vibration and noise was performed in this self-developed disc brake dynamometer. Moreover, a numerical analysis was performed by using Abaqus/Explicit to simulate the experimental process and investigate the relationship among the friction heat, interfacial wear and system stability. Both the experimental and numerical results showed that the friction system of brake pad on disc generated intermittent high frequency vibration and squeal noise during the friction process. The contact pressure of brake pad concentrated on the leading and trailing areas of the pad surface, which resulted in the high temperature and consequently local severe wear of these areas. Moreover, the vibration amplitude for the finite element model with thermal effect was lower compared to the model without thermal effect.
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