Table of Content

    10 June 2021, Volume 32 Issue 11
    Overview of Micro Friction to Macro Dynamics for Bolted Connections
    CAO Junyi, LIU Qinghua, HONG Jun
    2021, 32(11):  1261-1273.  DOI: 10.3969/j.issn.1004-132X.2021.11.001
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    As a typical mechanical assembly method, bolted connections played an important role in the design and operation of key mechanical equipment in the field of aerospace, military weapons, energy and chemical equipment and transportation industry. Moreover, due to the introduction of the nonlinear factors of stiffness and damping by bolted connections, new challenges in performance predictions and operation reliability were come into being to propel us to comprehensively understanding the characteristics of bolted connections from interface micro friction to macro structural dynamics. Therefore, the micro-macro dynamics of bolted connections reviewed and the fractal characterization modeling, statistical summation modeling and Iwan modeling methods of bolt joint friction constitutive model were summarized. Several experimental benchmarks for testing the friction energy consumption of bolted connections in the world were analyzed in detail. The latest research progresses of nonlinear modeling, parameter identification, numerical simulation and structural health monitoring in the macro dynamics of bolted connections were discussed, and the development trend of this field was prospected.
    Research on Metamorphic Self-recovery Strategy and Characteristics of Metamorphic Quadruped Robots after Overturning#br#
    WANG Shengjie, DAI Jiansheng,
    2021, 32(11):  1274-1282,1292.  DOI: 10.3969/j.issn.1004-132X.2021.11.002
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    When the robots were working in unmanned environments, it was difficult to avoid overturning and loss of movement due to external forces and terrains. Therefore, it was necessary that the robots had the self-recovery ability. In the static self-recovery method, the traditional recovery method could only be achieved by the movement of the legs. Based on the movable trunks of the metamorphic robots, different from traditional method a self-recovery strategy with the movement of the trunk was proposed when the quadruped robot overturned. The strategy used bionic inspiration to design the action and compared this method with the case of the trunk without metamorphosis from the perspective of force and energy. The optimized centroid trajectory and the shock absorption method were obtained. In addition, the simulation software and the prototype experiments were used to verify the feasibility of this method and it is proved that the strategy reduces the difficulty of achieving static self-recovery. Besides, experiments under different conditions prove that the strategy has certain stability and adaptability on different terrains.
    Study on Tribological Properties of Phenolic Resin Impregnated Graphite/SiC Ceramic Sealing Materials#br#
    PENG Xudong, HE Liangjie, JIANG Jinbo, MENG Xiangkai, HU Liguo, GUO Jungang
    2021, 32(11):  1283-1292.  DOI: 10.3969/j.issn.1004-132X.2021.11.003
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    UMT-3 multifunctional friction and wear testing machine was used to study the tribological characteristics of 3 kinds of homemade typical matching friction pairs of impregnated phenolic resin graphite and SiC ceramic under dry friction and oil lubrication conditions. Results show that the friction coefficient presents a downward trend with the increase of the product of load p and speed v (pv values) under dry friction conditions. The wear mechanism is mainly abrasive wear and adhesive wear when the pv value is low, but it changes to severe adhesive wear, abrasive wear and fatigue wear when the pv value is high. The influences of speed on wear rate is greater than that of load under the same conditions. Under the conditions of oil lubrication, the friction coefficient is always kept at about 0.1, and the wear mechanism is mainly adhesive wear and fatigue wear. When the pv values increase to 5 MPa·m/s, the surface maximum temperature rise of the 3 kinds of impregnated graphite is as 21.1 ℃ under dry friction conditions, and that is as 14.9 ℃ under oil lubrication conditions, meanwhile the temperature rises of H1 graphite are both the lowest. Considering the mechanics properties, tribological properties and face temperature rise of the impregnated resin graphite, the recommended graphitization degree is as 45%~55%.
    Vacuum Boundary Lubrication Performances of Three Solid-liquid Composite Lubrication Systems#br#
    XU Zengchuang, , CUI Weixin, HE Jingjian , HAO Lichun, LIU Shishen
    2021, 32(11):  1293-1298.  DOI: 10.3969/j.issn.1004-132X.2021.11.004
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    In order to study the lubrication characteristics of the MoS2/815Z, MoS2/RP4751 and MoS2/RIPP4758 solid-liquid composite lubrication systems under vacuum boundary lubrication conditions, vacuum reciprocating sliding friction  test and vacuum spiral orbit tribometer(SOT) test studies were carried out on three solid-liquid composite lubrication systems. Scanning electron microscope(SEM) and X ray energy dispersion spectrometer(EDS) analysis were performed on the surface of the ball-disk friction pair after the SOT test. The test results show that the selective combination of solid-liquid lubricants in the MoS2/815Z and MoS2/RIPP4758 composite lubrication systems may well combine the advantages of solid-liquid lubricants during the friction processes, which is beneficial to the formation of transfer film and boundary lubrication film. The average lubrication life of MoS2/815Z reaches 2327 cycle/μg, which is greater than the sum of the lubrication life of solid and liquid lubricants. MoS2 film and RP4751 liquid lubricant may not combine the advantages of solid-liquid lubricant well. It is not easy to form an effective transfer film and boundary lubrication film during the friction processes, which makes the film consume a lot in a short time. The surface of the friction pair is in a state of depleted oil, which eventually leads to a rapid increase in the friction factor and lubrication failure of the MoS2/RP4751 composite lubrication system.
    Numerical Simulation of Abrasive Flow Machining in Multi-angle Elbows
    YIN Hongchao, LIU Xiao, ZHAI Zhende, MU Lin
    2021, 32(11):  1299-1306.  DOI: 10.3969/j.issn.1004-132X.2021.11.005
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    Abrasive particle flow processing technology was applied to complete the numerical simulation of inner surface polishing processes of multi-angle elbows. Effects of inlet flow velocity and abrasive concentration on abrasive particle flow polishing processes were studied by FLUENT software under different bending angles. Effect laws of inlet flow velocity and abrasive concentration on local pressure differences of bent pipe, inlet and outlet pressure differences, and turbulence intensity were obtained. The overall effects of the pressure and velocity were analyzed. Then the suitable working conditions of the inner surfaces of abrasive particle flow polishing pipes were obtained. Based on this, an unsteady numerical simulation of heat accumulation was carried out during abrasive flow polishing processes. Simulation results show that the temperature changes are small during the processes.  These results provide a reference for actual abrasive flow processes.
    Extrapolation Method of Vehicle Big-data Service-loads Based on Non-parametric KDE Method#br#
    YU Jiawei, ZHENG Songlin, ZHAO Lihui, JING Qing
    2021, 32(11):  1307-1314.  DOI: 10.3969/j.issn.1004-132X.2021.11.006
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    A customer-usage-behavior characteristic statistical method and vehicle life cycle service-load extrapolation method were presented based on non-parametric KDE method. After the national wide investigation of customer-usage-behavior data survey and big-data collection of road load spectra, a statistical analysis method for 90% quantile customer usage typical behavior characteristics was studied by applying non-parametric one-dimensional KDE method. Combining non-parametric two-dimensional KDE method with Monte Carlo simulation, a vehicle life cycle service-load extrapolation method was carried out based on the collected customer road loads. Furthermore, the variation characteristics of multiple extrapolations with different KDE methods were studied. Results show good consistency of load spectra damage and distribution of multiple load extrapolations. 
    Design and Force Control of Composite Axial Force Loading Apparatus
    YANG Fang, SI Donghong, MA Xiqiang, XUE Yujun,
    2021, 32(11):  1315-1320,1329.  DOI: 10.3969/j.issn.1004-132X.2021.11.007
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    The aeroengine main bearing test needed accurate and stable axial load to meet the performance test requirements, for this purpose,the design principle of the combined action of preloaded spring force and hydraulic force was analyzed, and a compound axial force loading apparatus with a built-in miniature force sensor was designed. Based on disturbance rejection control theory, the extended state observer was designed to observe feedback information, and combined with a nonlinear PID controller to develop a compound axial force control strategy. Finally, the compound axial force loading apparatus and its force control method were applied to the double rotor test rig of the aeroengine main bearing. The testing results show that the control accuracy of axial loading force is greatly improved.
    Effects of Cooling Parameters on Tool Vibration and Surface Roughness in Turning Austenitic Stainless Steels#br#
    LIU Niancong, WU Shenghong, XIE Jingliang, YANG Chengwen, LIU Baolin, JIANG Hao, CHEN Yun
    2021, 32(11):  1321-1329.  DOI: 10.3969/j.issn.1004-132X.2021.11.008
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    Aiming at investigating the limitations of weak cooling effects to difficult cutting materials under minimum quantity lubrication (MQL) conditions, the influences of cooling parameters on tool vibration and surface roughness under MQCL conditions were analyzed. The orthogonal test was designed based on Taguchi method, and cutting test was carried out based on MQCL conditions, then the effects of cooling parameters (cold air temperature, oil flow rate, wind speed and jet surface type) on tool vibration and surface roughness were analyzed by the analysis of variance, main effects plot, response surface methodology and metal-cutting principle. The prediction model of tool vibration and surface roughness were established related to parameters. The improved genetic algorithm was used to optimize the support vector regression (SVR)prediction model synchronously to obtain the optimal values of cooling parameters. The experimental results show that the temperature has the greatest influence on the tool vibration, and the tool vibration increases with the increase of temperature. The influences of wind speed on the surface roughness are the greatest, when the wind speed is less than 10 m/s, the surface roughness increases with the increase of wind speed, when the wind speed is greater than 10 m/s, the surface roughness decreases with the increase of wind speed. When the surface to be jetted is the toos minor flank, the surface roughness and the vibration are the least. The cooling parameter optimization results show that, when the cold air temperature is as -2.36 ℃, the wind speed is as 7.31 m/s, the oil flow is as 300 mL/h, and the spraying surface is the tool minor flank, the surface quality of the workpiece is the best, and the value of surface roughness is as 0.6588 μm. The verification experimental results show that the prediction errors of surface roughness and RMS of vibration are as 4.4% and 5.9% respectively.
    Structural Design Optimization of Spindle Unit of CNC Lathes for Energy Saving
    HE Jixiang, LI Congbo, LYU Yan, LI Juan
    2021, 32(11):  1330-1340.  DOI: 10.3969/j.issn.1004-132X.2021.11.009
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    In order to reduce the energy consumption during the use of CNC lathes, an energy-saving structural optimization design method was proposed for the spindle units in the main drive system. Firstly, the power model of the spindle units was constructed and the dynamic and static performance indicators were analyzed. Then, the size parameters that had a large impact on the energy consumption, dynamic and static performance of the spindle units were selected as optimization variables, based on the uniformity test and sensitivity analysis, and the indicators were fitted by response surface method. Thirdly, the principal unit analysis method was used to reduce the function dimension, and an optimization model for energy-saving design of the spindle unit structures was established. Finally, physical experiments were used to verify the reliability of the simulation results, and the simulated annealing-particle swarm hybrid algorithm was used to solve the optimization model. The comparative results of the harmonious response analysis and the simulation experiments of the spindles before and after optimization show that the maximum deformation of the spindles is reduced by 1.67%, the second-order frequency is increased by 6.83%, and the un-load energy consumption is reduced by 3.69%. This optimization design method reduces the spindle energy consumption, and improves the dynamic and static performances of the spindles at the same time.
    Inversion Model of Maximum Riveting Force in Aluminum Alloy Self-piercing Riveting Processes#br#
    SUN Xiaoting, ZENG Kai, HE Xiaocong, XING Baoying
    2021, 32(11):  1341-1345,1353.  DOI: 10.3969/j.issn.1004-132X.2021.11.010
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    Based on the virtual work principle of material plastic deformation and the upper bound theorem, the inverse analysis of maximum riveting force in the SPR processes was carried out. The inverse calculation model of maximum riveting force was established by taking the geometric characteristic parameters of the joints, such as rivet flaring, rivet geometry parameters, thickness of the connected material, mechanics properties of rivet and connected material, contact conditions between punch and rivet as the model control parameters. At the same time, the verification tests were carried out on the maximum riveting force for a variety of aluminum alloy SPR processes. The results show that average error between the model calculation value and test value is as 7.82%, which verifies the validity of the inversion model for the maximum riveting force. The maximum riveting force is proportional to the strength and length of the rivet and inversely proportional to the depth of the rivet cavity. To obtain self-piercing riveted joints with higher static performance, the maximum riveting force should be appropriately increased. In addition, under the action of near maximum riveting force, the connection materials with lower hardness and rivets with lower hardness are easy to obtain joints with large rivet flaring.
    A New Constitutive Model for Hot Deformation Behavior of SiCp /2024Al Composites under High Strain Rate#br#
    FAN Yihang, ZHAN Chunyong, HAO Zhaopeng
    2021, 32(11):  1346-1353.  DOI: 10.3969/j.issn.1004-132X.2021.11.011
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    Through the dynamic compression tests of the split Hopkinson pressure bar(SHPB), the thermal deformation behavior of the aluminum-based silicon carbide particle reinforced composite(SiCp/2024Al) with a volume fraction of 45% in a large strain rate and deformation temperature range was studied. The influence of thermal deformation parameters(deformation temperature and strain rate) on flow stress is analyzed. It is found that the deformation temperature and strain rate have significant effects on the flow stress, compressive strength, elastic modulus, and strain rate sensitivity of the composites. The compressive strength and elastic modulus decrease with the increase of deformation temperature, while the compressive strength, elastic modulus and strain rate sensitivity show an inflection point with the increase of strain rate. According to the experimental results, combined with thermodynamics and statistical damage mechanics theory, a continuous damage constitutive model describing the dynamic thermal deformation behavior of SiCp/2024Al composites was established. The predicted flow stress is in good agreement with the experimental ones, indicating that the model established may accurately describe the dynamic thermal deformation behavior of SiCp / 2024Al composites.
    Study on the Residual Stress of Large Deformation Free Pushing Diameter-reducing Tube Blanks#br#
    LIU Heng, WANG Liandong, WANG Xiaodi, LIU Chao,
    2021, 32(11):  1354-1360.  DOI: 10.3969/j.issn.1004-132X.2021.11.012
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    The ends of large deformation free pushing diameter-reducing tube blanks were warped, that is, the outer diameters of the ends were larger than that of the sizing areas. For the end warpage areas, based on the deformation analysis and mechanics equilibrium conditions, the formula of circumferential residual stress was deduced from the warpage deformations and shear stress. It is revealed that the circumferential residual stress is characterized as tensile stress from the inner to outer surface. The double-sided large deformation diameter-reducing of 219 mm × 7.5 mm seamless steel pipes were carried out on the three-dimentional hydraulic press. With the diameter-reducing sample intercepted, the measuring points were selected in the inner and outer surfaces of the end warpage areas and sizing areas, and the residual stress was measured by X-ray diffraction method. The trend of end warpage area measurements were consistent with the theoretical analysis. For the diameter-reducing processes, the finite element simulation was carried out with ABAQUS software, the results of the deformation and force are in good agreement with the diameter-reducing experiments, and the results of residual stress in the inner and outer surfaces are consistent with the X-ray measurement. Furthermore, the distribution laws of residual stress along the wall thickness direction and the axial direction from the sizing areas to the end are revealed respectively.
    Optimal Design of Solid Surface Deployable Antennas Based on Twin-Bennett Linkage#br#
    ZENG Xiang, ZHOU Yijun, YUAN Weiqin, LUO Chen
    2021, 32(11):  1361-1369,1376.  DOI: 10.3969/j.issn.1004-132X.2021.11.013
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    In order to solve the interference of Twin-Bennett (TB) linkage which controled the deploying processes of the solid surface deployable antennas and improve package capacities, the traditional sunflower-like segmentation scheme was improved. The optimization model between geometric parameters and the package ratio of the solid surface deployable antennas was established by exponential product formula. Then the package ratio was taken as objective function to optimize the segmentation scheme, with the optimal geometric parameters obtained by the sequential quadratic programming of multiple initial value points. Aiming at the synchronization of deployment, the umbrella synchronous deployment linkage was designed. The synchronous mechanisms might convert the linear movement into the deploying of the solid deployable antennas, and ensureed a single degree of freedom and synchronization. Finally, the software simulations and model tests were implemented to verify the deploying ability of the solid surface deployable antennas. It is indicated that the design may increase package capacities of the sunflower-like solid surface deployable antennas from 44% to 37%, and achieve the simplicity of the drive systems. The simulation results and the 3D prototype demonstrate the feasibility and rationality of this method.
    Disc Cutter Wear Evaluation Method Based on Regression Analysis of Multiple TBM Engineering Data#br#
    YANG Yandong, SUN Zhenchuan, ZHANG Bing, YAN Changbin
    2021, 32(11):  1370-1376.  DOI: 10.3969/j.issn.1004-132X.2021.11.014
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    In order to evaluate the influences of different tunnel engineering surrounding rocks on the TBM disc cutter wear, and solve the problems of the disc cutter wear which was difficult to accurately predict, thus the parameters of the rock uniaxial compressive strength, rock equivalent quartz content, rock abrasiveness index, rock mass integrity index, disc cutter wear rate based on broken rock volume were selected to do regression analysis, based on the data of TBM disc cutter wear from multiple TBM tunnel projects, including North Xinjiang Water Supply Project, the water diversion from Songhua River to Changchun City, the water diversion from the Han to the Wei River, Darui Railway Gaoligongshan Tunnel Project and Shenzhen Metro Line 10 Project. The results show that, rock abrasion index has a logarithmic function relationship with the product of uniaxial compressive strength and equivalent quartz content, disc cutter wear rate based on broken rock volume has an exponential function relationship with the product rock mass integrity coefficient and rock abrasion index, and disc cutter ring life has a negative exponential function relationship with the product of the rock mass integrity coefficient and the rock abrasive index. Based on this, the graded evaluation criteria for rock abrasion and disc cutter wear are established.
    Torsional Impact Fatigue Test Method for Electric Vehicle Differentials
    ZOU Xihong, LI Jinxiao, HU Qiuyang, XI Shuaijie, FU Lingfeng, YUAN Dongmei
    2021, 32(11):  1377-1385.  DOI: 10.3969/j.issn.1004-132X.2021.11.015
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    According to the actual load situation of the differential which were the key component of the electric vehicle transmission systems, a torsional impact fatigue test system for the differentials of the electric vehicles was designed based on hydraulic servo. The stress concentration parts of the key components of the differentials were analyzed under the current test technical conditions, and the loading waveform, loading frequency, loading amplitude and loading frequency were researched in theory and load characteristics. The torsional impact fatigue strain test system and test method of electric vehicle differentials were constructed, and a large number of strain tests were carried out. The test data of different frequencies and amplitudes were statistically analyzed. Combined with the analysis results and the material stress-life (S-N) curve, a complete torsional impact fatigue test method of electric vehicle differentials was established. The results indicate that the fatigue failure site and form of differentials are consistent with those of real vehicles and stress concentration measuring points.