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Table of Content

    28 March 2018, Volume 52 Issue 3 Previous Issue    Next Issue
    Simulation of 3-D Viscous Non-Reflection Numerical Wave Tank and the Interactions of Waves and Structures
    YANG Yuntao,ZHU Renchuan,JIANG Yin,MIAO Guoping
    2018, 52 (3):  253-260.  doi: 10.16183/j.cnki.jsjtu.2018.03.001
    Abstract ( 915 )   Save
    Based on the Navier-Stokes equations, a 3-D viscous non-reflection numerical wave tank is established by using mass source method, and the interactions of waves and floating structures are investigated in the tank. In the tank the mass source region and working zone are surrounded by two sponge layer zones at both ends of the tank in order to avoid the reflected waves. Regular traveling waves and the interactions of wave and bottom-mounted wall, floating structures are simulated. The results show that the waves gene-rated by mass source method and their propagation agree well with the theoretical results. In the wave tank standing waves form before the structures, which reveals the tank’s non-reflection function. The interaction of waves and two floating bodies of Wigley and rectangular box side by side are simulated and analyzed. The computed wave forces at various frequencies are in good agreement with the experimental results, especially near the resonant frequency that they are much closer to experimental ones comparing with results over-predicted by the potential flow method.
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    Roll Damping Prediction for a Three Dimensional Rectangle Floating Production Storage Offloading
    YANG Jixiang1,2,WANG Tianying3,TANG Wenyong1,2,FAN Ju1,2
    2018, 52 (3):  261-267.  doi: 10.16183/j.cnki.jsjtu.2018.03.002
    Abstract ( 878 )   Save
    Based on computational fluid dynamic theories,the simulations of roll decay and forced roll motion of a three dimensional rectangle floating production storage offloading, a new concept ocean floating structure, were carried out by using overset mesh technology and solving Reynolds Averaged Navier-Stokes equations with the consideration of free surface effect. In addition, the scale factor and gird study verification were considered. Energy method was adopted to compute the roll decay damping coefficients. To verify the methods, a roll decay motion was predicted for a surface combatant. The results show a good agreement with the experimental data. And then a series of prescribed roll motions on various amplitudes and frequencies of different modifications to origin design were executed due to its lack of roll stability.
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    Influence of Bowshape on Hydrodynamic Performance of Mono Wave-Piercing Craft
    WEI Chengzhu,YI Hong,LI Yinghui
    2018, 52 (3):  268-275.  doi: 10.16183/j.cnki.jsjtu.2018.03.003
    Abstract ( 1075 )   Save
    Typical wave piercing bows were modeled to study the influence of bowshape on hydrodynamic performance of mono wave-piercing craft. Numerical methods were developed by solving URANS (Unsteady Reynolds Averaged Navier-Stokes) equations and adopting different dynamic mesh methods for this study. Simulations of hulls with different wave-piercing bows running in calm water and waves were conducted. Mono wave-piercing craft with slender wave-piercing bows are not sensitive to bow forms in short waves, and have smaller resistance, hull motions and acceleration than a planning boat. Resistance and wave making in calm water of a mono wave-piercing craft in large scale are not sensitive to bowshape, while bowshape has great influence on resistance, hull motions and wave making in calm water of a mono wave-piercing craft with small scale and high speed.
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    Effect of Submergence Depth on the Resistance of a Small Waterplane Area Twin-Hull with Inclined Struts
    MAO Lifu,WEI Chengzhu,LI Yinghui,YI Hong
    2018, 52 (3):  276-282.  doi: 10.16183/j.cnki.jsjtu.2018.03.004
    Abstract ( 854 )   Save
    A small waterplane area twin-hull (SWATH) ship with inclined struts and the DARPA (Defense Advanced Research Projects Agency) Suboff model as torpedoes and an NACA (National Advisory Committee for Aeronautics) airfoil as the strut cross section is developed. Based on this design, a systematic and targeted study based on CFD has been conducted to figure out how the torpedo submergence depth impacts the resistance of the torpedo and the entire ship of the SWATHmodel above. Viscidity was consi-dered. It is found that, through the study, the torpedo submergence depth has a significant impact on the hull resistance of a SWATH with inclined struts, and the impact increases with speed rising. Although the wave makes resistance of torpedoes near the free surface increase obviously with the torpedo submergence depth decreasing, the total resistance of the whole ship decrease obviously with the torpedo submergence depth decreasing.
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    Model Selection Study on Motion Prediction Methods of IMO’s Parametric Rolling Level 2 Criteria
    ZHOU Yaohua,ZHANG Gaofeng
    2018, 52 (3):  283-290.  doi: 10.16183/j.cnki.jsjtu.2018.03.005
    Abstract ( 914 )   Save
    The International Maritime Organization (IMO) lunched a new round of model selection for motion prediction method of the Level 2 parametric rolling (PR) criteria in 2016. The model selection study on prediction method is very important for developing reasonable dynamic stability criteria and increasing the safety level of ship. According to test data, three alternative nonlinear dynamics methods are verified, validated and compared, including time-domain method and averaging method, and the reasons for difference of prediction precision have been analyzed. On this basis, vulnerability levels for large scale sample calculations and accident ship have been obtained and compared, and several suggestions about model selection for motion prediction method of the Level 2 PR criteria have also been given. The accuracy validation and comparison study are executed firstly for the motion prediction methods of Level 2 criteria of PR in this study, and parameters setting of time-domain method are also provided. This is helpful to the development of second generation stability criteria.
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    A Body Force Model for Tunnel Thrusters and Application
    YU Cheng,DONG Xiaoqian,YANG Chenjun
    2018, 52 (3):  291-296.  doi: 10.16183/j.cnki.jsjtu.2018.03.006
    Abstract ( 1067 )   Save
    Aiming at predicting the hull thrust at the preliminary design stage for a tunnel thruster, an RANS (Reynolds-averaged Navier-Stokes) simulation method incorporating the body force model for the rotor is studied. Considering the big loading distribution difference between the open propeller and the tunnel thruster, common body force models are not suitable for the tunnel thruster. According to the cha-racteristic loading distribution of tunnel thruster rotor blades, a new body force model is proposed. To account for the blockage effect of the rotor, we propose a flow rate correction approach, together with empirical formulas of the flow rate correction coefficient for the cases of with and without the gearbox. Numerical examples indicate that the present method is capable of predicting the hull thrust, and hence the rotor thrust, and determining the required thrust with reasonable accuracy. Besides, the body force-based simulation method can also be applied to simulating the ventilation phenomenon of tunnel thrusters.
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    Hydraulic Shock Absorber Orifice Cavitation and Noise Analysis
    AN Songgwang,CAO Yang,ZHANG Jianwu
    2018, 52 (3):  297-304.  doi: 10.16183/j.cnki.jsjtu.2018.03.007
    Abstract ( 1123 )   Save
    Based on road and bench test, abnormal noise mechanism and reduction measures in twin-tube hydraulic absorber were studied, and fluid dynamic models of the damper orifices, disc valves and spring valves were established by using AMESim software and validated by the test results. Through the numerical simulation and damping parameters impact analysis, the state of the orifice cavitation appears in the compression and rebound stroke was determined, and relationship between orifice cavitation, abnormal vibration of the rod and the orifice, inflation pressure were found. In order to reduce the abnormal vibration noise of the damper, further improvements in abnormal noise clearing were proposed on the premise of guaranteeing the external characteristics of the damper.
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    Investigation on the Camber and Cornering Characteristics of a Catenary Non-Pneumatic Wheel with Brush Model
    DU Xianbin,ZHAO Youqun,XIAO Zhen,LIN Fen
    2018, 52 (3):  305-311.  doi: 10.16183/j.cnki.jsjtu.2018.03.008
    Abstract ( 1039 )   Save
    To investigate the influence of camber angle on the cornering characteristics of the catenary non-pneumatic wheel, the wheel structure and bearing mechanism were analyzed. The brush theory model under the combined conditions of camber and cornering was established based on the assumption that the elastic characteristics of catenary non-pneumatic wheel are all concentrated in the tread, which has brush deformation characteristics. The camber and cornering characteristics test was carried out with tire dynamic test rig, and the experimental results and the analytical results of the theory model were compared and discussed in detail. The results show that the established theoretical model can accurately express the camber and cornering characteristics of the catenary non-pneumatic wheel. Moreover, the existence of the camber angle will increase the lateral force and decrease the self-align moment when the camber and sideslip angle are both positive or negative; otherwise, the lateral force will be reduced and the self-align moment will be increased. This research provides a theoretical guidance for the structure optimization and the modeling of the catenary non-pneumatic wheel under the combined conditions.
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    Simulation Analysis on Fracture Modes of Ultra-High Strength Steel Spot-Welded Lap-Shear Joints
    XIAO Fenglin,ZHANG Yansong
    2018, 52 (3):  312-317.  doi: 10.16183/j.cnki.jsjtu.2018.03.009
    Abstract ( 916 )   Save
    In this paper, a finite element model of ultra-high strength steel spot-welded lap-shear joint is established by taking the 1.5mm stamped boron steel as example, the geometric dimension and material properties of the heat affected zone are defined, and the effect of the nugget size on the fracture modes of a spot-welded joint is analyzed. The results show that PPF (part interfacial fracture) occurs in the softening zone and fails inside the nugget along the thickness direction of the sheets; PF (pull-out fracture) occurs outside the nugget along the thickness direction of the sheets. The critical nugget sizes of different fracture modes (interfacial fracture, part interfacial fracture and pull-out fracture) are obtained. The study provides technical reference for the evaluation and prediction of the fracture modes of ultra-high strength steel spot-welded joints.
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    Automobile Door Fitting Based on Frenet Frame
    HENG Dezheng1,YANG Jun2,LI Zhimin1,JIN Aijun2,JIN Sun1
    2018, 52 (3):  318-323.  doi: 10.16183/j.cnki.jsjtu.2018.03.010
    Abstract ( 985 )   Save
    In order to improve the fitting quality, firstly, contours are extracted from scanning data points to fit Fourier series, then unit tangent and binormal can be got at any point based on Frenet frame of curve theory, and the objective function of fitting quality referencing Hausdorff distance can be constructed. The global optimal transform parameter can be found based on differential evolution. Effectiveness of the method is demonstrated by one practical door-fitting example. Results indicate that the proposed method can significantly improve the fitting consistency and improve automobile dimension quality.
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    Quality Analysis of Multi-Stage Assembly Systems Based on Markov Model
    SONG Tingting1,ZHAO Ziren1,DU Shichang1,REN Fei2,LIANG Xinguang2
    2018, 52 (3):  324-331.  doi: 10.16183/j.cnki.jsjtu.2018.03.011
    Abstract ( 879 )   Save
    In manufacturing systems, a product usually goes through a series of assembly stages before it is completely finished, making it of great significance to analyze the product quality in assembly systems. A Markov model is developed to evaluate the quality performance of assembly systems in this paper. The quality of a product is not only related to the state of the current stage, but also has something to do with the quality of coming parts from upstream stages. Quality propagation is taken into consideration along the assembly production line. Finally, a case of multi-stage assembly system of astronautical valve is used to validate the effectiveness of this Markov model.
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    Preventive Maintenance of a Single Machine System with Batch Production Pattern under Time-Varying Workload
    HU Jiawen1,JIANG Zuhua1,HOU Wenrui2,PEI Haiyan1,WANG Haili1,SUN Xiaoming1
    2018, 52 (3):  332-339.  doi: 10.16183/j.cnki.jsjtu.2018.03.012
    Abstract ( 976 )   Save
    This paper takes a single-machine system as the research object. The situation where the workload varies from batch to batch is considered. An extended hybrid imperfect maintenance model taking operational condition (OC) into account is developed. Maximum likelihood method is adopted to estimate the parameters. This study proposes a preventive maintenance (PM) policy with a short-term production plan for the situation where production plan is updated after the completion of each batch; meanwhile, PM can only be implemented at each batch-shift point. A numerical example is provided to illustrate the necessity of integrating OC with PM optimization and to validate the effectiveness of the proposed PM strategy.
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    Antifriction and Lubrication Mechanism of Imitate Raindrop Textured Broach
    NI Jing,LI Bin,XU Jing
    2018, 52 (3):  340-347.  doi: 10.16183/j.cnki.jsjtu.2018.03.013
    Abstract ( 950 )   Save
    Laser processing technology was used to generate raindrop surface texture on the flank of keyway broach. Broaching load test of 45# steel was carried out. A fluid dynamics model was established to analyze the lubrication oil flow characteristics and the lubricating mechanism of micro-textured broach by the fluid dynamics analysis method. Research shows that micro-textured broach can not only reduce the broach-ing load and tool wear, but also improve the response and broaching performance. Meanwhile, flow resistance of the lubricating fluid was effectively reduced by raindrop micro-texture, which leads to an increase in flow velocity of the lubricating fluid, and the lubricant could took away more heat in unit time, so that broaching temperature was effectively reduced. The textured broach can greatly improve cutting efficiency and machining accuracy. The micro-textured groove can also be used to store micro lubricating fluid, to be a supplement under the state of micro-lubrication.
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    Topological Transformation and Transmission Characteristics Analysis of Vehicle Auto Transmission Based on Graph Theory
    FU Shengping,LI Shengbo,LUO Ning
    2018, 52 (3):  348-355.  doi: 10.16183/j.cnki.jsjtu.2018.03.014
    Abstract ( 1104 )   Save
    Auto transmission is one of the complicated mechanical mechanisms behaving multi freedom degrees under different working conditions. The present models of auto transmission used for intelligent computing are limited by adaptability, intelligence and consistency from design to characteristics analysis. Therefore, a more efficient, intelligent and systematic method based on graph theory is proposed in this paper. Firstly, the general topological model and shifting topological transformation model of vehicle auto transmission under different working conditions are constructed in the sense of relative speed. And shifting process is mathematically interpreted to judge the topological characteristics of different shifts. Secondly, the general system graph model of planetary gear transmission is established in the sense of absolute speed. The mathematic rules of graph theory model topological transformation are defined. And the transmission characteristics analysis method of planetary gear mechanism is proposed based on graph theory. Finally, the proposed method is proved to be feasible and correct according to the demonstration analysis. Moreover, the research results provide the references for more efficient, intelligent and systematic design of vehicle auto transmission.
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    2-D Cosinusoidal Phase-Modulated Scatter-Wave Jamming to Multi-Channel SAR-GMTI
    FANG Mingxing1,2,BI Daping1,SHEN Aiguo1
    2018, 52 (3):  356-364.  doi: 10.16183/j.cnki.jsjtu.2018.03.015
    Abstract ( 888 )   Save
    Two-dimension (2-D) cosinusoidal phase-modulated scatter-wave jamming for multi-channel synthetic aperture radar-ground moving target indication (SAR-GMTI) is studied. First, based on the traditional scatter-wave jamming for SAR, 2-D cosinusoidal phase-modulated scatter-wave jamming theory is introduced. Then, the countering performance against SAR-GMTI is analyzed by using the dual-channel displaced phase center antenna (DPCA) technique. Finally, strong scattering baits are set as scattering targets to carry out computer simulation and application analysis. The research result shows that the jamming method can produce 2-D netted multi-false targets with real targets scattering information for multi-channel SAR-GMTI. In practical application, the distribution of jamming targets can be flexibly controlled by the rational allocation of jammers and bait targets, and the vivid moving false target jamming performance can be realized by the baits’ motion.
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    The Algorithm of Energy Cooperation in Cellular Networks with Energy-Harvesting Base Stations
    LIU Didi1,2,LIN Jiming3,WANG Junyi3,QIU Hongbing3,PENG Jie1
    2018, 52 (3):  365-372.  doi: 10.16183/j.cnki.jsjtu.2018.03.016
    Abstract ( 1172 )   Save
    The problem of energy cooperation in cellular networks with energy-harvesting (EH) base stations is studied in this paper. Specially, the base stations (BSs) are powered by individual hybrid power supplies (including both the conventional grid and renewable energy sources), connected by resistive power lines for energy sharing. First, we proposed a new model for energy cooperation between cellular BSs, and the energy harvested was stored in individual limited rechargeable batteries before usage. We employed linear programming, greedy algorithm and Lyapunov optimization to develop energy cooperation schemes under three different scenarios based on the proposed new model, and gave the corresponding optimal offline algorithm and online algorithm. The goal in this work is to minimize the sum of the energy consumed by the BSs from the conventional power grid, that is, to improve the utilization efficiency of the energy harvested and reduce carbon emissions. We validate the effectiveness of the proposed algorithm through numerical simulations, at the same time the impacts of the transfer efficiency and the capacity of the battery on the property of the BSs are given under energy cooperation.
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    Hydrodynamic Analysis of Variable-Pitch Vertical Axis Tidal Turbine Under Surging Motion
    WANG Shuqi1,ZHOU Nianfu2,ZHANG Liang3,XU Gang1
    2018, 52 (3):  373-378.  doi: 10.16183/j.cnki.jsjtu.2018.03.017
    Abstract ( 1159 )   Save
    Under the condition of actual sea state, hydrodynamic characteristic of variable-pitch vertical axis tidal turbine is related to wave characteristics and floating carrier wave motion response. This paper simulates the wave response motion of the variable-pitch vertical axis tidal turbine by combining the turbine rotation and the axial forced surge. Using ANSYS CFX software, we analyze the flow field and hydrodynamic performance of the turbine with forced surge in the uniform flow, and study the influences rule of different surge frequencies and surge amplitudes on turbine hydrodynamic performance. The research results showed that compared with the turbine which only has rotation motion in the uniform flow, the surge motion leads to the change in the interval of wake vortex. The peak envelope mean value of turbine hydrodynamic loads makes an obvious fluctuation in surging. The fluctuation frequency is equal to the turbine’s surge frequency, and the fluctuation amplitudes have a positive correlation with the frequency and amplitude of the surge. The maximum fluctuation range of hydrodynamic loads gradually increases with the increasing frequency and increasing amplitude of the surge, while the minimum gradually reduces. The results of this study can provide a reference for turbine structural strength check.
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