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Table of Content

    28 August 2018, Volume 52 Issue 8 Previous Issue    Next Issue
    Deflection of a Circular Diaphragm-Type Piezoactuator Under Loads of Voltage and Pressure
    HU Yuanlin,WANG Wen
    2018, 52 (8):  883-890.  doi: 10.16183/j.cnki.jsjtu.2018.08.001
    Abstract ( 1090 )   Save
    Analytical equations are developed to calculate the static deflection of a circular diaphragm-type piezoactuator under loads of driving voltage and uniform resisting pressure. The solution is derived using the energy minimization method and the Rayleigh-Ritz method based on the Kirchhoff thin plate theory. The proposed solution is validated via the experimental measurements under loads of voltage only, pressure only, and combined loads of voltage and pressure, respectively. The analytical and experimental results agree within 9.3%, which suggests the solution is accurate. Based on the proposed equations, the effects of the radius ratio and thickness ratio of the lead zirconate titanate (PZT) layer to the passive layer on the actuator deflections are investigated. Moreover, the effects of the pressure loads on the actuator deflections are studied as well. The results indicate that there exist the optimal radius ratio and the optimal thickness ratio to generate maximum stroke volume. It is also observed that the diaphragm deforms reversely near the periphery under the pressure load when the actuator radius ratio is lower than 0.71, which weakens the actuator performance.
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    Guided Waves Propagation in High-Speed Train Axle and Wheelset with Interference Fit
    CAO Xiao,LI Fucai
    2018, 52 (8):  891-897.  doi: 10.16183/j.cnki.jsjtu.2018.08.002
    Abstract ( 901 )   Save
    The connection between high-speed train axle and wheel hub is interference fit joint. Because of alternating load during the process of train running, fretting fatigues usually emerge in stress concentration region of axle. Guided waves can propagate at a long distance with low attenuation. It is very suitable to detect fretting fatigues owing to its sensibility to tiny damage. However, most methods need to tear the axle down, and few researchers have yielded useful information on guided waves propagation in high-speed train wheelset with interference fit. Firstly, the influence of assembly quality on guided waves propagation was studied by changing interference fit tolerance. Secondly, whether the energy difference method can be applied to damage detection in wheelset was discussed. The results indicate that interference fit tolerance has a significant influence on guided waves propagation. The guided waves amplitude reduces when the interference fit tolerance increases. The energy difference method is used to detect damage based on the axial symmetry of structure, so it still can be applied to damage detection of the axle assembled with wheels.
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    Research on Transverse Shear Property of Composite Circular Cell Honeycomb
    JIANG Bingyun,KONG Xianghong, ZHOU Xubin,LI Dayong
    2018, 52 (8):  898-903.  doi: 10.16183/j.cnki.jsjtu.2018.08.003
    Abstract ( 1056 )   Save
    The transverse shear stiffness of carbon fiber reinforced plastics (CFRP) circular cell honeycomb (CCH) was studied using analytical method, numerical method and experiments, and the equivalent transverse shear modulus of CFRP CCH was found. The in-plane shear modulus of the laminate used for CCH was found by calculating the stiffness of laminate, and the analytical solution of shear modulus of CCH was obtained using a rectangular representative volume element (RVE). Configuration of composite tubes was designed according to the finite element (FE) analyses of CCH. The numerical solution of shear modulus of CCH was found by FE analysis using twin-shear FE model of CCH. The analytical and numerical solutions were corrected using experimental results. The correction coefficient was found, and it is a very important parameter for the study of mechanical property and application of CCH.
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    Load of Wind Turbine Affected by Icing
    HU Liangquan,CHEN Jinge,SHEN Xin,ZHU Xiaocheng,DU Zhaohui
    2018, 52 (8):  904-909.  doi: 10.16183/j.cnki.jsjtu.2018.08.004
    Abstract ( 33 )   Save
    Aiming at the wind turbine blade icing problem, the NREL Phase VI wind turbine was used as the research object. The Fluent and the aero-elasticity program FAST were used to study the load effects of the asymmetry icing (i.e., just one blade is covered with ice) and the symmetry icing (i.e., two blades are covered with ice). Results show that the icing can decrease the blade aerodynamic performance, its rotor torque will be decreased. The symmetry icing can decrease the rotor torque up to 34.99%. The asymmetry icing can induce the unbalance shear force on the low speed shaft, and will increase the low speed shaft fatigue load. The symmetry icing can decrease the rotor thrust, the blade root moment and the tower base moment up to 6.07%, 40.32% and 37.32%, respectively.
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    The Simulation of the Velocity and Morphology of Ice Dendrite Growth Using Phase Field Method Under Different Supercooling
    HU Shufan,KONG Weiliang,LIU Hong
    2018, 52 (8):  910-917.  doi: 10.16183/j.cnki.jsjtu.2018.08.005
    Abstract ( 54 )   Save
    At present, the study only discusses the icing law between supercooling 0—20K, which is half of the icing range of flight. To solve this problem, a diffusive interface phase field method which is suitable for large supercooling simulation of crystal is adopted, and anisotropy and thermal disturbance are considered. The characteristics of growth speed, morphology and tip radius in the supercooling range of 20—40K are quite concerned. The analysis of ice growth law shows its slope is significantly higher than the existing data of 0—20K. This is due to the increase of the tip’s curvature, which has a rapid decrease of thermal diffusion length, and promotes the thermal diffusion, and the increasing of curvature leading to the dynamic supercooling. Both of them lead to the increase of ice growth rate with supercooling. Using the ice growth law obtained to analyze the runback icing in aircraft, it is found that the ice runback distance is sensitive to the liquid water content (LWC) when the supercooling is larger than 20K and the LWC is large. Under this condition, the abnormal icing characteristics of fast growth and severe runback may occur simultaneously.
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    Investigation on Substrate Icing Growth Affected by Surface Energy in Cush of Ice Branch
    SHEN Jiaying,KONG Weiliang,LIU Hong
    2018, 52 (8):  918-923.  doi: 10.16183/j.cnki.jsjtu.2018.08.006
    Abstract ( 41 )   Save
    In this paper, the influence of the degrees of supercooling and free energy of substrate surface on substrate icing was studied through the experiment. Then, this paper analyzed the velocity of substrate icing growth with different surface contact angles theoretically and computationally, and compared with the experimental results. The results show that single ice branch grows on the near adiabatic surface under a low degree of supercooling of 2K. And the free energy of the substrate can rather make a significant effect on the icing rate, instead of the shape of dendrite tips. The scale law of dendrite tips on substrate is similar to that of free icing, and the theoretical calculation and experimental comparison show that the different shapes of dendrite tips cannot completely explain the growth rate changing. Hence, the surface energy is not frozen by heat transfer, but changing the nature of ice.
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    Experimental Study on the Anti-Icing Performance of Plasma Jet I. Parametric Analysis of DBD-PA and Verification on the Anti-Icing Performance
    ZHAO Binbin,DONG Wei,LIU Juan,ZHANG Yi
    2018, 52 (8):  924-929.  doi: 10.16183/j.cnki.jsjtu.2018.08.007
    Abstract ( 55 )   Save
    The anti-icing performance of plasma jet fixed on NACA0012 wing model is studied in icing wind tunnel. A plasma jet actuator is designed and installed on the wing model surface, and thermocouples are cleverly embedded beneath the actuator to detect the anti-icing effect. A parametric analysis is performed to investigate the relationship of the anti-icing performance with voltage and frequency, respectively, and the anti-icing effect of plasma jet above insulated electrode is verified.
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    Product Platform Planning Method Based on Virtual Orthogonal Test and Improved QFD
    YUAN Zhenlong,CHU Xuening,ZHANG Lei
    2018, 52 (8):  930-937.  doi: 10.16183/j.cnki.jsjtu.2018.08.008
    Abstract ( 36 )   Save
    Sensitivity analysis is a method of product platform planning considering the influence of design parameters on performance. However, the current sensitivity analysis method is difficult to apply to products where there is no clear mathematical function between the performance parameters and design parameters. In view of this deficiency, a sensitivity analysis method based on virtual orthogonal test is proposed, and the product platform planning is carried out in combination with improved QFD. Firstly, the virtual test scheme is determined based on the orthogonal experiment design method. Secondly, a virtual test environment is built by built-in software, in which the design parameters is set of different values and the performance parameters’ change is recorded in real-time. And the sensitivity of the design parameters is calculated based on the ratio of the two parameters. Then the sensitivity matrix is constructed and used to replace the traditional correlation matrix in the QFD house to measure the degree of correlation between the design parameters and the performance parameters so as to reduce the subjectivity of the traditional QFD method. Finally, the improved QFD method is used to identify the product platform parameters, and the effectiveness of the method is verified.
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    Wave-Current Loads on the Horizontal Cylinder with Varying Submergence Depths
    BAI Junli,MA Ning,GU Xiechong
    2018, 52 (8):  938-945.  doi: 10.16183/j.cnki.jsjtu.2018.08.009
    Abstract ( 46 )   Save
    The interaction between wave-current and the horizontal cylinder located near the free surface is studied experimentally and numerically. Experiments of wave-current interaction on cylinder are conducted in the circulating water channel. The current loads, wave loads and wave-current loads on the cylinder with varying submergence depths are measured. The numerical model applied in this paper is based on RANS equations solved by finite volume method. Based on the simulation results, the free surface deformation and wave reflection in the interaction between wave-current and cylinder are investigated. Then, peak values of the wave force and wave-current force on the cylinder with various axis depths are discussed in detail. The effects of wave reflection and blockage on the peak value of the force are discussed based on the comparison between the measured force and the force calculated by the Morison’s equation. In general, wave reflection increases the peak value of the force while the wave blockage decreases it. Under the combining effect of wave reflection and wave blockage, the variation of forces on the cylinder with the submergence depth is different for partially submerged and fully submerged cases.
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    Impacts of Obstacle on Gravity Currents Propagating Along a Flat Bed
    LV Yafei,ZHAO Liang,HE Zhiguo,LIN Yingtien,YUAN Yeping,HU Peng
    2018, 52 (8):  946-953.  doi: 10.16183/j.cnki.jsjtu.2018.08.010
    Abstract ( 34 )   Save
    Obstacles on the bed have important impacts on the hydrodynamic behaviors of gravity currents in hydraulic engineering. In this paper, a high-speed camera and a laser particle image velocimetry (PIV) technique were applied to investigate the characteristics of lock-exchange gravity currents encountering different obstacles at the slumping stage on a flat bed. The experimental results show that the obstacle influenced the head velocity of gravity currents within about 5-lock length, while the reduction of maximum speed of the head before meeting the obstacle was small, with a value of about 1%. When the thickness of the gravity current was equal to the height of the obstacle, the maximum height of the gravity current on the environment may be nearly doubled. In the same condition, the height caused by the rectangular obstacle was about 20% larger than that by the triangle one. The time for the peak thickness of the gravity current at three characteristic sections (i.e. in front of, behind, and on the top of the obstacle) varied from 1.5 to 2s later than that for the energy. The energies at the characteristic sections in front of and behind the obstacle followed a unimodal distribution, while that at the top section followed a bimodal distribution. The peak thickness at the characteristic sections in front of the obstacle increased about 20%, but the peak energy decreased about 40%. The present results provide useful information for pollutant in water environment, submarine cable protection, and reservoir deposition, etc.
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    Case Acquisition in Biological Domain Based on Text Mining
    SHEN Jian,HU Jie,MA Jin,QI Jin,ZHU Guoniu,PENG Yinghong
    2018, 52 (8):  954-960.  doi: 10.16183/j.cnki.jsjtu.2018.08.011
    Abstract ( 43 )   Save
    To tackle the problem of knowledge acquisition in biological field related to design problem based on natural language, the vector representation model based on natural language is used and a method of obtaining biological field based on text mining is proposed. Based on the construction of corpus text vector space and knowledge mining, the feature selection, similarity measure and instance retrieval method of biological domain text are studied while the technical support for design demand driven biological field instance acquisition is provided. The results show that, on the one hand, the method of text mining based on the vector space model has a great advantage in both the precision and the recall rate. On the other hand, the text retrieval mechanism based on vector space has good adaptability and expansibility, which can meet the needs of semantic retrieval in different environments.
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    Measurement of Rice Flag Leaf Angle Based on Redefined Clustering Method
    WANG Tao,GONG Liang,ZHANG Jingwei,WU Linlizi,MA Zhihong,YANG Gang,MAO Yuhan,HONG Jun,LIU Chengliang
    2018, 52 (8):  961-968.  doi: 10.16183/j.cnki.jsjtu.2018.08.012
    Abstract ( 39 )   Save
    The flag leaf angle is one of key parameters for determining the rice yield, achieving accurate, efficient and in vivo measurement of flag leaf angle is significant to rice breeding, plant type research and production instruction. However, the stems in sample images are usually obscured, moreover, current algorithms cannot recognize flag leaf nodes and axes of diverging, bifurcate rice ears. Hence, a flag leaf node searching algorithm is presented, then the cluster center of rice ear and leaf is generated by a redefined clustering method in order to recognize the angles between rice ear and flag leaf. The leaf node searching algorithm quantifies the fuzzy localization of leaf node, and it is proved to be robust and accurate by experiment. The redefined K-means method is based on the statistical information of samples, it can solve the problem that current algorithms cannot measure angles between diverging, bifurcate rice ear and flag leaf. Furthermore, it is practical in measuring the intersection angles in various plants’ bifurcate form. Hence, the paper proposes a new thought of clustering in multi-axial data set. Experimental results show that, the algorithm had an error of 1.89% with low limitation, stronger robustness and higher degree of accuracy.
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    The Mechanical Constitutive Model of Shape Memory Polymer Based on Generalized Maxwell Model
    FAN Pengxuan,CHEN Wujun,ZHAO Bing,HU Jianhui,ZHANG Daxu,FANG Guangqiang,PENG Fujun
    2018, 52 (8):  969-975.  doi: 10.16183/j.cnki.jsjtu.2018.08.013
    Abstract ( 48 )   Save
    In order to reveal the viscoelastic mechanism and conduct simulation of SM (shape memory) effect, the stress and strain evolutions and fixity ratio equation were derived from the generalized Maxwell model with time temperature superposition principle. Fixity ratio equation shows that the shape fixity ratio can be lifted by raising the ratio of holding time over tension time. The evolution equations reveal the viscous-elastic nature of the SM effect. The shift function is decreased because of the dropping of temperature, which will reduce the actual time and result in delaying of shape recovery. When the temperature raise up, the reducing effect is weakened, the shape recovery will occur. Simulation methods are established based on the viscoelastic model in Abaqus and user subroutine of Arrhenius equation and WLF equation. The material parameters of epoxy shape memory polymer are obtained by tension-relaxation tests. Then the test and simulation of SM process were conducted. Results indicate that the simulation methods are accurate enough, and Arrhenius equation results in more accurate simulations than WLF equation for epoxy SMP used in the tests.
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    The Cognitive Mechanism of Brain Cortex on Aircraft Flyover Noise
    LIAN Yidan,CAI Jun,ZHANG Zhongwei,LIU Jiahang,WANG Tao
    2018, 52 (8):  976-981.  doi: 10.16183/j.cnki.jsjtu.2018.08.014
    Abstract ( 41 )   Save
    In order to study the cognitive mechanism of human cerebral cortex on aircraft flyover noise, 25 healthy subjects were studied and functional magnetic resonance imaging (fMRI) technique was carried out. The data were processed statistically and the brain functional regions were located. The results have shown that 25 subjects significantly activated the visual combined cortex, prefrontal cortex, primary motor cortex, and brain regions associated with cognitive memory, which means the cerebral cortex is not only involved in the auditory treatment, may also involved in negative emotions, cognitive, attention, memory and other reactions.
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    Semi-Analytical Solution of Limit Support Pressure on Shield Tunnel Face Subjected to Water Level Fluctuation
    YING Hongwei,SHEN Huawei,ZHANG Jinhong,ZHU Chengwei
    2018, 52 (8):  982-990.  doi: 10.16183/j.cnki.jsjtu.2018.08.015
    Abstract ( 53 )   Save
    In order to study the influence of tides on shield tunnel excavation, by using the finite element software COMSOL, a three-dimensional numerical model is established to obtain the seepage field in front of the tunnel face. Phase delay and amplitude decay of seepage are found in the ground. The seepage force from the numerical results is applied to the “wedge-prism” limit equilibrium model, in order for the computation and analysis of the limit supporting pressure under the condition of water level fluctuation. Fluctuation of the limit supporting pressure is related to the ratio of the overburden thickness to the diameter of the tunnel, soil properties, boundary water level fluctuation, etc. With the increase of the ratio of the overburden thickness to the diameter of the tunnel and the decrease of the fluctuation period, the phase delay and amplitude decay of the limit supporting force are more notable. The seepage force on the tunnel face varies with time and the maximum value is smaller than that calculated in static water condition with the highest tidal level. The supporting force and tidal level reach the maximum value at different time.
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    Multi-Magnetic Source Discrimination Technology Inside the Spacecraft
    XU Chaoqun,YI Zhong,CHEN Jingang,WANG Bin
    2018, 52 (8):  991-996.  doi: 10.16183/j.cnki.jsjtu.2018.08.016
    Abstract ( 58 )   Save
    In order to analyze the nonlinear magnetic field equations in research of multi-magnetic source resolution in spacecraft, a multi-magnetic dipole model of spacecraft is established. The scanning extremum method is used in Gauss-Newton algorithm to break through the difficulty of the number of magnetic sources and the initial iteration values, and the inversion problem is well done. The results show that Gauss-Newton algorithm sometimes fails due to incorrect selection of initial iterative values, but the good one can accelerate the convergence. When the calculated dipoles are more than the real ones, the method can be used, but the result is not reliable. On the contrary, it will fail. The influence is big and inclines to increase with the increasing dipoles. Gauss-Newton method fails due to the excessive number of inversion parameters when the dipoles are more than four.
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    Research on Bio-Electromagnetic Compatibility of Artificial Anal Sphincter Based on Transcutaneous Energy Transfer
    ZAN Peng,ZHANG Chundong,LIU Yankai,GAO Zhiyuan
    2018, 52 (8):  997-1002.  doi: 10.16183/j.cnki.jsjtu.2018.08.017
    Abstract ( 57 )   Save
    Bio-electromagnetic compatibility for artificial anal sphincter is investigated in this paper. Through segmentation of the image, the tissues are divided and identified. Electromagnetic model of human body is established with 40 kinds of tissues. The radiation dose of the transcutaneous energy transfer system on biological tissues is calculated using the finite difference time domain (FDTD) method. The specific absorption rate distribution of different tissues is obtained in the electromagnetic field. The safety analysis is carried out according to the international standard for electromagnetic safety of human body. The simulation results show that the transcutaneous energy transfer system has good biocompatibility to human tissues when transmitting power is 1500mW and resonant frequency is 358kHz in the experimental environment.
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    Optimal Estimation of Fractal Dimension for Two-Dimension Sea Surface Infrared Image
    CHEN Yu,TENG Kenan,TANG Jinguo,WANG Liying
    2018, 52 (8):  1003.  doi: 10.16183/j.cnki.jsjtu.2018.08.018
    Abstract ( 45 )   Save
    Aiming at the problem that fractional Brownian motion model can only calculate the fractal dimension when the sea surface wind speed is slow and the image spectrum is isotropic, the fractal model of the sea surface with the isotropic and anisotropic characteristics of sea surface infrared image was proposed. In view of the improper selection of scale range in variation method, the fractal dimension of sea surface infrared image can not be accurately estimated. First the selection criterion of the minimum scale was proposed for maintaining the fractal property of infrared image and avoiding the aliasing effect of image. Then the optimal function relationship among scale interval and the fractal dimension of sea infrared image, fundamental spatial wavelength of image and pixel size was determined by choosing the established sea surface model as reference model of sea infrared image, building minimum costs as target function, using the optimization of the algorithm and least square fitting. Finally, the necessity of the optimal estimation for scale range is proved by simulation.
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