Table of Content

    25 January 2021, Volume 32 Issue 02
    Detection Method for Internal Wall Corrosion of Drill Pipes Based on MFL Testing under AC and DC Magnetization
    WANG Rongbiao1;KANG Yihua1,2;DENG Yongle1;WANG Biyao1;WANG Shenghan2;TANG Jian1
    2021, 32(02):  127-131,140.  DOI: 10.3969/j.issn.1004-132X.2021.02.001
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    The internal wall corrosion of drill pipes after long-term service is the main reason for the fracture of the drill pipes. For the detection of the inner wall corrosion of the drill pipes, a magnetic flux leakage detection method was proposed based on the composite magnetization. The induction coil array was applied to pick up the changes of the AC magnetic fields on the outer wall of the drill pipes. The wall thickness reduction caused by the corrosion of the inner walls might be evaluated. The insufficient range and insufficient sensitivity of hall sensors might be avoided when they were used to measure magnetic fields under strong background magnetic field. The relative magnetic permeability distribution above the wall thickness reduction was analyzed by the finite element simulation software, and the magnetic flux density change rates with and without wall thinning were compared. Simulation and experimental results show that the detection of wall thickness reduction of the drill pipes may be achieved by this method.
    Experimental Investigation of Crystal Glass in Multi-wire Saw with Reciprocating and Rocking
    LIN Zhishu1,2;HUANG Hui2
    2021, 32(02):  132-140.  DOI: 10.3969/j.issn.1004-132X.2021.02.002
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    Slicing experiments of crystal glass with different shapes were carried out in multi-wire saw with reciprocating and rocking. Surface roughness of the slicing crystal glass wafers were measured with various wire speeds and feed speed ratios, and the influences of processing parameters on the surface roughness of the slicing wafers were studied. The experimental results show that rocking motion effectively reduces overall surface roughness of the slicing wafers, the increase of wire speed reduces overall surface roughness, feed speed ratio has a greater impact on the roughness of slicing surfaces on different locations. The material removal per unit length of wires has a good correspondence with the surface roughness of the slicing wafers,the decrease of the material removal per unit length of wire may effectively reduce the surface roughness of the slicing wafers. Multiple control parameters in slicing movement in multi-wire saws with reciprocating and rocking may be normalized to the indicator of material removal per unit length of wires.
    Fatigue Life Prediction of SWH Springs Based on Finite Element Method
    LIU Zhipeng;ZHOU Jie;WANG Shilong;WANG Sibao;YANG Wenhan
    2021, 32(02):  141-146.  DOI: 10.3969/j.issn.1004-132X.2021.02.003
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    Aiming at the fatigue failure of SWH springs, the special SWH springs used by UAE companies were introduced as the research object. Firstly, the stress-strain history of the SWH springs was analyzed by finite element simulation, and the stress-strain distribution of the key region was accurately calculated by the sub-model technology. The correctness of the finite element model was verified through static response experiments. The fatigue properties of steel wire material were derived from the tensile test and the Manson model. Finally, the fatigue life of the SWH springs was predicted by combining the stress-strain history and the fatigue life prediction criteria, and the experimental verification was performed. The results show that:when SWH springs are compressed, the maximum stress is located at the outer steel wire of the end position and the outer steel wire is mainly subjected to bending stress, which is consistent with the situation of the fractured outer-layer steel wire at the end of the springs. The errors between the response simulation and the measured value do not exceed 5%; The fatigue life predicted by the SWT criterion is in good agreement with the experimental fatigue life, and the predicted fracture positions are consistent with the actual fracture positions.
    Rolling Bearing Fault Diagnosis Based on GCMWPE and Parameter Optimization SVM
    DING Jiaxin ;WANG Zhenya ;YAO Ligang ;CAI Yongwu
    2021, 32(02):  147-155.  DOI: 10.3969/j.issn.1004-132X.2021.02.004
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    Aiming at the two key links of rolling bearing feature extraction and fault identification, a fault diagnosis was proposed based on GCMWPE and parameter optimization SVM. First, the GCMWPE was applied to comprehensively characterize rolling bearing fault feature information, and a high-dimensional fault feature set was constructed. Then, the S-Isomap(isometric mapping) was utilized for efficient secondary feature extraction. Finally, BAS(beetle antennae search)-SVM was employed to diagnose and identify fault types. The proposed method was applied to the experimental data analysis of rolling bearings, and the results show that the feature extraction effect of GCMWPE is superior than that of multiscale weighted permutation entropy, composite multiscale weighted permutation entropy, and generalized multiscale weighted permutation entropy; the feature extraction method combining GCMWPE and S-Isomap may effectively distinguish different fault types of rolling bearings in low-dimensional space; the recognition accuracy and recognition speed of BAS-SVM is better than that of particle swarm optimization SVM, simulated annealing SVM and artificial fish swarm algorithm support vector machine; the proposed method may effectively and accurately identify each fault types.
    Simulation and Experimental Study of Internal Urethral Valves with External Magnetic-controlled
    FU Qingyun1;LI Xiao1;LI Shu1;PENG Weihong1;GUAN Ting2
    2021, 32(02):  156-162,170.  DOI: 10.3969/j.issn.1004-132X.2021.02.005
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    In order to overcome the problems of tissue necrosis caused by continuous compression on urethra of artificial urethral sphincter, an internal urethral valve that controlled by external magnet was designed. Flow-pressure characteristic mathematical model and magnetic driving force calculation model were established. Finite element method was used to analyze flow field distribution, influence factors of liquid resistance and magnetic driving force. Simulation experimental system of lower urinary tract was established to study the urine flow rate-intravesical pressure characteristics and magnetic driving force characteristics. The results show that the flow rate increases with the increasing of opening of valve port and semi-cone angle of valve core, magnetic driving force increases with the increasing of outer magnet thickness and the reducing of air gap. The maximum urinary flow rate may reach 28.7 mL/s, in line with the law of human urodynamics.
    Influences of Dynamic Gurney Flap on Performance of  Vertical Axis Wind Turbines
    XIANG Bin1;MIAO Weipao1,2;LI Chun1,2;NI Lulu1
    2021, 32(02):  163-170.  DOI: 10.3969/j.issn.1004-132X.2021.02.006
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    According to the aerodynamic efficiency caused by the strong unsteady and unsteady flow caused by the periodic variations of the blade angle of attack with the phase angle during the operations of the VAWTs, a flow control method for arranging dynamic Gurney flaps at the trailing edges of the blades was proposed. Taking the three-blade linear wing VAWTs as the research object, the numerical simulation method was utilized to study the influences of different movement methods and extension height of Gurney flap on the aerodynamic performance of VAWTs based on SST k-ω turbulence model. The results show that the power coefficient of VAWTs is significantly improved with the addition of dynamic Gurney flaps arranged on the trailing edges of the blades. When the dynamic Gurney flap is constantly maintained at the pressure surfaces, the maximum power coefficient of the whole machine may be increased by 27.9%. Simultaneously, the optimal tip speed ratio is reduced, and the running stability of the wind turbines is improved. Under the low tip speed ratio,the tangential forces of single blade and starting torques of the whole machine are improved with the addition of the Gurney flaps.When the Gurney flap height exceeds a certain range, as the tip speed ratio increases, the power coefficient improvement effectiveness of the whole machine is gradually reduced, meanwhile the blade fatigue load is increased.
    Numerical Study of Cavitation Effects of Electro-hydraulic Actuator System of FAST
    QIN Yalu1,3;CAI Wei1,3;WANG Liugen1,3;LEI Zheng2;ZHAO Jingyi1,3;WANG Qiming2
    2021, 32(02):  171-179.  DOI: 10.3969/j.issn.1004-132X.2021.02.007
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    Aiming at the problems of vibrations and noises in FAST electro-hydraulic actuator reliability growth tests, the Mixture multiphase flow model of CFD were used to establish the flow field and suction pipeline model of oil source in FAST electro-hydraulic actuator hydraulic system. According to the experimental data, the correctness of the model was verified. The pressure fluctuation and cavitation phenomena in the oil source were simulated. The results show that the cavitation may be significantly reduced by expanding suction pipeline when the suction pressure is less than 130 kPa; when the speed of the oil source is less than 3500 r/min, the change of the speed has little influence on the cavitation; when the speed is greater than 3500 r/min, the cavitation increases with the increase of the speed; Under the conditions of constant working pressure, with the increase of suction pressure, the cavitation phenomenon and pressure fluctuation decrease. Finally, the experiments of improved FAST electro-hydraulic actuator show that there is no vibration and the noise level is below 60 dB. The results provide a theoretical basis for judging the causes of cavitation in FAST and improving the reliability of FAST actuators.
    Stable Control of Underactuated Biped Walking for Uneven Ground
    YAO Daojin1;DONG Wengtao1;WANG Xiaoming1;YANG Lin2
    2021, 32(02):  180-187,194.  DOI: 10.3969/j.issn.1004-132X.2021.02.008
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    To realize stable underactuated biped walking on uneven ground, a stabilized control strategy was proposed based on the motion state of CoM of a robot. Considering ground compliance, a compliant contact model was used to describe foot-ground interaction, and a robot–ground coupling dynamic model of sagittal and lateral planes was established through decoupling modelling.Based on the gait characteristics of human variable-speed walking, a feedforward control strategy was proposed based on the motion state of CoM. Underactuated bipedal walking control was decoupled into sagittal and lateral master-slave control. The velocity of robot CoM was considered as a system output, the control was achieved by controlling the displacement of CoM, and thus stable walking was realized. Finally, the underactuated bipedal walking with the average walking speed of 0.216 m/s and the step of 0.31 leg length was realized on uneven ground where the ground height is less than 0.032 m. The experimental results show that the underactuated stable walking on uneven ground may be realized by using the proposed control strategy to control robot CoM velocity.
    Tripping Fault Prediction of Heavy-duty Gas Turbines Based on Improved Particle Filter
    TENG Wei;HAN Chen;ZHAO Li;WU Xin;LIU Yibing
    2021, 32(02):  188-194.  DOI: 10.3969/j.issn.1004-132X.2021.02.009
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    Heavy-duty gas turbine was the significant equipment in clear energy, and the vibration level of the shafting system is a visual representation of the operating states. Tripping faults were as a kind of unplanned sudden shutdown triggered by increasing vibrations, which would cause a large impact on the core components of the gas turbine, such as blades and tie rods, resulting in equipment damages. A method for predicting the vibration trend of heavy-duty gas turbines was proposed based on improved particle filter. By analyzing the particle filter, a secondary resampling strategy was proposed to make the improved particle filter more resistant to particle degeneracy and improve the adaptability of particle filter. The improved method was verified in a tripping fault of a 300 MW heavy-duty gas turbine, which shows a superior prediction accuracy of tripping fault time. The proposed approach may guide the control strategy of gas turbines.
    Adaptive Curved Breast Ultrasound Scanning Method Based on Improved Impedance Control
    SHEN Yun1;XIE Rongli2;ZHAO Yanna3;FU Zhuang1;WANG Yao1;ZHANG Jun2;FEI Jian2
    2021, 32(02):  195-203.  DOI: 10.3969/j.issn.1004-132X.2021.02.010
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    For the problems of skin curved-surface fitting in robot-assisted ultrasonic scanning, the interaction between ultrasonic probe and skin surface during scanning was analyzed. According to the mechanics principle of the interaction, a scanning algorithm via impedance control was first proposed to ensure the consistency of the normal force between the probe and skin surface. Besides, the ultrasonic probe and the skin surface were also kept perpendicular during the scanning processes. Moreover, based on the historical trajectory data of the ultrasonic probe, the scanning algorithm was improved to enhance the surface fitting accuracy. In addition, the experiments on both of breast phantom and actual human body were designed to demonstrate the effectiveness of the designed control algorithm on the surface adaptive fitting problems and the integrity of the proposed scanning method. The experimental results show that the improved impedance control scanning algorithm achieves high performance on constant force control, and the normal force bias was within ±0.2 N. The tracking effectiveness of the probe rotation angles is also significantly improved, and the average tracking errors decrease from 4.9° to 2.2°. Also, the experiments truly confirmed the effectiveness of the control algorithm and the integrity of the ultrasound scanning.
    Fitting Method of Reflector Positions Based on Lidar Echo Intensity
    FANG Dehao1;XU Wan1;CHEN Youping2;YU Leitao1;ZHU Li1
    2021, 32(02):  204-211.  DOI: 10.3969/j.issn.1004-132X.2021.02.011
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    Aiming at problems of low fitting accuracy and poor data fault tolerance in existing fitting algorithms of lidar positioning systems, a reflector position fitting method was designed based on echo intensity. Firstly, the original scanning data was filtered,and the filtered data were segmented by echo intensity segmentation method and point distance-based segmentation. After segmenting, the data was fitted into a circle center, as a reflector actual position. Finally, a stacking forklift equipped with lidar R2000 was used for experiments. Experimental results show that the proposed method has high fitting accuracy and effectively improves data fault tolerance.
    Effects of Carbon Steel Chips Density on Properties of Stainless Steel/Carbon Steel Chips Composite Plates
    LIANG Yu;WANG Tao;REN Zhongkai;HAN Jianchao;JIA Yi;HUANG Qingxue
    2021, 32(02):  212-219,226.  DOI: 10.3969/j.issn.1004-132X.2021.02.012
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    The stainless steel/carbon steel chips composite plates were prepared by the method of pressing at room temperature and three passes of vacuum hot rolling with the reduction rate of 40%, 40% and 50%, respectively. The relationship between the pressing forces at room temperature and the relative density of carbon steel chips was studied. The mechanics properties and microstructure of the composite plates with relative density of carbon steel chips 50%, 60%, 70% and 80% were analyzed before rolling. The results show that the brittle inclusions formed at the combined interfaces of the composite plate with 50% relative density of carbon steel chips before rolling hinder the diffusion of Cr, the composite plates do not produce metallurgical bonding, and the bonding strength is lower than the national standard of China. Inclusions at other relative densities are crushing, the composite plate meet the requirements, and the greater the relative density of carbon steel chips, the thicker the decarburization layers of the carbon steel chips layers, the better the metallurgical bonding effectiveness of the composite plates. There are no obvious inclusions at the combined interfaces of composite plates with a relative density of more than 70%. The composite plates with relative density of 70% have the highest tensile strength, reaching 589.97 MPa; the composite plates with relative density of 80% have the best elongation, which is 56.51%.
    Research on Whole Process Route of Electromagnetic Flanging of  Aluminum Alloy Sheets
    XIE Bingxin1,2;HUANG Liang1,2;HUANG Pan1,2;LI Jianjun1,2;SU Hongliang1,2
    2021, 32(02):  220-226.  DOI: 10.3969/j.issn.1004-132X.2021.02.013
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    The service conditions of aluminum alloy components in aerospace were getting severer, and the higher strength and accuracy of components were required. Regarding electromagnetic flanging and heat treatment processes of aluminum alloys, whole process route of electromagnetic flanging was proposed through comparing and optimizing various process routes, so that structural parts with better performance were obtained. The flanged parts following the selected whole process route show excellent forming quality with satisfied size accuracy and good circumferential uniformity. The mechanics properties of the flanged parts were substantially improved, since the hardness was increased significantly and distributed uniformly. The proposed optimal electromagnetic flanging process was annealing-solution quenching-electromagnetic flanging-artificial aging. The proposed whole process route may be widely applied to forming local features on components in aerospace, for example, the hole flanging on propellant tanks for launch vehicles.
    Design and Experimental Study of Magnetoresistive Electromagnetic Energy Storage Needlel-free Injection System
    NI Yuji ;WANG Mingdi;CHEN Tianyu;ZHANG Xiao;NI Chao;LIU Jincong
    2021, 32(02):  227-234.  DOI: 10.3969/j.issn.1004-132X.2021.02.014
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    Aiming at the problems of existing needle-free syringes such as large volume, high noise, low injection efficiency, small driving force, and difficulty in adjustment, a magnetoresistive electromagnetic energy storage needle-free injection system  which adopted empty stroke energy storage method was designed. Electromagnetic drive part and ampoule liquid jet part of the injection system were simulated, and an experimental platform was established to further verify the correctness of theoretical design by experiments. The scheme greatly reduces volume of the needle-free injection system and enlarges adjustable range of driving forces. It is safe and stable, and may meet the injection requirements, which make the syringe has certain practicability and feasibility.
    Framework of Knowledge Acquisition and Representation Reasoning for Gas Turbine Health Maintenance
    WANG Zhong1;GU Yujiong1;HAN Xudong1;SUN Shumin1;ZHU Junjie1;HUANG Yuanping2
    2021, 32(02):  235-241.  DOI: 10.3969/j.issn.1004-132X.2021.02.015
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    Aiming at the problems of incomplete knowledge collection, poor knowledge portability, and inefficient knowledge reasoning in current gas turbine health maintenances, a systematic framework for knowledge acquisition, expression, and reasoning was proposed. Firstly, using combination of failure mode and effect analysis, and fault tree analysis, necessary expert knowledge of gas turbine health diagnosis was obtained from different perspectives. Secondly, acquired expert knowledge was structured, expressed and managed based on ontology modeling. The combination of ontology axioms and custom rules was used to realize searching and reasoning of fault knowledge. Finally, a real gas turbine was selected as an example to illustrate the application of knowledge engineering framework in gas turbine health maintenance systems.
    An Intelligent Vehicle Robust Lane Line Identification Method Based on Machine Vision
    LI Maoyue;LYU Hongyu;WANG Fei;JIA Dongkai
    2021, 32(02):  242-251.  DOI: 10.3969/j.issn.1004-132X.2021.02.016
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    A robust lane recognition method for intelligent vehicles was proposed based on machine vision herein to solve the problem that the traditional lane recognition algorithm was difficult to recognize in the complex road environments. Firstly, in order to eliminate noise interference and improve the efficiency of feature detection, an adaptive region of interest (ROI) calculation method was designed, which could adaptively separate the lane region from the non lane region according to different conditions. Secondly, to improve the environmental adaptability of the algorithm, the detection operator of improved partition angle was used to detect the lane line features, and the multi-color threshold processing was used to deal with the lane images. Finally, DBSCAN clustering and NURBS curve were used to fit the lane line after changing the view angle, and random sampling consistency method was used to optimize the lane line model to filter out mismatches. Experimental results show that the algorithm may effectively identify lane lines under various road conditions.