Table of Content

25 December 2019, Volume 30 Issue 24

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Interface Adhesion Characteristics of Sealing Ring on Single Loop Protective Valves

NI Jing1,2;SHI Yu1,2;MENG Zhen1,2;HUANG Haofeng1

2019, 30(24):  2899-2905. 

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In view of the complex surface adhesion characteristics of the single loop protective valve sealing ring (vulcanized on the spool) in the processes of opening the spool, a specific adhesion testing bench was built to study the variation laws of surface adhesion forces between the sealing ring and the metal face（valve sleeve）in the processes of separation at different preloading forces, different preloading time and different separation speeds. The results show that the separation speed has the most significant effect on the peak adhesion forces and and the influence of preloading forces is the smallest. When the separation speed increases from 0.25 mm/s to 2 mm/s, the peak adhesion forces increase by 4047%. When the preloading forces increase from 80 N to 120 N, the maximum increase of the adhesive force peaks is only 8.5%. According to the analysis of the high-speed microscope observation results of the adhesion and detachment processes of the interfaces between the sealing ring and the valve sleeve table, the reasons are as follows: the interface of the two tables is affected by the viscoelastic properties of the sealing ring itself in the separation processes, and the real contact area presents a time domain nonlinear characteristics.

Surface Reconstruction and Tool Path Generation Method for Remanufacturing of Damaged Blades

ZHAO Xusheng1,4;YANG Jianzhong1;CHEN Jihong1;Alexander FRADKOV2;Oleg GRANICHIN3;HU Pengcheng1

2019, 30(24):  2906-2915,2924. 

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A model reconstruction and CNC tool path generation of broken blades was proposed for the conditions that damage regions locatesd on the leading/trailing edges and on the tips. Measured data points were sorted, adjusted, and then utilized to construct sectional spline curves. The section curve was smoothed based on the theory of minimized energy, a method of aligning the sectional curves according to the curvatures was proposed. A model reconstruction method based on the lofting strategy was presented for the edge broken blades and the tip broken blades. The damaged regions were extracted, based on which the algorithm for generating zigzag tool path and the spiral tool path was given for CNC machining. Preliminary simulation results reveal that the proposed method guarantees the smoothness of the reconstructed surfaces and the approximation to the blade's real size. The feasibility of the proposed tool path generation method was testifiecl.

A Time-varying Mesh Stiffness Calculation Method for Cracked Gears Based on Parameter Inverse Technique

WU Jiateng;YANG Yu;CHENG Junsheng

2019, 30(24):  2916-2924. 

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An inverse calculation method of TVMS was proposed based on the tooth root strain measurement technology and optimization theory, the method was applied to the research of gear failure mechanism. Firstly, the inverse model of tooth root dynamic stress and TVMS were constructed, and a strain test rig of the gear crack failures was built to collect tooth root strains. At the same time, the corresponding finite element model was established. The calculation stress and measurement stress were brought into the inverse model. The results show that the proposed method has higher reliability and accuracy than that of the finite element method and analytical method, respectively. Furthermore, the dynamics model of gear system with tooth root crack faults was established. By analyzing the dynamic responses in time domain and frequency domain, the theoretical basis for the fault diagnosis of gear cracks is provided.

Analysis of Dilatancy Effect and Material Removal Characteristics of Soft-consolidation Abrasives

ZHENG Qianqian1;ZENG Xi1,2;JI Shiming1;QIU Lei1;SHI Meng1;XI Fengfei1;QIU Wenbin1

2019, 30(24):  2925-2933. 

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In order to solve the precision machining problems of complex curved surfaces with soft-consolidation abrasives pneumatic wheel, a soft-consolidation abrasives dilatancy analysis model was proposed. The influences of dilatancy effect on the material removal characteristics of the workpieces were studied by the microscopic angle of view as the starting point. According to the dilatancy effect analysis of abrasives, the mathematical model of the porosity and the damping coefficient of the bonded abrasive systems was established, and the relationship between the void ratio and the average stress was also combined to obtain the stress equation of the contact surfaces of the abrasives. A soft-consolidation abrasives material removal model was established. The influences of the dilatancy effect on the contact forces was verified by the PFC3D simulation and the force sensor as the force measuring device. The contact stress may be changed by the adjustment of the damping coefficient of the abrasives binder. The results of finishing tests show that the binder damping coefficient may be increased to improve material removal effectivess of the surface molds according to the law of dilatancy effect. In the same processing time, the damping coefficient increases about 5.0×105, the material removal amount increases nearly 31.91%, the surface mold roughness decreases nearly 32.34%, and the workpiece scratches may be significantly reduced.

Influence Mechanism of Grain Refining Effect Caused by Vibration Cast-rolling on  Strip Hydrogen Embrittlement Susceptibility

SUN Minghan;LI Lingxiao;FAN Meichen;GUO Shipeng;DU Fengshan

2019, 30(24):  2934-2938,2952. 

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Influence mechanism of grain refining effect caused by vibration cast-rolling on strip hydrogen embrittlement susceptibility was studied. In order to evaluate the hydrogen embrittlement sensitivity of vibration cast-rolled strips, slow strain tensile tests were carried out after electrochemical hydrogen charging. The results show that the hydrogen embrittlement susceptibility of cast-rolled strips may be greatly reduced by the new processes of vibration cast-rolling. A crystal plastic finite element model was established to simulate the hydrogen diffusion processes of strips with different grain sizes based on the actual grain sizes of vibration cast-rolled strips and conventional cast-rolled strips. It is found that grain refinement may significantly reduce the apparent hydrogen diffusion coefficient, and reduce the diffusible hydrogen content under the same hydrogen environments.

Study on Lifting Motor Pumps for Coarse Particle Slurry in Sea Bed Mining

ZOU Weisheng1 ;LIU Ruixian1;LIU Shaojun2

2019, 30(24):  2939-2944. 

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The optimum design method was put forward based on the N-S equation and standard k-ε turbulence model for coarse particle and high head lifting motor pumps for deep sea mining, that included optimum design of pump structural parameters, flow analyses, performance parameter prediction and reverse revise design. Optimum design, flow analyses, performance parameter prediction of 8-stage lifting motor pumps were carried out for China' deep sea poly-metallic nodule mining pilot systems by using this design technique. Comparing this research results with the experimental ones of China' first 2-stage lifting motor pumps, it is shown that 8-stage lifting motor pump has nice performance parameters and satisfies requests for the deep sea mining pilot systems, the single-stage head and efficiency are improved, which shows that the optimum design is reasonable and feasible.

Deployment Forward Dynamics Analysis of Hoop Truss Antennas

REN Weifeng;HE Baiyan;NIE Rui

2019, 30(24):  2945-2952. 

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Based on the Lagrange dynamics equation, the dynamics model of the hoop truss antennas was established considering the kinetic energy of the system, the elastic potential energy of the cable nets, the gravitational potential energy and the dissipative energy of the system. According to the dynamics model and the predesigned drive sections, forward dynamic analysis was carried out to simulate the complete development processes of the antennas under the real conditions. The torsion spring and the rope pulled by the motors were combined to drive the deployment, and the effects of parameter changes of torsion spring and drive rope on the deployment processes were studied, respectively. The simulation results have great reference significance for the deployment processes of the antennas.

Effects of Ultrasonic Cavitation Micro Jet-flow on Impact Fine Particle Breakage  Near Rigid Walls

SUN Yi;HUANG Shaowei;MAO Yalang;ZHU Lihao

2019, 30(24):  2953-2960. 

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In order to solve the problems of fine particles agglomeration which caused the minimum limit size by grinding, taking advantages of the effect of ultrasonic dispersion and cavitation in the fluid phase, the influences of ultrasonic cavitation micro jet-flow near the rigid walls on crush fine particles were conducted. The effective breakage distance between the cavitation bubble and the rigid wall was calculated,when a fine particle was impacted by the micro jet-flow. The effect of frequency, ultrasonic pressure, and media ball size on micro jet-flow velocity were discussed and ten kinds of tests under different conditions were conducted herein. The SEM technique was used to characterize the powder morphology. The key parameters of the particle size distribution such as median particle diameter D50, 10% cumulative particle diameter D10 and specific surface area（SSA） were analyzed. The theoretical analysis is basically consistent with the experimental results. Results show that the breakage rate of fine particles below 800 mesh may reach 79.35% and production rate more than 10,000 mesh may reach 12.84% after parameter optimization. The media ball area has a greater effect on the breakage rate than that of the power, media ball size, and the mass concentration. The effect of crushing fine particles may be effectively improved by optimizing the parameters of the ultrasonic cavitation micro-jet flow and by increasing the surface area of the media ball.

A Dynamic Mesh Method Used to Calculate Oil Film Performance of Journal Bearings

WU Chao1;YIN Xuemei2;LI Mengmeng1;LI Yijun1;WANG Wen3

2019, 30(24):  2961-2967. 

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In order to avoid the phenomenon of mesh distortion and reduce the errors in the applications of dynamic mesh method to calculate oil-film bearing performance, a dynamic mesh updating method was proposed based on CFD. This method ensured that all of the updated radial mesh lines along oil-film clearance were well-distributed along the circumferential direction. During the mesh updating processes, the radial mesh lines in the direction of film thickness were always perpendicular to the journal surfaces, which could ensure oil-film mesh not distortions and improve accuracy of mesh computation. The new dynamic mesh updating method was used to calculate the oil-film forces of the journal bearings and the static balance positions of the rotors. The results were compared with the calculating ones and the experimental ones of typical examples, the effectiveness, feasibility and stability of the dynamic mesh updating method proposed may be verified. By using the method, effects of different inlet oil pressures and loads on static balance positions of the rotors supported by oil-film bearings were analyzed. The proposed method may provide reference for accurately calculating the performance of the oil-film bearing-rotor systems.


Fuzzy Information Granulation for Casting Speed of Billets and Limited Weight Cutting Forecast Based on ELM

WANG Fubin1;PAN Xingchen1;SUN Yuge2;GUO Baojun3

2019, 30(24):  2968-2973. 

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In order to improve the precision of limited weight cutting of billets, the relationship between the quality of billets and the average casting speed of billets was analyzed. The fuzzy information granulation model of billet casting speed was established, the average casting speed data of each 5 billets were changed into a triangular fuzzy granule, 3 parameters in fuzzy particle: the minimum vLow, average vmid and maximum vup values of variations of average casting speed of billets were obtained, the complexity of the casting speed data of billet was reduceds, the granular subset of casting speed data containing different informations was obtained. SVM regression model was established based on information granulation data, the fuzzy granule parameters were used as input vectors to predict the average casting speed of the billets, the prediction value of average casting speed of the next billet was obtained. Some factors were considered comprehensively, such as cross-sectional area of billets, average casting speed, fixed length, the prediction value of average casting speed of the next billet and so on, a neural network prediction model was established based on ELM and the prediction of limited weight of billets was realized.

Inverse Kinematics Analysis of Redundant Manipulators Based on BP Neural Network

LIU Shiping;CAO Junfeng;SUN Tao;HU Jiangbo;FU Yan;ZHANG Shuai;LI Shiqi

2019, 30(24):  2974-2977,2985. 

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General 7 DOF redundant manipulators inverse kinematics solution was complicated, and the inverse kinematics of manipulators with different configurations were less versatile. In order to find a general 7 DOF manipulator inverse kinematics solution, a neural network model was established. Model parameters such as appropriate excitation function, numbers of hidden layer neurons, numbers of neural network layers, and learning rate were selected. Trajectory tracking experiment was designed to verify the neural network model. Experimental data show that the method has efficiency and high precision, which is a feasible method for solving the inverse kinematics of redundant manipulators.

Dynamics Modeling and Analysis of a Rolling Sealed Wall-climbing Robot

QIN Jiwei1,2,3;CHANG Yong1,2;YUAN Bingbing1,2,3;FU Xingwei4;WANG Tianlong1,2

2019, 30(24):  2978-2985. 

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A rolling sealed wall-climbing robot was introduced herein and its sealing and motion mechanisms were analyzed. A dynamics modeling method of wall-climbing robots with multi-track coordinated motions was proposed, and the linear motion and steering dynamics equation of the robots were derived. The relationship among the tracked traction forces and the attitude angles of the robot during linear motion and steering was established. The frictional resistance during the motion of the robot using sliding seal and rolling seal was calculated and compared. The simulation and prototype experiments verify that the wall-climbing robot may walk along the wall and overcome obstacles, and has the characteristics of small friction resistance, large load capacity and strong adaptability to wall surfaces.

Vibration Characteristics and Optimal Control of On-orbit Assembling Manipulators with Solid Lubricated Joints

QIN Li;XU Zhiying;LIU Fucai;XU Jilong

2019, 30(24):  2986-2993,3003. 

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On-orbit assembling manipulators for large space structures possessed high requirements for dynamic performance of the end-effectors. A dynamics model of solid lubricated manipulators with axial sizes and clearances was proposed，and the contact force of solid lubricated joints was modified based on semi-physical simulation experiments. The radial vibration characteristics for different gravity and its releasing environments of the manipulators under different structural parameters and working conditions were investigated by simulations. Focus on the demands of frequently start-stop operations throughout the assembly processes, the vibration characteristics of load mass changes at the start-stop operations of the manipulators were analyzed. Then, a optimal control strategy was presented to improve dynamic performance.

IMSSA for TFT-LCD Panel Array Process Scheduling Problem Considering Energy Saving

YAO Yuanyuan;YE Chunming

2019, 30(24):  2994-3003. 

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Array process of TFT-LCD panel manufacturing was a reentrant hybrid flow shop scheduling problem, and an effective IMSSA was proposed to solve the problem. Firstly, a multi-objective mathematical programming model with makespan, total tardiness, and total energy consumption criteria was formulated. Secondly, considering the characteristics of the problem, a series of improvements were made based on basic multi-objective salp swarm algorithm(MSSA), which included ranked order value based random key encoding, PS decoding methods, updating the position of the leading salps based on Lévy flight, and embedding a variable neighborhood search strategy in external archive. Influences of parameter setting were investigated by means of Taguchi method. Finally, the proposed IMSSA was compared with the basic MSSA, multi-objective particle swarm optimization (MOPSO) and fast nondominated sorting genetic algorithm (NSGA-Ⅱ) based on several benchmarking instances. Experimental results show the effectiveness of IMSSA.

Non-contact Electromagnetic Loading Monitoring System for Water-lubricated Bearings

WANG Nan1,2,3;YANG Litao1,2;LIANG Yingxuan1,2;WANG Peng1,2;YUE Xiaokui3

2019, 30(24):  3004-3009. 

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At present, there were some issues (vibration, noise, heat, frictional wear, et al) of traditional mechanical or hydraulic contact loading methods in experimental studies of water-lubricated bearings. In addition, the monitoring system, especially the function of software, was imperfect. All of the issues mentioned above would affect the shafting stability and the accuracy of test results. In order to solve the existed problems, a non-contact electromagnetic loading device (the size and angle of electromagnetic loading force might be adjusted) was designed, a monitoring system was developed based on LabVIEW for water-lubricated bearings, and the film pressure test on water-lubricated rubber bearings was conducted. The results were compacred with simulation ones, and the results show that the running of system is stable, the test data is reliable and the practical effectiveness is well.

Performance Analysis and Structural Parameter Optimization of High Bending Drilling Tool Joints for Slim Hole Window Sidetracking

KUANG Yuchun;CHEN Yonglong;MIN Taoyuan

2019, 30(24):  3010-3017. 

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With the wide applications of window sidetracking drilling technology in the slim holes, the failure problems of the drilling joints caused by the downhole bending section became increasingly prominent. In order to solve the failure problems of the drilling joints induced by deformation caused by bending load, a three-dimensional finite element model of the drilling tool joints was established based on the theory of elastic-plastic mechanics and experimental results of constitutive model of central pipes, and the connection strength and sealing performance of the drilling tool joints under the bending loads were studied and verified the reliability of the finite element analysis results by the tool joint expansion tests. Then, the key structural parameters were optimized using the orthogonal optimization method, obtaining the optimal parameter combination of the tool joints, and calculating the mechanics properties of API drilling joints and high bending joints. The results show that the optimized connecting thread in tensile / pressure, torque and bending performance is superior to the API thread, which may better satisfy the requirements of slim hole sidetracking drilling.

After Reading Towards the Re-industrialization of Europe:a Concept for Manufacturing for 2030 to see manufacturing in China

XIE Youbai

2019, 30(24):  3018-3023. 

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A right attitude we should have was discussed in reading foreign political documents or books, for example the book titled with towards the re-industrialization of Europe:a concept for manufacturing for 2030（abbr. as EM2030). The attitude is to look the object investigated as a physical-psychological-social system（PPSS) rather than a cyber-physical system（CPS) which is stylish at present. EM2030 talks about a vision of European manufacturing, but it does not include the whole European manufacturing and deal with only problems arisen due to move low-tech manufacturing into underdeveloped countries. The problems are unemployment and trade imbalance. It is not the situation of manufacturing in China. Since the founding of PRC the manufacturing in China has experienced two extensive transformations and is confronted with a third transformation at this moment. The fundamental problem with manufacturing in China is no enough design competitiveness while the foundation of design competitiveness is knowledge. Even so, there is huge space of development in the digital age, Europe has abundant experiences in knowledge supply to manufacturing, while the knowledge supply has not been connected closely to the design competitiveness of manufacturing in China. The possible developing modes of knowledge supply and efficient knowledge utilization were analyzed in the digital age. It might be a chance of overtaking in curve for manufacturing in China.