Table of Content

25 December 2018, Volume 29 Issue 24

Previous Issue    Next Issue

Method and System of High-speed Magnetic Flux Leakage Detection for  Small-diameter Cartridges

MENG Jie1;WANG Zhe1;WANG Rongbiao1;KANG Yihua1;QIU Chen2

2018, 29(24):  2899-2905. 

Asbtract ( )   PDF (765KB) ( )  

References | Related Articles | Metrics

In order to solve the problems that the traditional detecting system was difficult to achieve high speed and high precision detection for cartridges, a high-speed magnetic flux leakage detection for cartridges was designed. Cartridge spins around covered array probe which made up of magnetic head that might pick up the leakage magnetic fields of microcracks. U-shaped magnetic yoke magnetization and adjustable detection shoe were designed to meet the demands for cartridges with different sizes. According to the specifications of cartridges, effective detection signals were collected and the signal processing methods that might reduce misjudgments were used. Eventually, the automated testing processes of cartridges were achieved. The research results show that the system may improve testing efficiency of testing a cartridge every four seconds and with the minimum detection depth of 0.05 mm.

Mechanism of Droplets from Stationary to Moving on Electrowetting-on-dielectric Chips

XU Xiaowei1;SUN Lining2;ZHANG Yuliang1;JIANG Haibing1

2018, 29(24):  2905-2911. 

Asbtract ( )   PDF (683KB) ( )  

References | Related Articles | Metrics

Aiming at the problems that the moving processes of droplets on electrowetting-on-dielectric chips under electric fields, the mechanism of droplet moving from stillness to motion was studied. Based on the principle of electromagnetic polarization and Clausius-Mosotti equation, the polarization mechanism of solid-liquid interface was analyzed, and the connection between polarization and dielectric constant was established. Then, the electric field was modeled and simulated by means of COMSOL Multiphysics software. The influences of electric field intensity and Maxwell stress tensor on the forces of droplet in the chips were analyzed. In addition, the equation of hydrostatic pressure difference inside the droplets was obtained, and the moving processes and mechanism of droplets were analyzed. Finally, the moving processes of droplet were verified by experiments.

Variable Stiffness Spring Reciprocating Pump Poppet Valves and Their Dynamic Characteristic Simulation

ZHU Ge;DONG Shimin;ZHANG Weiwei;ZHANG Junjie;ZHANG Chao

2018, 29(24):  2912-2916. 

Asbtract ( )   PDF (487KB) ( )  

References | Related Articles | Metrics

A variable stiffness spring reciprocating pump automatic poppet valve was designed herein. Furthermore spring stiffness was a function of valve disc lifts. On the basis of differential equation of the pump valve motion by Adolph, considering the influences of fluid compressibility on continuous flow condition in pump cylinders, the differential equation of the valve disc motion was established under the conditions of spring variable stiffness. Taking an example of spring stiffness as a linear function of lifts, dynamic characteristics of the valve discs of variable stiffness spring reciprocating pumps were analyzed. Simulation results show: the changes of spring stiffness have a significant influence on the dynamic characteristics of the valve discs； compared with the dynamic characteristics of the constant stiffness spring valve discs, impact velocities and lag heights of the valve discs with variable stiffness spring are decreased under the conditions of maximum lift determination. It is beneficial to improve the volumetric efficiency of reciprocating pump and improve the fatigue lifes of valve discs and valve seats.

Performances of New Oil-free Scroll Compressors

PENG Bin;ZHAO Shengxian;LI Yaohong

2018, 29(24):  2917-2924. 

Asbtract ( )   PDF (756KB) ( )  

References | Related Articles | Metrics

Based on the first law of thermodynamics, the law of conservation of mass and the gas state equation, the thermodynamic modeling of the oil-free scroll compressors was constructed by considering the internal leakage of the working chambers and the heat transfers between the wrap of the working chamber and the gas. The variety of volume, temperature, pressure and mass of gas in the whole processes of suction-compression-discharge was obtained using Euler method to solve the established thermodynamic model. The variation law under different heat transfer and leakage conditions was compared and discussed. The performance test of an oil-free scroll compressor under different crankshaft speeds was carried out. The temperature, displacement, power were tested for different discharge pressures respectively. The results show that heat transfer has the greatest influence on pressure and temperature, and the leakage has the greatest influence on the working chamber mass. With the increasing of speed, temperature, displacement, power a clear upward trend is shown. The developed thermodynamic model provides some guidance and reference for the researches and performance analyses of oil-free scroll compressors.

Characteristics and Control of Rolling Mills under Nonlinear Spring Forces of Hydraulic Cylinders

LIU Bin1;PAN Guixiang1;LI Peng1;JIANG Jiahao1;LIU Shuang1;LIU Zhaolun2

2018, 29(24):  2925-2932. 

Asbtract ( )   PDF (713KB) ( )  

References | Related Articles | Metrics

A vibration model of rolling mill system was established, and the amplitude frequency response equations were obtained by average method. The amplitude frequency characteristic curves of different nonlinear spring forces and the initial displacements of piston rods were simulated, and the effects of these factors on vibration behaviors of the rolling mill system were analyzed. System bifurcation responses changing with external excitation amplitudes were analyzed, and the influences of the external excitation amplitudes on system stability were studied. At the same time, a vibration absorber control device was introduced, and the effectiveness of the vibration absorber was verified by comparing time domain curves and amplitude frequency curves with and without vibration absorber. Influences of vibration absorber masses, spring forces and friction forces on amplitude frequency curves were simulated and analyzed. The results indicate that the changes of nonlinear spring forces and external excitations will change the roll system vibration characteristics of rolling mill; control effects of the absorber are related to the masses of the absorber, the spring forces and the friction forces.

Transverse Vibration Characteristics and Stability of Moving Membranes of Gravure Printing Machines Based on Theory of Non-moment

WU Jimei1,2;SHAO Mingyue1;TIAN Zhen2;LEI Wenjiao2;WANG Yan3

2018, 29(24):  2933-2939. 

Asbtract ( )   PDF (703KB) ( )  

References | Related Articles | Metrics

Transverse vibration characteristics and stability of moving membranes were studied. Based on non-moment theory, a transverse vibration model with intermediate rigid support moving membranes under multi-color group printing processes was established. Differential motion equations of the vibration system were derived according to D'Alembert principle. Relationship of membrane vibration frequency and velocity, relationship of membrane vibration frequency and tension, and relationship of membrane vibration frequency and support position were numerically analyzed. The results show that the critical velocity of vibration divergence of single rigid support membrane is as 35.855 m/s. The effects of support position changes on the vibration frequency of membrane are more obvious when axial velocity of membrane is lower for the printing moving membrane with two intermediate rigid supports.

Effects of Structural Parameters on the High-pressure Water Descaling Nozzle Performance

LIANG Bojian1;GAO Dianrong2

2018, 29(24):  2939-2946. 

Asbtract ( )   PDF (723KB) ( )  

References | Related Articles | Metrics

In order to determine the structural parameters of the descaling nozzles and improve the descale effects,The numerical simulation method was used to analyze the effects of the nozzle divergence angle, the depth of inner cone hole, convergence angle on the nozzle spray angle and the volume flow rate. Herein, the orthogonal experiment method was adopted to simulate structural parameters and their interactions of the descaling nozzles and the significance and importance order of influence. Obtained the optimal combination of structural parameters was validated by experiments. The results show that when the divergence angels are increased, the nozzle spray angles will reduce but the volume flow rates will increase. When the depths of inner cone holes are increased, the nozzle jet performance will be comprehensively promoted. When the convergences are increased, the nozzle spray angles and the volume flow rates will be simultaneously reduced. The depths of inner cone holes are significantly correlated to the three factors,the optimal aggregative index may be obtained under the conditions of nozzle divergence angle is 80°, the depth of inner cone hole is 8 mm, the nozzle convergence angle is 65°. Under these conditions, the efficiency of the descaling nozzle performance is mostly improved. The experimental research designed by the optimized parameters show that the nozzle spray angle increases from 35.7° to 44.1° and the volume flow rate increases from 10.17 L/min to 28.3 L/min.

Feature Extraction of Composite Faults of Rotating Machinery Based on Nonlinear Mode Decomposition

YANG Yu;LI Xin;Pan Haiyang;CHENG Junsheng

2018, 29(24):  2947-2953. 

Asbtract ( )   PDF (722KB) ( )  

References | Related Articles | Metrics

For the non-linear and non-stationary characteristics of composite fault vibration signals in rotating machinery, a fault feature extraction method was proposed based on NMD. Firstly, the original vibration signal was decomposed into several nonlinear mode (NM) components with practical physical meaning and a residual component by using NMD, then the fault features were extracted by envelopment spectrum analysis of each NM component. The results from simulation signals show the obvious advantages of the NMD method, then the NMD is applied to the composite fault diagnoses of the rotating machinery, the experimental results show that the method can effectively extract the complex fault characteristics.

The Axial Vibration Characteristics of Rod Fastening Rotor Considered Contact Normal Stiffness

HE Qian1,2;WANG Ailun2;CHEN Zhongxiang1;YANG Jun1

2018, 29(24):  2954-2958. 

Asbtract ( )   PDF (541KB) ( )  

References | Related Articles | Metrics

The experimental and statistical parameters which relied on the analytical models is hard to determine, the accuracy is difficult to guarantee and other issues. A method of finite element analysis of the Micro-element Deformation of the elastic-plastic rough surface was proposed herein to determine the normal stiffness of the disk surface. In order to accurately obtain the axial vibration characteristics of the rod rotor, a concentrated mass dynamic model considering the normal stiffness of the roulette joint was established. The natural frequency of the axial vibration of a certain type of experimental rotor was calculated by using the above method and model. The results were compared with the measured data, and the error is less than 5%, which demonstrates the validity of this method. The effect of the pre-tightening force on the dynamic behavior of the rotor was further studied by changing the value of the pre-tightening force. The results show that there is a saturation region for the effect of the rod pre-tightening force on the rotor, which provides important design basis for the determination of the rod pre-tightening force.

Analysis and Test of Dust Removal on Photovoltaic Plate Surfaces Based on High Speed Airflow

DU Xiaoqiang1,2;LIU Enxiao1;WU Chuanyu1,3;XU Nannan1;YUAN Bo1

2018, 29(24):  2959-2965. 

Asbtract ( )   PDF (722KB) ( )  

References | Related Articles | Metrics

Aiming at the influences of dusts on the power generation efficiency of the photovoltaic panels, the adhesion model of the dust particles on the surfaces of the photovoltaic panels was established based on the analysis of the interactions among dust particles and the surfaces of the photovoltaic panels combining the gravity and air buoyancy of the particles themselves. By analyzing the forces of dust particles in the flow fields, the detachment model of dusts under the actions of airflow was established, and the required airflow velocity with respect to the particle sizes and densities and the surface properties of the photovoltaic panels was determined. Finally, a dust removal test scheme was designed based on super air knife to remove dust particle samples in sampling areas. The test results verify the correctness of the theoretical model, and prove the high speed airflow generated by super air knife has good dust removing effect, which may avoid damaging the surfaces of the photovoltaic panels and reducing the energy consumption during cleaning.

Solving Uncapacitated Facility Location Problems Using Pseudo-Boolean Model and Heuristic Algorithms

LING Haifeng

2018, 29(24):  2966-2971. 

Asbtract ( )   PDF (537KB) ( )  

References | Related Articles | Metrics

The UFLPs were solved based on pseudo-Boolean model and heuristic algorithm herein. Firstly, the pseudo-Boolean representation of UFLPs was given, and the Khumawala rules were used to preprocess the input instances. Finally, two heuristic branching criterions were presented to solve the problems. Experimental results show that the new method is simple and efficient.

Coupling Error Measurement Model and Experimental Analysis of Orthogonal Parallel Six-axis Force Sensors

NIU Zhi1, 2;ZHAO Tieshi1, 2;ZHAO Yanzhi1, 2;HU Qiangqiang1, 2;JI Wenjie1, 2

2018, 29(24):  2972-2979,2987. 

Asbtract ( )   PDF (1002KB) ( )  

References | Related Articles | Metrics

In order to solve the problems of the ranges of parallel six-axis force sensors, an orthogonal parallel six-axis force sensor was designed. Orthogonal parallel six-axis force sensor had an improvement in configuration based on parallel six-axis force sensors. So a lot of advantages, such as large load capacity and excellent decoupling performance were obtained. However, coupling errors of the orthogonal parallel six-axis force sensors had certain characteristics. Consequently, considering the coupling errors caused by frictions among branches and the orthogonal structures, ameasurement model of the coupling errors was established. Based on the model, relationship among the sensor parameters and outputs of the two types coupling errors was analyzed by numerical examples. Then a prototype of the orthogonal parallel six-axis force sensor was developed. Finally, the experiments were carried out to obtain error distributions and test accuracy. Each force/torque errors in each direction are 0.43%/0.31%, 0.18%/0.68%, 0.80%/1.28%, respectively.

Trajectory Planning of Robots for Milling Intersecting Curves of FRP Pipes

YOU Bo;ZOU Yu;XU Jiazhong

2018, 29(24):  2980-2987. 

Asbtract ( )   PDF (817KB) ( )  

References | Related Articles | Metrics

In light of existing problems in the process of cutting intersecting curves of FRP pipes at present, such as various types of pipes, difficulties in manual processing and poor adaptability in ordinary milling machines, the trajectory planning of robots for milling intersecting curves of FRP pipes was researched by using flexible characteristics of robots, such as high degree of sensitivity, wide application range and high automation level. The groove models of pipe's intersecting lines were established. The thicknesses of every track points were calculated. Based on robot inverse kinematics, continuous space trajectories of robots were planned. The robot milling workstation was designed to run the track, the milling property of working station was tested in experiments. The experimental results show that the groove surfaces are smoothing. The robot station has good continuity and high automation level, and may complete the milling work on intersecting curve of FRP pipes may be greatly.

Match-pruning Pattern Backtracking Algorithm for Exclusion Constrained Workflow Satisfiability Decision

ZHAI Zhinian1;LU Yahui2;WAN Jian1,3;WANG Zhongpeng1;WU Mingwei1

2018, 29(24):  2988-2998. 

Asbtract ( )   PDF (594KB) ( )  

References | Related Articles | Metrics

To address the issue of balancing the performance and cost in pattern backtracking (PB) technique for workflow satisfiability decision，an optimizing method was proposed where the authorization matching was enforced in time on partial pattern solutions to strengthen pruning by giving up some validating efficiencies. The overall performance was analysed by utilizing the polarizing phenomenon of ease or the complexity of instances on exclusion-constrained problems. Experiments on randomly generated data sets show that the optimization reduces the solving time of PB on hard instances greatly with little influence on the run-time of easy instances. Besides，the optimized algorithm has notably better time and space performances than other representative algorithms based on dynamic planning.

Active Heave Compensation Active Disturbance Rejection Control System of Electric Driven Marine Winchs

LIAO Wei1;ZHAO Yanming2;LIU Deshun1,3;JIN Yongping1,3

2018, 29(24):  2999-3008. 

Asbtract ( )   PDF (771KB) ( )  

References | Related Articles | Metrics

According to the characteristics of nonlinear and time-varying of active heave compensation systems of electric driven marine winchs, an active heave compensation control system of electric driven marine winchs was proposed based on ADRC. First, the dynamics of the drive marine winch control systems was analyzed.Then, the mathematical model of the drive marine winch was carried out,then the active heave compensation active disturbance rejection control system simulation model was set up, and the simulation and analysis were carried out. The simulation of the system was carried out under the conditions of different sea states, different depths, different cable diameters and different loads, and compared with the PID controller. The results show that when the sea model parameters and model parameters of electric driven marine winch control systems change, ADRC controller may still maintain good dynamic performance . ADRC has faster response speed, stronger robustness and anti-interference ability than that of the PID controller.

Influence of Adhesive Sealant on Resistance Spot Welding of Stainless Steel Sheets with Different Thickness

GUO Taiji1;ZHANG Qingxin2,3;SUN Xiaoguang1;HAN Xiaohui1;ZHANG Zhiyi1;LI Yongbing2,3

2018, 29(24):  3009-3014. 

Asbtract ( )   PDF (823KB) ( )  

References | Related Articles | Metrics

The influences of adhesive sealant on weldability, nugget morphology, mechanical property and manufacturing process of resistance spot welding were systematically studied by 301L stainless steel with obvious different thickness (close to 7∶1) of sheets. The results show that the thermal decomposition processes of adhesive sealant may change current density distribution, which in turn affects the nugget diameter and penetration depth, and finally change the acceptable current range. In addition, the introduction of adhesive sealant has little effect on the weld spacing, and also shows a good tolerance to the initial gap.

Irradiation Creep Life Extrapolation Method

HU Jingdong;XUAN Fuzhen;ZHANG Xiaocheng;LIU Changjun

2018, 29(24):  3014-3019. 

Asbtract ( )   PDF (590KB) ( )  

References | Related Articles | Metrics

The austenitic stainless steel was selected as the structural material for the core part of the Gen Ⅳ liquid metal fast breeder reactor (LMFBR), and the in-plie lifetime was mainly affected by coupled creep and irradiation damage. In order to provide a proper in-pile irradiation creep life extrapolation method, the time-temperature parameter (TTP) method, which is usually used in material creep life prediction, was studied. Based on this, the irradiation-time-temperature parameter(ITTP) method was presented involving a new dimensionless factor called irradiation influence factor. The Larson-Milller parameter equation and the Dorn parameter equation with irradiation influence factor were deduced by ITTP method and checked by in-pile irradiation creep data. The newly defined irradiation influence factor generally appears to decrease firstly and then stabilize when temperature increases.