Table of Content

10 June 2018, Volume 29 Issue 11

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Thrust Ripple Reduction Method of Electromagnetic Suspension Actuator Considering Cogging Forces and Ripple Forces

YANG Chao1;LI Yinong1，2;HU Yiming1;ZHONG Yinhui1

2018, 29(11):  1261-1267. 

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A novel permanent magnet linear electromagnetic suspension actuator was designed based on in-wheel motor electric vehicle.Aiming at reducing thrust ripple of the actuator， a method was proposed based on optimizing cogging forces under no-load conditions and ripple forces under load condition.Theoretical model of the actuator was established， and the finite element model （FEM） was verified through comparisons of simulation results and analytical ones， including the winding flux-linkages and induced electromotive forces（EMF）.Based on the FEM， the influences of the actuator end tooth lengths on cogging forces were conducted under no-load conditions by using parameter analysis method.The actuator stator lengths were optimized.In addition， total harmonic distortion （THD） was taken as evaluation index to induced EMF，ripple force was considered under load conditions， THD and thrust ripple were reduced by optimizing slot widths.The results show that the minimum cogging force is as 24.0N， which is obtained at the stator length 182 mm， and cogging force is reduced by 75.6N.Minimum THD of induced EMF is 4.5%， which is obtained at the slot width  4.5 mm.Ripple force is reduced 3.2N， electromagnetic force ripple of improved actuator is only 20.8N and is reduced by 80.1%.Thus， the disadvantages of the serious thrust ripples are solved effectively.

Sound Beam's Divergence and Focus of Ultrasonic Point Focusing Probes in Spheres

PU Haiming;WANG Zhe;KANG Yihua

2018, 29(11):  1268-1273. 

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Firstly， the propagation path of sound beam was researched when the focus of ultrasonic point focusing probes was at different positions of the sphere.Focus and divergence of ultrasonic beams entering workpiece were discussed.Next， the expression formula of actual focal length of point focusing probes in the sphere was calculated and analyzed.The relationship among actual focal length and thickness of water layer and other parameters was presented.Then， a transient simulation model of focal length changes of ultrasonic point focusing probes in the sphere was established by finite element analysis software.The simulation results are in good agreement with the calculated ones.Finally， actual focal length formula was used to determine the type of point focusing probes and water layer thickness when detecting different radii of spheres.Experimental phenomena show the reliability of results.

Research on Inertial Drives of Two-degree-of-freedom Ultrasonic Motors

WANG Jian;BAI Yang;GUO Jifeng

2018, 29(11):  1273-1278. 

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A novel two-degree-of-freedom ultrasonic motor with a single stator was designed， which required a single-phase power to drive rotary and linear motions.A SIDM was proposed which was close to the resonant frequencies.The inertial drive models of the motor was established based on motor construction mechanism and driving principles.The influences of square wave signal parameters on motor performances were analyzed quantitatively.The simulation examples show that the stator surfaces may output suitable sawtooth waves using the asymmetric square wave excitations near the resonant frequencies.The optimum drive frequencies and duty cycles of the square waves are also given.The simple and efficient drive method may eliminate the influences of the phase differences on multiple degree-of-freedom motor performances totally.

Research on Heat Transfer Performances of Spherical Focused Ultrasound Assisted Ultrasonic Atomizing Cooling System

CAO Yang1，2;LI Hua1;REN Kun1;LIU Sujuan2;WANG Zhongwang1

2018, 29(11):  1279-1284. 

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Based on the theory of ultrasonic atomization and focused ultrasound， a spherical focused ultrasound assisted ultrasonic atomizing cooling system was proposed to use for precision grinding.The ultrasonic atomization was used as a cooling method， at the same time， the mists were converged to the specified heat positions by focused ultrasound to increase the utilization rates of mists.With the use of Fluent numerical simulation and steady state heat transfer experiments under the conditions of plane heat sources， the effects of focused mists and focused ultrasound on the heat transfer performances of the focused ultrasound assisted ultrasonic atomizing cooling system were analyzed.The results show that when the specimens are located in the focal area of the focused mists， the heat transfer performances of the focused mists are the best， the surface temperature of specimens is the lowest.Moreover， focused ultrasound may help to strengthen the heat transfers in the central areas，and further improve the heat transfer performances of the focused ultrasound assisted ultrasonic atomizing cooling systems.

A Novel Guide-type Nozzle for Oil-air Lubrications

LIU Muyuan1;GUO Feng1;JIAO Yihang1;PENG Shuling2;WANG Xi2

2018, 29(11):  1284-1288. 

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A novel guide-type nozzle was designed herein， and some tests were carried out to study air parameters，jet flow properties， droplet sizes and droplet distributions.Comparisons were completed for this new nozzle and classical nozzles.Results show that the guide-type nozzle presents higher oil supply efficiency than that of the classical needle nozzle.For qualified lubrication performances，the new nozzle reduces lubricant supply by 40% and suppresses pressurized air consumption by 28%，which leads to direct energy and cost saving.

Design and Research on Time-overlapping Gearshift Systems for AMTs

ZHOU Yingchao1;CHANG Siqin1;LI Bo2

2018, 29(11):  1289-1296. 

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In order to shorten the power interruption duration of AMT， a time-overlapping gearshift system was developed based on the electromagnetic linear actuators.The structures and working principles of the electromagnetic linear actuators were presented.A coupling system model including mechanical， electric circuit and magnetic circuit subsystems was built.The characteristics of the actuator were analyzed by experiments.The time-overlapping control strategy was presented， and the position compound controller was designed based on the two-degree-of-freedom control principle.The simulation and experimental results show that the proposed position cascade controller achieves good response and disturbance rejection performance.When the speed difference is as 500 r/min and the synchronized equivalent inertia is as 0.01 kg·m2， gear-change from 2nd to 3rd， the time is about 130 ms， the time-overlapping control method has about 20ms time-saving， and the total time is reduced by more than 15%.

Nonlinear Characteristics of Gear Transmission Systems of Locomotive Excited by Torque Fluctuation of Traction Motors

WANG Junguo;XIAO Yao;YANG Xufeng;ZHAO Yongxiang;FANG Xiuyang

2018, 29(11):  1296-1302. 

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Considering the external and internal excitations such as torque changes of traction motors， load torque fluctuations caused by stick-slip vibrations of wheel/rail， backlashes， time-varying mesh stiffness and transmission errors， a centralized mass model of the spur gear drive system was established for a typical locomotive HXD.The system responses were calculated by numerical methods combining with the bifurcation diagrams， phase plane portraits， Poincaré maps， displacement time curves and spectrograms.The influence law of torque changes of traction motors on the nonlinear system was also analyzed.The research results reveal a complex nonlinear dynamic evolution mechanism comprising one-periodic responses， multi-periodic responses and chaotic responses.

Accurate Straight-line Deployable Mechanism and Its Dynamics Analysis

CHANG Boyan1，2;LI Wenqi1;JIN Guoguang1，2;SONG Yanyan1

2018, 29(11):  1303-1309,1315. 

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Combining Hart straight-line mechanism with scissors mechanism， a new type straight-line deployable unit was proposed which consisted of revolute joint only.Then an accurate straight-line deployable mechanism was designed.According to the mechanism and machine theory， modular principles of the deployable mechanism were explained and the mechanism was composed with three kinds of modules including bottom module，middle module and top module.These modules were all composed by the straight-line deployable units.The kinematics model of a single straight-line deployable unit was established.Combining the modular principles of the mechanism， the recurrent relations of any module kinematics were derived which might be used to solve the whole kinematics model of the accurate straight-line deployable mechanisms consisted of multi-layer modules.The whole dynamics model of the mechanism was presented by Lagrange method based on the whole kinematics model.Taking mechanism consisted of three-layer modules as an example， the dynamics numerical calculation and virtual simulation were carried out， and the correctness and effectiveness of the kinematics and dynamics equations were verified.On the basis of geometric and physical parameters of real mechanism， required driving torque may be obtained when the motion of end-effector was given.The results show that there is no impacts during the whole working cycles by setting sine acceleration movement for end-effectors.

ELID Grinding and CMP Compound Processing Technology for Sapphire Substrates

XU Zhiqiang1，2;YIN Shaohui3;JIANG Shengqiang1，2;ZHU Kejun1，2

2018, 29(11):  1310-1315. 

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The machining principles and characteristics of ELID grinding and CMP were analyzed， a new technology integrated with ELID grinding and CMP was applied to machine ultra smooth and nano-precision sapphire substrates.At first， the critical depth of cut was calculated through the theory analyses， the ductile and brittle processing ways of sapphire substrates discussed by different particle sizes of the grinding wheels.The high-quality machined surfaces were obtained by a series of ELID grinding experiments with these grinding wheels， and the sub-surface damages of ground surfaces were measured by the magnetorheological finishing （MRF） method； as the final finishing， CMP was used to decrease subsurface damages and to further improve surface quality， and the sub-nanometer of surface roughness was achieved.

Mathematical Model of Vehicle Handling Stability Based on Suspension K&C Characteristics Parameters

LI Guang1，2;LIU Fang1，2;TAN Runhua1，2;LI Xuepeng3;WANG Tianyu1，2

2018, 29(11):  1316-1323. 

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Based on classic two-degrees of freedom linear mathematical model about handling stability，a linear mathematical model and MATLAB model which included suspension K&C characteristics parameters were established by the mechanics analysis method.Then the relationship between suspension K&C characteristics and handling stability was researched by comparing the understeer and yaw rate of classic two-degrees of freedom linear mathematical model with the linear mathematical model which included suspension K&C characteristics parameters.The accuracy of mathematical model which included suspension K&C characteristics parameters was validated by contrasting the results from mathematical model simulations and two mathematical model data which came from suspension K&C of three small sport-utility vehicle（SUV） and vehicle step test.

Research on Magnetic Abrasive Finishing Processes of  Aluminum-magnesium Alloy Permanent Magnet Poles

ZHANG Peng;ZHANG Guixiang;LIANG Wei;QIN Pu;JIANG Linzhi

2018, 29(11):  1324-1328. 

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Based on the XK7136C CNC milling machine with spindle modification， the AZ31 series magnesium alloy and 7075-T651 aluminum alloy were used as the research objects.The theoretical calculation and magnetic field simulation were used to design the strong permanent magnet material for the machining of aluminum-magnesium alloy structural material magnetic poles， and the use of atomized fast-rolling spherical abrasive particles was tested to verify the feasibility of the finishing method and spherical abrasive performance.“Tian word slot” and “Mi word slot” magnetic poles were used to test the two kinds of materials respectively.The experimental results show that two kinds of end slotting methods may prevent the local accumulations of abrasives， ensure the abrasive flowability， and increase the magnetic flux density and improve the grinding efficiency.The surface roughness of the two poles are as 0.126 μm and 0.148 μm respectively.The end faces with a stronger magnetic flux density of the“ Tian word slot” magnetic pole are more efficient in the prophase polishing processes.

Load Characteristic Modeling and Verification for Texture Broaches

NI Jing1;SHU Yang1;MENG Qingxin1;LYU Junjie1;WANG Shuying1;HU Chunmei2

2018, 29(11):  1329-1335,1341. 

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Aiming at the problems that traditional model of broaching load is not clearly and the modeling errors are quite big， the slots on the broach teeth were defined as surface texture grooves herein.A more detailed computational model of broaching load for texture broaches was provided with a consideration on texture groove parameters of cutter teeth， the circular holes of workpieces and tooth contacting cycle in broaching.First of all， based on the classical theory of cutting loads， a single tooth broaching load model for texture broaches was proposed.Then， the single tooth broaching load model was optimized with the influences of workpiece circular holes on the cutting areas.Finally， a universal computational model of broaching loads was obtained by adding tooth contacting cycle effects decided by workpiece lengths.The simulation and experimental results show that the proposed model may predict broaching load well.Moreover， it is proved that the texture groove may be used to reduce the broaching loads.And groove numbers aren't the more， the better.There is a optimal value for groove numbers.

Experimental Research on Hydraulic Power Units of Motor-Flywheel-Pumps

LUO Wanxian;CHEN Baijin;YAN Xiaopeng

2018, 29(11):  1336-1341. 

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Concerning the high installed powers of forging hydraulic presses and large amount of powers wasted by the system， an energy-saving hydraulic unit was proposed.The pump was actuated by a flywheel driven by a three-phase induction motor which was controlled by frequency conversion， and the controller regulated the flywheel to store and release energies.Flywheel stored energy in light load stages， and released energy in full load phases.Theoretical and experimental researches were carried out， and the relationships of forming energies， motor powers and motor speeds in different work speeds were obtained.The experimental results show that the power unit may decrease 30% installed power at least， and hydraulic press works stably.

Energy Management of a 4WD HEV Based on SMPC

QIAN Lijun1;JING Hongjuan1;QIU Lihong1，2

2018, 29(11):  1342-1348. 

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The energy management optimization of 4WD HEV were studied based on the basic principles of SMPC.A Markov model was built to describe the changing processes of the acceleration， so as to predict required torques.The optimization problem was established to minimize fuel consumption while maintaining the balance of battery state of charge （SOC）.This nonlinear optimization problem with finite time horizon was solved with DP algorithm.The proposed control strategy was validated with a software-in-the-loop experiment using dSPACE.The results show that the SMPC may realize the basic energy management of the 4WD HEV and the fuel economy is improved while all power components are working well.Average fuel economy of SMPC is improved by 8.30% comparing with the frozen-time MPC （FTMPC） approach， and is close to the results of the prescient MPC （PMPC） approach.

Optimal Control of MTMD in Floating Wind Turbine Stability Based on MIGA

HUANG Zhiqian;DING Qinwei;LI Chun;TANG Jinhua

2018, 29(11):  1349-1356. 

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MTMDs were introduced into the field of floating wind turbine controls to improve the stability of floating wind turbines.By NREL 5 MW wind turbine and ITI Barge platform as the research objects， two TMDs with different parameters in the nacelle and tower of the floating wind turbines were proposed.Based on the MIGA， the optimal parameters of the MTMD system were calculated.Based on the simulated calculations of three kinds of typical operating conditions， with or without MTMD were equipped with a floating wind turbine， the optimal control effects of MTMD were studied.The results show that MIGA may optimize MTMD parameters effectively and MTMD control is better than single TMD control.After optimization of parameters， MTMD has better control over the vibrations of floating wind turbines.The standard deviation inhibition rate of tower longitudinal displacement and platform roll angle increase by 80.4% and 83.8% respectively.MTMD has different control effects on different parts of floating wind turbines， and the best control position is the tower top longitudinal displacement， tower root lateral bending moment and platform roll angle.Under different environmental conditions， MTMD has obvious control effects on floating wind turbines.The standard deviation inhibition rate for vertical loads and displacements are 10.3% to 12.1% and 76.1% to 78.3% respectively.The standard deviation inhibition rate for lateral load and displacement are 75%~77.7% and 8.9%~10.8% respectively.

Multi-mode Coordination Control of a Kind of Regenerative Energy Hybrid Suspensions

KOU Farong;WEI Dongdong;LIANG Jin;TIAN Lei

2018, 29(11):  1356-1363. 

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In order to realize the damping control and regenerative energy recovery of vehicle suspension effectively， ball screw actuator and magnetorheological damper were introduced into vehicle suspension systems and a kind of regenerative energy hybrid suspension structure was put forward.For the following simulation analysis of suspension performance， a quarter vehicle dynamics model of hybrid suspension was established.The active control mode of hybrid suspension was analyzed， and the analysis of the semi-active control mode of hybrid suspension with feedback control of electromagnetic damping forces was done.The multi-mode coordination control system of hybrid suspension was designed.The dynamic performances and the self-powered of multi-mode coordination control of hybrid suspension were simulated by MATLAB/Simulink software.Then， the bench tests of hybrid suspension system were done.The simulation and experimental results show that compared with passive suspension， the root mean square of the body acceleration of hybrid suspension decreases by more than 30% under random roads.The damping effects of hybrid suspension system are obvious.

Hot Rolling Clad Symmetrical Billet for Producing High-chromiun Cast Iron/Low-carbon Steel Wear Resistant Composite Boards

LI Yanwei;WANG Xiaogang;LI Yugui;HAN Peisheng

2018, 29(11):  1364-1368,1374. 

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The carbon steel and high-chromium cast iron plates were symmetrically cladded with a six-layer billet， and then multi-pass hot-rolled to prepare a wear-resistant composite plate at a temperature of  1 200 ℃ with 30% and 60% reduction rates.The microstructure of the samples was observed by SEM.The experimental results show that the plate deformations after hot rolling are straight and warping-free.Due to the coordinated deformation and stress release of the soft carbon steel during hot rolling， the sensitivity of hot deformation cracking of high chromium cast iron is reduced， and the brittle high chromium cast iron layer achieves a certain degree of thermal deformation.The two material interfaces with good quality， there is no discernable interfacial interlayers and gaps and other defects.Energy dispersive spectrometer（EDS） tests find that a transition zone free of carbides on the high-chromium cast iron sides and the hardness values on both sides of the interface continuously changes indicates metallurgical bonding between the two materials.

Coining Simulation of Commemorative Coins Based on Strain Gradient Plasticity Theory

YI Guofeng1;LI Qiaomin2;ZHONG Wen2;LIU Yuqi2

2018, 29(11):  1369-1374. 

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To exactly describe the size effects caused by the fine patterns in coining simulation of commemorative coins， a constitutive equation was developed based on the Taylor dislocation model and the strain gradient plasticity theory.A nanoindentation test was conducted to obtain the mechanical properties of the Ag999 material， including the intrinsic material length and the nonlinear coupling relation between the statistically stored dislocation density and the geometrically necessary dislocation density.The proposed constitutive equation was applied to calculate the coining processes of a key-shaped coin， with the obtained coining force curves compared with the experimental ones.It is demonstrated that the proposed constitutive equation is capable of reflecting the size effects in coining and improves the accuracy in predicting coining forces.

Seamless Steel Tube with Wall Thickness Deviation in Pushing-pulling Necking

LIU Chao1，2;WANG Liandong1;LIU Heng1;GAO Yuan1;WANG Zhipeng1

2018, 29(11):  1375-1379,1385. 

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A geometric model of tube with wall thickness deviation and a mechanics model of push-pull necking were established， through measuring wall thickness distribution of the tube used in 6.5t automobile axle-housing.The difference of stress and deformation between the side of thinner and thicker wall of tube were analyzed.The numerical simulation of the different wall thickness deviations was set up， and the influences of the deviations on the stresses of the transmission area and law of wall thickness deformations were revealed.In addition， the maximum value of the circumferential wall thickness deviations of the tube were given based on the stability of the transmission area.The samples were successfully produced on the special nencking equipment.The experimental results are consistent with the finite element simulation.