China Mechanical Engineering

Kinematics Analysis of 6-PUS Parallel Mechanism

WANG Chao-Qun-1, 2, TUN Hong-Chao-1

2013, 24(07): 853-856.

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Kinematics analysis of a 6-PUS parallel mechanism was done herein, and we focused on the forward kinematics solving method. Decoupling the position and orientation variables of the moving platform, the position variables would be expressed with the orientation variables. Three equations about orientation variables were obtained through Cayley formula and the relationship among position variables. Solving these equations, the orientation variables can be obtained. A specific example was introduced to verify the method offered herein.

Fluid-Structure-Interaction Modeling and Dynamic Behavior Analysis for Hydrobushing of Suspension

MA Tian-Fei-1, LIU E-Chuan-1, JIAO Xue-Bing-1, WANG Pan-Hui-1, 2

2013, 24(07): 857-861.

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Due to their own inherent physical limitations the conventional elastomeric bushings cannot simultaneously satisfy the conflicting requirements of low frequency shake control versus high frequency vibration isolation. But the hydrobushings can solve this problem well. The structure and the operational principles of a hydrobushing used by the suspension system in a passenger car were introduced. Meanwhile, dynamic stiffness and loss angle, two dynamic characteristic parameters were illustrated. A model of hydrobushing was built in simulation software AMESim. Based on the model, the simulation results can be gained. The mathematical software MATLAB was used to process the simulation results and make an analysis. The dynamic characteristic tests were performed with MTS831 servo-controlled hydraulic test rig. The test results prove that the model is correct and believable. Finally, this model was used to research how the model parameters affect on the dynamic behavior of hydrobushings. 

Line Spacing Optimization and Experimental Research of Gasbag Polishing with Continuous Precession

JIN Meng-Sheng, JI Shi-Ming, ZHANG Li, CHEN Wei-Jiang, JIANG Xin-Xin

2013, 24(07): 861-865.

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In order to improve and control mould quality, simulation analysis and experimental research on line spacing optimization of gasbag polishing were made with continuous precession by line cutting method. On the basis of gaining the optimal feed rate and superposition times, simulation analysis of the effect on material removal characteristics of gasbag polishing regarding line spacing was carried out under MATLAB. Both the polishing efficiency and polishing quality were considered, and dichotomy theory was applied. Then, the optimal line spacing D=8.2mm was obtained. Finally, the simulation tallies well with experimental result, which are carried out on the established off-line planning prototype system of gasbag polishing with continuous precession. 

Speed Optimization for Lapping Plates in RDP Lapping Mode Based on ADAMS

YU Wei-1, 2, LV Bing-Hai-1, TAO Wei-Feng-1, YUAN Ju-Long-1

2013, 24(07): 866-872,881.

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RDP lapping mode is used to grind high-precision balls. In order to study the influences of rotation speed of the lapping plates on the lapping uniformity, a numerical simulation model of RDP lapping mode was established based on multi-body dynamics analysis software ADAMS. Based on the simulation model,the influences of the speed curve of the lapping plate in lower plate on the distribution law of the contact points between the plate and the ball(lapping trace) was analyzed, and the speed curve was optimized, so the “double trapezoid-triangle”(DTT) speed curve is get. The simulation results show that the standard deviation(S) of the lapping uniformity is effectively lower(from 1.4409μm to 0.9748μm) under the DTT speed curve condition. After 3 hours' lapping under the same experimental conditions, the average sphericity error reduces 0.168 72μm(from 0.388 04μm to 0.219 32μm) under the DTT speed curve conditions comparing with the original speed curve before optimization. In another lapping experiment, the average sphericity error reduces 0.0308μm(from 0.103 64μm to 0.072 78μm) under the DTT speed curve conditions comparing with the original speed curve before optimization. The changing tendency of the test results is consistent with the simulation ones, which proves that the optimization is validity.

Double Closed-loop Load Control of a Combine Cylinder

LI Ju, DIAO De-An, QIN Yun

2013, 24(07): 873-877.

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In order to improve the control performance of a combine harvester, and ensure the harvester system work in a reasonable load range, the threshing cylinder load torque was used to indicate threshing cylinder load.Two independent regulators of roller palstance and roller torque were used in double closed-loop control. In view of the delay of conveyor belt, the modification that the conveyor belt was powered by walking system of the combine was put forward. Then the conveyor belt was a proportional element. The relation between threshing cylinder load and feed rate was analyzed. And a dynamic model of threshing cylinder was built. Based on that, fuzzy PID double closed-loop control system of the threshing cylinder load was set up and simulated in MATLAB. The simulation results prove the effectiveness and practicability of the control system. 

Research on Properties of Compound Linkage Recapitulation Rolling Trace

MA Li-Feng, WANG Gang, HUANG Qiang-Hua, CHU Zhi-Bing, HUANG Zhi-Quan, HAN He-Yong

2013, 24(07): 877-881.

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Through analyzing the theory of a new multi-degree -freedom composite linkage rod rolling shear mechanism,position loop equations of the link shear mechanism were established,and the guide rod and frame hinged position determination method was corrected.Based on a large steel mill hydraulic rolling shear machine development,the new shear movement trajectories were simulated.The precise simulation data for the electric hydraulic servo control system provides a guarantee to realize the speed and position control precision.The production of high quality steel plate shear section confirmes the reasonable institutions stem size can reduce knife arc horizontal displacement,improve the evenness of shear blade overlap, realize high precision cutting.

Experimental Reaserch on Re-equiping Ultra-precision Grinding Machine to Do Ultra-precision Turning

TUN Qiang-Tang-1, 2, NIE Feng-Meng-2, SHI Guo-Quan-1, TUN Huan-2, LI Shan-2, GUO Bei-2

2013, 24(07): 882-885.

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Re-equiping a T-shaped structure ultra-precision grinding machine independently developed, a single-point diamond circular turning tool was fixed on turntable of the ultra-precision grinding machine. The structure, precision, stiffness of ultra-precision grinding machines and lathes were analyzed and compared to ensure the feasibility of the re-equiped ultra-precision grinding machine. Through micro-adjusting the oil pressure of hydrostatic guideway and tool hydrostatic rotary table the redressal of ultra-precision turning tool and the workpiece rotation center height were achieved. The removement problem of workpiece rotation center area was solved. Using the precision swing of the tool rotary table, fine-tuning of the cutting edge position was completed during the cutting process,so as to make sure the feasibility of ultra-precision turning. Using aluminum alloy and oxygen-free copper as workpiece to do turning test at different speeds and feed rates, the surface roughness is as 10.8nm, reaching the level of ultra-precision turning.

Design on Adjusting Mechanism for Micro/Nano-Actuation Parameters of Ultrasonic Motor

XU Cong-Yu, SUN Ya-Qiong, FANG Wen-Qiong, LUO Xiang, YUAN Hang-Zhou

2013, 24(07): 886-889.

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To improve the controllability of locus and micro-displacement adjustment for nanopositioning of ultrasonic motor, an adjusting mechanism based on double PZT was designed to establish the relation of double PZT control with the locus control and mirco-displacement control of ultrasonic motor and the structure of adjusting mechanism was analyzed by finite element software of ANSYS Workbench. The experiments show that, when 0~54V control voltage is exerted on double PZT, the adjusting mechanism can realize ±1.2μm up to ±2.36μm displacement adjustment in x direction and ±4.0μm displacement adjustment in y direction with 1~2nm resolution of ultrasonic motor head, which meets the requirements of ultrasonic motor for locus control and micro-displacement control for nanopositioning.

Study on Specific Grinding Energy of Alumina Grinding with a Brazed Diamond Wheel in High Speed Regime

CHEN Jian-Yi-1, XU Xi-Feng-2

2013, 24(07): 890-894.

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The energy of alumina grinding with a brazed diamond wheel was investigated in high speed regime. The effects of the grinding parameters on the specific grinding energy were also investigated. The results indicate that the specific grinding energy increases with the rise of peripheral wheel speeds, while decreases with the increase of depth of cut, workpiece velocity, and the rate of material removal. The specific grinding energy is found to be related with the maximum undeformed chip thickness. During the grinding process, the grinding energy expended may be mainly associated with sliding and ductile plowing.

Study on Depth of Subsurface Crack Layer by Free and Fixed Abrasive Lapping

LI Biao, LI Jun, GAO Beng, SHU Yong-Wei, LUO Hai-Jun, ZUO Dui-Wen

2013, 24(07): 895-898,905.

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Different depths of subsurface crack layer were generated by different lapping ways. Measurement of subsurface crack layer depth had important significance for determining the material removal amount in subsequent process and improving processing efficiency. Magnetorheological finishing spotting method was adopted to measure the depth of subsurface crack layer after free and fixed abrasive lapping of K9 glass, respectively. The abrasive sizes of W40 and W14 were selected in each lapping way. The results show that the depths of subsurface crack layer after lapping K9 glass by free abrasive with 40μm and 14μm particle size are as 20.1μm and 3.646μm, respectively. And the corresponding depths are as 3.37μm and 0.837μm after fixed abrasive lapping. Fixed abrasive lapping can reduce the depth of surface crack layer effectively, improve processing efficiency and surface quality, and enhance the device performance. 

Reliability Analysis of Multi-state Hydraulic System Based on T-S Fuzzy Fault Tree and Bayesian Network

CHEN Dong-Ning-1, 2, TAO Cheng-Yu-3, DANG Zhen-3

2013, 24(07): 899-905.

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In order to solve the disadvantages of calculation complexity and single inference of T-S fuzzy fault tree analysis method in hydraulic system reliability analysis, a reliability analysis method of multi-state hydraulic system based on T-S fault tree and Bayesian network was proposed. The model structure and conditional probability table of Bayesian network were determined according to the method of converting T-S fuzzy fault tree to Bayesian network; the probability of top event, posterior probability of events and importance of basic events were computed by means of inference algorithms of Bayesian network. The method can calculate the system reliability indices and importance by forward inference, as well as carry out fault diagnosis by backward inference, and the calculation formula is simple. Finally, the feasibility and effectiveness of the proposed method were illustrated by the engineering example of hydraulic driven system of the 900t gantry-crane.

Research on Modeling and ECU in-the-loop Simulation for Two Stroke Piston-aero Engine

ZHANG Jian-Liang, QIN Qi-Feng, HUANG Xiang-Hua, CHENG Jing

2013, 24(07): 906-910.

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A type of two-stroke piston-aero engine model was carried out for a full study. The mean value model of the engine was made up while the simulation of the engine was carried out based on the engine model under MATLAB/Simulink environment. The simulation results of engine speed, output torque and power external characteristic data coincide with the actual engine experimental data. Besides, using the engine model and the simulation software, the physical in-the-loop simulation was carried out, and both of the original ECU and the rapid control prototyping are tested. The deviation of injection pulse width between the original ECU and the rapid control prototyping is not larger than 0.050ms.

Experimental Study on Level Detection of Bulk Material Entrucking Based on Image Texture

TIAN Meng-Dui-1, HU Yong-Biao-1, JIN Shou-Feng-2

2013, 24(07): 910-914.

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In order to solve the problem that the ultrasonic level detection cannot reflect the actual level of bulk material entrucking, a new method was presented based on image texture recognition. First, the image was enhanced with the homomorphic filter, and the binarization processing was applied to cut down the amount of calculation of the texture features extracting. Then, the co-occurrence matrix texture features were calculated, and principal component analysis method was used to reduce the dimensionality of the feature space. Finally, the image partitions were recognized by decision tree, and the level was linear fitted by the image segmentation result. Experimental results indicate that the mean error is as 6.5 pixels, and the recognition rate is as 96%. The processing time is as 0.2 seconds per frame. It can satisfy the real-time level detection of bulk material entrucking.

Parameter Identification and Experimental Research of a Linear Servo System

DAO Da-Jin-1, KE Da-Guan-1, YUAN Liu-Bin-2, SHU Dan-Feng-1

2013, 24(07): 915-921.

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In order to improve the control performance of a linear servo system, system modeling and identification, control performance of the system were studied. The error of the modeling results worked out by traditional method was large. In order to work out the model parameters, a step response identification with least square method was applied to build the model. The fitting error and correlation coefficient between experimental and simulation data were 0.0018 and 0.9970 respectively. The simulation results show that the model identification is feasible and the resulting parameter estimation is insensitve to measurement noise. The position controller was designed by pole placement method. Then an experimental investigation was conducted to study the control performance of the position controller. The Influence of friction on system performance can be reduced dramatically by pole placement method.

Drag Reduction Experiment and Mechanism Analysis of Concave Groove Needle

WAN Yan-Ling-1, 2, CONG Qian-1, JI Ying-Chun-1, JI Xin-1

2013, 24(07): 922-925,931.

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From the bionics point of view, this paper designed a concave groove shape needle, according to the microstructure of mosquito mouthparts, produced the bionic needle using the JG20-1 laser surface texturing processor, and measured the force during the needle piercing into the silica, and analyzed the mechanical mechanism. Results show that the bionic needle has the drag reduction effect, and the drag reduction effect increases with increase of the number of grooves. The drag reduction effect changes with the contact area between the needle and silica, the more contact area is, the better the effect is. To some extents, concave grooves of needle produce eddy current effect, make the sliding friction turn to rolling friction, and reduce the friction.

Fault Prediction for Hydraulic Pump Based on EEMD and SVM

TIAN Hai-Lei, LI Hong-Ru, HU Bao-Hua

2013, 24(07): 926-931.

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The performance of hydraulic pump will directly affect the entire hydraulic system, so it is essential for its condition monitoring and fault prediction. The vibration signals for hydraulic pump were collected and a kind of method was presented,which can get fault feature based on EEMD and smoothed energy operation separation. Wavelet packet was used to decompose energy of frequency area in order to get fault feature vectors. On the basis of studying the principles of SVM regression estimate, a prediction model was built,which was based on wavelet packet theory and SVM. The model were validated through the historical data of the hydraulic pump, and the experimental results show that the SVM regression model and fault mapping model can predict the faults effectively.

Effect of Particle's Young Modulus on Joint's Resistance in COG Packaging

CHEN Xian-Cai, DAO Bei, YIN Zhou-Beng

2013, 24(07): 932-936.

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This paper presented a structure-electric field coupling method with the cohesive model to analyze the contact and fracture of a conductive particle in COG packaging.Meanwhile,the electric conduction mechanism of COG was also investigated. The results show that the effect of particle's Young modulus on the mechanical and electrical properties of COG packaging is very significant. When the Young modulus is small,the contact surface between the particles and bump/pad is just a circle ring and it makes the joint resistance too large.However, when the Young modulus is large enough, the contact surface will become a circle. In this case,the resistance will be smaller a lot, but the greater bonding pressure should be loaded so that the mechanical reliability will become worse. 

Influence of Eddy Current Sensor's Posture on Coating Thickness Measurement in Oil Pipelines and Posture Correction

ZHANG Dong-Li-1, WANG Shao-Ba-1, CHEN Zhen-Mao-2, LI Yong-2

2013, 24(07): 937-942.

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To decrease the influence of eddy current sensor's inclination or deviation on measuring precision of coating thickness in oil pipeline, some effective correction measures were adopted according to the characteristics of eddy current signals due to the sensor's inclination or deviation, which gave an effective theoretical guide to the centering and verticality control of the sensor in practice. By using electromagnetic field simulation method, the influences of the sensor's inclination or deviation and the signal features for pipe with different sizes and sensor with different liftoff distances were both studied. Then, the correction measures and signal processing method were proposed to decrease the influence of sensor's inclination or deviation. Numerical simulation results show that the correction measures are effective, which can enhance the measuring precision of coating greatly to meet the requirements of engineering practice. 

Design and Sea Trial Research of New Hydrostatic Corer

QIN Hua-Wei-1, CHEN Jian-Qiao-1, WANG Jian-Jun-2, SHU Jing-Ru-1, CHEN Ying-2

2013, 24(07): 942-945.

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Based on the operation principle analysis of hydrostatic corer, a novel sediment corer driven by marine hydrostatic was proposed, which was supported by the research of operational mode trigger mechanism of hydrostatic corer controlled by sampling tube's support reaction force, and the research of hydrostatic pressure driven sampling mechanism based on distribution flow spool position's control in driven units. Mechanical structure of the corer was designed firstly. Then, the prototype was completed. Finally, a practical sea trial was conducted successfully. The results of the sea trial verify the reasonableness of the hydrostatic corer's design.

Study on Large-Strain Sensing for Trapezoidal Frame

CHEN Xiao-Yan-1, LIN Yu-Che-2

2013, 24(07): 946-951.

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Aiming at the ‘flexible beam' type, ‘unit load method' was firstly employed to deduce the large strain transfer model of the trapezoidal frame. The model expression was clear and understandable. The finite element model of the trapezoidal frame was established in ANSYS, and the simulation results are in accordance with the deduced transfer model. A large strain sensor specimen based on the trapezoidal frame with a mounted fiber Bragg grating was home made. In experiments, the specimen's large strain was supplied by the motorized translation stage, and the fiber Bragg grating's wavelengths were interrogated by the manual optical inspector(MOI) instrument. The experimental results show an agreement with the theoretical analysis. And the spiecimen has a strain measuring range of -16%~33.3%, with the linearity less than 1%, the repeatability less than 1% and the hysterisis error less than 0.9%.

Research on Decision-making Method of One-dimensional Cutting Stock Problem Based on Multi-objective Optimization

LIU Lin, GE Fei-Fei, LIU Xin-Bao

2013, 24(07): 951-955,963.

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A multi-objective cutting stock problem was studied. The objects were to minimize trim loss, the number of cutting patterns and usable leftovers. A decision-making method for this cutting stock problem was designed. First, the Pareto-optimal set was gotten by using the improved non-dominated sorting heuristic evolutionary algorithms. Then the weights of the every object were calculated by combining the subjective and objective method. Finally, a satisfactory solution, which was regarded as cutting scheme, was finded from the Pareto-optimal set by employing the multi-attribute decision making method. The experimental results show that the proposed method is effective. 

Affect Factors of Axial Dynamic Buckling of Anti-climber Energy-absorbing Structures and Design of Square with Axisymmetric Deformation

JIN Ping-1, 2, NIE Hong-1

2013, 24(07): 956-963.

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Mechanism of axial dynamic buckling of thin-walled square was studied, and design method of axisymmetric deformation square was indicated, it was used mainly for design of energy-absorbing structures of subway anti-climbers. Dynamic load characteristics of axisymmetric dynamic buckling of thin-walled square were revealed, mathematical models of average impact force and plastic transverse, longitudinal waves were built, it was proposed that thin-walled square's deformation mode was decided by propagation velocity of the plastic stress wave and overall bending stiffness of thin-walled square, and it was explained that design of axisymmetric deformation square is easier than that of tube. Axisymmetric deformation square was designed according to certain safety requirements, energy-absorbing structures of anti-climbers can be designed in parallel by thin-walled squares of different thicknesses,materials and cross-sections. Mathematical models can guide design of square with axisymmetric deformation, can save a lot of manpowers, financial resources and time, and it has an important significance for engineering practice.

Safety Simulation of Rear-end Collision and Experimental Study for Extended Range Electric Vehicle

SU Zhong-Gen-1, LONG Jiang-Qi-2, ZHOU Shi-Jia-2

2013, 24(07): 964-970.

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The finite element (FE) model of E-REV rear-end collision safety was built to calculate and optimize the performance of vehicle safety. The bending mode, torsional mode and rotary rigidity of E-REV and archetypal vehicle were compared. Through displacement control of X axis direction of power battery box and Z axis direction of hook at the upper part of the rear seat backrest, the existing structure and the safety performance of whole vehicle rear-end collision were optimized and redesigned. The simulation results of modified E-REV safety structure were testified by calculation and entire vehicle crash tests.

Oriented Mechanism and Simulation for Electrical Coupled Wheelsets of Railway Vehicles

SUN Xiao-Jie-1, LIU Zheng-Gang-1, ZHOU Wen-Xiang-2

2013, 24(07): 970-974.

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A electrical shaft system was applied to railway vehicles for the first time with independently rotating wheel. A new type of coupled wheelsets was proposed by electrical coupled method. Studying coupled torques and its influence factors of this coupled wheelsets, it is true that the coupled capacity can be adjusted. The oriented mechanism of this electrical coupled wheelsets is as same as feedback control based on angular differences between two wheels. Numerical model of metro vehicles with independently rotating wheel was established to simulate the steering performance. The results show that vehicles with electrical coupled wheelsets are better than the one with independently rotating wheel,and same to the elasto-damper coupled wheelsets; low-speed and high-torque winding induction motor and appropriate public resistance can improve self-steering ability of electrical coupled wheelsets effectively.

Lightweight Design of Bus Body to Satisfy Rollover Safety

RUAN Cheng-Xin-1, 2, CAO Li-Bei, DAN Xiang-Na, XU Zheng

2013, 24(07): 975-979.

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According to the ECE R66, the structure of bus body was optimized for lightweight based on the tube filling method herein. Uniform design method was used to set the experimental scheme on the side pillars and roof crossbeams of bus body with different thicknesses of steel tube and lengths of filler in the tube, simultaneously a series of simulation studies on bus rollover safety were conducted. Based on the regression analysis of the simulation results, the regression functions were established by SAS software, the design variables were optimized by MATLAB software. The results show that, under the conditions of bus body meeting ECE R66 for living space, the total weight of optimized side pillar and roof crossbeam structures is decreased by 23.7% and the lightweight design of bus body is realized.

Research and Development of Fiber Bragg Gratings Detection Technology Based on Ultrasonic Excitation

MENG Li-Jun-1, TAN Ti-Gang-1, ZHOU Jie-De-1, LIANG Bao-Kui-2, YANG Wen-Yu-3

2013, 24(07): 980-988.

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The FBG detection technique has several advantages of FBG in electromagnetic interference immunity, distributed sensing and the ultrasonic features such as good directivity, high penetrating power. A review of the FBG high speed demodulation method, FBG strain transferring characteristics and sensitivity property was given as well as the application of this technique in health monitoring was analyzed. Finally, the existing problems and future directions were outlined and proposed.

Advances in Contact Stiffness Measurement Using Ultrasonic Method

WANG Shi-Jun, SUN Jia-Sai, DIAO Jin-Juan, XU Lei

2013, 24(07): 988-993.

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Theory, trial and influence factors of contact stiffness measurement using ultrasonic method were introduced, whose history and current situation were also analyzed and summarized. Because wavelength of ultrasonic wave is much longer than contact size of asperity, reflection coefficient and incidence coefficient of contact surface are function of contact stiffness. If the coefficients were obtained through trial, the contact stiffness can be calculated. Frequency of ultrasonic, contact pressure and physical property of material also have certain influence. When contact pressure is high, reflection coefficient and incidence coefficient of longitudinal wave are insensitive to variation of load. Under this condition, transverse wave is more suitable for contact stiffness measurement than longitudinal wave. The contact stiffness obtained by ultrasonic method accords well with theoretical result, it shows ultrasonic method may be used to measure contact stiffness and has certain reliability. Problems and difficulties are pointed out in research of
contact stiffness measurement using ultrasonic wave and its development tendency was forecasted.

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