Table of Content

25 September 2014, Volume 25 Issue 18

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Analyses of Kinematic Accuracy Reliability and Sensitivity for a Planar Linkage Mechanism

Pang Huan, Yu Tianxiang, Song Bifeng

2014, 25(18):  2415-2421. 

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Planar linkage mechanisms are widely applied to many machines. But such a long transmission distance will cause a  large error accumulation,and the impact on the kinematic accuracy can not be ignored. A modeling method of kinematic accuracy reliability analyses and simulation  process was proposed considering multi-factor coupling effects of manufacturing errors, structure deformation, assembly tolerance and hinge wear. The dynamics analyses of the mechanism were carried out after the clearance joints were dealt with momentum exchange approach. Based on the results of dynamics analyses, the Hook's law or finite element method was used to analyze the deformation of the  components and Archard's model was used to analyze the wear depth of each joints. Follow that, the closed vector position equation of the mechanism was established after the clearance joint was replaced with massless link considering manufacturing errors, structural deformations, and a kinematical accuracy modeling method was also proposed considering the multi-factor coupling effects. The feasibility of the proposed method was proved by the kinematic accuracy reliability and sensitivity analysis of an aircraft door retractable mechanism and finally gives some valuable advices for manufacture and maintenance process.

Optimal Design Theory of Cam-rotor Servomotor Based on Parameter Comparisons

Xu Chuanhui, Wang Xuyong, Zhang Wenjun, Miao Zhonghua

2014, 25(18):  2421-2426. 

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Because the type of hydraulic motor using for continuous revolving servo drive is not so much, research on a novel cam-rotor vane motor was carried out and an optimal design theory based on parameter comparisons was proposed herein. The relationships among the press angle and the cam radius, the motor displacement and the axial length of cam, the flow fluctuation rate and vane thickness, the positive pressure of the motor's cam and the radial length of vane were obtained based on the analytical derivation and analyses of pressure angle of transition curve, motor's displacement formula, motor's instantaneous flow fluctuation rate and positive pressure of the motor's cam. Optimized parameters of cam-rotor and vane which were the most important parts of the motor were obtained from the simulation comparisons of different parameters. The hydraulic servo cam rotor vane motor designed with the optimized parameters is successfully applied to the continuous revolving electro-hydraulic servo system and shows  a very good servo precision, proves the feasibility and effectiveness of the optimal design theory herein.

Error Compensation Algorithm to Spiral Bevel Gear Precise Numerical Controlled(NC) Machining

Xing Yuan, Zhang Jianxun, Zhang Lianhong, He Baiyan

2014, 25(18):  2427-2431,2438. 

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For higher precision in spiral bevel NC machining,machine characteristics were brought into the construction of original NC machining model and compensation model in linear space. With a parameter of surface error taken to justify machining quality, the compensation model was divided into two parts,machine coordinate compensation and dynamic cutting compensation. Multi-axis cooperation motion would keep the required precision in machining due to in-time compensation on each tooth surface. It is demonstrated that the new principle will  realize multi-axis cooperation in continuous cutting and improve machining precision effectively.

Micro-cutting of Driving Force and Controllable Influencing Factors in Abrasive Flow Machining

Zhang Kehua, Min Li, Ding Jinfu, Xu Yongchao, Cheng Guangming

2014, 25(18):  2432-2438. 

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The driving force mode of micro-cutting and the controllable factors of polishing effects in abrasive flow machining were studied. The source of micro-cutting force contained medium force, squeezing load among gains and grain impact force  were presented and their force models were built. Controllable influencing factors contained process temperature, process pressure, piston velocity and medium viscosity, grain properties(such as size and hardness) and so on. The relation among controllable influencing factors and the polishing effects of surface roughness and material removing rate was studied by the physical quantity ‘force', and the effect extent on the workpiece surface were quantized by active grain force acting on workpiece surface. Active grain forces acting on workpiece surface were translated into axial force and radial force, the ratio of which would affect micro-cutting effect. The handy measuring equipment of axial force and radial force was proposed. The method of mode and research's validity were verified by experiments, it is found that the direction of processing track on workpiece will affect the final roughness and material removing rate severely.

Research on Ideas Generation Process for Mechanical Product Radical Innovation Based on TRIZ

Ping Enshun, Tan Runhua, Sun Jianguang

2014, 25(18):  2439-2446. 

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To solve the problem of ideas generation for mechanical product radical innovation, the theory of invention problem solving(TRIZ) was applied to the fuzzy front end stage of new product development. The main function substance-field model for product technology system was set up, on the basis of that a mechanical product radical innovation method was put forward. Based on global idealization of TRIZ, the function trimming and available resources analysis were applied for the realizing the product main function technical subsystems. Then, technology forecasting was carried out for the realizing product main function technical subsystems by taking advantages of technology evolution theory. And, the ideas generation process model for mechanical product radical innovation was established by using computer aided innovation(CAI) software tools. The Innovation ideas generation for Chinese medicine dropping pill machine validated the effectiveness of the proposed method.

Nonlinear Vibration Behavior of Flexible Rotors under Unbalanced Magnetic Pull

Liu Qing, Li Kun, Wang Xiaofeng, Zhang Kunpeng, Cao Shuqian,

2014, 25(18):  2446-2450. 

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A multiple scale approach was applied to the nonlinear dynamics model of the flexible rotor in a motor, to study the first approximate primary resonance of the rotor. The results show that the formant makes a left shifting in the frequency response curve. In addition, the linear part of the unbalanced magnetic pull will decrease the natural frequency in the system, and the nonlinear part will increase the left shifting of the formant. The numerical simulation was carried out to verify the results obtained through the analytical method. The results given here make a foundation for further optimization and control of permanent magnet  synchronous motors.

Analysis of Optimal Driving of Rotary Inertial Piezoelectric Motor

Xing Jichun, Xu Lizhong

2014, 25(18):  2451-2455. 

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A novel rotational inertial piezoelectric motor was proposed. The equation of inertial impact torque and the average output torque of rotary inertial piezoelectric motor were derived in asymmetric excitation signals. The influences of system parameters on  the difference of inertia impact torque of excitation signal mutation moment were analyzed. The optimal driving frequency range of output speed and torque of the rotary inertial piezoelectric motor were given. With experimental system, the correctness of theoretical calculation and analysis was verified.

Design and Experiments of Driving System for Chain CVT

Zhang Yiyang, Li Shaobo, Cheng Yue, Cheng Naishi

2014, 25(18):  2456-2460. 

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Through the development of chain CVT machine experimental system, the transmission principles and working characteristics of chain CVT were studied, the hydraulic drive and control strategy were test. Through the establishment of a chain CVT axial thrust model, the driving characteristics of chain CVT speed control principles were explored. On the basis of the above work, the fluid power system was designed and developed to chain CVT. Through the bench test, transmission characteristics of chain CVT was further discussed. The new solution to the control system was presented. The speed ratio control model was verified.

Incremental Quantitative Design and Optimization of Column in Forming Gear Grinding Machine Based on Finite Element

Sun Guodong, Li Huan, Zhao Daxing, Peng Ling

2014, 25(18):  2460-2466. 

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Taking the column of a forming gear grinding machine as the research object, the static characteristics of the column  were analyzed under the partial center of gravity load, meanwhile its modal analysis was completed. And it is found that the column has poor force condition in X direction. On the basis of that, the conception of incremental quantitative design was proposed. Adopting incremental quantitative counterweigh design on the column, the research fruit shows that this method has reduced the column's displacement and stress in X direction effectively, and the fourth order modal of column has appeared vibration shift under this incremental quantitative design. In order to obtain the optimal static stiffness and the smallest increment of the column, a multi-objective optimization model was established on design parameters for column counterweight, and a group of optimal incremental quantitative design parameters are achieved.

Pseudo-extrema-based EMD and Its Application to Rotor Fault Diagnosis

Zheng Jinde, Cheng Junsheng, Zeng Ming, Luo Songrong

2014, 25(18):  2467-2472. 

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A novel method PEEMD was proposed for restraining the mode mixing problem of EMD.Compared with ensemble  EMD(EEMD), which was by adding white noise before ensemble and averaging, PEEMD fulfilled this aim by defining the least extrema scale(LES)  to measure other extrema scales and by adding pseudo-extrema to homogenize the scale distribution. EMD and PEEMD are introduced herein firstly and then PEEMD was compared with EMD and EEMD by analyzing simulation signals. Also, PEEMD was applied to diagnose rotor rubbing faults, and the results indicate that PEEMD is more accurate in components and more efficient in inhibition of mode mixing than that of EMD and EEMD.

Early Fault Intelligent Diagnosis of Tool Wear

Cao Weiqing, Fu Pan, Li Xiaohui

2014, 25(18):  2473-2477. 

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In view of the difficulties of fault feature extraction from strong background noise in tool wear early fault diagnosis, a method was proposed based on twice sampling SR and B-spline neural network. First, SR was employed to remove noise in tool wear vibration signals because of its benefits for enhancing the signal-to-noise ratio, then, tool wears with the good fault features were identified by B-spline neural network. In order to improve the deficiency of a single parameter be optimized in the traditional SR and achieve the best SR parameters, an adaptive SR was proposed based on genetic algorithm, which realized multi-parameter synchronous optimization. The experimental results show that this method can realize the weak signal detection and apply to tool fault diagnosis effectively.

Study on Damage Identification Methods of Large and Complex Steel Tube Welded Structures

Ma Liyuan, Li Shilong, Wang Weifeng, Li Yongjun

2014, 25(18):  2478-2483,2531. 

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According to the excellent learning ability and generalization of SVM even with small samples, combined the RSM with  LS-SVM, then a new RSM was established based on LS-SVM, and it was used in model updating and damage identification. A weight method was proposed in kernel function, and the linear-and-Gaussian kernel function was proposed which combined the linear fitting ability of the linear polynomial kernel function and the nonlinear fitting ability of the Gaussian kernel function. At the same time, the training samples had a scale transformation, and the selection method of training samples was improved. By a identification example and experimentation, compared with the traditional sensitivity method, the results show that the improved RSM is better, and the convergence is also improved greatly.

Research on Design Methods of Active Disassembly Structure Triggered by Temperature-pressure Coupling

Liu Zhifeng, Zhan Yifei, Li Xinyu, Cheng Huanbo

2014, 25(18):  2484-2489. 

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Active disassembly structures are usually triggered by single physical field. These structures can be triggered automatically in extreme or accidental circumstances, thus causing the low reliability of products. For improving the reliability of active disassembly products, this paper expounded the triggering mechanism and characteristics of active disassembly structure triggered by temperature-pressure coupling, and studied the design principles and methods of active disassembly structure triggered by temperature-pressure coupling. The feasibility of these design methods was proved by a case analysis. The results show that the reliability of active disassembly structures triggered by temperature-pressure coupling is improved greatly.

Study on Convection Heat Transfer Model of Isothermal Chamber during Discharge

Yang Lihong, Shen Hangming, Song Yuanming

2014, 25(18):  2489-2495. 

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In order to improve the performance of isothermal chamber, a convection heat transfer model of isothermal chamber  was studied during discharge. Four solenoid valves with known flow rate characteristics were used in four different isothermal chambers deflated experiments respectively, pressure curve during discharge was collected, and the temperature curve was collected by “stop method”. Based on the convection heat transfer model and combined with pressure curve and temperature curve during discharge, the convection heat transfer coefficient was determined. Finally, the convection heat transfer empirical formulae in sound velocity and subsonic speed phases were fitting by similarity principle respectively. The two empirical formulae include deflated speed and the copper wire filling density. That is to  say the deflated speed and porosity can influence the heat transfer. The air compression ratio was introduced in the empirical formula of sound velocity phase. It can explain the problem that the heat transfer is influenced by compressibility while the air in the conditions of high compression.

Product Design Alternative Selection:an Integrated Approach with HOQ and PROMETHEE

Guo Qian, Wang Zengqiang, Pu Yun

2014, 25(18):  2496-2500. 

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In order to select conceptual design schemes through coordination between customer requirements and experience knowledge, an integrated approach combining HOQ and PROMETHEE was proposed. The correlation matrix and autocorrelation matrix of fuzzy HOQ were utilized to realize the transformation from customer requirements to technical characteristics. The conceptual decision matrix was established after the HOQ outputs to use the fuzzy weights of technical characteristics to conduct comprehensive ranking of fuzzy PROMETHEE, where preference functions were constructed according to expert knowledge. A case study shows the feasibility and effectiveness of the proposed method.

Magnetic Circuit Structure Optimization Design for Electronic Gasoline Injector Based on MOSA Algorithm

Chen Qiang, Zhang Zhendong, Guo Hui, Zhu Xi

2014, 25(18):  2501-2505. 

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Taking the automotive electronic gasoline injector as an object,a computational model of the injector's working process was established from the basic principles of electromagnetism and mechanical kinetics. The relationship functions were derived between dynamic response characteristics and magnetic circuit structure parameters based on the coil current change after power on. As the goal to improve the dynamic response characteristics, the magnetic circuit structure parameters of the injector were optimized with the help of MOSA algorithm. The electromagnetic field simulation results show that the magnetic flux and magnetic induction intensity distribution are more reasonable after the injector optimized; the experimental results show that the opening delay time and closing delay time of the optimized injector  are reduced respectively by 29.41% and 29.23% compared with before optimization. Above results verify the effectiveness of the optimization algorithm from simulation and experiments.

Synthesis of Spatial Symmetrical 2-DOF Parallel Mechanism with Constraint Screw Theory

Liu Ping'an, Huai Chuangfeng, Hu Changfeng

2014, 25(18):  2506-2510. 

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The spatial symmetrical parallel mechanisms with 2-DOF were sorted into two classes firstly, i.e. Type 2Ryz 2-DOF parallel mechanism with two rotations about y-and z- axes in the plane of fixed platform and Type 1Rz1Tz 2-DOF  parallel mechanism with one rotation about z-axis and one translation along z-axis. The limb constraint system and the mechanism constraint system of the two kinds of parallel mechanism were enumerated with the geometrical conditions which guaranteed the combined effects of all the limb constraint screws equal to the desired mechanism constraint system. Then, the type synthesis for the two classes of 2-DOF spatial symmetrical parallel mechanisms were performed  systematically with the constraint screw synthesis theory, and the structure of the mechanisms were obtained, which could continuously realize the required rotations about the two axes in the base or rotation about the normal of the base plane and translation along it. The structures of limbs of the mechanisms as well as their constraint characteristics were gained also. The types of lower-mobility symmetrical parallel mechanism are expanded into 11 from 9, and their synthesis methodologies are also provided; all of these makes the type synthesis perfect.

Calculation and Experimental Verification of Helical Gear Churning Power Loss Based on Finite Element Analysis

Liang Wenhong, Liu Kai, Cui Yahui

2014, 25(18):  2510-2515. 

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The finite element numerical estimation of single helical gear churning power loss was carried on by using two phase flow theory in fluid mechanics and theorem of momentum in axial flow and radial flow wind turbine. Considering the impacts of lubricant density and viscosity, and the impacts of gear helix angle, gear module, number of teeth, rotation speed, and the impacts of the surrounding temperature, gearbox case size, acceleration of gravity and lubricant immersion depth of gear, the numerical simulations of churning flow field and power loss were carried on by using finite element software Fluent. In the simulation, churning flow field of helical gear was three-dimensional flow field, and there were several gears with different  parameters were simulated groupingly. And then, some parameters in the simulation results were validated and compared through experimental data, the results prove that the value of churning power loss can be forecasted by using the simulation method under the conditions of low and medium speeds. At the same time, the method basis and theoretical reference can be provided for numerical simulation of churning power loss under meshing helical gears.

Analysis of Frequency Stability of Vibratory Roller during Compaction Stage

Li Yu, Zhao Liping, Shen Jianjun, Zhang Xiaobo

2014, 25(18):  2516-2519. 

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By analyzing the phenomenon and causes of the frequency fluctuation, the basic laws were found that the vibration frequency changed with vibration load. And by mathematical analysis, the factors that influenced the frequency stability were derived theoretically. Then correctness of the proposed conclusions was validated by experiments with a hydraulic single drum roller. A series of methods are proposed to improve the frequency stability, such as improving the engine's performance, adjusting the configuration of hydraulic systems.

Nominal Stress Approach for Fatigue Life Prediction of Multi-fastener Joints under Vibration Loading

Cui Sipeng, Yao Weixing, Xia Tianxiang

2014, 25(18):  2519-2522. 

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A stress mean square severity factor of joints in vibration excitation was given aiming at fatigue life estimation problem herein. This stress mean square severity factor considered comprehensively the concentration degree of root mean square stress, surface status and block coefficient at hole edge. Then a model was presented combining with the dynamic characteristics of hole edge. With this model, the nominal stress approach of vibration fatigue life analysis of joints was obtained. A vibration fatigue test was designed and carried out on 304 stainless steel. According to the results, the method can predict the vibration fatigue life of multi-fastener joints well.

Influence of Triaxiality on Sandwich Plane Laser-welded Joint of Hull Steel to Equivalent Fracture Strain

Li Jinmei, Cao Rui, Chen Yong, Zhu Liang, Chen Jianhong

2014, 25(18):  2523-2526. 

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In order to achieve mechanical property under different stress triaxiality at tensile test from sandwich plane laser-welded joint of hull steel CCS-B, the flat grooved specimens with different radius and sizes were designed to study the effects of the stress triaxiality on the fracture plastic strain. The different stress triaxiality was determined by groove radii and the specimens' size. The results indicate that: whether the specimens are at the state of plane stress or plane strain, the strength of welded joint increases and meanwhile the plastic of weld joint decreases with increasing of initial stress triaxiality. The relationship of the initial stress triaxiality and the equivalent strain to fracture were fitted using an exponential function. The fracture equivalent strain decreases with increasing of stress triaxiality. The fracture surface of specimens are mainly dominated ductile fracture with more dimple.

Optimization of Several Segmental Binder Force in Sheet Forming Based on BP Neural Network and Fish Swarm Algorithm

Wang Xinbao, Xie Yanmin, Qiao Liang, Wang Jie

2014, 25(18):  2527-2531. 

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Relationship of several segmental binder force and forming quality was bulit, which was based on BP neural network and fish swarm algorithm. The first approach was gotten training samples for BP neural network by Latin hypercube designs based on maximum and minimum principle. Then simulation software was used to get forming quality and used as training outputs for BP neural network. Fish swarm algorithm was used to optimize BP neural network, which built relationship of several segmental binder force and forming quality.PSO was adopted to obtain optimal result of function relation. Compared with whole binder force,forming quality is improved greatly.The research fruits indicate that the method can calculate optimal several segmental binder force quickly. It can make up computational difficulties of several segmental binder force.

Research on Vehicle Path Tracking Based on Fuzzy Control

Wang Wei, Zhao Youqun, Xu Jianxiong, Liu Wenting

2014, 25(18):  2532-2538. 

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The path tracking method was one of the major researches in vehicle handling inverse dynamics. A precise mathematical model was established difficultly because of a very complex nonlinear dynamic system of the vehicle. Fuzzy control method was suitable to establish a precise difficult mathematical mode. Fuzzy control theory was introduced into the vehicle handling inverse dynamics. Vehicle model of three freedom degrees was researched. The fuzzy controller of path tracking was designed with considering lateral deviation and rate of change. The driving conditions were obtained by simulating path tracking according to given the double lane change and the serpentine path. Simulation results show that the fuzzy control algorithm can ensure tracking given path of vehicles accurately, and can be used as an effective control method good for a vehicle path tracking.

Analysis and Optimization for Roll Response of Mining Dump Truck on Soft Terrain Surface

Dong Zhijun, Gu Zhengqi, Xu Ya

2014, 25(18):  2538-2543. 

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The road conditions that mining dump truck rided were always the soft terrain surface, the interaction between road and tire had settlement deformation, this made a big influence on roll response in the vehicle driving process. Thus, this paper established an elastic tire-soft terrain interaction model, and combining the vehicle with the tire's jump degree, then a vehicle dynamics model of eleven degrees of freedom was established. Through the MATLAB/Simulink the road-tire-vehicle coupling system was established, the accuracy of the model was proved by the comparison between the simulation results and experimental data. And the roll response under soft road increases by 1.28° than that of the rigid road excitation, the increase amplitude is as 23.81%, thus the effects of the tire's settlement deformation on the soft terrain surface on the roll response were verified. The physical parameters of the hydro-pneumatic suspension were optimized by genetic algorithm, the roll  angle reduces by 16.7% after optimization, the dump truck's roll stability is improved obviously. 

Modeling and Parameter Identification of Shock Absorber with Consideration of Throttle-Slices' Large Deflection

Kang Yu, Zhao Liang, Guo Konghui,

2014, 25(18):  2544-2549,2555. 

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To establish parameterized mathematical model of damper, based on large deflection theory of circular plate and elastic mechanical principals, a deformation equation related with radius was established. The mechanics model of annular superposition throttle-slices with partial equal external radius was established. Meanwhile, a solution of equivalent model was proposed combined with large deformation and finite element analysis. Moreover, the analytical formula of large deflection for annular superposition throttle-slices was deduced. According to the series deformation theory of superposition throttle-slices and piston valve spring, the mathematical model of double cylinder shock absorber for rebound and compression stroke was established. Some parameters which were difficult to measure were identified by using NSGA-Ⅱ. The simulation results of outer characteristic of shock absorber after identification agree well with test data, demonstrating that the established parametric model is relatively reliable and has guiding significance for tuning of the damper performance.

Applications of Semi-active Hydro-pneumatic Suspension System Based on Fuzzy Control in Articulated Dump Truck

Zhang Chunhui, Zhao Jingyi, Tian Xing, Luo Lijun

2014, 25(18):  2550-2555. 

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Aiming at the phenomenon of rolling over of an articulated dump truck when streering around, a semi-active hydro-pneumatic suspension system was designed based on fuzzy control with the function of anti-roll. The principles of the system were elaborated and the characteristic analysis was made with established mathematical model. It shows that the semi-active hydro-pneumatic suspension system meets the basic performance requirements in the condition of non fuzzy control. Based on this, the anti-roll analysis of the fuzzy control was  also made and the simulation was applied using the fuzzy toolbox. Through simulation studies and field trials comparition,it can be concluded that the suspension system under the way of fuzzy control improves the system's anti-roll capability effectively, providing a new way of thinking for the domestic research and development of the hydro-pneumatic suspension system.