Table of Content

10 January 2018, Volume 29 Issue 01

Previous Issue    Next Issue

Research on Dynamic Reliability and Sensitivity of Indexing Accuracy of End-toothed Discs with Wearing Error Factors

WANG Xingang;ZHANG Heng;WANG Baoyan;HUANGFU Yifan

2018, 29(01):  2-7. 

Asbtract ( )   PDF (605KB) ( )  

References | Related Articles | Metrics

The levels of end-toothed disc indexing accuracy might have direct effects on the indexing accuracy of the tool rests. Tooth thickness wear errors and a variety of machining errors were analyzed. An indexing accuracy error model of the end-toothed discs with multiple error factors was established. On the basis of the indexing accuracy model of the end-toothed discs, a dynamic reliability sensitivity mathematical model was established by combining reliability sensitivity analysis method. The evolution rules of reliability sensitivity for each random parameters of the end-toothed discs were given. The influences of the random parameters on the reliability of the end-toothed disc indexing accuracy were analyzed. The results show that the reliability of the indexing accuracy of the end-toothed discs decreases gradually with the the loading and unloading processes. The variation tendency of the sensitivity of each design parameters at the same time is different. The sensitivity parameters should be controlled in order to improve the reliability of the indexing accuracy of the end-toothed discs.

Modal Characteristic Analysis of RV Reducers

MENG Cong;CHEN Chuan;YANG Yuhu

2018, 29(01):  8-13. 

Asbtract ( )   PDF (650KB) ( )  

References | Related Articles | Metrics

This paper aimed at reveal the influences of ring gear stiffness on RV reducer natural characteristics, a translational-rotational-coupling dynamics model was developed, where the ring gear support stiffness, bear stiffness, mesh stiffness and the bending stiffness of crank shaft were taken into account. A certain type of RV reducer was taken as an example, by using the numerical integration approach, natural frequencies and vibration modes were achieved, which were classified into two groups, the effects of ring gear support stiffness and bear stiffness on natural frequencies of the reducer were studied respectively. The results imply that the loci veering/crossing exist in the processes of natural frequency changes of RV reducer. The present research may provide reference for parameter optimization design of RV reducer.

Design and Kinematics Performance Analysis of a 3T1R Parallel Mechanism

ZHU Wei;GU Kairong;WANG Chuanwei;LIU Xiaofei

2018, 29(01):  14-21. 

Asbtract ( )   PDF (2740KB) ( )  

References | Related Articles | Metrics

A 4 degree of freedom (DOF) parallel mechanism was designed which consisted of a 3-DOF translational motions and a 1-DOF rotational motions about a fixed axis (3T1R). Firstly, the characteristics of topological structure were analyzed in the light of the position and orientation characteristics theory (POC). Secondly, the mathematical model of the forward solution and inverse solution of the mechanism was presented, and was verified on numerical values by way of two-dimensional searching. Then, the workspace analysis, Jacobian matrix modelling and singularity analysis were performed. In addition, two kinds of additional active limb were designed to cope with the singularity problem. The results show that the additional RRR active limb may effectively eliminate the internal forward singularity, and the workspace being kept.

Adaptive Active Screw Driving Mechanism Analysis for Pipeline Robots

YAN Hongwei;JIAO Biaobiao;MA Jianqiang;CUI Zizi;WANG Yang

2018, 29(01):  21-29. 

Asbtract ( )   PDF (741KB) ( )  

References | Related Articles | Metrics

The crawling conditions of variable pipeline robots were analyzed, and an adaptive creeping device driven by a micro-hydraulic was proposed herein. First of all, the three-axis motions in different speeds of the drive wheels and that of drive wheels'angles were realized by means of driving method, which allowed the device to meet the turning requirements. Secondly, the method of limiting the power outputs was proposed by adjusting the flow rates of the corresponding branch when the drive wheels slip and idle. so that the driven system might maintain the required torques steadily. Thirdly, the changes of the load might be perceived by the signals of internal work pressures in the system during the movement, the signals might also adjust the angles of each corner cylinder to achieve mutual conversion from traditional drive to spiral drive; adjust the overall load capacity of the crawler to adapt to the changing external load conditions during the movement. Finally, the load regulation and differential motion mechanism of the device were simulated by virtual prototype technology.

Experimental Study on On-line Monitoring Device for Wear Particles

ZHANG Haicong;LIU Tonggang;LI Linning;QIU Xianming

2018, 29(01):  30-35. 

Asbtract ( )   PDF (587KB) ( )  

References | Related Articles | Metrics

A fast on-line monitoring device was developed for wear particle monitoring based on magnetic field forces, which solved the problems of complex implementation and poor anti-interference performances of traditional methods. The effects of magnetic field strength, oil viscosity and flow velocity on particle deposition were studied. The linearity, relevance, repeatability, quantitative error, sensitivity and capture range of the monitoring device were tested based on kinematic analysis of wear particles in the magnetic fields and numerical solutions of motion traces of wear particles by MATLAB. The results show that the device may effectively capture ferromagnetic particles with size larger than 10μm, which is stably and satisfies the demands of on-line monitoring, and then achieves rapid prediction of the initial mechanical faults of the equipment.

Singularity Analysis of Single Degree-of-freedom Complex Planar Linkages

WANG Jun1;NIU Kejia1;NIE Liangyi2;HE Hongxiu1;CHEN Zhilong1;WANG Quan1;REN Jun1

2018, 29(01):  36-40. 

Asbtract ( )   PDF (489KB) ( )  

References | Related Articles | Metrics

The singularity of complex planar linkages was very difficult to find because they consisted of multiple links and more complex loops and input-related. Using the concept of instance center and the characteristics of planar linkages, the concept and method of equivalent four-bar linkages for the singularity analysis of single-DOF complex planar linkages were proposed. The geometric characteristics were employed when the equivalent linkage was at dead point positions. The proposed method is geometry-based and may be applied to the singularity analysis of more complex linkages such as the double butterfly linkages.

Research on Identification Method of Harmful Functions Based on Game Theory

SONG Ruofei1,2;CAO Guozhong1,2;Guo Zhibin1,2;LIU Zhenhui1,2

2018, 29(01):  41-48,56. 

Asbtract ( )   PDF (816KB) ( )  

References | Related Articles | Metrics

To provide the behavior decision-making basis for handling before happening of the harmful functions, a dynamic identification method of harmful functions was proposed based on game theory. Firstly, the formation reasons of the harmful functions were studied and harmful functions were classified based on the effects of TRIZ. Then the effect space game model was established, the effects of utility functions were determined, and a dynamic identification algorithm of the harmful functions was proposed. Finally, this method was used to design the automatic teller machine(ATM) correction module. The results show that this method may better fulfill the dynamic identification of the harmful functions and has certain effectiveness and feasibility.

Measurement and Analysis of Torsional Vibration Signals for Diagnosing Planetary Gearbox Faults

WANG Xuan1,2;WANG Xiyang1

2018, 29(01):  49-56. 

Asbtract ( )   PDF (878KB) ( )  

References | Related Articles | Metrics

Planetary gearbox health is of great importance for the flight safety of the helicopters. They were usually operating in harsh conditions, so the faults occured easily, such as petting and fatigue cracks.The incremental encoder was presented to measure torsional vibration signals from planetary gearboxes. The torsional vibration signals of the input shaft and the output shaft were measured respectively, and made some contrastive analysis to the signals sensitive for planet gear faults, the results show that the input shaft is more precise than output shaft for diagnosing faults. Via comparing the effects over heavy loads, the torsional vibration signals of the output shaft are more sensitive to the fault features.

Parameter Identification Method of 6-DOF Radiotherapy Beds Based on Combined Genetic Algorithm and Mini-max Optimization

LI Song1,2;YANG Shiyi1,2;ZHANG Fengfeng1,2;SUN Lining1,2

2018, 29(01):  57-62. 

Asbtract ( )   PDF (584KB) ( )  

References | Related Articles | Metrics

In order to conduct structural calibrations of the radiotherapy beds, and to improve their positioning accuracy, a new parameter identification method was proposed, which combined the genetic algorithm with mini-max optimization. Firstly, the calibration model of the radiotherapy bed was established based on the inverse kinematics. Then, the genetic algorithm and mini-max optimization methods, whose advantages were combined to identify 60 parameters, the residuals of the target function were reduced effectively. Finally, the laser tracker was taken to conduct two precision experiments, i.e. absolute positioning accuracy and repeated positioning accuracy experiments, for several groups of arbitrary poses, which were used to verify the results of parameter identification. The experimental results show that, for the positioning accuracy of calibrated radiotherapy beds, for the absolute positioning accuracy the position errors are less than 0.3mm, and the attitude errors are less than 0.1°; for the repeated positioning accuracy, the position errors are less than 0.01mm. Therefore, the parameter identification method may realize the calibrations of the radiotherapy beds, and the accuracy may meet the requirements.

Development of Special Structure Thin-film Sensors for Axle Temperature Measurement of High-speed Electric Multiple Units

CUI Yunxian;HU Xiaoyong;XUE Shuaiyi;LIU Yi;MU Yu

2018, 29(01):  63-69. 

Asbtract ( )   PDF (685KB) ( )  

References | Related Articles | Metrics

According to the characteristics that axle box bearing temperature changed rapidly in high-speed electric multiple units, a kind of special structure thin-film sensors was developed, which adopted NiCr/NiSi thin-film as the sensitive materials prepared by DC pulsed magnetron sputtering technique. A self-developed calibration system was used to calibrate the static and dynamic characteristics of the sensors. The results show that the sensors have good linearity in the temperature ranges of 30~400 ℃, the Seebeck coefficient is as 37.84μV/℃ with a nonlinear fitting errors less than 0.7% and the dynamic response time is as 53.72ms. The wear tests on the special structure thin-film sensors show that the wear of the sensor's thermo-junction has little influences on dynamic and static characteristics of temperature measurements. It means partial wears of temperature measuring ends of the sensors do not affect the test performances.

An Equivalent Calculation Method of Clearances in Revolute Pairs in Pose Error Analyses of a Planar Heavy-duty Mechanism with Low Speed

DENG Aoran;SUN Qipeng;ZHANG Yan;LI Gangyan

2018, 29(01):  69-74. 

Asbtract ( )   PDF (573KB) ( )  

References | Related Articles | Metrics

Aiming at the structure and movement characteristics of the planar heavy-duty mechanisms with low speed, this paper considered comprehensively the influences of structure errors, position errors and the clearances in revolute pairs on the pose errors. Based on the basic principles of the differential method, a new equivalent calculation method of the clearances was proposed, which were equivalent to the structure errors and position errors of the components, and a mathematical model of pose errors was established. Finally, by the collaborative simulations of MATLAB and ADAMS, the pose error curves were obtained. The calculations may provide the references for the tolerance designs of components and the error analysis of mechanisms.

Multi-object Lightweight Design of BIWs Based on Response Surface Model

WANG Zhenhu1,2;ZHOU Qiaoying1,2;LIU Kaiyong1,2;FANG Xiangdong3;LI Luoxing1, 2

2018, 29(01):  75-81. 

Asbtract ( )   PDF (719KB) ( )  

References | Related Articles | Metrics

The finite element model of BIW of a MPV type vehicle was established based on MSC/NASTRAN software platform. The thicknesses of 19 BIW panels were selected as lightweight design variables by using relative sensibility analysis method. Then, the metamodels of five different performance indexes were established using Latin hypercube sampling method and one order response surface model. The models have high accuracy which the multiple correlation coefficients R2 of all the models are close to 1.0. Finally, taking the minimum mass and maximum torsional stiffness as the objective function, and the bending stiffness and first-order bending and torsion modes as the restraints, a multi-objective lightweight optimization on the BIW was conducted by using NSGA-Ⅱ algorithm. The optimization results indicate that the changes of body performances after lightweight are less than 1.0%, and a weight reduction of 6.4kg is achieved.

Design and Characteristics Experiments of Composited Electro-magnetic Actuators

PENG Hu1;ZHANG Jinqiu2;LIU Yile2;PENG Zhizhao2;ZHANG Jian2;ZHANG Lijun3

2018, 29(01):  82-88. 

Asbtract ( )   PDF (684KB) ( )  

References | Related Articles | Metrics

In order to recover vehicle suspension vibration energy, solve the contradictions between vibrations and energy recoveries, and improve the reliability of suspension systems, based on some military wheel type cross-country vehicles, a composited electro-magnetic actuator was designed, that was constituted with rotary motor and magneto-rheological damper in parallel. Taking gears and splines as motion transition devices, multi-objective genetic algorithm（ MOGA） was applied to evaluate MRD parameters, and the parameter calculations and type selection of motors and reduction boxes were conducted, a principle prototype was built. Some experiments on the basic resistances, active force characteristics, energy recovery characteristics and indicator characteristics of MRD were carried out. The results indicate that this composited electro-magnetic actuator may realize maximum active force to 1930N, when suspension relative speed is as 0.52m/s, energy recovery voltage may reach 43V, while MRD may export maximum damper force of 1100N when the current input is as 2A, the multiple that may be adjusted is as 6, each index may satisfy design requirements, and the MRD will be suitable for the areas of vehicle engineering.

Evaluation Index and Performance Analysis of Power Consumption Ratio of Spherical Parallel Mechanisms

HOU Yulei;WEI Xiaochen;ZHOU Zhiyu;ZENG Daxing

2018, 29(01):  89-94,103. 

Asbtract ( )   PDF (703KB) ( )  

References | Related Articles | Metrics

It was one of main problems for the practical applications of bionic mechanisms with low transfer efficiency of energy in the moving processes. The performance evaluation index of the power consumption ratio was put forward herein. Two kinds of 3-DOF spherical parallel mechanisms, 3PSS/S parallel mechanism and 3RRR parallel mechanism, were taken as the research objects, and their mathematical models of power consumption ratio were established. In the ranges of given attitude angles, the theoretical power consumption ratios of the two parallel mechanisms were calculated respectively. The power consumption ratio curves of the two parallel mechanisms were plotted in order to compare the energy transfer performance. Meanwhile, the power consumption ratio experiments of 3PSS/S parallel mechanism were carried out, and the experimental power consumption ratio curves of the experiments were plotted. The comparison between the theoretical numerical analysis and the experimental results was analyzed, which validate the rationality and practicability of the power consumption ratio performance index.

Flatness Pattern Recognition Based on Wavelet De-noising and Optimized SVM

WU Zhongqiang;KANG Xiaohua;YU Danqi

2018, 29(01):  95-103. 

Asbtract ( )   PDF (781KB) ( )  

References | Related Articles | Metrics

Improving the precision of flatness pattern recognition was useful to get high precision control effectivenesses. Among the measured strip shape signals there were noise signals. Firstly, bivariate wavelet threshold method was used to eliminate noises which might overcome the disadvantages of the soft and hard threshold function methods in dealing with wavelet coefficients, and better de-noising effectivenesses might be got. The flatness signals were discretized after de-noising, and as learning samples of SVM, so a recognition model was established. The cuckoo algorithm was introduced to optimize the parameters of SVM. The simulation results show that compared with the particle swarm, genetics algorithm, the cuckoo optimization algorithm needs less matching parameters, and the better optimal solutions will be obtained.

Effects of Laser Shock Processing on Fatigue Performances of TC4 Titanium Alloy Single-side Laser Modification Welding Joints

HUANG Xiao1,2;CAO Ziwen2;CHANG Ming1;ZOU Shikun2

2018, 29(01):  104-109. 

Asbtract ( )   PDF (606KB) ( )  

References | Related Articles | Metrics

The standard fatigue specimens made of TC4 titanium alloy single-side laser modification welding joints were treated by laser shock processing. The tension fatigue tests were conducted to verify the reinforcement effects, and the fracture analyses were utilized to analyze the fatigue mechanism of the treated specimens. The strengthening mechanism of fatigue performances was explained by the experiments of micro-hardness, microstructure and residual stress. The results show that the fatigue cracks of all specimens are initiated in the welding undercut, while the fatigue life of the treated specimens is increased to 3.77~9.15 times by LSP. Coarse martensite refinement is generated in the welding undercut of the treated specimens, and LSP introduces a great compressive residual stress in the surfaces of the welding joints. The residual stress in the welding undercut may reach -564.37±9.85MPa, while the surface hardnesses are increased. The combined actions of high structure refinement and high compressive residual stress are the main causes of the fatigue performance improvements, which blocks fatigue crack initiations and reduces crack growth rates.