Table of Content

10 October 2010, Volume 21 Issue 19

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Research on Reliability Allocation Technology of CNC Machine Tools Based on Task

ZHANG Gen-Bao, WANG Guo-Jiang, HE Wen-Hui, CENG Hai-Feng

2010, 21(19):  2269-2273. 

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First, the limitations of existing research of reliability allocation were analyzed, then the GO methodology was used to establish a reliability model considering relevancy among the parts of CNC machine tools. A practical function for estimation of reliability cost was proposed, and method to determine the parameters of the function was provided. A non-linear programming model for reliability distribution model of the CNC machine was established. Genetic algorithms were used for solving the non-linear programming problem. In the end, the method was used in reliability analysis of a spindle drag bar, and the meaningful numerical solutions was obtained, which shows that the method is useable and correct and provides a practical solution for reliability allocation and optimization of CNC machine tools.

Study on Load Transfer Properties of Bolted Joints Based on Experiments and Three-dimensional Finite Element

YU Da-Zhao, CHEN Ti-Liang, ZHANG Yong, GAO Yong

2010, 21(19):  2273-2278. 

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Three-dimensional finite element model of a bolted joint was developed in the non-linear finite element code MSC.Marc and attempts were made to validate it by comparing results with those of experiments and other finite elements.Experimental measurements of load transfer ratio(LTR) were compared with results from finite element analysis. The results show that the results obtained from three-dimensional finite element model of bolted joint are in close agreement with experimental ones. Three-dimensional finite element analysis assists to study the effects of different parameters on the mechanical behaviour of single lap bolted joints with and without crack. The simulated results may be serving as reference for damage tolerance design of the similar structures.

Strongly Nonlinear Vibration Study of Electromechanical Integrating Toroidal Drive System

HAO Xiu-Gong, HU Li-Zhong, ZHENG Da-Zhou

2010, 21(19):  2278-2284. 

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Electromechanical integrating toroidal drive is a new-style generalized composite transmission, in which drive, power and control are integrated. For the nonlinear electromagnetic mesh forces among planets, worm and stator, strongly nonlinear dynamic differential equations with quadratic nonlinearities of toroidal drive were presented herein. The secondary approximate analytic solutions of time responses were obtained by multiscale method. Time responses of drive system gained by approximate analytic solutions and numerical solution were figured respectively. Principal resonance, subharmonic resonance and ultraharmonic resonance were studied when excitation frequency was near to natural frequencies, 2 times and 0.5 times of natural frequencies of derived system respectively.The results show that approximate analytic solutions gained by multiscale method have high precision. There are more resonance region during work, so external excitation frequencies should be removed from these resonance frequencies.

A Fault Detection Approach Based on Immune Neural Network

SHAO Xu-Guang, FAN Shou-Wen, XIONG Jing-Qi

2010, 21(19):  2285-2291. 

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A fault detection approach based on radial basis function neural network(RBFNN) was presented herein, this approach consisted of system identification, filtered residual generation and fault alarm concentration(FAC). The system identification was based on immune strategy RBFNN, and the residuals were generated by on-line comparing the system model outputs with the actual system ones. The generalization capability of immune strategy RBFNN was enhanced by introducing generalization capability interfering factor in the affinity function of the clone selection algorithm. The proposed immune model-based fault detection approach is only sensitive to the residuals caused by faults because of the introduction of residual filtering and FAC. Simulations on a parallel manipulator were conducted to evaluate and validate the effectiveness and robustness of above fault detection approach, simulation results show that it can detect and locate actuator faults and sensor faults efficiently, and it is sensitive to faults while at the same time insensitive to unspecified uncertainties.

Application Research on Open Assembly Modeling

WU Mei-Ping, LOU Cong-Fang, ZHANG Qiu-Ju

2010, 21(19):  2292-2295. 

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The key technologies of open assembly modeling (OAM) method such as the UML expression of the model, assembly feature, and mate tolerance analysis and hierarchy correlation investigation were further studied. Open assembly modeling method was adopted in the research and development of laser products, structural design, linkage design of parts and assembly, and assembly simulates were carried out. Meanwhile, DMU of product and primary components was constructed. The application instance shows OAM can depict the product design more effectively from the conceptual to the detailed stages.

Analysis of Static Performance of Porous Graphite Aerostatic Thrust Bearings

TUN Ding-Zhu, DAO Ji-Zhong

2010, 21(19):  2296-2301. 

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Numerical simulation was processed with FLUENT based on finite volume method. Analyses and researches were implemented on the relatled factors, such as the supply gas pressure,the permeability of the porous graphite, which will affect the static performance of porous aerostatic thrust bearings, and thus the curve diagram was produced accordingly. According to the experiments implemented on a self-manufactured rig, a series of experimental data was produced, revealing the static performance of load capacity, static stiffness and volume flow. Good agreement has been achieved between the experimental results and the numerical simulation ones, which has approved the feasibility of the numerical calculation. The results also indicate that when the gas film thickness is distributed in the scope of 3μm and 5μm, the static stiffness value of the entire porous graphite aerostatic bearing can be more than 70N/μm if the porous graphite restrictor is one with the viscous permeability of 7.95×10-15m2, with the thickness of 10mm, and with the diameter of 45mm.

PDAG Algorithm Based Trajectory Tracking for Industrial Robots

TUN Xiao, SHU Shi-Jiang, LIU Song-Guo

2010, 21(19):  2302-2307. 

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A PDAG algorithm to form the feedback controller was proposed according to the characteristics that industrial robots often executed tasks repeatedly. The establishment of mathematical model of PDAG algorithm, with the application of a learning matrix to the error data, proved the stability and convergence of PDAG algorithm in theory. The gravity compensation was regarded as feed-forward control quantity to eliminate the effect of articulation gravity in dynamic process, to improve the convergence rate and the trajectory tracking precision of iterative learning control, and to conduct PDAG algorithm simulation as well. The experimental results show that with the PDAG algorithm control performance, compared to traditional non-compensation algorithm, the trajectory tracking error tends to be stable after iterative learning. Both the maximum positioning tracking error and the average tracking error of each articulation drops by 0.5 time compared to the condition without gravity compensation. Compared to PD algorithm with gravity compensation, the PDAG algorithm increases accuracy by max 81%, which means that the proposed PDAG algorithm is capable of achieving trajectory tracking effect with higher precision.

Statics Optimum Design of a New Parallel Robot

TUN Meng-Li, WANG Li-Wen

2010, 21(19):  2308-2312. 

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Aiming at handling the airplane structures, this paper dealt with a new sub-6 DOF asymmetrical parallel mechanism, named “TAM”.The

robot was a modified version of the SKM400.The innovation of the new parallel robot

 was systematically addressed. Amendment of virtual displacement was used for statics analysis of the robot.The virtual displacement was in conjunction with the influence coefficients and generalized coordinates, so the generalized velocity and virtual displacement

were unified. The spring was used and with parametric optimization, the static balancing for TAM is achieved. 

Nonlocal Elastic Medium’s Parameter Identification Method of Bolted Joint Interface

QIN Gong-Ling, TIAN Gong-Liang, SHU Da-Lin

2010, 21(19):  2313-2318. 

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A link relation among two contacting surfaces and nonlocal elastic medium of joint interface was put forward. A series of analytical solutions, such as between elastic modulus and space, time, between shear modulus and those, between Poisson ratio and those, and density formula were deduced for nonlocal elastic medium of joint interface by adopting nonlocal elastic theory and in view of space, time and surface roughness simultaneously. Strain is proportional to σ1.5p when standard deviation of surface heights acts alone. It is observed that when local elastic volume fraction is increased, relative error of deviatoric compressive pressure is increased from 0 at first and decreased to 0 afterward. Relative error of deviatoric compressive pressure is seen increasing from 0 with the increase of Eringen parameter. Calculation of bolt group connection between hot-rolling channelbar and armor plate shows that nonlocal elastic medium’s elastic parameters for joint interface are all time-varying. When nonlocal elastic medium’s elastic modulus for joint interface is negative, nonlocal elastic medium of joint interface gives bracket and armor plate some energy through influence length of hot-rolling channelbar and armor plate. Hot-rolling channel and armor plate make self-excitation vibration in normal direction. Creep of two surfaces is one of the principal reasons to let nonlocal elastic medium’s elastic parameters for joint interface become time-varying.

A Revised Solution for Moment-deflection Relation of Torsion Spring

LI Bao-Fu, LIU Beng-Fang, FAN Dun-Wei

2010, 21(19):  2318-2321. 

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The interaction between a helical torsion spring and its accessories (spring seats and spindle) was investigated with finite element contact analysis. The result of simulation shows that the twist deformation of the spring can be divided approximately into several stages by the variety of contact regions between the spring parts. Accordingly, a piecewise linear relation of moment-deflection was established based on elementary theory of beam. It has been proved that the equations present herein are more precise than the classical algorithms which take no account of the effect of spring accessories.

Mixed-model Assembly Line Optimization Design Based on Improved Genetic Algorithm

JIANG Yan, LI Xiang-Feng, ZUO Dui-Wen, JIAO Guang-Meng, XUE Shan-Liang

2010, 21(19):  2322-2328. 

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The workload balancing problem and the sequencing of products in mixed-model assembly line were both taken into account. A mathematical model was presented to minimize the total utility and idle time of the line, which included the utility work caused by the last product at the end of a cycle in each workstation, so as to ensure the continuity of assembly process. A genetic algorithm improved by employing niche technology was designed in detail, which was used to optimize the assembly line collaboratively. The computational results show that the proposed algorithm outperforms the simple genetic algorithm and the simple genetic algorithm with elitist strategy both in the aspects of convergence rate and convergence reliability, and that under the situation of a given number of workstations with equal length, total utility and idle time of the mixed-model assembly line is decreasing with the increasing of each workstation length and converges finally.

Study on Hybrid Shop Robust Scheduling Problem with Known Probability Distribution

LU Jian-Sha, SHI Jin-Feng, LI Xiu-Lin, SHANG Hong-Chao

2010, 21(19):  2328-2333. 

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On the basis of production scheduling literature research, this paper presented a hybrid shop scheduling problem for solving a scheduling problem including job-shop workpiece production and flow-shop workpiece assembly, given out a robust scheduling method with known probability distribution, and built a robust scheduling model with operation time perturbation. This paper designed an improved genetic algorithm to seek for the optimal robust solution. At last, the paper given out a project example to verify the theoretical model and the outstanding optimization ability of genetic algorithm. 

Model and Algorithm for No-wait Flow Shop Scheduling Problem Based on E/T

WANG Jing, WANG Wei-Ling

2010, 21(19):  2334-2338,2344. 

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For the no-wait flow shop scheduling problem with a delivery time window to minimize the punishment of the E/T, a constraint satisfaction model was established, and a algorithm was proposed based on constraint propagation and neighborhood search. Firstly, an initial scheduling was generated using heuristic method embedded constraint propagation. Secondly, a swap search based on neighborhood structure was designed for iterate operation, in order to avoid falling into local optimum, a disturbance strategy based on dynamic swap was used.The simulation results show the effectiveness of the algorithm.

Study on Output-pin-wheel Cycloid Drive

BAO Jun-Hua, HE Wei-Dong, LEI Qi, LI Li-Hang

2010, 21(19):  2339-2344. 

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By analyzing the shortcomings of various types of cycloid drive,a kind of new drive named as output-pin-wheel cycloid drive was innovated.The

usage of the pin-wheel as output part is the biggest difference compared with the traditional cycloid drives.The construction of reducer and the structural dimensions of specific components were designed after analyzing its working principles. In order to validate the working principles of the drive and assembly relations of virtual solid models, three-dimensional

solid models and virtual prototyping were built,and dynamic simulation analysis of virtual prototyping and finite element modal analysis were done in both of the no-load and full load conditions,which provides the theoretical basis for manufacture and optimization of the reducer.

A HMC-based Equipment Operation Reliability Prediction with Multiple Observation Sequences

TUN Jun, SHAO Xin-Yu, DENG Chao

2010, 21(19):  2345-2349. 

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A novel HMC-based operation reliability prediction method was proposed herein in order to achieve the near-zero breakdown status of core equipment. The HMC model was introduced considering the complicated relation with dynamic characteristics and operational state of the equipment, and the hidden state transition process was identified through monitoring the dynamic characteristics of the equipment with multiple observation sequences. Furthermore, Chapman-Kolmogorov equation was adopted to infer the operation reliability level of the equipment. Finally, an experiment was implemented on OTM 650 CNC milling machine to validate the feasibility of the proposed method.

Research on Attenuation Factor of Air-coupled Ultrasonic Testing

ZHOU Zheng-An, WEI Dong, XIANG Shang

2010, 21(19):  2350-2354. 

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Major attenuator factor of air-coupled ultrasonic was analyzed. Finite difference time domain method was used to research transducer’s pulse ultrasonic sound field characteristics and diffuse attenuator. Practical transducer’s ultrasonic sound pressure distribution and far field region’s distance attenuator characteristics were obtained by measuring experiments. Ultrasonic interface loss was analyzed according to transmission principal on air-solid interface, the relationship between oblique incidence angle and transmission ratio was acquired by numerical simulation and practice testing. Research results provide instruction to testing scheme and parameter selection of air-coupled ultrasonic testing.

Copula-based Method for High Multiplicity Risk Prediction of CCF-involved Systems

ZHOU Jin-Yu, XIE Li-Yang, HAN Wen-Qin, SUN Kui-Zhou

2010, 21(19):  2354-2358. 

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Copulas were introduced for CCF analysis in redundant systems and Copula-based modeling methods for system risk probability was discussed. The safety margins of components were chosen as the analytic variables and the typical mechanism of CCF was brought to light. Considering the fact that only low multiplicity failures data being known, a practical method for high multiplicity CCF probability prediction based on mixed Archimedean Copulas was put forward. An example was given to verify the new model and method, in which a redundant system consisting of identical valves was studied successfully. Copula-based modeling methods can give a new path for reliability analysis of complex systems with failure dependence.

Improving Dynamic Stability of Varying Cross-section Beck’s Column with Piezoelectric Layers

YANG Feng, WANG Zhong-Min

2010, 21(19):  2359-2363. 

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To improve the stability of a varying cross-section Beck’s column with certain boundary conditions, an external voltage was applied on the piezoelectric layers bonded on the surfaces of Beck’s column. The mathematical model of the piezoelectric composite varying cross-section Beck’s column was established and the differential equations of motion were derived. With DQ method, the effect of geometrical and physical parameters of piezoelectric layers on the stability of varying cross-section Beck’s column were studied. Stability of Beck’s column can be improved by the piezoelectric layers.

Research on Friction and Wear Performance of MoSi₂ Coating at High Temperature of 1100℃

HU Xiao-Beng, YA Jian-Hui, HUANG Zhi-Chu, ZHANG Hou-An

2010, 21(19):  2364-2368. 

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In order to improve the wear resistance of K403 nickel-based alloy at high temperature in air, a molybdenum disilicide coating was prepared on its surface by air plasma spraying.Phase composition,morphology and component of the worn surface were observed by scanning electron microscope (SEM) with energy dispersive spectrometer (EDS) and X-ray. The friction and wear properties of the bare K403 alloy and MoSi₂ coating at 1100℃ were also studied. Results show that the friction factor of K403 alloy ranges from 0.35 to 0.5 and that of MoSi₂ coating fluctuates around 0.65. The wear rate of MoSi₂ coating is about half of that of K403 alloy. Compared with the bare K403 alloy, the wear resistance of substrate was improved after coated MoSi₂ coating. The wear mechanism of nickel-based alloys is oxidation wear and fatigue fracture. When the load is smaller (10N), the main wear mechanism of MoSi₂ coating is oxidation. However, the main wear mechanism of MoSi₂ coating is oxidation and brittle fracture when the load is higher (40N).

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LIU Dun-Bai, ZHOU,KAI,ZHANG Ba-Feng

2010, 21(19):  2369-2374,2378. 

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Contact Stress Analysis of Thermal Barrier Coatings and Multi-asperity Surface

LIN Fu-Hua, XU Ying-Jiang, JIN Shao-Jie

2010, 21(19):  2375-2378. 

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A engine part with TBC can in effect improve anti-hot capability,but the distribution of stress of coating in contact with multi-asperity and collapse have 

not been mastered.According to TBC contacted by the rabbet of the aircraft engine blade,a rigid multi-asperity surface was abstracted as micro-contact pattern and the contact pressure and stress in the subsurface was analyzed with the elastic-plastic finite element method.The effect of coating thickness,elastic moduli,yield strength on the distribution of residual stress for the TBC was investigated.

Study on Controllable Vibration Powder Spreading System in Electron Beam Selective Melting

YAN Nai-Sheng, LIN Feng, JI Hai-Bei, LIU Wei, ZHANG Jing

2010, 21(19):  2379-2382,2389. 

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This paper analyzed the merits and faults of the existing powder supply and spread system. A new controllable vibrating powder spread system was proposed, considering the experimental conditions of EBSM: difficult to interfere in the vacuum chamber, high temperature in the melting zone, large stiffness of manufacturing parts, together with contacting powder spread system bringing down the whole process upon meeting bump unable to overcome. A new designation, non-contacting overhead sieve with feedback weighting sensor, capable of powder arching and arch vibrating elimination, realized powder spreading function by varying its speed and acceleration. The experimental results have verified the steadiness of the system, uniformly spreading can be achieved with certain amount of powder in the sieve, and the depth can be decided by moving speed and acceleration of the sieve, with 0.1mm the minimum. 

A Design-oriented Generation Method for Automotive Body Key Cross-section Based on Ant Colony Algorithm

SONG Kai, CHENG Ai-Guo, CHEN Shao-Wei, WANG Guo-Chun, ZHONG Zhi-Hua

2010, 21(19):  2383-2389. 

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According to the dimensional constrains of automotive body styling, interior space and packing in conceptual design phase, taking into account the shape constrains of the formability of pressed metal sheets, proposes a cross-sectional shape optimization generating method for achieving the cross-sectional properties assigned was proposed by design engineers. Using grid ideas, the method dispersed the feasible design domain of a cross-section into a number of discrete nodes, which controled the shape of the section. Based on ant colony optimization algorithm, the relevant mathematical models and corresponding programs were established. A application has proved this method is suitable for automotive engineering.

Research on Automotive Active Safety Technology Based on Driving Behavior

XIAO Xian-Jiang, WANG Ji-Dong

2010, 21(19):  2390-2393. 

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The paper advanced the researches of active automotive safety technology based on driving behavior, the vehicle active safety control system adopted all the various sensor signals of vehicle, those signals were gathered by ARM processor,and the circumstance signals were gathered by CCD sensors, the control system introduced the signals of vehicle and circumstance signals to forecast dangerous driving behavior based on driving behavior model, and given away dangerous warn. On account of a driving behavior composed of all kinds of driving operations , the paper adopted weight decision matrix to deal with all the signals, and seted up driving behavior forecasting weight decision matrix. Test shows the method put forward by the paper can decide the typical driving behavior,and offers an effective method for researching automotive active safety technology.