Table of Content

10 November 2013, Volume 24 Issue 21

Previous Issue    Next Issue

Simulation and Experimental Study on Optimization of Combustion Chamber Structure in Natural Gas Engine

2013, 24(21):  2841-2846. 

Asbtract ( )   PDF (798KB) ( )  

References | Related Articles | Metrics

In-cylinder flow and combustion characteristics of natural gas engine with bathtub combustion chamber were analyzed,two optimization schemes were proposed and performance of engine was studied when original combustion chamber and squish-injection combustion chamber were adopted.The results show that changing shape of piston head can achieve coupling between swirl and squish flow for constant compression ratio,control gas velocity near spark plug,increase mean turbulent kinetic energy,extend area of flame front and then improve combustion quality.Test was carried  out at conditions of wide-open throttle and different speed to determine the effect of piston geometry on the performance and emissions.It shows that 2# chamber can accelerate speed of combustion greatly and improve power performance and fuel economy of engine.Power increases from 75kW to 78.7kW,fuel consumption decreases by 4.4%,HC and CO emissions decrease slightly.

Influence of Hydraulic Oil Viscosity on Characteristics of Liquid Hydrostatic Slide

Zhao Jianhua;Gao Dianrong

2013, 24(21):  2847-2851. 

Asbtract ( )   PDF (497KB) ( )  

References | Related Articles | Metrics

In order to improve the characteristics of a liquid hydrostatic slide, the influences of the viscosity of five different grades of hydraulic oil on the characteristics of the slide system were analyzed quantitatively. First, based on the practical working conditions, the initial design parameters of the hydrostatic slide system and the dynamic viscosities of different brands of hydraulic oil at different temperatures were calculated. Then based on force balance equation and flow equation of the hydrostatic slide, the linearized mathematical models of power loss, static performance and dynamic performance of the hydrostatic slide were established. Total power loss, bearing capacity, static stiffness, natural frequency, adjusting time, dynamic stiffness were regarded as the key performance indexes of the hydrostatic slide system. Finally, the influences of the hydraulic oil viscosity on the characteristics of ultra-precision hydrostatic slide system were simulated with MATLAB software. The results indicate that as the grade of hydraulic oil increases (VG22→VG100) and the working temperature decreases (60℃→10℃), the viscosity increases accordingly, and then the total power loss decreases from 507.58W (VG22, 60℃) to 33.93W (VG100, 10℃), the bearing capacity, the static stiffness and the natural frequency remain constant, the adjusting time decreases from 29.84μs (VG22, 60℃) to 0.46μs (VG100, 10℃), and the dynamic stiffness increases from 173kN/μm (VG22, 60℃) to 10 369kN/μm (VG100, 10℃). So it is best to increase the viscosity of hydraulic oil in order to decrease the power loss and to improve the dynamic characteristics of hydrostatic slide system, but the static characteristics are not affected.

Compressor Surge Active Control Based on Second-order Sliding Mode

Huang Wei;Huang Xianghua

2013, 24(21):  2852-2855. 

Asbtract ( )   PDF (476KB) ( )  

References | Related Articles | Metrics

In order to make compressors operating in the high efficiency and pressure ratio region，a second-order MG surge model was presented using a close-coupled valve as actuator．Then，one active surge controller was designed based on second-order sliding mode．Compressor active surge control simulation platform was established under Simulink environment．Simulation results show that the designed controller stabilizes compression system outside the surge line and enlarges compressor's working range．Additionally，the robustness of the controller on uncertainties such as un-modeled dynamics，flow and pressure disturbances is verified．

Research on Contact Strength of Gear Drive with Meshed Medium Belt

Fan Zhimin;Li Huimin;Gao Liang

2013, 24(21):  2853-2860. 

Asbtract ( )   PDF (561KB) ( )  

References | Related Articles | Metrics

Based on Merritt theory, a simplified contact model of a gear drive with meshed medium belt was established for its contact strength analysis. The foundation was laid for the study of frictional characteristics and lubrication mechanism of the rubbing pair consisting of metal teeth and non-metallic medium belt. The contact model of FEA was set up and then the biggest contact stress was compared based on analysis by ANSYS. The results show that the biggest contact stress is reduced due to the existence of the medium belt, and agree well with the theoretical predictions. The gear drive will be affected by the meshed belt with different parameters. The modulus of elasticity is the most important factor to the contact strength of this gear drive.

Experimental Research on Force Transmission Behavior of Redundant Driving Thrusting System of Shield Machines with Various Grouping Strategies

Li Jianjun1;Yu Haidong1;Zhao Yong1;Lai Xinmin1,2

2013, 24(21):  2861-2867. 

Asbtract ( )   PDF (693KB) ( )  

References | Related Articles | Metrics

It is an important tool for shield machine to comply the external loads by using the different grouping strategies for the redundant drive propulsion system when it excavates in the complex geological structures.An instrument was designed based on the mechanical structure of shield and its load conditions,which can be used to study the force transmission behavior of the redundant driving system subjected to the variable loads.The force transmission model for the redundant driving thrusting system was established by using a grouping matrix.The validity of equipment was studied by comparing the results from the numerical simulation and testing data.According to two typical grouping strategies of shield machines,the equivalent grouping strategies in the equipment was given to study the force transmission behavior of the thrusting system at various loads.Experimental results show it can reduce the load fluctuations effectively and increase their ability to adapt to the
various loads by using different grouping strategies.The results can provide guidance for the grouping design method of the redundant actuating thrust system of the shield machine in the complex geological conditions.

Simulation of Reynolds Number's Effect on Performance of  High Bypass Ratio Turbofan

Zhao Yunsheng;Hu Jun;Tu Baofeng;Wang Zhiqiang

2013, 24(21):  2867-2871. 

Asbtract ( )   PDF (640KB) ( )  

References | Related Articles | Metrics

For assessing the Reynolds number's effect
on a high bypass ratio turbofan,the correction methods such as Wassell were used for
the main component characteristics,and cooperated with a new performance program to simulate
the effects of Reynolds number on engine's performance.
Results show that Reynolds number has grievous effects on the turbofan in high flight and low
Mach number region,the thrust  is declined by near 1.98%,the specific fuel consumption
is  escalated by near 3.04%,the stall lines and operating lines are affected and the stall margin
is  declined as well.

Experiments on CNC Milling of  Bent Pipe Internal Surfaces

Sun Jianli;Wang Xuyue;Gao Hang;Yang Lianwen

2013, 24(21):  2872-2875,2920. 

Asbtract ( )   PDF (538KB) ( )  

References | Related Articles | Metrics

Based on the principles of 5-axis machining,a method was introduced,which avoided processing interference and improved the cutting condition on the internal surfaces of bent pipe.Experimental process planning,machining zoning,and CNC programming were carried out.A sample piece was worked out in the 4-axis and 5-axis machining process using a ball-end miller and the posture of the tool was adjusted.Meanwhile,the angle between the miller and workpiece was nearly constant.The results show that the ball-end miller avoids both partial and whole interferences,and the cutting status keeps stable.The final surface quality has a good uniformity and satisfies the technical request (Ra=3.2μm).The research provides a machining technology of main pipe internal surfaces for nuclear power station and similar type of bent pipes in theory and application.

Optimization of Processing Methods for Powder Metallurgy Oil Bearing Hole and Expanding Force Calculations

Cai Jinda;Xu Pengcheng

2013, 24(21):  2876-2880. 

Asbtract ( )   PDF (506KB) ( )  

References | Related Articles | Metrics

A new type processing method was put forward for powder metallurgy oil-retaining bearing holes. According to the characteristics of powder metallurgy oil-retaining bearing material, an unit mechanics model of hole diameter deformation area was established.Considering the material work hardening in the expanding process and the influence of hydrostatic pressure in deformation and densification process,a bearing expanding force formula was derived through the slab method, and an aluminum oil-retaining bearing was tested with self-designed equipment. The rationality and correctness of expanding force formula and the new type method were proved by expanding tests.

Research on Demand-overflowing Customer Satisfaction Model

Liu Jiqing;Zhao Han;Xu Zhaoyun;Wu Zhenhua

2013, 24(21):  2880-2884. 

Asbtract ( )   PDF (500KB) ( )  

References | Related Articles | Metrics

To solve the problem of reasonable customer satisfaction assignment when the product quality characteristic value was beyond customer demand expectation, a method was presented aiming at demand-overflowing phenomenon which existing in comprehensive customer satisfaction calculation. First, types of demand quality characteristics and intervals of customer satisfaction were divided. Then, subsection exponential functions were used to build customer satisfaction model for different types of demand characteristics. At last, results of comprehensive customer satisfaction for different products were established by using analytic hierarchy process. Taking customer selection on dump trucks as an example, validity and practicability of this application of customer satisfaction model was illustrated.

Research on Quality Control Theory Based on Product Quality Genes

Sun Libo;Guo Shunsheng;Li Yibing

2013, 24(21):  2885-2890. 

Asbtract ( )   PDF (670KB) ( )  

References | Related Articles | Metrics

To solve the problems of quality information complexity and quality control difficulty in manufacturing enterprises, quality control theory based on quality gene was put forward. This theory dealt mainly with constructing and running of a quality control model based on quality genes, integrated several technologies such as quality gene, quality management and so on. Furthermore, some of the key technologies were studied in detail, including extracting quality gene, storaging and transforming quality gene, process monitoring quality gene, diagnosing quality gene. This mode provides a way to achieve a high precision, digital processing.

Discrete Dynamics Model and Numerical Solution for Multiple Friction and Contact

Gao Haitao;Han Yali;Hao Fei;Zhu Songqing

2013, 24(21):  2891-2894. 

Asbtract ( )   PDF (424KB) ( )  

References | Related Articles | Metrics

Aiming at multi-rigid-body with multiple friction and contact, a multi-rigid-body dynamics model expressed by complementary equations was firstly given. Secondly, dynamics models for multi-rigid-body with multiple friction and contact were discretized into a discrete mixed nonlinear complementary model for application of computer simulation based on fixed time-stepping methods. Thirdly, aiming at solution problem for mixed nonlinear complementary model, the mixed nonlinear complementary model was changed into a linear complementary model to resolve by Coulomb friction approximation methods and simplification methods of equality constraints. Finally，the validity of the dynamics model for multi-rigid-body with multiple friction and contact and its numerical solution method was verified through a numerical example.

On-line Detecting and Diagnosing of Mean Shifts in Multivariate Processes Using Selective DAG-SVM Ensemble

Zhu Bo;Liu Fei

2013, 24(21):  2895-2902. 

Asbtract ( )   PDF (730KB) ( )  

References | Related Articles | Metrics

Aiming at mean shifts in multivariate processes, a selective DAG-SVM ensemble was proposed, which was used as pattern recognition tool to construct an on-line detecting and diagnosing model for the shifts. To produce diverse candidate components of the ensemble, a double disturbance mechanism of data and model was implemented, i.e. , through the Bootstrap sampling approach from Bagging method to create different training data sets, and to randomly adjust the structure of DAG-SVM. Finally, the BPSO(binary particle swarm optimization) algorithm was adopted to obtain the optimal ensemble. The simulative off-line test verify that the selective DAG-SVM ensemble have better performance on both classification rate and efficiency. The simulative on-line test shows that the model based on the selective DAG-SVM ensemble outperform χ2 chart and BPN(back propagation neural network) model on detecting mean shifts, and identify the sources of shifts more accurately than the BPN model. An application examination on actual gear machining process data further verified the validity and practicability of this model.

Real-time Error Compensation and Applications Based on Bottom Communication of CNC System

Yang Tangyong

2013, 24(21):  2903-2908. 

Asbtract ( )   PDF (656KB) ( )  

References | Related Articles | Metrics

In order to improve the machining precision of NC machine tool, a real-time error compensation function module was developed based on the bottom communication of CNC system. The error compensation module can exchange data with CNC system through GSK-Link network communication protocol. The machine temperature and the coordinate of each axis can be real-time collected through the temperature acquisition module and the data communications module. The compensation values can be calculated through error compensation module and can be delivered to the CNC system through PLC. The real-time error compensation can be realized through the external coordinate offset function. The error compensation results on GSK 25i CNC system shows that the real-time error compensation function module can improve the accuracy of machine tools effectively, and the machine tool errors can be reduced by 91.7% compared with without compensation. The error compensation module has strong practical values.

Multi-objective Optimization of Shape Memory Alloy Actuator Based on Thermodynamic Performance

Tang Yuangui;Ma Yange

2013, 24(21):  2908-2912. 

Asbtract ( )   PDF (540KB) ( )  

References | Related Articles | Metrics

A kind of SMA differential drive method and its experimental equipment was presented,which can be used in swing joint of micro underwater vehicles. The motion principles of the swing joint differential driven by SMA were analyzed. According to thermodynamic performance of the SMA actuator with different structural parameters in various driving conditions and environments, experimental researches and analyses on the response ability, driving force and energy consumption of the SMA actuator were carried out. The multi-objective optimization theory and algorithms were adopted for the comprehensive optimization of the SMA actuator. At last, the optimal structural parameters and driving values of the SMA actuator fitting for the application conditions are achieved.

Research on Cavitation Effect on Lubrication Performance for Misaligned Journal Bearings

Zhang Junhong;Li Zhouyu;He Zhenpeng;Zhang Guichang;Xie Weisong

2013, 24(21):  2913-2920. 

Asbtract ( )   PDF (3481KB) ( )  

References | Related Articles | Metrics

In order to analyze lubrication performance of misaligned journal bearings more accurately, an universal lubrication control equation including cavitation region was built based on control volume mass conservation, considering both macroscopic cavitation and inter-asperity cavitation. Effects of two kinds of cavitation on lubrication performance for misaligned journal bearings were analyzed. The results show that cavitation has little effect on the maximum oil film pressure. Macroscopic cavitation increases areas where oil film pressure is low, formes large cavitation region, at the same time, outlet boundary of the oil film lags behind. Inter-asperity cavitation makes both the inlet boundary and oulet boundary of oil film shift forwards slightly. In the cavitation region, lubricant has small density, which respects that cavitation happens with great extent. Inter-asperity cavitation has large effect on lubricant distribution, especially in places where it is adjacent to cavitation boundary. Macroscopic cavitation has a great influence on total end leakage flow-rate of lubricant, the bearing capacity of oil film ,the total moment of oil film. The effect of inter-asperity on external lubrication performance for misaligned journal bearings can be ignored.

Nonlinear Time-varying Sliding Mode Control for NC Machine Magnetic Levitation Systems

Liu Chunfang;Zhang Jian

2013, 24(21):  2921-2927. 

Asbtract ( )   PDF (657KB) ( )  

References | Related Articles | Metrics

In order to reach high-precision air gap of electromagnetic levitation grip a novel time-varying sliding mode was proposed. At first, a new exponential time-varying sliding surface was designed and guaranteed the sliding mode occurrence from beginning to end. The global robustness of parameter perturbation and external disturbance was realized. After that a control law of time-varying sliding mode was designed based on the sliding surface of exponential term and its stability was proved by the Lyapunov stability principle. Simulation results demonstrate that the time-varying term is introduced to improve the convergence speed of the sliding surface in the context of ensuring global stability of the system and to eliminate system chattering effectively.

Grinding Capability of Polymer-based Solid Lubricant Coating Wheels

Ding Lanying1，2;Su Honghua1;Xu Hongjun1;Ding Wenfeng1;Fan Min1

2013, 24(21):  2927-2932. 

Asbtract ( )   PDF (658KB) ( )  

References | Related Articles | Metrics

Comparative dry grinding experiments of Ti-6Al-4V alloy were conducted with polymer-based solid lubricants (hexagonal boron nitride and graphite) coated grinding wheels and conventional green silicon carbide grinding wheel(GC) wheels without coating. The effect of solid lubricants on grinding temperature and surface quality were evaluated. The results show that there is a considerable improvement on the performance of dry grinding Ti-6Al-4V alloy by using polymer-based solid lubricant coating wheels in terms of grinding temperature and surface quality. Compare to the conventional GC wheels, the grinding temperature is decreased by 11%~ 40% using polymer-based solid lubricant coating wheels and no distortion occurred in subsurface layer during dry grinding.

Effects of Step Dynamic Interference Fit on Transmitting Torque Capacity of Motorized Spindle

Ma Ping;Mo Deyun;Wu Guangrong

2013, 24(21):  2933-2938. 

Asbtract ( )   PDF (672KB) ( )  

References | Related Articles | Metrics

A GD-Ⅱ motorized spindle was introduced herein, the magnitude of step interference was also determined based on the dynamic interference fit theory, then the finite element model of the jointed structure was built and the effect of different initial interferences was also analyzed under different running conditions. The analysis results show that the ability to transmit torque and the contact stress decrease with increasing spindle speed constantly, and the higher the spindle speed will lead to greater decreases of the transmitting torque capacity. The results also indicate that using 66H6/s6 and 65.9H6/t6 ladder interference magnitude can well meet the job requirements.

Study and Comparison of Two Decoupling Algorithms for Six-axis Accelerometer

You Jingjing1,2;Li Chenggang1;Wu Hongtao1;Xia Yuhui1

2013, 24(21):  2938-2943. 

Asbtract ( )   PDF (567KB) ( )  

References | Related Articles | Metrics

According to the facts that the development of a six-axis accelerometer was limited by technical bottleneck, Newton-Euler equation in configuration-space and Hamilton canonical equation in phase-space were used to derive the complete decoupling algorithms of the six-axis acceleration respectively. The advantages of the two algorithms were independent on external devices and unrestricted by the motion law of carriers compared with traditional algorithms. Decoupling mechanism was revealed by contrasting the accuracy, efficiency and numerical stability of the two algorithms qualitatively and quantitatively. Meanwhile, five selection principles of decoupling algorithms were obtained. Physical prototype was installed on a standard vibration exciter, and the experimental results consistent to the theoretical analysis.

Analysis on Phase Change Stress after Pulse Current Discharging of Metal Component with Half-embedding Cracks

Fu Yuming;Wang Junli;Zhang Shuai;Zheng Lijuan

2013, 24(21):  2944-2947,2954. 

Asbtract ( )   PDF (543KB) ( )  

References | Related Articles | Metrics

The relationship between pulse discharge voltage and arrest-strengthening
effect was analyzed by pulse discharge experiments of 45 steel metal components with half embedding crack.According to the comparisons of the morphology and the micro-hardness near the crack tip before and after the discharge,the micro-hardness near the crack tip after the discharge was improved greatly.The theoretical arithmetic of phase transformation stresses of phase transition region around crack tip after crack arrest strengthening by using the equivalent inclusion principle of Eshelby shows phase transformation stress is compressive stress and it prevents crack propagation,and then a theoretical foundation for the practical applications of electromagnetic thermal arrest techniques is provided.

Research on Control Performance of Energy Regeneration System Based on Hydraulic Excavators

Lin Tianliang1,2;Ye Yueying1;Wang Qingfeng2

2013, 24(21):  2948-2954. 

Asbtract ( )   PDF (731KB) ( )  

References | Related Articles | Metrics

After analyzing the typical working conditions of boom energy regeneration system, a energy regeneration system based on a motor and a generator was proposed. Then, a mathematical model was constructed. The effects and improvements of system dynamic response were analyzed. The united simulation of the energy regeneration system was carried out with AMESim and MATLAB/simulink and the influences of the pipe length, the time constant of the generator and the rotary inertia of the motor and the generator on the control performance was brought forward. Finally, a test rig was constructed.

Research on Collaborative Optimization Method of Mechanical Parts,Mechanical System and #br# Controller Parameters in Mechatronic Products and Its Applications

Wang Yanwei;Li Yafei;Huang Zhengdong

2013, 24(21):  2955-2959. 

Asbtract ( )   PDF (515KB) ( )  

References | Related Articles | Metrics

In order to solve the problems of interactions among mechanical parts, mechanical system and control system which was hard to be considered in a traditional mechatronic product design process, based on multi-body dynamics, finite element analysis, topological optimization and PID control, a collaborative optimization method for mechatronic products was presented using co-simulation methods,which included part optimization,mechanical system optimization and controller.Based on MATLAB,ANSYS and Tosca,the software framework of the optimization process was given.And the effectiveness was verified by using a controlled crank-connecting rod mechanism with flexible connecting rod.

Research on Variation Rule of Reduction Zone Based on Transient Casting and Its Applications

Shi Xueliang1;Ren Tingzhi1;Qin Xu2

2013, 24(21):  2960-2966. 

Asbtract ( )   PDF (666KB) ( )  

References | Related Articles | Metrics

To reduce center segregation and center porosity and improve internal quality of casting slabs based on adopting dynamic soft reduction，according to the measured data of the slab surface temperature during the actual production process of transient casting，a solidification heat transfer model was corrected. The variation rule of the effect of casting speed，superheat degree，and specific water flow on reduction position was analysed. The results show that for every 0.1m/min increases in casting speed，the reduction length of AH36 and Q235B increases 0.15m and 0.21m respectively，and for every 10℃ increases in superheat degree，the reduction length of AH36 and Q235B increases 0.01m and 0.015m respectively，and for every 0.1L/kg increases in specific water flow，the reduction length of AH36 and Q235B increases 0.04m and 0.06m respectively. After the solidification heat transfer model was applied to production，the center segregation reduces to 1.0B~0.5C，and the center porosity less than level 1.5 increases from 35.25% to 85.16%，and the slabs internal quality is improved obviously.

A Study of Friction and Lubrication in Incremental Forming of TA1 Pure Titanium Sheet

Shen Changyan;Gao Lin

2013, 24(21):  2966-2971. 

Asbtract ( )   PDF (630KB) ( )  

References | Related Articles | Metrics

The friction and lubrication mechanism of TA1 pure titanium steel during incremental forming were analyzed firstly, and the friction region was divided into three parts-adhesion friction, boundary friction and fluid lubrication. In order to improve the surface quality, hardness enough high speed steel forming tool was selected; the mixture of MoS2 and Vaseline in 4∶1 was used as a lubricant; the pores of the coating developed by micro-arc oxidation will cover on the TA1 pure titanium steel surface. The experimental results show that: after the surface treatment of tool and TA1 pure titanium steel, and lubricant covers on the surface, the components have good surface quality and the roughness of 0.92μm can be got.

Research on Driving Behavior Prediction Method Based on HMM

Xiao Xianqiang;Ren Chunyan;Wang Qidong

2013, 24(21):  2972-2976. 

Asbtract ( )   PDF (487KB) ( )  

References | Related Articles | Metrics

According to time and space relationship of driving behavior and driving intention, driving intention of driver drived driving behavior and manoeuvre,The driver first produced driving intention, and then driving manoeuvre. On the basis of the time difference between driving intention and driving manoeuvre,this paper researched driving behavior prediciton method based on multi-characteristics of driving manoeuvre and HMM. The results show that the method has successfully forecasted three type driving behaviors of lane departure, steering and urgent steering. In the vehicle safety warning term, if was understood the demand of the driver to vehicle in the future can be calculated the driving behavior of driver.The method presented herein will help to correct and intervene the hazardous driving behavior of driver for the vehicle safety warning.

Differential Braking Control for Lane Departure Avoidance

Wu Yiwan;Huang Zhi;Liu Lipan

2013, 24(21):  2977-2981. 

Asbtract ( )   PDF (591KB) ( )  

References | Related Articles | Metrics

A large number of lane departure accidents in high way is due to inattention of the drivers.Herein,a new method for lane departure avoidance was presented,which is applied additional yaw moment to correct lane departure of the vehicle by means of four wheels differential braking.The desired yaw rate was calculated by considering vehicle-lane deviation,vehicle dynamics and limitation of road adhesion.A SMC was designed to control the additional yaw moment.The yaw moment was produced by the distribution of break forces between the same side brakes with fixed ratio,and lane departure avoidance was carried out by tracking desired yaw response.The proposed LDAS was evaluated via Carsim/Simulink.Simulation results show that the proposed method can restrict the vehicle into lane range and avoid lane departure accidents.