Volume 42,Issue 4,2019 Table of Contents

1 Modeling and analysis of transmission efficiency of high-speed wheel speed reducer for electric vehicles

WEI Changxu , SONG Chaosheng , ZHU Caichao , TAN Cong , GUO Wanlong

2019, 42(4):1-8. DOI: 10.11835/j.issn.1000-582X.2019.04.001

[Abstract](1213) [HTML](657) [PDF 2.22 M](2593)

Abstract:
Taking the high-speed wheel reducer of an electric vehicle as the research object, the systematic efficiency model of the reducer was established considering the gear meshing loss, oil mixing loss, windage loss, bearing loss and other factors. Then, the influence of different operating parameters and design parameters on the various losses and total efficiency of the reducer were investigated. The results show that the system efficiency decreases with the increase of operating parameters of rotating speed, torque, friction coefficient, tooth height and kinematic viscosity. And the rotating speed, torque, and friction coefficient have an obvious influence on the systematic efficiency. But the tooth height multiple and kinematic viscosity have unsubstantial influence on the systematic efficiency. The increase of the pinion teeth number and normal module tends to increase the systematic efficiency first, and then decrease it. The increase of the helix angle can significantly increase the systematic efficiency.

2 Research and application of vehicle dynamic weighing system algorithm based on PVDF sensor

WANG Hao , JI Shaobo , HAN Wenyang , WEI Jincheng , LI Meng , ZHAO Tongjun , GE Zhi

2019, 42(4):9-16. DOI: 10.11835/j.issn.1000-582X.2019.04.002

[Abstract](821) [HTML](531) [PDF 986.48 K](921)

Abstract:
In order to effectively manage overload and provide data support for road design and planning, a dynamic weighing system for expressway based on PVDF sensor is proposed. Aiming at PVDF sensor signal, charge amplifier circuit, SCM signal acquisition circuit and SD card storage circuit are designed. The sliding average filtering algorithm is proposed to further process the sampling signal, and the design process of the software system is analyzed. In order to verify the accuracy of the data processing scheme, outdoor site simulation tests were carried out. Furthermore, the data of vehicle load spectrum are obtained by field test, and the structure of the actual traffic volume is obtained by analyzing the data. The test results show that the weighing system can meet the accuracy requirement of dynamic weighing and has high practical application value.

3 Lightweight design of electric rear axle of pure electric vehicle

LIN Lihong , LI Yulong , LI Congbo , ZHAO Laijie

2019, 42(4):17-28. DOI: 10.11835/j.issn.1000-582X.2019.04.003

[Abstract](1188) [HTML](821) [PDF 4.40 M](2078)

Abstract:
In order to solve the non-coaxial problem of electric rear axle and reduce environmental pollution, the lightweight design of electric rear axle is carried out. A novel coaxial integrated electrical rear axle system is proposed in this paper. The strength and stiffness simulation is analysed under four kinds of limiting operational conditions. Based on the finite element analysis results, an electric rear axle housing lightweight optimization model is established with the axle thickness as the design variables and the axle housing quality as the objective function. Goal-driven optimization scheme is used to solve the optimization model, and the response relationship between the axle thickness and the maximum displacement, maximum stress and the total mass is analyzed. The simulation analysis about the optimized electric rear axle is done based on the four kinds of limiting operational conditions, and the results show that the electrical rear axle reduces its weight by 8.4% compared with that before the lightweight, meeting the requirement of electric drive rear axle.

4 Study on aerodynamic performance of rear wing for Formula SAE racing cars based on finite element method

YAN Zeyuan , DU Changqing , HU Yifeng , WANG Jiapeng

2019, 42(4):29-39. DOI: 10.11835/j.issn.1000-582X.2019.04.004

[Abstract](1009) [HTML](1302) [PDF 3.48 M](1474)

Abstract:
The negative lift generated by the aerodynamics package plays an important role in improving the track performance of the Formula One racing. The rear wing is one of the main components that generate negative lift. In this paper, Computational Fluid Dynamics(CFD) technology is used to study the aerodynamic characteristics of the rear wing of formula racing car for college students. The results show that the value of negative lift generated by the empennage increases with the increase of the angle of attack of the main wing in a certain range. The external factors affecting the negative lift of the tail in the Formula SAE vehicle flow field are mainly the body blockage and the upstream airflow of the front wing. The maximum negative lift loss is about 40%; designing different main wing angles of attack for the tail sub-region can effectively improve the ability of the Formula SAE tail to produce negative lift.

5 Binocular photogrammetric vibration measurement method introducing character recognition and tracking

WANG Wenyun , CHEN Anhua

2019, 42(4):40-48. DOI: 10.11835/j.issn.1000-582X.2019.04.005

[Abstract](803) [HTML](429) [PDF 3.54 M](959)

Abstract:
Coded targets are widely used in photogrammetry for large-scale structures. A coded target based on a circled character is designed and applied in vibration measurement through binocular vision system,in which English or Chinese characters are used for coding information and the circle is used for positioning. Weiner filter method is employed to de-noise image. Further, character feature is segmented using adaptive local threshold method.Character information is identified through BP neural network. Target position is calculated with gray value gravity center method. The vibration responses of the coded targets position are measured by the binocular vision system. A 3 kW wind turbine blade was tested with the presented method. The first three natural frequencies were identified and the relative errors were less than 0.9% compared with those from hammer impact experiment.The results show that the method is reliable and feasible.

6 Direct preparation of Fe-TiC composite powders and its ceramics by vacuum carbothermal reduction

WU Kehan , ZHANG Guohua , CHOU Kuochih

2019, 42(4):49-55. DOI: 10.11835/j.issn.1000-582X.2019.04.006

[Abstract](765) [HTML](390) [PDF 2.58 M](1084)

Abstract:
In traditional route to produce TiC-type steel-bonded carbides, steel powder and TiC powder are mixed mechanically and sintered after pressing. The cost of the raw materials in this method is high, and the surface of TiC powder is easily oxidized which makes the wettability between TiC and Fe terrible in following powder metallurgy process. The terrible wettability makes it difficult for Fe to combine tightly with TiC, seriously affecting the properties and purity of the product. The present experiment uses titanium dioxide powder, graphite powder and reduced iron powder to produce Fe-TiC composite powder by vacuum carbothermal reduction firstly, and then the composite powder is used to produce TiC-type steel-bonded carbides. This route successfully avoids the surface oxidation of TiC powder and has the advantages of low cost of materials, high purity of the products and excellent properties of the prepared ceramics. The results indicate that, with the increase of carbon ratio in the raw materials, the hardness of the product decreases while the bending strength increases firstly and then decreases. Besides, the addition of Ti powder enhances the hardness and bending strength of products. The optimal product with a hardness of 11.7 GPa and a bending strength of 1 776 MPa is obtained when the raw material ratio TiO₂:C:Fe is 20:8.6:15, temperature is 1 400℃ and holding time is 6 h with Ti powder of a mass fraction of 1% as the additive.

7 Vacuum carbothermal solid phase reduction of Panzhihua ilmenite concentrate

HUANG Run , LYU Xiaodong , WU Qinghui , LI Yulian , ZHANG Jinzhu

2019, 42(4):56-62. DOI: 10.11835/j.issn.1000-582X.2019.04.007

[Abstract](750) [HTML](366) [PDF 2.50 M](1060)

Abstract:
The phase transformation and reduction process of vacuum carbothermal reduction ilmenite concentrate at the temperature from 1 000℃ to 1 400℃ were studied by using FactSage, XRD and BSE-EDS. The results showed that reduction temperature promoted the reduction reaction and the nucleation and growth of the metallic iron. The reaction was most intense at the temperature from 1 200℃ to 1 300℃. At 1 350℃, silicon entered the iron phase region. Except for a small amount of Fe₂TiO₄→FeTiO₃ at the initial stage, the reduction process of ilmenite concentrate was basically carried out along the FeTiO₃→FeTi₂O₅→Ti₃O₅→Ti₂O₃. Iron oxides were reduced to metallic iron and aggregated and grown, while titanium oxides changed from high valence to low valence. Finally, the main phases of the reduction were Ti₂O₃ and metallic iron. A solid solution of (Fe, Mg)TiO₃ and M₃O₅ was formed during the reduction process, which restrained the reduction effect of iron.

8 Upgrading Panzhihua-Xichang ilmenite using a fluidizing oxidation-magnetic separation process

LI Zhe , FAN Chuanlin , PAN Feng , YANG Haitao , ZHU Qingshan

2019, 42(4):63-71. DOI: 10.11835/j.issn.1000-582X.2019.04.008

[Abstract](819) [HTML](382) [PDF 2.81 M](1210)

Abstract:
With the continuous development of titanium dioxide production using chlorination method in China, the production of Ti-rich materials for chlorination process from Panzhihua-Xichang ilmenite concentrate becomes an inevitable trend. In order to use Panzhihua-Xichang ilmenite that contains a high volume of impurities and is unfit for the electric furnace reduction-upgraded titanium slag process, which is a feasible technical route, the fluidization oxidation roasting-magnetic separation process for upgrading Panzhihua-Xichang ilmenite was studied in this work. The transformation of phase structure during oxidation process, the effects of roasting parameters, and magnetic separation conditions were investigated. Based on the principle that weak oxidation of ilmenite can form a magnetic ilmenite-hematite solid solution, the results of experiments showed that high magnetic ore can be obtained by fluidization oxidation in the temperature range of 650℃ to 750℃, and the concentrate yield of direct magnetic separation is over 70% with magnetic field intensity of 3 500 Gs. Furthermore, the upgraded ore that meet the material requirements for producing upgraded titanium slag(UGS)were obtained by ball-milling and magnetic separation, with a titanium recovery rate of 49.29%. The process could be further improved by optimizing magnetic separation. It is proved that fluidization oxidation-magnetic separation is feasible for upgrading and utilization of Panzhihua-Xichang ilmenite.

9 Performance prediction of asphalt pavement based on grey relational analysis and support vector machine regression

ZHAO Jing , WANG Xuancang , DING Longting , FANG Naren , LI Shanqiang

2019, 42(4):72-81. DOI: 10.11835/j.issn.1000-582X.2019.04.009

[Abstract](872) [HTML](545) [PDF 1.44 M](1202)

Abstract:
Asphalt pavement performance prediction is complex and nonlinear when it involves multi-factor. In order to overcome the defects existing in traditional prediction models, a long-period and multi-factor prediction model with high precision needs to be established, on which the dimension of each factor is reduced by grey relational analysis, and the important relational factors are selected for nonlinear prediction by support vector machine regression. Accordingly the performance prediction model of asphalt pavement based on GRA-SVR was proposed and the measured RDI from Guangyun freeway were collected as an example to validate the proposed model. The results show that GRA-SVR model has better accuracy and maneuverability compared with GM(1,1)and PPI models. It can be used in long-term process and provide model reference for large data maintenance decision-making.

10 The heat transfer optimization analysis of tube heat exchanger in waste heat recovery of mixed gas

CHUAN He , DUAN Yang

2019, 42(4):82-91. DOI: 10.11835/j.issn.1000-582X.2019.04.010

[Abstract](727) [HTML](768) [PDF 2.98 M](1223)

Abstract:
In order to study the heat exchange characteristics of high temperature mixed gas in tube heat exchanger, a three-dimensional steady state numerical model based on the k-ε turbulence model, heat transfer theory and Maxwell-Stefan diffusion theory was established to investigate the influence of material diffusion on the temperature field distribution of heat exchanger. The heat exchanger was then parametrically analyzed involving the inlet temperature and velocity of cold and heat fluid and its heat transfer efficiency was examined from the view of exergy. The results show that the substance diffusion changes the distribution of the components in the heat flow mixed gas and the hydrogen which is dominant in the heat transfer diffuses reversely, exchanges heat repeatedly, thus consuming the heat of high temperature fluid, leading to a reduced level of the heat transfer performance of heat exchanger. The equivalent heat transfer coefficient reduces from 16.564 W/(m²·K) to 15.955 W/(m²·K). Within a certain range of operating parameters, the exergy efficiency of heat exchanger is between 10% and 30%, and the cooling effect is obvious.

11 Research on optimal arrangement of multi-factor water quality monitoring points based on the hydraulic model

CHEN Bingrui , ZHANG Zhen , FU Hao , TU Jie , WANG Tong , ZHAO Ming , DING Xiang , WU Fenfen , LIU Wenrui

2019, 42(4):92-100. DOI: 10.11835/j.issn.1000-582X.2019.04.011

[Abstract](679) [HTML](402) [PDF 1.04 M](1196)

Abstract:
With the rapid development of the city, the scale of urban water supply pipe network is also expanding, and its topological structure is becoming more and more complex, which adds difficulties to water supply security. Among them, the safety of water quality is most urgent. Therefore, a certain number of water quality monitoring points need to be set up in the water supply pipe network. Aiming at optimizing the layout of water quality monitoring sites for water distribution networks, the model was built based on the single node water age method with the effects of other influencing factors on the water quality of the pipeline network taken into consideration and the water supply pipe network of a city in the north as experimental object. By the hydraulic simulation software, the node water age method was optimized, and the optimized layout procedure of water quality monitoring points based on the multi-factor optimization method was designed. The results showed that the location of the water quality monitoring points calculated by the multi-factor water quality monitoring point optimization method based on the hydraulic model is 43.75% coincident with their actual location, not only covering the key water quality monitoring sites of the conventional pipe network in operational water plants and pressurized pump stations but also adding some monitoring points to the water supply demarcation line, pipe network, and pipe network terminal. And the early-warning time for pollution accidents was shorter than that before optimization. In conclusion, using this method to analyze the conditions of the water supply pipe network can provide a better implementation plan for optimizing the layout of the water quality monitoring points.

12 Block system optimization by stages for inclined seam long narrow open-pit mine

CAO Bo , TAO Yabin , BAI Runcai , BAI Wenzheng , LIU Guangwei

2019, 42(4):101-110. DOI: 10.11835/j.issn.1000-582X.2019.04.012

[Abstract](753) [HTML](610) [PDF 1.91 M](1308)

Abstract:
In the narrow and long open-pit mine of inclined coal seam, the mining procedure of vertical mining and horizontal mining are often adopted. In view of the influence of the change of the distribution of logistics on the economic reasonable stripping ratio, the block system optimization by stages was proposed, which involved two patterns, namely A pattern (the first mining area was located in the right side of the mining right) and B pattern (the first mining area was located in the middle of the mining right). In addition, the process of mining was divided into three periods according to the change of the separation of logistics to the flow:all external drainage, partial internal drainage and total internal drainage. By constructing the location model of stripping, mining and drainage, the paper systematically studied the principle and the conditions applicable to the state optimization of two mining modes, and put forward the model of state optimization. The research was applied in the practice of the Zhundong surface coal mining and the results show that the economic stripping ratio has increased from 1.50 m³/t to 1.62 m³/t, the economic mining depth by 24.7 m, the overtopping distance by 45.65 m and the economically recoverable reserves by 85.27 Mt, realizing the economic interest maximization of open-pit mining.

Home

Volume 42,Issue 4,2019 Table of Contents

Current Issue

Volume

Issue

Most Read

Most Cited

Most Downloaded