Volume 40,Issue 10,2017 Table of Contents

1 Analysis and optimization of the dynamic characteristics for high speed wheel reducer used in electric vehicle

CHEN Xi , SONG Chaosheng , ZHU Caichao , WENG Yanxiang , XIANG Chao , GUO Wanlong

2017, 40(10):1-11. DOI: 10.11835/j.issn.1000-582X.2017.10.001

[Abstract](972) [HTML](582) [PDF 4.86 M](1362)

Abstract:
For the key problems of high noise and vibration of high-speed wheel reducer used in electric vehicle, a dynamic model of the wheel reducer is developed and the mesh characteristics and dynamic characteristics are investigated under rated power, maximum speed and maximum torque load conditions. Then the amplitude of structural noise is calculated and analyzed. Also the effect of contact ratio on the dynamic performance of the system is evaluated and macro geometry parameters of the transmission system are optimized by using MASTA. Results show that the peak-to-peak values of the transmission errors for the output gears are relatively higher and the main structural noise comes from the high-speed input shaft. Compared with the design with contact ratio as a non-integer value, the design with an integer contact ratio leads to a lower changing ratio of total length of contact lines and the contact load fluctuation, the changing ratio of the mesh stiffness and the structural noise from the bearings supporting locations are decreased obviously. The optimization of macro parameters makes the dynamic performance of gear pairs better.

2 Analysis of elastoplastic contact performances for deep groove ball bearing considering roughness

PU Chao , DU Minggang , MENG Fanming , ZHANG Qing

2017, 40(10):12-22. DOI: 10.11835/j.issn.1000-582X.2017.10.002

[Abstract](953) [HTML](325) [PDF 10.16 M](1004)

Abstract:
To reveal the effect of surface roughness on elastoplastic contact performances for a deep groove ball bearing, the contact between the rolling element and inner raceway is reduced as the extremum problem of a quadratic function based on the load distribution of this kind of bearings. The elastoplastic contact model for a rough deep groove ball bearing is modeled, and solved with the proposed semi-analytical method so as to obtain the elastoplastic contact performance for the bearing. Numerical results show that the surface roughness yields decrements in the pressure peaks at the two contact endpoints along the inner raceway's width direction. Meanwhile, the maximum contact pressure, von Mises stress, and residual stress and deformation for the inner raceway are all larger than the corresponding values for the smooth situation. Moreover, the roughness also causes fluctuating distributions of contact pressure and residual deformation, and brings out a stress concentration at the inner raceway's subsurface, which can lead to a decay of the bearing lifetime.

3 Thermal error compensation technology of CNC machine tools based on Grey Model(1,4)

JU Pinghua , HUANG Luo

2017, 40(10):23-29. DOI: 10.11835/j.issn.1000-582X.2017.10.003

[Abstract](927) [HTML](337) [PDF 2.26 M](1400)

Abstract:
To reduce the influence of temperature field on the machining accuracy of machine tools, we analyze the heat source composition and the thermal error mechanism in the production process of CNC machine tools, select 4 key points for temperature-measuring from the original 8 temperature-measuring points according to the theory of grey relational degree, and establish a grey (4,1) prediction model. The model builds the mapping relationship between the changes of the 4 key points and the thermal error of machine tools. It can predict the thermal error of machine tools in real time by acquiring the temperature of the key points and then compensate the predicted thermal error to the tool feed position, and thus a machine thermal error compensation mechanism is formed. The precision horizontal machining center experiment THM6380 is taken as the experimental object, the gap between the test results of GM(4,1) model and the actual thermal error value is calculated, and the fitting residual error is within ±1 μm, which shows the fitting effect is good.

4 Optimization on vehicle routing problem with simultaneous pickup-delivery for urban express joint distribution

NI Lin , LIU Kaipeng , TU Zhigang

2017, 40(10):30-39. DOI: 10.11835/j.issn.1000-582X.2017.10.004

[Abstract](963) [HTML](654) [PDF 2.17 M](1546)

Abstract:
In order to minimize the total cost of distribution system and increase the vehicles' loading rate, the influence of simultaneous pickup-delivery on vehicles' loading rate is considered and a VRPSPD (vehicle routing problem with simultaneous pickup-delivery) model for urban express common distribution is established under the condition that express companies carry out joint distribution. Then an improved genetic algorithm is proposed to solve the model. Finally, the practicability and validity of the model and algorithm are tested by examples.

5 Optimal aerodynamic design for formula SAE car using curved wings

ZHOU Tao , ZENG Zhong

2017, 40(10):40-52. DOI: 10.11835/j.issn.1000-582X.2017.10.005

[Abstract](1408) [HTML](1542) [PDF 9.80 M](1690)

Abstract:
Optimizing the design of the aerodynamic packages can effectively improve the performance of the formula SAE (FSAE) racing car. Following the rules of Formula Student China, we take the lead in using the curved wings to optimize the front wing and rear wing for Chongqing University formula SAE racing car. Profili and Xfoil are used to choose the wing sections and optimize the attack angles. An in-depth study is undertaken to analyze the flow field around the formula car in the rectangular parallelepiped wind tunnel simulation via numerical simulations (CFD, computational fluid dynamics). The results indicate that downforce is increased with a sword cured front wing and a rear wing. The rear wing contains a main straight wing and upwarp flap. The downforce coefficient is improved to 1.68 and downforce-drag ratio is improved to 1.91.

6 Effect of carbonyl iron powder morphology on the absorption properties of microwave

YANG Fuli , HOU Xingzhe , ZHENG Ke , YANG Pingan , YU Miao

2017, 40(10):53-59. DOI: 10.11835/j.issn.1000-582X.2017.10.006

[Abstract](1125) [HTML](819) [PDF 4.44 M](1669)

Abstract:
Because carbonyl iron powder (CIP) has the advantages of good temperature stability, wide absorption band and strong design ability, it has been widely studied and used. In this paper, the electromagnetic wave absorption properties of two kinds of carbonyl iron powder which have the same basic parameters but different morphologies (spherical and dendritic) have been tested to study the influence of morphology on the absorption properties of carbonyl iron powder. The experimental results show that the morphology of carbonyl iron powder has a great influence on the electromagnetic wave absorption performance. Compared to the spherical CIP, the maximum reflection loss(RL) of the dendritic CIP increases by 94%, reaching -47.14 dB. Moreover, the frequencies corresponding to the minimum RL values of absorption peaks shift form 11.88 GHz (spherical CIP) to 6.44 GHz (dendritic CIP). This is because the dendritic morphology is conducive to form discontinuous network, increase the diffuse scattering of incident electromagnetic wave as well as form more interfacial charge polarization, resulting in enhancing the absorption intensity of electromagnetic wave. In addition, this study shows that the anisotropic structure is an effective way to improve the dielectric constant and dielectric loss, and obtain the absorber with the characteristics of wide absorption bandwidth and light weight.

7 Analysis on rotor starting temperature rise of induction motor with heavy rotary inertia load

HAN Li , LEI Yi , WANG Tongbin , WANG Shihong , ZHANG Liqiao , XIONG Yingdan

2017, 40(10):60-69. DOI: 10.11835/j.issn.1000-582X.2017.10.007

[Abstract](966) [HTML](509) [PDF 2.85 M](1023)

Abstract:
The induction motor with heavy rotary inertia load is a specialized motor which drives the coal mill in the power station. Due to the heavy rotary inertia, the large starting current and long starting time resulting from the coal mill with heavy rotary inertia load, the loss and heat problems of the motor rotor in the starting process are more serious. To improve the starting reliability of the motor, an induction motor which is the largest capacity with heavy rotary inertia load in China is chosen as the research object. By the methods of discrete point calculation and curve fitting, the models of rotor core loss, rotor copper loss and rotor surface heat transfer coefficients with the change of rotor speed are established respectively at the starting process. And then, the rotor loss and the temperature rise at the starting process are calculated and analysed by the finite element method. The results show that the starting time of the motor is as long as 48 s. The rotor core loss, rotor copper loss and rotor surface heat transfer coefficients change with the rotor speed at the starting process. When the starting is completed, the highest rotor temperature rise is 141.1 K.

8 The evolution of precipitate and microstructure during hot band annealing of grain-oriented silicon steel

ZHOU Bowen , LI Guangqiang , ZHU Chengyi , HOU Ruogu

2017, 40(10):70-78. DOI: 10.11835/j.issn.1000-582X.2017.10.008

[Abstract](866) [HTML](472) [PDF 4.99 M](1117)

Abstract:
The changes of precipitate and microstructure during hot band annealing were studied by transmission electron microscope (TEM) and electron back scatter diffraction system (EBSD). The results show that a lot of precipitates precipitate during hot rolling and hot band annealing. The precipitates are mainly MnS and a little of MnS-AlN composite in hot-rolled band, while there are mainly AlN and a little of MnS-AlN composite in annealed hot-rolled band. The amount of precipitates in annealed hot-rolled band is 1-2 order higher than those in hot-rolled band, and the average size in annealed hot-rolled band is about 16 nm smaller than those in hot-rolled band. The microstructure of hot-rolled band is heterogeneous along the thickness and the Goss orientation grains with an intensity of about 2 are mainly in the deformed structures of subsurface. After hot band annealing, the microstructure along the thickness is more homogeneous and uniform and fine grains of subsurface can be obtained, but the intensity of Goss texture decreases to about 0.8.

9 Electronic structure and optical properties of Zn-doped anatase TiO₂

XIE Fengyu , GAO Jiacheng , WANG Ning

2017, 40(10):79-86. DOI: 10.11835/j.issn.1000-582X.2017.10.009

[Abstract](926) [HTML](343) [PDF 4.42 M](940)

Abstract:
The structure optimization, band structure, density of states and light absorption characteristics of Zn-doped anatase TiO₂ are studied with the first-principles calculation method based on density functional theory(DFT). The calculations results show that Zn-doped anatase TiO₂ is indirect band gap semiconductor, and the impurity energy level is introduced due to the couping between O-2p and Zn-3d, which can increase the TiO₂ absorption edge to the visible region, and therefore enlarge the absorption region of TiO₂. The experimental results show that Zn-doped TiO₂ leads to the red shift of the optical absorption edges to visible-light region and enhance thephotoelectric effect of anatase TiO₂. The effect is useful for the photocathode protection of photoelectric performance.

10 Effect of solution heat treatment on microstructures and stress rupture properties of a third generation Ni-based single crystal superalloy

FANG Xiang , ZHAO Yunsong , ZHANG Jian , YANG Zhenyu , JIANG Hua , YANG Yan , CHEN Hao , WU Qinghui , LUO Yushi

2017, 40(10):87-98. DOI: 10.11835/j.issn.1000-582X.2017.10.010

[Abstract](939) [HTML](541) [PDF 4.28 M](1683)

Abstract:
Effect of solution heat treatment on microstructures and stress rupture properties of a third generation Ni-based single crystal superalloy with content of 6.5%(mass fraction) Re has been investigated. The experimental results show that the as-cast alloy exists significant solidification segregation and a large percentage of (γ+γ') eutectic. During the solution heat treatment, the (γ+γ') eutectic initially solves rapidly when the temperature is higher than 1 335℃. However, the solidification segregation especially the segregation of Re is not significantly reduced until solution heat treatment temperatures exceed 1 360℃. The micropore content after solution heat treatment at 1 365℃ is about 0.21%(volume fraction), which is 5.2 times of that before heat treatment. The stress rupture properties of the as-cast alloy and the alloys after different solution heat treatment at 1 360℃ and 1 365℃ are investigated respectively at the conditions of 1 080℃/190 MPa, 1 100℃/140 MPa and 1 150℃/83 MPa. The results show that the heat treatment significantly improves the stress rupture properties, and the higher solution heat treatment temperature is, the longer the stress rupture lives are. During the process of high temperature stress rupture, most of cracks distribute in the interdendritic and cracks initiat from the (γ+γ') eutectic in the as-cast alloy. The alloy with solution heat treatment at 1 360℃ has some cracks which distribute both in the dendritic core and interdendritic area. A large amount of TCP(topologically close-packed) precipitation distributes in the dendritic core possibly due to the residual segregation of Re. However, as the alloy with solution heat treatment at 1 365℃, there is less TCP precipitation.

11 Adsorption property of biochar from soybean straw for Ni(II) in wastewater

XIANG Wenying , LI Ning , DENG Guobin , XIE Bingbing

2017, 40(10):99-107. DOI: 10.11835/j.issn.1000-582X.2017.10.011

[Abstract](810) [HTML](348) [PDF 3.56 M](983)

Abstract:
To remove Ni(Ⅱ) in wastewater more effectively and economically, soybean straw with low cost is chosen to make biochar to absorb Ni(Ⅱ). The effects of carbonization temperature, solution pH, adsorbent dosage, solution temperature and Cd(Ⅱ) concentration on the adsorption are investigated to find the optimal adsorption condition. A new method for removing heavy metal nickel is developed, and the adsorption kinetics and adsorption isotherm are studied. The experimental results show that the adsorption performance of the adsorbent is good, and when Ni (Ⅱ) concentration is 20 mg/L, carbonization temperature is 500℃, pH is 7, dosage is 0.2 g, temperature keeps at 25℃ and the concentration of Cd (Ⅱ) is 0, the adsorption condition is the best. The adsorption reaction accords with the second-order kinetics equation. The adsorption isotherm accords with Langmuir model, and the saturated adsorption capacity is 14.38 mg/L at 25℃. Scanning electron microscope analysis shows that the pore structure of straw, the surface roughness and the specific surface area increase, which improves the adsorption performance.

12 Study on the enrichment characteristics of the geothermal water in typical layered thermal reservoir-Taking the east flank of Guanyinxia anticline as an example

LYU Yuxiang , TAN Lin , ZHANG Zhongju

2017, 40(10):108-114. DOI: 10.11835/j.issn.1000-582X.2017.10.012

[Abstract](863) [HTML](341) [PDF 1.39 M](1324)

Abstract:
The Guanyinxia anticline is a typical layered thermal reservoir, and 11 geothermal wells have been successfully implemented in its southeast flank. Using comparative study, correlation analysis and other methods to analyze the data of these wells, we research the enrichment characteristics of the geothermal water in typical layered thermal reservoir. The results show the larger the thermal reservoir buried depth is, the weaker the karst development and the poorer the geothermal water is. While, the larger the thermal reservoir buried depth is, the better the heat insulation performance of the thermal reservoir and the higher the temperature of hot water is. The thicker the layered thermal reservoir is, the stronger the karst development and the richer the geothermal water is. While, the thicker the thermal reservoir and the stronger the karst fissure's development is, the lower the temperature of hot water is. The layered thermal reservoir with gradually changed occurrence is relatively rich, and the average water yield of the geothermal wells is 2 136.75 m³/d, while the layered thermal reservoir with rapidly changed occurrence is relatively poor, and the average water yield of the geothermal wells is 584.93 m³/d.

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