Volume 41,Issue 2,2018 Table of Contents

1 Vibration noise prediction and tooth modification effect analysis of a four-stage planetary gearbox

LIN Tengjiao , CAO Hong , LYU Hesheng

2018, 41(2):1-9. DOI: 10.11835/j.issn.1000-582X.2018.02.001

[Abstract](1095) [HTML](384) [PDF 21.34 M](1264)

Abstract:
In order to investigate the vibration noise of multi-stage planetary gearbox under complex excitation before and after tooth modification, with taking the lifting gearbox of an offshore platform as the research object, a finite element model of the gearbox including coupling four-stage planetary gear train, bearings and housing is established, and vibration mode of the gearbox is analyzed. Internal dynamic excitations of gear pairs before and after tooth modification are solved by static and dynamic contact finite element methods, then a vibration noise prediction method considering tooth modification is developed, vibration responses of the gearbox before and after tooth modification are solved by mode superposition method, and accordingly radiation noise of the gearbox is predicted by acoustic boundary element method. The results show that the vibration noise of the four-stage planetary gearbox after modification are decreased apparently, and calculated vibration noise is in good agreement with experimental values.

2 Analysis on the dynamic gear shift schedule of AMT vehicles in plateau environment

WANG Yuxiang , LIN Fu , HU Minghui

2018, 41(2):10-20. DOI: 10.11835/j.issn.1000-582X.2018.02.002

[Abstract](751) [HTML](525) [PDF 10.58 M](1332)

Abstract:
In the plateau area, the performance of internal combustion engine vehicles will be affected by the altitude. Based on the analysis of the fact that engine performance changes with the altitude, a simulation model of AMT vehicles' power transmission system is established, and the dynamic gear shift control schedule of AMT vehicles in plateau environment is studied. By modifying the control parameters of the optimal-power shift schedule, the formulation method of dynamic shift schedule based on different altitudes is proposed and simulated. The simulation results show that the proposed plateau dynamic shift schedule can acclimatise AMT vehicles to the plateau environment, and improve the dynamic performance of AMT vehicles obviously.

3 A comprehensive evaluation method of projection pursuit for CNC machine tool quality

LIU Ying , YIN Gang , ZHANG Genbao , RAN Yan

2018, 41(2):21-28. DOI: 10.11835/j.issn.1000-582X.2018.02.003

[Abstract](1026) [HTML](501) [PDF 1.12 M](1125)

Abstract:
A comprehensive evaluation method based on projection pursuit (PP) model is proposed to solve the problem of quality evaluation index multi-dimension for computer numerical control (CNC) machine tools. Firstly, the sine cosine algorithm (SCA) is introduced to calculate the objective weight of quality evaluation index for CNC machine tools. Then, analytic hierarchy process (AHP) combined with expert experience is utilized to obtain the subjective weight of each index. Furthermore, the combinational weight of CNC machine tool quality evaluation index is calculated with combining objective weight and subjective weight on the basis of the minimum entropy principle. Finally, the comprehensive evaluation values are calculated with projection algorithm of projection pursuit. The case study indicates that the method is feasible.

4 Research on load distribution influence factors of large-size double row four-point-contact ball bearing

DU Jing , ZHANG Lu , YANG Xiangang

2018, 41(2):29-36. DOI: 10.11835/j.issn.1000-582X.2018.02.004

[Abstract](644) [HTML](699) [PDF 6.87 M](1172)

Abstract:
In order to research the load distribution of a large-size-double row four-point-contact ball bearing, first, the supper element method is used to model the contact between raceways and rolling elements, and the equivalent beam method is used to model the bolt. Then, a simplified finite element model for a large-size double row four-point-contact ball bearing is obtained and its correctness is verified through the results comparison of theoretic algorithm and empirical formula. Finally, the influence of the bolt pretension, the mounting surface flatness and the differences between pitch angles on the load distribution of the bearing is analyzed by the model. The results show that with the increase of the even bolt pretension, the maximum contact load of bearing increases firstly and then slightly decreases. The uneven bolt pretension causes the exacerbated fluctuations of the bearing contact load. The surface flatness errors cause sudden changes of the contact loading distribution. When the degree of pitch-control synchronization is negative, the contact load of bearing increases.

5 The crack propagation numerical simulation of stamping of aluminum alloy sheets under different fracture critera

WAN Xinming , LIANG Bin , ZHAO Yan , GUO Yihui , ZHOU Jia

2018, 41(2):37-43. DOI: 10.11835/j.issn.1000-582X.2018.02.005

[Abstract](1038) [HTML](545) [PDF 14.38 M](1345)

Abstract:
Under different pressure and different pulling speed conditions, the dynamic and the average friction coefficient of 6016 aluminum alloy sheets during the stamping process is tested by self-developed friction coefficient test equipment of metal sheets. A numerical model of aluminum alloy sheet expansion test is established with importing average friction coefficient to consider the friction boundary conditions. With taking forming limit diagram and critical thickness reduction rate as cracking criterion respectively, the numerical model is calculated by finite element method and the calculation results are verified experimentally. The results show that the crack initiation position and the crack morphology are more accord with experimental verification results when the critical thickness reduction rate is taken as cracking criterion, which proves the critical thickness reduction rate parameters obtained in this paper are suitable for analyzing the crack initration and propagation of aluminum alloy sheets in the stamping process.

6 Optimization of the sintering proportioning of rich ore fines

ZHANG Qi , LIU Ran , WANG Xiaoai , SUN Yanqin , LIU Xiaojie , LYU Qing

2018, 41(2):44-52. DOI: 10.11835/j.issn.1000-582X.2018.02.006

[Abstract](848) [HTML](465) [PDF 2.83 M](1408)

Abstract:
In order to reduce sintering cost and energy consumption of sintering process, and improve the quality of sinter, we conduct experiments on optimizing the sintering proportion of South African rich ore fines, Brazilian ore fines, South African concentrate ore fines 1 and 2 in a steel company. The results show that the optimal ore matching scheme is No.6. Its proportion of Brazilian ore fines, South African rich ore fines and South African concentrate ore fines 1 is 15:70:15. The utilization coefficient is 2.66 t/(m²·h), tumbler index is 63.39%, RI and RDI_+3.15 is 70.06% and 51.30%, respectively, and the value of molten drop performance "S" is 1 419 kPa·℃.

7 A laser drive current and temperature control system for TDLAS methane detection

JIANG Jianguo , ZHAO Yu , LIU Songbin

2018, 41(2):53-60. DOI: 10.11835/j.issn.1000-582X.2018.02.007

[Abstract](849) [HTML](745) [PDF 9.63 M](1681)

Abstract:
In order to satisfy the requirements of laser on the output wavelength stability in the methane gas detection, a current driving and temperature control system is designed with taking STM32F103RCT6 as the microprocessor core, including signal generating circuit, filter circuit, and temperature acquisition and control circuit, etc. The signal chip is used to generate sawtooth frequency sweep signal, sine modulated signal and DC bias signal, and all the signals are stacked as laser injection current. At the same time, a secondary cooling system for laser is built to make the laser wavelength scan near the methane gas absorption peak(1 653.72 nm) through the tuning of temperature and current, and thus the gas can be fully absorbed. Experiments show the whole system works stably, and it can work sustainably more than 36 h with temperature error of ±0.008℃,current drive error of 0.09 mA or less and wavelength error in micrometer level, which meets the design requirements.

8 Microbial degradation mechanisms and differences of plant and mineral insulating oil of transformers

CHEN Jiangbo , WANG Feipeng , CAI Shengwei , LI Jian , HE Yan , WEN Gang , CHEN Cheng , FAN Fan , WU Liya , LIU Ruitong

2018, 41(2):61-68. DOI: 10.11835/j.issn.1000-582X.2018.02.008

[Abstract](892) [HTML](433) [PDF 2.77 M](1331)

Abstract:
The microbial degradation performance of rapeseed plant insulating oil (RDB), FR3 transformer insulating oil (FR3) and 25^# transformer insulating oil is studied by methods in Rapid Biodegradability:Closed Bottle Test. The results show that the degradation rates of RDB, FR3 and 25^# transformer insulating oil are 98.87%, 99.57% and 37.73%, respectively. According to the New Chemical Hazard Assessment Guidelines (HJ/T 154-2004), RDB and FR3 are biodegradable chemicals, while 25^# transformer insulating oil belongs to chemicals difficult to biodegrade. The degradation difference between plant and mineral insulating oil is mainly because the types of constituent substances and the content of unsaturated chemical bonds are different. As the research on the degradation difference of different kinds of plant insulating oil is very limited, the degradation mechanisms of different kinds of plant insulating oil are revealed from the perspective of hydrolysis kinetics in this paper.

9 Fault surface reconstruction based on Morphing method

LIU Guangwei , SONG Jiachen , BAI Runcai , LI Peng

2018, 41(2):69-77. DOI: 10.11835/j.issn.1000-582X.2018.02.009

[Abstract](737) [HTML](484) [PDF 8.38 M](1457)

Abstract:
In order to improve the accuracy and smoothness of reconstrucing fault planes with sparse data, a method for building fault plane model is put forward. The method analyzes and selects the fault level modeling data, then uses Morphing method to construct transition curves of adjacent sparse fault lines, and at the same time, uses CD-TIN to reconstruct smooth fracture surface. Based on the basic theory of Morphing method, the correspondence of feature points of fault line data is analyzed and feature points' matching is realized by distance dichotomy. With reference to the finite extrapolation method, the location of the fault tip is determined. The method of Lagrange interpolation is used to extrapolate the curve of node of fault line and realize the cutting of intersecting fault plane. And the smooth construction of broken layer under sparse data is realized. The forms of fault plane model generated by Kriging interpolation method and Morphing method are compared. It is concluded that the fault surface formed by Morphing method is smooth and natural, and it can better restore the bending details of the fault.

10 Laboratory study on RA value fractal feature of shale acoustic emission under conventional triaxial compression

GU Yilei , WANG Zepeng , LI Qingmiao , FANG Ju , LIAO Shuai

2018, 41(2):78-86. DOI: 10.11835/j.issn.1000-582X.2018.02.010

[Abstract](1024) [HTML](524) [PDF 3.64 M](1271)

Abstract:
Shale acoustic emission test is conducted under the condition of conventional triaxial compression, and the time series of acoustic emission RA value is obtained. In order to study the micro mechanism and fractal feature in the process of shale destruction under the condition of conventional triaxial compression, the coupling relationship between fractal dimension and time is obtained and analyzed with using the calculation of correlation dimension of time series on MATLAB software. Results show:1) Crack in the process of shale destruction is the combination of tensile crack and shear crack, and shear crack is the main crack. Moreover, tensile cracks mainly appear at the peak strength, and the number of tensile crack is significantly reduced with the increase of confining pressure. 2) The RA value of shale acoustic emission has self-similarity characteristics and fractal feature in the time domain. The evolutionary pattern of fractal dimension is:rise-sudden drop-fluctuation. 3) The fractal dimension rises in the first stage, indicating that in rock interior tiny cracks first disorderly extend until fracture surfaces form. Then the fracture dimension suddenly decreases, suggesting the fracture surfaces extend and macro cracks form, and the rock is about to break. Therefore, the first sudden decrease of fractal dimension can be taken as the premonition of rock destruction.

11 Open-pit path optimization based on improved genetic algorithm

CHAI Senlin , BAI Runcai , LIU Guangwei , CAO Bo , LIU Peng , DAI Lin

2018, 41(2):87-95. DOI: 10.11835/j.issn.1000-582X.2018.02.011

[Abstract](612) [HTML](586) [PDF 3.33 M](1313)

Abstract:
In order to solve the impractical problem of path optimization in open-pit mines adoping equivalent haulage distance as weight coefficient, we establish an optimization modeling with the aim of minimizing transport work path to describe the stochastic fluctuation in real open-pit road network. Firstly, a calculation model of transport work is established, and then a probability optimization model based on stochastic process is proposed. Finally, the convergence speed of solution is further improved from the aspect of modifying genetic algorithm. Compared with other algorithms, the experimental results show that this algorithm can not only quickly obtain low energy consumption optimization path, but also greatly improve the convergence speed of solution. Thus the cost of the whole transport network can be reduced. The algorithm is more efficient in the process of actual scheduling.

12 Analysis on the difference of breakthrough time for different injection gases to replace-displace methane in coal seams

YANG Hongmin , LU Xiaokai , CHEN Liwei

2018, 41(2):96-102. DOI: 10.11835/j.issn.1000-582X.2018.02.012

[Abstract](767) [HTML](568) [PDF 1.15 M](1159)

Abstract:
Coal gas injection is an intensive extraction technology which is gradually developed in recent years, and the breakthrough time of gas injection is one of the important parameters of the technology. The breakthrough time is the required time of injection gas goes from one end of the coal seam to the other end, and it is closely related to the adsorption and the permeability of the source gas. In order to study the laws of permeability and adsorption on the breakthrough time, the laboratory simulation experiment is carried out with injecting He, N₂ and CO₂ in coal seams to replace-displace CH₄. The results show that the breakthrough time on pure seepage of N₂ and CO₂ is very short, only 5.93% and 0.28% of the total breakthrough time, which indicates that gas adsorption performance is the main factor that causes the difference of breakthrough time. The breakthrough time increases as the gas adsorption performace of injection gas increases, and the breakthrough time of He, N₂ and CO₂ is 0.92 min, 14 min and 246 min, respectively. According to the laboratory experiment and theoretical model analysis, it can be concluded that the stronger the adsorption performance of injection gas is, the longer the breakthrough time and the more obvious the replacement effect in the initial stage of gas injection is, but the displacement effect gradually increases as the adsorption of the injection gas tends to be saturated.

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