Table of Content

10 June 2017, Volume 28 Issue 11

Previous Issue    Next Issue

Experimental Study on Surface Quality of Single Crystal DD98 in Micro-milling Processes

CAI Ming, GONG Yadong, YU Ning, GAO Qi

2017, 28(11):  1261-1265. 

Asbtract ( )   PDF (538KB) ( )  

References | Related Articles | Metrics

In order to explore the surface quality of single crystal DD98 in micro-milling processes, a three-factor and five-level orthogonal experiments of single crystal DD98 in micro-milling processes were conducted by a micro-milling tool with 0.6mm diameter. Firstly, after range analysis and variance analysis, the spindle speeds have the greatest effects on surface quality. Then the milling depth follows. The feed rate has the least effect on surface quality. The optimized processing parameter combinations are as the following: spindle speed of 36000r/min， milling depth of 5μm, feed rate of 100μm/s, and the surface quality of single crystal DD98 is the best. Then the influences of spindle speeds， milling depths and feed rates on surface quality were obtained respectively. Deeply analysis of their causes were also given, providing a theoretical basis for the processing of single crystal DD98 material in micro-milling processes.

Fabrication of PCD Slotting Tools Applied to Machine Micro Slot Arrays of Multiple Materials

2017, 28(11):  1265-1268. 

Asbtract ( )   PDF (474KB) ( )  

References | Related Articles | Metrics

Firstly, slotting tools characterized by specific geometry, sizes and angles were designed from the combination of flying cutting tools and sawing blades. Secondly, the ultra-hard PCD slotting tools were manufactured by wire cut electrical discharge machining. At last, micro slot milling experiments were performed, and typical micro slot arrays were machined by employing the self-fabricated PCD slotting tools.

Structural Topology Optimization Based on Density-volume Interpolation Scheme

XU Xiaokui, GUO Baofeng, JIN Miao

2017, 28(11):  1269-1273. 

Asbtract ( )   PDF (489KB) ( )  

References | Related Articles | Metrics

A density-volume interpolation scheme applied in the variable density method was proposed, which was used for controlling grayscale elements in the topology optimization of continuum structures. In the new interpolation scheme, a linear relationship was established between the element stiffness and the relative density to ensure that the element stiffness changed smoothly with the changes of relative density in each iteration. And a penalty function was established between the element volume and the relative density in order to penalize the intermediate densities, which is better for reducing the number of grayscale elements acompained with the intermediate densities approaching both ends.The new interpolation scheme was introduced into the minimum volume optimization problems subjected to displacement constraints. The examples show that the optimization process changes little when increasing the penalty and it indicates that this algorithm is relatively stable. When solving the topology optimization problems with the same structures, it shows that there are less grayscale elements in the optimization results by using the new interpolation scheme than the results optimized by the SIMP and RAMP method. It is because a large penalty may be implemented on intermediate density in the new interpolation scheme.

Modal Testing for Small-size Turbocharger Rotor with Additional Constraints

BIN GuangfuZHOU WeiWANG GangCHEN Wen

2017, 28(11):  1274-1278. 

Asbtract ( )   PDF (588KB) ( )  

References | Related Articles | Metrics

As modal parameters usually were difficult to obtain for small-size turbocharger rotors, a rotor modal testing with additional constraints was proposed. A gasoline engine turbocharger rotor including multi materials and components was used as the example to demonstrate the proposed approach. A finite element (FE) model for turbocharger rotor with free boundary conditions was built to calculate the modal frequencies for the former three orders. Then impact modal testing was carried out based on four different additional constraints including horizontal hanging, vertical hanging, supporting on spongy cushion, and supporting on hardboard. The modal frequencies were evaluated from the stability diagrams. It is found the recognition values from constraint way of hanging are lower than that of the constraint way of supporting compared to the FE simulation. However, the modal frequencies identified under the vertical hanging constraint is the best for all kinds of constraints.

Coupling Effects of Surface Micro-cavity and Textural Directionality on Interface Frictions

HOU Lixia, LIU Xiaojun, ZHANG Tong, LIU Kun

2017, 28(11):  1279-1286. 

Asbtract ( )   PDF (858KB) ( )  

References | Related Articles | Metrics

The effects of texture direction and surface micro-cavity of aluminum alloy on frictional properties at the sliding contact interface was investigated. Three different surface textures were obtained by cutting, then manufactured micro-cavity with different area densities on the surface. A series of frictional experiments were carried out with different contact pressures under oil lubrication on a tailored friction tester, the angels between the sliding and surface texture directions were as 0°, 45°,90° respectively during the experiments. The three dimensional surface topography of samples before and after friction tests were measured with non-contact optical profilometer, and the variations of surface topography at the sliding contact interface were analyzed by choosing such parameters as Sa,Str,Vvvand Vvc. The experimental results show that the aluminum alloy exhibits anisotropy in the processes of sliding contact friction due to different surface texture directions. And the micro-cavity with different area densities on the surface may weaken the effects of texture direction on the contact interface friction, which reflects the coupling effects of surface micro-cavity and texture on the interface friction. The effects of interface friction on surface topography lead to regular changes of the three dimensional surface parameters of Str, Vvv, Vvc.

3D Reconstruction and Characterization for Surface Topography of Mechanical Seals

ZHANG Hao, SUN Jianjun, MA Chenbo, TU Qiaoan

2017, 28(11):  1287-1291,1299. 

Asbtract ( )   PDF (689KB) ( )  

References | Related Articles | Metrics

In order to characterize the surface 3D topography and leakage path of mechanical seal end faces accurately and conveniently, a 3D reconstruction program for surface topography of mechanical seal end faces was developed and studied based on 2D sectional images. A new characterization parameter for surface topography of mechanical seal end faces was proposed and based on voxel an algorithm was established to calculate the fractal dimensions and the porosity. The results show that it is effective to reflect the 3D box-counting dimension, porosity and other parameters of surface topography of mechanical seal end faces with 3D reconstruction based on sectional images. The surface porosity of different layers has a law of change, so when the volume porosity is constant, the formation and the scale of leakage path of mechanical seal end faces will be dominated by the change of surface porosity distribution on different sectional images. The sampling number of layers have a great influence on the calculating results when it is fewer, however, the influence becomes smaller as the number reaches a certain value.

Multi-level Evolutionary approach for the Black-and-white Topology Optimization Design

FU Yongqing, ZHANG Xianmin

2017, 28(11):  1292-1299. 

Asbtract ( )   PDF (655KB) ( )  

References | Related Articles | Metrics

A multi-level evolutionary method for the 0-1 topology optimization design was proposed. The binary constraints on design variables were relaxed based on the scheme of  SIMP. And the checkerboards were filtered and removed by sensitivity. The ineffective intermediate elements were considered as redundant materials. Then, a multi-level continuation scheme on the volume ratio was used to approach the objective volume ratio of the optimization problem gradually. Meanwhile, based on relative densities an evolutionary screening strategy for elements was applied to remove ineffective materials in the design stratified, to remain the most effective materials, and to diminish the available material domains of topology optimization models with the changing layers. By this way, the 0-1 topology design was transformed into a multi-level evolutionary procedure of the topology optimization. Consequently, a preferable black-and-white topology satisfying the objective volume ratio could be obtained as expected. Finally, numerical examples of the topology design including compliance minimization and compliant mechanism problems were employed to verify the feasibility of the proposed method. The results demonstrate that the present method may achieve a relatively good 0-1 convergent effect.

Optimization of Carbon Fiber Reinforced Polymer Reinforcing Center Hole Steel Plates

WU Xizhi, CHENG Junsheng

2017, 28(11):  1300-1304,1311. 

Asbtract ( )   PDF (581KB) ( )  

References | Related Articles | Metrics

A multi-stage optimization method was adopted for carbon fiber reinforced polymer reinforcing center hole steel plate. The method was divided into two steps: firstly, sample points were selected based on the Latin hypercube method, an agent model was fitted by the moving least square, and the thickness of basic laminate was optimized based on the adaptive response surface optimization method. Secondly, considering composite's manufacturing constraints, the stacking sequence was optimized by use of Optistruct software to obtain optimum design. Through the multi-stage optimization design, the stress of center hole steel plate is distributed more reasonable, and the maximum Mises stress is reduced by 56.6%.

Dynamics Modeling and Experiments of Horizontal-axis Washing Machine Suspension System

WANG Hao, LIU Lei

2017, 28(11):  1305-1311. 

Asbtract ( )   PDF (782KB) ( )  

References | Related Articles | Metrics

Considering the effects of top balancing weights of washing machine suspension system, a dynamics model of this system was set up with Lagrange equations. Experiments were designed to measure vibrations of washing machine drum under multiple working conditions. An modification for parameters of dynamics model was performed based on the relation curves between the vibration amplitudes and speeds of the drum. The results calculated by dynamics model were compared with those obtained by experiments. The validity of dynamics model was verified. 

A Novel Avoid Singularity Algorithm for 6-DOF Manipulators

CUI Hongxin, LI Huanliang, HAN Jinhua, LI Pei

2017, 28(11):  1312-1318,1325. 

Asbtract ( )   PDF (641KB) ( )  

References | Related Articles | Metrics

Aiming at the problems of the heavier calculation burden and worse real-time of traditional singularity avoidance algorithms, a novel approach (named “singularity separation plus exponential order damped reciprocal” algorithm) was proposed for 6-DOF manipulators. Firstly, the singularity configurations were analyzed and the singularity parameters were separated based on the kinematics calculation. Then, the principle of exponential order damped reciprocal algorithm was introduced and error coefficient caused by the exponential order damped reciprocal algorithm was analyzed. The simulation and experimental results show that the proposed algorithm may achieve smooth transition of joint angular velocities and only part velocities accuracy of the end-effector are sacrificed, the effectiveness and practicability of the proposed algorithm are proved.

Modeling and Numerical Analysis of a Novel Anti-reverse Ratchet Wave Energy Collector

WANG Gongxian, ZHENG Chunling, CHEN Kaikai

2017, 28(11):  1319-1325. 

Asbtract ( )   PDF (775KB) ( )  

References | Related Articles | Metrics

To avoide the bottleneck problems of existing wave energy converters such as complex structures, low reliability and low conversion efficiency, a novel anti-reverse ratchet wave energy collector was proposed，which could generate electricity by wave reliably and efficiently for the whole period. The dynamics nonlinear equations were established with external excitations based on wave characteristics. The efficiency of energetic transduction with load effect was deduced. The sensitivity analyses of the system parameters were performed and combined with typical wave characteristics, key parameters for floating body and convert efficiency were simulated. The results show that, under the poor situation of the sea, the generator still has periodic input torque characteristics and high average efficiency of power generation.

Study on Combined Error Compensation Method for CNC Machine Worktables

MIAO Enming, XU Jianguo, LYU Xuanxuan, WEI Xinyuan

2017, 28(11):  1326-1332. 

Asbtract ( )   PDF (716KB) ( )  

References | Related Articles | Metrics

To avoid of the relative position problems changing between the worktable and the main spindle of any CNC machine because of geometric errors and thermal errors. The error data at different temperatures were obtained through experiments, the rules of the flatness errors on worktables were obtained remaining unchanged with the thermal deformation, and a kind of comprehensive compensation method of the flatness error and thermal error on worktables of CNC machine tool was proposed. In this method, the flatness error model and thermal error model were established separately, then the comprehensive error compensation model was established by using the superposition principle. The principle's defects of the traditional fixed point model compensation method were corrected. Based on the real-time temperature values of the key parts of CNC machine and the real-time coordinate values of the tool positions, the error compensation values of each stage of the whole working table were calculated. And then the real-time compensation of the overall axial errors of the spindle on the whole working table was realized. The accuracy of CNC machine are improved by using the proposed thermal error compensation method. Compared with the traditional single point thermal error compensation method, the standard deviation of the integrated model is reduced by about 7μm after analysis, and the accuracy ratio is up to 50%.The maximum compensation residual is reduced by about 11μm, the accuracy ratio of lift is up to 60%.

Effects of Oil Properties on Flow Pulsation of Axial Piston Pumps by Simulation Analysis

GAO Yanjun, GU Lichen, JIAO Longfei

2017, 28(11):  1333-1338. 

Asbtract ( )   PDF (607KB) ( )  

References | Related Articles | Metrics

In order to study the effects of oil characteristics on flow ripple of the axial piston pumps, the relationship among the oil compressibility, viscosity, gas hole, the flow state and flow pulsation was researched based on the movement characteristics of axial piston pumps using the FLUENT software.The results show that the effects of oil compressibility, viscosity, gas hole and the flow state on the flow pulsation are all existed where the oil compressibility has the biggest effects and the flow state has the smallest effects. And the proportion of effects is as 86.8%,9.45%, 3.59%, and 0.16% respectively. Then the simulation results were validated by experimental tests and the accuracy of the simulation was acceptable. So it provides a theoretical basis for the dynamics modeling of piston pumps and simulation and analysis on the global coupling performance of electrohydraulic systems.

Rolling Bearing Fault Diagnosis Method Based on Composite Multiscale Entropy and Laplacian SVM

DAI Junxi, ZHENG Jinde, PAN Haiyang, PAN Ziwei

2017, 28(11):  1339-1346. 

Asbtract ( )   PDF (675KB) ( )  

References | Related Articles | Metrics

Since the unclear of early fault of rolling bearings and it was difficult to extract the features from the mechanical systems, a new judging time series complexity testing method called composite multiscale entropy (CMSE) was applied to extract the fault features from the vibration signals of rolling bearings. CMSE overcome the defects of coarse-graining in MSE and was an effective method for measuring the complexity of time series with better consistency and stability. Besides, as it was easy to collect a large number of samples, but difficult to label them in mechanical fault intelligent diagnosis, the LapSVM was applied to the intelligent fault diagnosis of rolling bearings. Then a new fault diagnosis method for rolling bearings was proposed based on the CMSE, sequential forward selection and LapSVM. Finally, the experimental data were analyzed based on the proposed method. The results show that the fault features of rolling bearings are extracted effectively by CMSE, compared with SVM that may only be trained by the labeled samples, the LapSVM combining with sequential forward selection for feature selection and studying from a large number of unlabeled samples may significantly improve the accuracy of fault diagnosis for fewer number of labeled samples.

Automatic Segmentations and Recognitions of Assembly Motions Based on Machine Vision

LIU Mingzhou, JIANG Qiannan, GE Maogen

2017, 28(11):  1346-1354. 

Asbtract ( )   PDF (782KB) ( )  

References | Related Articles | Metrics

The observations, decompositions and records of motions were usually accomplished through artificial means during the processes of motion analyses. This method had a heavy workload, and the efficiency was very low. A novel method was put forward herein to segment and recognize continuous human motions automatically based on machine vision for mechanical assembly operations. First, the content-based dynamic key frame extraction technology was utilized to extract key frames from video stream, and then automatic segmentations of actions were implemented. Further, the SIFT feature points of the region of interested were extracted, on the basis of which the characteristic vectors of the key frame were derived. Finally, a classifier was constructed based on SVM to classify feature vectors, and the motion types were identified according to the classification results. Experimental results demonstrate that the proposed method achieves correct recognition rates of 96% on sample videos which were captured on the assembly lines.


Laser Welding Parameters and Tensile Properties of Partial Penetration Lap Joint for Stainless Train Body

WEN Peng , WU Ruifeng, WANG Xiuyi, AN Ji, WANG Xiaolong , ZHANG Yan

2017, 28(11):  1355-1361. 

Asbtract ( )   PDF (693KB) ( )  

References | Related Articles | Metrics

Partial penetration lap laser welding was used for 301L-H stainless steel train bodies to solve the heats and the weld distortion problems. The effects of focused laser spot diameter and welding parameters were investigated with using fiber laser. Relationship among processing parameters and welding quality index like formation quality, heat trace on the surface, penetration shape and shear tensile performance, were concluded. The principles and methods were discussed for the selection of optimized parameters. For the combination of 0.8mm and 1.5mm high tensile strength plates, which were typically used for light weight train bodies, the outputs of laser machine should be over 2kW, and the focused spot diameters should be over 0.4mm if a large processing window was obtained to satisfy both appearance and mechanical requirements. For fiber laser with 0.4mm spot diameter, the penetration should be less than 1.4mm to make the outside surfaces no heat traces, and the fusion width in the interfaces between inner and external plate should be more than 0.8mm to make the tensile strength higher than that of resistance spot welding. For 301L-H stainless steel with tensile strength over 930MPa, the fractures are always located in the fusion zones at the interfaces between inner and external plates, so the tensile capacity is linearly related to the fusion widths in the interfaces.

Growth Modeling and Numerical Analysis of Diffusion Transition Zone for Silver Brazing Alloys with Tin Coatings

WANG Xingxing, HAN Linshan, QIAO Peixin, LI Quancai

2017, 28(11):  1362-1367. 

Asbtract ( )   PDF (533KB) ( )  

References | Related Articles | Metrics

The silver brazing filler metals with tin coatings were thermal diffused using temperature gradient method, then it would occur diffusion transition zone during the silver brazing filler metals with tin coatings. The thickness and surface morphology of diffusion transition zone were analyzed by optical microscope and atomic force microscope. The results show that the diffusion rate of Sn atom is accelerated by the thermal diffusion method and the concentration of tin atom during the silver brazing alloys is increased. The thickness of diffusion transition zone is also increased. According to the object for the concentration gradient of diffusion transition zones, the mathematical model for the thickness of diffusion transition zone was established and numerical analyzed by Arrehenius equation. The model was solved by MATLAB software and the experimental data of diffusion transition zone. The constitutive equations for growth behavior of Sn atoms during diffusion transition zone at 200℃ and 220℃ were established. The experimental results indicate that constitutive equation may quantitative analyze the growth behavior of Sn atoms at the diffusion transition zones for silver brazing alloy with tin coating.

Influences of Welding Parameters on Temperature Field Characteristics during Laser Welding of 304 Stainless Steels

HU Yaguang, WANG Xuanguo, DUAN Aiqin, MA Xuyi

2017, 28(11):  1367-1374. 

Asbtract ( )   PDF (801KB) ( )  

References | Related Articles | Metrics

Based on infrared thermograph technique, the laser welding processes of 304 stainless steels were recorded to study the influences of welding parameters on temperature field characteristics. The results show that, when the laser power is constant, the lengths and the widths of the melting zone are increased with the decrease of the welding speeds, but the basic characteristic of the temperature field distribution will not be changed. When welding speed is constant, with the increases of laser power, the temperature of the welding seam is increased ,especially the temperature and area of sub-high temperature are increased significantly, but the distribution of temperature is invariable. When the energy input is close to each other，the “keyhole” temperature of the high power/high speed combination is higher. Meanwhile, the temperature and area of the sub-high temperature zone in the combination of low power/low speed is higher, but it has a lower temperature at the back of the weld than the combination of high power/high speed.

Impacts of Cold Forced Strengthening on Diaphragm Spring's Clamp Load Characteristic

GONG Yubing, ZHANG Defeng, PAN Shunying

2017, 28(11):  1375-1379. 

Asbtract ( )   PDF (529KB) ( )  

References | Related Articles | Metrics

Based on the finite element method，the forced strengthening processes were simulated and the clamp load characteristics before and after forced strengthening processes were obtained respectively. The impacts of the stroke and the numbers of the stroke on the load characteristics of the spring were investigated. And two impact mechanism of forced strengthening processes on the clamp load characteristic of the diaphragm spring was studied. The results show that the diaphragm spring is suffered the greatest damping impact from forced strengthening at the first time. The increase of the stroke of the forced strengthening, the damping of the load value of the spring is also increased. Compared with the number of the stroke, the stroke has greater impact on the load value of diaphragm spring. Although the changes of structural parameters and residual stress effects both induced by the forced strengthening process have attribute to the decreasing of the clamp load value of the diaphragm spring, the former one is the main mechanism.

Study on Characteristics of Axial Ultrasonic Assisted Grinding of Sapphire with Different Crystal Surfaces

HU Zhongwei, SHAO Mingjian, FANG Congfu, YU Yiqing, XU Xipeng,

2017, 28(11):  1380-1385. 

Asbtract ( )   PDF (712KB) ( )  

References | Related Articles | Metrics

AUAG test study was carried out on sapphire A-plane, C-plane, M-plane and R-plane, and the grinding characteristics of the four crystal surfaces of sapphire were compared with and without AUAG from the grinding forces, specific grinding energies, surface roughnesses and surface topography. The grinding forces, specific grinding energies and surface roughnesses of ultrasonic vibration assisted grinding are decreased when compared with that of general grinding, the surface damage cracks are small and the surface quality is better. However, when the ultrasonic vibration was applied to the different crystal surfaces of sapphire, the reduction rates of the grinding forces, specific grinding energies and surface roughnesses are different, the reduction rates of C-plane are the minimum, the reduction rates of M-plane and A-plane are larger, and the reduction rates of R-plane are the maximum. When ultrasonic vibration assisted grinding of four crystal surfaces of sapphire, the improvements effects of R-plane are the best, followed by the M-plane and A-plane, the improvement effect-ivenesses of C-plane are the minimum. This shows that the greater brittleness of workpiece material, the more obvious the effectiveness of ultrasonic assisted grinding on the machining quality.