Table of Content

10 August 2017, Volume 28 Issue 15

Previous Issue    Next Issue

Actuator Configuration of Optimal Motion Posture for Underactuated Hopping Robots

MENG Xiangyan;GE Wenjie

2017, 28(15):  1765-1770. 

Asbtract ( )   PDF (572KB) ( )  

References | Related Articles | Metrics

This paper dealt with the trajectory planning problems of three joints underactuated hopping robots with one passive joint. Firstly, the dynamics model of the robot was established. Secondly, the angles of three joints were obtained by the numerical iterative method and the optimization objective was minimization of the active joint torques. Finally the joint angle trajectory, motion postures and driving torques of three kinds of actuator configurations were obtained by simulation, then the differences were analyzed and compared. The results show that the proposed motion planning method is feasible, and the hopping robot with actuation at hip and ankle is the most reasonable.

Control Strategy Optimization of Plug-in Hybrid Electric Vehicle Based on Driving Cycles

GAO Jianping1;ZHANG Leimin1;SUN Zhongbo2;XI Jianguo1

2017, 28(15):  1770-1777. 

Asbtract ( )   PDF (870KB) ( )  

References | Related Articles | Metrics

According to the operation types and operation line, the city bus coverage area, 20 representative bus lines on the 20 bus driving data acquisition for a month were selected, a reasonable classification analysis method combined with the K mean clustering algorithm of principal component analysis and optimization of the implementation of each segment of the short stroke, thus the driving cycle that reflects the running characteristics of the city bus was fitted. The effectiveness and necessity of the Isight simulation platform was verified by the AVL-Cruise simulation platform, and the optimization of the key parameters of the vehicle control strategy for the city bus was introduced. The results show that the overall fuel consumptions of the vehicles are reduced by 8.7% and the relative errors of the simulation results with the RCP tests are only 2%, which verifies the effectiveness of the optimized control strategy.


Data Processing in Residual Stress Measurements Using Contour Method

XIE Guozhen1,2,3;WU Yunxin1,2,3;GONG Hai1, 2,3;LI Chen4;LIU Yaoqiong1,4;JI Hao4;ZHANG Wei4

2017, 28(15):  1778-1783. 

Asbtract ( )   PDF (667KB) ( )  

References | Related Articles | Metrics

The quenched residual stresses of T-shaped aluminum alloy were tested using the contour method, and the data processing of measurement errors was focused. The final contours were calculated by envelop processing, contour averaging, Gauss mixed model fitting and node interpolation, and then were reversed and loaded to the stress reconstruction FEM model as boundary conditions. Then the mapping of residual stresses along the cross section to be measured were obtained. The stresses at the edge were modified using X-ray diffraction method. The comparisons of measured results with quenching FEM results were analyzed via statistical methods. The results indicate that the quenched residual stress fields may be described accurately by combining contour method and X-ray diffraction method. The maximum tensile residual stress of the T-shaped specimen occurs at the junction of the rib and web, and close to the web.

Interference Detection Method on Stationary Internal Toroidal Gear Based on Discrete Model

HONG Mei;YAO Ligang

2017, 28(15):  1784-1789. 

Asbtract ( )   PDF (649KB) ( )  

References | Related Articles | Metrics

An interference detection method was put forward to effectively solve the problems of machining local and global interference phenomenons on stationary internal toroidal gear tooth surfaces. The introduction to interference detection plan clusters and the structure of interference detection line clusters were to obtain stationary internal toroidal gear tooth surface and tool scanning body discretization model. By using stationary internal toroidal gear tooth surface and tool scanning body discretization model, and through solving the cutting plane tool centers, stationary internal toroidal gear tooth surface machining local and global interference areas were determined. And through the example analyses, the feasibility of machining interference detection method of stationary internal toroidal gear tooth surface was further verified.

Lift Estimation of HRWs in Hovering and Forward Flights

WANG Xiaoyi;ZHANG Yuhua;DONG Yinping;QIU Han;CHEN Fuqiang;QIU Zhizhen

2017, 28(15):  1789-1795. 

Asbtract ( )   PDF (639KB) ( )  

References | Related Articles | Metrics

The lift models of HRW in hovering and forward flights were proposed based on analyses of the motion models of HRW and flow characteristics on the surfaces of the wing. According to the motion characteristics of HRW, the analytical expressions of lift were further derived. The lifts under different flight conditions were calculated using derived formula and numerical simulation based on CFD software respectively with same HRW prototype parameters, by which the changing rule of HRW lift in hovering and forward flights could be also got. The comparisons of lift curves between the theoretical calculation and the numerical simulation demonstrated that the analytical method to estimate lift of HRW is  effective and feasible. The research results mentioned above may provide important theoretical guidance for the parameter designs and lift prediction of the HRW air vehicles.

Firefly Neural Network Failure Symptom Structure Reliability Prediction Based on Blind Number Theory

DONG Qing;XU Gening

2017, 28(15):  1796-1805. 

Asbtract ( )   PDF (1005KB) ( )  

References | Related Articles | Metrics

Under any feasibility conditions, the reliability of large arm structure with failure symptoms was difficult to be determined due to various uncertain factors of load effects and resistances in notch-crack propagation. The firefly neural network prediction method of the reliability of structure with failure symptom was presented based on the blind number theory by building a blind number failure symptom structure reliability model (BNFSSRM),  serial type firefly neural network prediction model consisting of far field stress prediction sub-model (STFNN-FFSPS) and reliability prediction sub-model (STFNN-RPS) of damaged structure. On the basis of the stress-strength interference model, the firefly neural network being as a forecasting method, the idea converting the uncertainty problems to blind numbers was introduced into the interference model of intensity factors of notch-crack and fracture toughness according to the rule of notch-crack instability propagation, and the reliability of notch-crack damaged structure was obtained by the experiments and finite element simulation combined with STFNN-FFSPS under typical working conditions. The reliability being taken as the target output and the notch-crack size being as the input data of expanded samples, the real-time prediction of reliability of damaged structure may be achieved by BNFSSRM and STFNN-RPS, thus realizing the evaluation of the capacity of the structure resistant to failure and determining the orders of different conditions out of the feasible condition regions. QY130 remanufacturing arm structure was taken as an example and the effectiveness of the proposed method were verified.

Compilation Method of Fatigue Experimental Load Spectrum of Loader Working Devices

WAN Yipin1;SONG Xuding1;YUAN Zhengwen2;YU Luping1

2017, 28(15):  1806-1811. 

Asbtract ( )   PDF (592KB) ( )  

References | Related Articles | Metrics

In order to study the fatigue performance of the loader working devices, a method was proposed considering the load mean characteristics for the preparation of load spectrum of fatigue test program. The loads of the pin in 4 typical material shovel loading operations were collected, and the pin loads were converted to equivalent loads at the tip of the bucket. According to the load characteristics, each operation period was divided into 4 sections, which were no load transportation, shovel digging operation, heavy load transportation and unloading operation. The rain flow counting method was adopted to analyze the mean value distributions and amplitude distributions of the 4 sectional loads. The results show that the distributions of load mean and amplitude are independent and obey normal distribution and Weibull distribution with three-parameters respectively. Frequencies were extrapolated and synthesized and the load spectrum of the 8 stage load spectrum and the variable mean fatigue test program were worked out according to the mean amplitude probability distribution function and the wave center method. The method and results of load spectrum compilation provide references for fatigue life prediction and reliability bench test of the loader working devices.

Knowledge Personalized Push Based on Context Constraint

WANG Youyuan1;ZHAO Lu2;ZHANG Le'en3

2017, 28(15):  1812-1819. 

Asbtract ( )   PDF (684KB) ( )  

References | Related Articles | Metrics

Semantic description and analysis of context informations as restrictive condition between contextual concepts for product designs were presented, and a knowledge clustering method was proposed based on context constraints was proposed. Meanwhile, Bayesian theory was used to semantic annotation of clustering knowledges, and the semantic similarity and relevance of annotation concept and demand concept were calculated to expand the scopes of search. Experimental results show that the method may effectively improve accuracy and efficiency of knowledge query and push in the processes of product designs.

Investigation of Discharge Gap in Orthogonal Magnetic Field Assisted Dry Single-spark EDM

JIA Jianyu;WANG Yanqing;YANG Shengqiang;LI Wenhui

2017, 28(15):  1820-1825,1847. 

Asbtract ( )   PDF (717KB) ( )  

References | Related Articles | Metrics

The experiments for comparing the discharge gaps in EDM and MF-EDM were conducted. Then the effects of magnetic field strength, open circuit voltage, capacitance and extension length of toolelectrode on discharge gaps were analyzed.The experimental results show that the discharge gaps increase with the increases of the magnetic field strengths. The open-circuit voltages and discharge capacitances do not have significant effects on the discharge gaps. In addition, the increases of the electrode extension lengths lead to the decreases of discharge gaps. Finally, the fractional factorial analysis of the experimental data shows that the magnetic field strengths, the extension lengths of toolelectrodes and their interaction are the main factors that affect the discharge gaps in MF-EDM.



Static and Dynamic Performances of a Three-pad Gas Foil Journal Bearing

FENG Kai;HU Xiaoqiang;ZHAO Xueyuan;LI Wenjun

2017, 28(15):  1826-1835. 

Asbtract ( )   PDF (931KB) ( )  

References | Related Articles | Metrics

A novel three-pad gas foil bearing was analyzed herein. The stiffness was modeled by considering the Coulomb's friction. The static and dynamic characteristics of the bearing were obtained by solving the Reynolds equation. The effects of rotor speed, load, pad preload and installation angle on the bearing performances were discussed. Static results indicate that the preload may increase the load capacity significantly especially at high rotor speed. The installation angle effecting on the load capacity is based on the law of sine/cosine rules. With the increasing of rotor speeds, the installation angle corresponding to the maximum load capacity decreases constantly, and stabilizes at 70° eventually. Dynamic results show that the direct stiffness increases significantly with the increasing of the pad preload. However, the damping only has slightly variation. The installation angle effecting on the stiffness and damping is also based on the law of sine/cosine rule. And two direct stiffnesses show the trend of asynchronization with the increasing of installation angles. Meanwhile, two direct dampings also vary asynchronously.

Design and Analysis of Wheel-track Composite Loading Locomotion System with High Adaptability

WANG Shukun;CAO Xiaojie;ZHANG Lianqing;ZHU Renjie;ZHANG Bo

2017, 28(15):  1835-1841. 

Asbtract ( )   PDF (810KB) ( )  

References | Related Articles | Metrics

A new type of travel mechanism combined wheel and track was based on different kinds of complex unstructured pavement conditions. The wheel-track composite mechanism was mainly composed of diameter-variable wheel component and crawler system. This structure gave full play to the characteristics of the high efficiency of the wheel structure，and shown the crawler system which enhanced the stability of the whole machine and good adaptability to the ground. Simultaneously, an adaptive loading-lifting platform was designed. In order to achieve the horizontal platform always, the closed-loop control was established to the degree of platform by using Kalman filter algorithm through Gyroscope. A dynamic model was established for verification of climbing stairs performances by using RECURDYN. The results show that this new locomotion system has good adaptability for complex conditions and stability for maintaining loading platform, which has certain reference values for the design of associated transport machinery.

Reliability Analysis of Left-truncated Weibull Distribution Modified by BB Algorithm

KONG Xiangfen1;ZHANG Kaiqi1;ZHANG Jun2;ZHANG Fei2

2017, 28(15):  1842-1847. 

Asbtract ( )   PDF (557KB) ( )  

References | Related Articles | Metrics

A reliability analysis was done based on the failure data of B737-800 main landing gear shock strut oil leakages herein, which came from a domestic airlines' electronic records, in consideration of the life distribution type and parameter estimation method. The characteristics of data preliminarily demonstrated that the life distribution type might be left-truncated two parameter Weibull distribution, logarithmic normal distribution or exponential distribution. Next, the parameters corresponding to three types of distributions were estimated by using the MLE method. Then, the Kolmogorov-Smirnov(K-S) hypothesis test, which modified by BB algorithm and goodness-of-fit test , was used to identify and confirm the life distribution function model. The analysis results show that the distribution of the data is left-truncated two parameter Weibull distribution. In the end, reasonable maintenance plan and optimized maintenance scheme are provided.

Fault Diagnosis Method of Instantaneous Angular Speed Based on EEMD and Polar Representation

WANG Shuai1，2;XIANG Yang1，2;WANG Lei1，2

2017, 28(15):  1848-1853,1861. 

Asbtract ( )   PDF (744KB) ( )  

References | Related Articles | Metrics

In order to extract the time domain characteristic parameters and guarantee the diagnosis accuracy in high speed V-engine with high number of cylinders, the fault diagnosis method of IAS was studied by taking V12 diesel engine with unequal firing angel as object based on EEMD and polar representation. Results show that intrinsic mode function 6 (IMF6) has a main frequency component of 8.3Hz (0.5 harmonic order). The 0.5 harmonic order components are extracted effectively by EEMD and its amplitude may be used as an characteristic value of misfire faults. The misfire cylinder may be located accurately through the combination of polar representation, 0.5 harmonic order phases and its change rules.

Multidisciplinary Flexible Design and Decision Based on Mixed Game

CHEN Liang;LI Liaoping

2017, 28(15):  1854-1861. 

Asbtract ( )   PDF (639KB) ( )  

References | Related Articles | Metrics

For the problems of multidisciplinary and multiobjective design and decision, a novel method was given using game theory and flexibility mechanism to model and solve the problems. The coupling relations among disciplines or targets were presented by mixed game, and the mixed game model framework and the corresponding solving methods were proposed. Considering the influences of uncertainty and changes, in order to make the design and decision be flexible, the satisfaction function of performance was introduced to express the flexible design requirements, and the flexible range solutions of design variables were sought rather than a point solution to increase product flexibility. The flexible range solutions were in the feasible design spaces, where every discipline's performances were satisfactory and close to the expected values and had good stability. Probabilistic representation was used to model the corresponding design performance changes, and design preference index (DPI) was introduced to evaluate the flexible design. Finally, a gear reducer design example was given to verify the feasibility and effectiveness of the proposed method.

Design and Timing Control for Centrifugal Compressor Impeller Predecissional Remanufacturing

SONG Shouxu;BU Jian;KE Qingdi

2017, 28(15):  1862-1869,1878. 

Asbtract ( )   PDF (787KB) ( )  

References | Related Articles | Metrics

Aimed at the present situations of remanufacturing components that often occured the issues of ‘lag of remanufacturing' or ‘remanufacturing in advance', a design method of predecisional remanufacturing and timing control for centrifugal compressor impellers was presented herein. By choosing vital component characteristic structures, combined with the theory of fatigue life and basic design method of impellers, the structure and performance of the service mapping model was established, the predecisional remanufacturing design of vital components was implemented. Through the optimization of structure parameters, changing the service performances and remanufacturing points of components, and matching with product performance degradation inflection points, the predecisional remanufacturing timing control was implemented. Taking the PCL8L type of centrifugal compressor impeller as an example, three structure characteristis of impellers(outlet angle, entrance angle and the trailing edge thickness)were selected, the quantitative relationship among the impeller structure characteristics and the service fatigue lifes was built. Then, through the simulation analysis and considering the current preventive maintenance requirements, the predecisional remanufacturing of timing control for centrifugal compressors.

Design of Wing Shapes and Flight Operations of Commercial Aircrafts for Green Aviation

WANG Yu1;DENG Haiqiang1;YANG Zhenbo1;ZHANG Shuai2

2017, 28(15):  1870-1878. 

Asbtract ( )   PDF (725KB) ( )  

References | Related Articles | Metrics

The effects of the wing shape parameters and the flight conditions on the noises during approach, on the emissions during landing and takeoff (LTO) cycle, the total emitted greenhouse gas, the direct operating cost and the endurance were presented. The multiple perspectives of the environmental impact, airline operations and passenger experience were analyzed based on the multidisciplinary analysis framework. The analysis results indicate that the flap with fewer gaps may contribute to the noise reduction; meanwhile, a larger wing area is needed to compensate for the loss of aerodynamic effects. Reducing the cruise altitude may result in a decrease of the global warming impact but the increases of direct operating costs(DOC) and endurance. The steeper approach may reduce both of the noises during approach and the emissions during LTO. Considering economy and environmental impacts, two typical configurations of aircraft with the corresponding flight conditions are achieved after multi-objective optimization.

A Hexahedral Element Applied to Coining Simulations

YI Guofeng1;LI Qiaomin2;ZHONG Wen2;LIU Yuqi2

2017, 28(15):  1879-1883,1889. 

Asbtract ( )   PDF (597KB) ( )  

References | Related Articles | Metrics

In order to overcome the hourglass problems of the one-point integrated element used in the dynamic explicit coining simulation system COINFORM, a new multi-point integrated 8-node hexahedral element was proposed herein. The generation mechanism of volume locking and shear locking was deduced. With the assumed strain method, the volumetric locking in near-incompressible deformations and the shear locking in bending situations were avoided. Combined with COINFORM, the proposed hexahedral element was applied to the coining simulation of a Ag999 commemorative coin. The results show that the locking phenomena of the multi-point integrated element are successfully avoided in the coining simulation, and the proposed element achieves higher computational accuracy than that of the existing element of COINFORM.

Design and Simulation of Annular Clearances for Ultrasonic Plasticizing Injection Systems

LI Xia;TIAN Haigang;ZHANG Weiwei;ZHANG Sanchuan

2017, 28(15):  1884-1889. 

Asbtract ( )   PDF (620KB) ( )  

References | Related Articles | Metrics

In order to obtain the optimal annular clearance sizes of ultrasonic plasticizing injection systems, a theoretical study of annular clearances of ultrasonic tool heads and plasticizing cavities were proceeded, the theoretical formula of annular clearance leakages and frictions of ultrasonic tool head were acquired. Then annular clearance finite element models of ultrasonic tool heads and plasticizing cavities was established, the theoretical values and simulation values of annular clearance leakages and tool head frictions were studied and compared by mean of ANSYS CFX module, and the influence laws of annular clearance sizes and inlet total pressures on leakages and frictions of tool head were analyzed. The results show that annular clearances of ultrasonic tool head and plasticizing cavities are as 0.10~0.15mm, total pressures of inlet is 10~20MPa, leakages of annular clearances and frictions of tool head are smaller.