Table of Content

10 March 2019, Volume 30 Issue 05

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Review on the Management at Mechanical Engineering Discipline of the National Natural Science Foundation of China in 2018

LAI Yinan;YE Xin;CAO Zhengcai;LI Hongwei

2019, 30(05):  505-513. 

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The applications, evaluations and fundings of projects at Mechanical Engineering Discipline (Division Ⅱ of Engineering Sciences) of the National Natural Science Foundation of China(NSFC) in 2018, as well as the research progresses of undertaking programs and the achievements of finished programs, were reviewed. Typical innovative achievements during project execution were summarized. Specific measures and corresponding effects of Mechanical Engineering Discipline were stated, such as academic exchange and cooperation, talent cultivation, and academic team construction.

Analyses and Control of Influence Factors for Multi-plate Wet Clutches in Fast Oil Filling Processes

LI Chunfu1;XI Junqiang2;LIU Chunying3

2019, 30(05):  513-518. 

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In order to obtain the ideal control effectivenesses of fast oil filling for clutches, the influences of hydraulic oil temperatures, engine rotating speeds and clutch rotating speeds on fast oil filling time for clutches were studied through theoretical analyses and simulation model. The research results show that the main factors affecting fast oil filling time of clutches are hydraulic oil temperatures and engine rotating speeds. A fast oil filling control strategy for clutches was proposed and tested. The test results show that the proposed control strategy is feasible.

Simulation and Experimental Investigation of Disturbance Flow Channels for Abrasive Flow Machining of Titanium Alloy Surfaces

ZHANG Li;HUANG Yi;CHEN Guoda;FU Yufei

2019, 30(05):  519-527. 

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Aiming at the problems of uneven surface roughness Ra after abrasive flow machining of titanium alloy workpieces with complex curved surfaces, a profiling constrained flow channel with disturbance structure for machining was proposed. Combining with SST k-ω turbulence model, discrete phase model（DPM）and Oka erosion model in computational fluid dynamics（CFD） software, the dynamics characteristics of abrasive flow for original flow channel and five kinds of disturbance flow channels with different disturbance angles were analyzed. The simulation results show that abrasive flow in the disturbance flow fields has greater turbulent kinetic energy，dynamic pressures and erosion rates on the workpiece surfaces than that of the original flow field without disturbance structures, and the erosion effects are the best when the disturbance angle is as 30°. The abrasive flow machining platform was built and the original flow channel and 30° disturbance flow channel were used for the machining tests based on simulation conditions. The testing results show that the surface roughness value Ra with different curvatures regions of workpieces are dispersed by using the original flow channel after 5 h machining, and the machining effectiveness is uneven, while the surface roughness value Ra of different workpiece regions has better uniformity by using disturbance flow channels after 5 h machining.

Distribution Control of Drive-cycle Adaptation Driving Forces for Multi-axis Special Hybrid Vehicles

ZHONG Heng1;LI Guanghan2;ZENG Xiaohua2;YANG Xiangdong1;XU Nuo1;WANG Rui1

2019, 30(05):  528-534. 

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Aiming at multi-axis electronically driven special hybrid vehicles, a coordinated distribution control strategy of driving forces was proposed based on drive-cycle adaptive recognition algorithm. Firstly, the C-WTVC and WUVSUB standard drive-cycles were divided into several kinematics fragments and the drive-cycles of vehicles were classified by clustering analysis. And the online recognition mechanism of vehicle drive-cycle was established based on simplified neural network algorithm. According to the drive-cycle recognition results, the pre-distribution control strategy of driving forces was developed, including average distribution, dynamic distribution and economy distribution, and the economy distribution coefficients were calculated based on the optimal system efficiency. Then, on the basis of pre-distribution control strategy of driving forces, the failure distribution control strategy of driving forces was proposed to ensure certainty driving ability at error modes according to the redundant configuration features of the vehicles. Finally, the coordinated distribution control strategy of driving forces was validated by simulation tests. The simulation results show that the proposed strategy may effectively guarantee the dynamic performance of vehicles under the states of power source failures and improve the reliability of the vehicles.

Preparation Technology and Experimental Study of Magnetic Abrasive Particles by Bonding Method

ZHAO Wenyuan1,2;LI Wenhui1,2;BAI Xiaoyun1;LI Xiuhong1,2;YANG Shengqiang1,2;HAO Zhiming1,2

2019, 30(05):  535-541. 

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The original bonding preparation technology had the problems of uneven mixing, and magnetic medium phases and abrasive phases would separate during the crushing processes, which might be easy to cause waste, so the magnetic abrasive particle preparation technology was proposed by a new bonding method. Under the same condition, two kinds of magnetic abrasive particles were prepared by two different technologies and the experiments were carried out. The workpiece surfaces were observed by scanning electron microscopy and three-dimensional ultra-depth of field microscopy, and the electronic balance was used to measure the quality changes of workpieces before and after finishing. The experimental results show that when the workpiece is polished by magnetic abrasive particles for 10 min based on new bonding method, the surface roughness value of Ra is decreased from 0.800 μm to 0.076 μm, and the maximum material removal rate is as 0.67 μm/min. Compared with magnetic abrasive particles prepared by the original bonding method, the magnetic abrasive particles prepared by the new bonding method have good microstructures, uniform distribution of each component and better processing performance.

Study on Dual Sliding Mode Control of EHA Active Suspensions

KOU Farong1;XU Jianan1;LIU Dapeng2;ZHANG Kai1;SUN Kai1

2019, 30(05):  542-548,553. 

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In order to restrain the pulsations of the main power outputs from the actuators of the EHA active suspension and to improve the dynamic performance of the vehicles, a dual-sliding mode control strategy for the EHA active suspensions was proposed. The dynamics model of EHA active suspensions was established, and the outer loop sliding mode controllers and the motor inner loop sliding mode controllers were designed based on the model reference. The main dynamic characteristics of the suspensions and the dynamic characteristics of the vehicles under different road excitations were simulated and analyzed. The bench tests were carried out. The simulation and experimental results show that, the dual sliding mode control strategy may restrain the pulsations produced by the main power outputs of the motor, make the actual output main forces track the ideal main power effectively, and improve the dynamic characteristics of the EHA active suspensions.

Dynamic Reliability Evaluation Approach for Electromechanical Systems Based on Probabilistic Model Checking

HOU Yi1;YANG Peilin1;XU Kai1;LIU Qing2;FAN Juanni2

2019, 30(05):  549-553. 

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To overcome the shortcomings of the traditional dynamic reliability analysis methods， a dynamic reliability evaluation approach for electromechanical systems was proposed based on probabilistic model checking.The concept of probabilistic model checking and a probabilistic model checker PRISM were introduced. State transitions of system components were represented using formal modeling language provided by the model checker， from which the formal model of electromechanical systems was built. Reliability indices were described by means of continuous stochastic logic formulas to establish the formal specifications of the reliability indices. Based on the formal model and formal specifications， reliability indices were computed automatically with the probabilistic model checker， and therefore dynamic reliability evaluation was achieved based on probabilistic model checking. The approach presented herein simplifies the modeling processes and improves the efficiency of dynamic reliability analysis for electromechanical systems.

Robust Design Optimization Analysis of Experimental Results in High Speed Milling of an Alloy Cast Iron

DU Maohua1;WANG Junhua2;ZHANG Jianfei1;WANG Shensong1

2019, 30(05):  554-559. 

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Aiming at the problems of high tool costs caused by severe tool wear in high speed machining of difficult-to-cut materials such as a new type alloy cast iron, milling experiments on Cr15Mo were carried out with lower-cost cemented carbide tools. The effects of cutting parameters on cutting forces and surface roughness were investigated. The optimum parameter combination of achieving the grinding effectiveness(Ra=0.4 μm) was obtained, i.e. cutting speed vc=800 m/min, axial cutting depth ap=0.4 mm and feed rate f=0.6 mm/r. Furthermore, the experimental results were theoretically analyzed by using robust design optimization principle. The research results show that the theoretical analysis results are in good agreement with the experimental ones, which provides an effective way of exploring multi-objective parameter optimization for simultaneously realizing high speed, high quality and low cost in machining processes.

Oil Film Thickness Model in Deformation Zones during Double Cold Reduction Rolling

CUI Yaya1;BAI Zhenhua1,2;LI Xiaofeng1;JIANG Mingguang1

2019, 30(05):  560-567. 

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In order to quantitatively predict the oil film thicknesses in deformation zones during double cold reduction rolling, combined with the equipment and technological characteristics of the emulsion direct application systems in double cold reduction mill were analyzed, based on the foundation of the mechanism of the plate-out oil film on strip surfaces and adhesion oil film on work-roll surfaces, a model of oil film thicknesses was established on top and bottom strip surfaces in deformation zones during double cold reduction rolling. And the influences of emulsion flow density, emulsion concentration, emulsion plate-out distance, entry rolling velocity, rolling bite angle, entrance deformation resistance, back tension stress, initial rolling oil dynamic viscosity, rolling oil viscosity pressure coefficient on the oil film thicknesses were quantitatively analyzed on top and bottom strip surfaces in deformation zones. This model was applied to the productions of a 1220 double cold reduction mill with the corresponding model calculation software was compiled. And the prediction of oil film thicknesses in deformation zones during double cold reduction rolling was achieved, which laid theoretical foundation for the control of lubricity during double cold reduction rolling.

Multi-working Condition Topology Optimization of Forklift Door Frames Based on Working Condition Risk Assessments

ZOU Kun;HOU Liang;BU Xiangjian;FANG Yikai

2019, 30(05):  568-577. 

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The standard door frame of a 3T internal-combustion forklift was taken as an example, the global nonlinear finite element analyses of the door frame systems were realized under the typical conditions. Based on working condition data (work durations, structure stresses and deformation displacements), the working condition risk assessment method and the concept of working condition RI were put forward. According to the working condition RI, an objective weighting coefficient distribution method was proposed for multi-working condition topology optimization. Using the compromise programming approach, taking the door frames weighted flexibility minimum as the goal function under the multi-working conditions, the topology optimization of door frames was realized. According to the optimization results, the structures of the door frames were redesigned, and the finite element analyses were carried out. The results show that compared with the traditional average distribution method, the risk assessment method may get better target values. Compared with the original structures of door frames, the maximum stresses of the new door frames under three typical conditions are reduced by 10.05%, 10.25% and 1.58% respectively, the maximum displacements are reduced by 13.17%, 12.93% and 8.28% respectively, and the mass is reduced by 7 kg.

State Overview and Technology Analysis of Biomachining

MA Fei;HUANG Hui;XU Xipeng

2019, 30(05):  577-585. 

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The technical background, development situation and machining mechanism of biomachining were introduced. The types of materials, microorganism species and the kinds of culture media used in machining processes were reviewed in detail. The reasons of no commercial applications yet were analyzed and the probable further trends of biomachining were forecasted. There will be reference values provided herein for further studying machining mechanism and expanding the application fields of biomachining.

Optimization Design Method for Mechanical Products Based on Structural and Performance Similarity Analysis Functions

KE Qingdi;LI Jie;LYU Yan;LIU Guangfu;SONG Shouxu

2019, 30(05):  586-594. 

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Considering the structural design, the operating performance demands and key parts design requirements were analyzed in predecisional remanufacturing mode. With analyzing the mapping relationship among design parameters and operating performance, the performance similarity analysis function was established by support vector machine (SVM) method. And based on the structural and performance similarity analysis function, the optimizing design method of structure for predecisional remanufacturing was proposed to optimize and modify the remanufacturing time domains for the products. Finally, the impeller part was taken as an example to validate the effectiveness and feasibility of the proposed method.

Mechanical Product Green Design Knowledge Update Based on Rough Set

ZHANG Lei;ZHENG Chenxing;ZHONG Yanjiu;QIN Xu

2019, 30(05):  595-602. 

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In order to meet the green demands of modern product design， it is particularly important to update the knowledges of mechanical product green design in time. Based on ontology， the green design knowledges of mechanical products were expressed and the decision tables of green design knowledges of mechanical products were built through rough sets. The rules of green product design knowledges were extracted and the rule set of green design knowledges of mechanical products was established. Combined with the knowledge needs of designers， the knowledge update in the mechanical product green design processes was realized through the matching of green design knowledge rules. Finally， the proposed methodology was successfully applied to the piston green design knowledge processes update.

Studies and Applications of Cobalt-rich Crust Core Samplers Mounted on “Jiao Long” Manned Submersibles

LU Dequan;DING Zhongjun;LI Dewei;LIU Baohua;YANG Lei;REN Yugang

2019, 30(05):  603-607. 

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Combining the requirements of scientific researches of ocean voyages and the international seabed mining area investigations, as well as the work characteristics of “Jiao Long” manned submersibles, the work environments of the core samplers，the working conditions and technical demands were analyzed when core sampling. A small motor-driven deep seabed cobalt-rich core sampler was designed and developed, which mounted on “Jiao Long” manned submersibles and was operated by the manipulators and was driven by the deep-sea batteries and the deep-sea motors. The structural compositions and performance parameters of the core sampler were introduced，and the drilling tests were carried out.  The testing results show that the designed core sampler may meet the requirements of deep-sea applications.

1D/3D Co-simulation and Improvements of Thermal Management for SUV Engine Compartments

TANG Youming1;LOU Yuanbo1，2;CHEN Ji2;LI Zhihong1;CHEN Yi2;HUANG Qiuping2;YUAN Zhiqun1

2019, 30(05):  608-614,629. 

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During the forward R&D periods of a sport utility vehicle(SUV)，in order to solve the problems of engine outlet water temperature was rather higher in low or medium speed climbing and high speed climbing conditions, 1D/3D co-simulation tools were used to analyze the flow field characteristics of engine compartments and the performances of cooling systems. It is found that the design of the existing anti-collision beam affects the air flows and thus affects the engine outlet temperatures. An improved scheme was proposed based on the simulation results, the outlet water temperatures of improved engines are dropped 6.1 ℃ and 6.4 ℃ under the middle or low speed climbing conditions and high speed climbing condition respectively, and the co-simulation improved scheme is verified feasible. In the periods of the sample car，the vehicle thermal balance tests were performed on the chassis dynamometer, and the large mass flow fans and axial flow fans were used to simulate the inflow air during driving.  By comparing the improved simulation results with the experimental data, which verify the accuracy of the co-simulation model is higher than 95%.

Analysis for In-situ Corrosion-Multiaxial Fatigue Behaviors of 7075 Aerospace Aluminum Alloys

LIU Chenchen1;CHEN Yajun1;LI Ke1;WANG Chuan2

2019, 30(05):  615-621. 

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Focusing on the fatigue failure issues of the servicing aircrafts in coastal areas, non-corrosion and 3.5% NaCl salt spray in-situ corrosion multiaxial fatigue tests with 200 MPa, 250 MPa and 300 MPa of equivalent stresses were conducted on 7075 aluminum alloys with self-developed corrosion devices. Comparative analyses of multiaxial fatigue failure mechanism were implemented by cyclic loop and fracture morphology and modified Manson-Coffin-Basquin(MCB) criterion was brought up for life prediction. Results show that with the increase of equivalent stresseses, multiaxial fatigue life of both non-corrosion and in-situ corrosion 7075 aluminum alloy decreases. Under the same equivalent stresses, multiaxial fatigue life of in-situ corrosion specimens significantly deduces and area of both axial and torsional hysteresis loops augment in different extents compared with the non-corrosion specimens. With the equivalent stresses of 200 MPa, multiaxial fatigue life of specimen is 99 675 cycles under non-corrosion condition while decreases to 55 284 cycles under in-situ corrosion conditions. Cracks initiate at the outer surfaces of specimens in non-corrosion and in-situ corrosion environments. Sized salt occurs at the crack propagation regions for in-situ corrosion specimens. Inducing the influence of loading conditions and environmental factors, the modified MCB criterion gives fine prediction results that all predicted life values are within 2x scatter bands.

Influences of Two-dimensional Electro-hydraulic Flutters on Cold Extrusion Forming

YANG Qinghua;QIN Zhengyong;WANG Zhiheng;BAO Guanjun

2019, 30(05):  621-629. 

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Aiming at the problems of large die wear in cold extrusion forming caused by large deformation resistance, metal flow difficulty, a two-dimensional electro-hydraulic flutter assisted cold extrusion forming process was proposed. Deform-3D FEA software was used to establish the finite element model of two-dimensional electro-hydraulic flutter assisted cold extrusion forming, and the forming processes without flutter mode, forming processes under axial flutter excitation, forming processes under radial flutter excitation and forming processes under two-dimensional flutter excitation were compared and analyzed. The research results show that compared with the non-flutter forming mode , the forming loads are decreased by 26.1%, 13.2% and 5.7% under the two-dimensional flutter excitation, the axial flutter excitation and the radial flutter excitation respectively. The forming load is the smallest under the two-dimensional flutter excitation forming mode, and the metal flow velocity is further increased, and the stress field distribution is more uniform.