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Topology Optimization with Aperiodic Load Fatigue co.straints Based on Bidirectional Evolutionary Structural Optimization

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co.puter Modeling in Engineering & Sciences 2022年第1期130卷 499-511页

作者： Yongxin Li Guoyun Zhou Tao Chang Liming Yang Fenghe Wu Heavy-Duty Intelligent Manufacturing equipment Innovation Center of Hebei Province School of Mechanical EngineeringYanshan UniversityQinhuangdaoChina Space Star Technology co. Ltd.BeijingChina

Because of descriptive nonlinearity and co.putational inefficiency,topology optimization with fatigue life under aperiodic loads has developed slowly.A fatigue co.straint topology optimization method based on bidirectional evolutionary structural optimization(BESO)under an aperiodic load is proposed in this *** viewof the severe nonlinearity of fatigue damagewith respect to design variables,effective stress cycles are extracted through transient dynamic *** on the Miner cumulative damage theory and life requirements,a fatigue co.straint is first quantified and then transformed into a stress ***,a normalized termination criterion is proposed by approximatemaximum stress measured by global stress using a P-normaggregation ***,optimization examples show that the proposed algorithm can not only meet the requirements of fatigue life but also obtain a reasonable co.figuration.

关键词： Topology optimization bidirectional evolutionary structural optimization aperiodic load fatigue life stress co.straint

Insights into microstructural evolution and deformation behaviors of a gradient textured AZ31B Mg alloy plate under hypervelocity impact

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Journal of Materials Science & Technology 2021年第32期91卷 40-57页

作者： Weigui Zhang Kun Li Runqiang Chi Susheng Tan Peijie Li beijing Innowind Aerospace equipment co. Ltd.Beijing 100854China co.lege of mechanical and Vehicle Engineering Chongqing UniversityChongqing 400044China The State Key Lab of mechanical Transmissions Chongqing UniversityChongqing 400044China Hypervelocity Impact Research Center Harbin Institute of TechnologyHarbin 150080China Department of electrical and co.puter Engineering and Petersen Institute of Nanoscience and Engineering University of PittsburghPittsburghPennsylvania 15260USA Department of mechanical Engineering Tsinghua UniversityBeijing 100084China

We have for the first time elucidated the microstructural evolution and deformation behaviors of a gradient textured AZ31 B Mg alloy plate under the ultrahigh strain rate of ~10~6 s^(-1) that is generated by a two-stage light gas gun with the hypervelocities of 1.6-4.4 km s^(-1). The hypervelocity impact cratering behaviors indicate that the cratering deformation of AZ31 B Mg alloy is mainly affected by the inertia and strength of the target material. The crater prediction equation of AZ31 B Mg alloy target under impact velocity of 5 km s^(-1) is given. The 2017 Al projectile co.pletely melts in the Mg alloy target plate at the impact velocities of 3.8 km s^(-1) and 4.4 km s^(-1), and the microstructural evolution around the crater is: dynamic recrystallization zone, high-density twinning zone, low-density twinning zone, and Mg alloy matrix. It is found that the dynamic recrystallization, twinning and cracking are the main deformation behaviors for the AZ31 B Mg alloy to absorb the shock wave energy and release the stress generated by the hypervelocity impact. The main plastic deformation mechanisms of the Mg alloy target during hypervelocity impact are twinning and dislocation slip. Microstructure analysis shows the interactions of twins-twins, dislocations-dislocations, and twins-dislocations determine the strain hardening during the hypervelocity impact process, which eventually co.tributes the dynamic mechanical properties. The evolution of microhardness around the crater further demonstrates the microstructural evolutions and their interactions under the hypervelocity impacts.

关键词： AZ31B Mg alloy plate Hypervelocity impact Deformation behavior Shock wave propagation Microstructural evolution

AUTOREGRESSIVE MODEL AND POWER SPECTRUM CHARATERISTICS OF CURRENT SIGNAL IN HIGH FREQUENCY GROUP PULSE MICRO-ELECTROCHEMICAL MACHINING

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Chinese Journal of mechanical Engineering 2006年第2期19卷 260-264页

作者： TANG Xinglun ZHANG Zhijing ZHOU Zhaoying YANG Xiaodong Department of Precision Instrument ＆ Mechanics Tsinghua UniversityBeijing 100084 China School of mechanical ＆ Vehicle Engineering Beijing Institute of TechnologyBeijing 100084 China equipment ＆ Energy Department Guizhou Branch of Aluminum Co. Ltd.Guiyang 550014 China

The identification of the inter-electrode gap size in the high frequency group pulse micro-electrochemical machining （HGPECM） is mainly discussed. The auto-regressive（AR） model of group pulse current flowing across the cathode and the anode are created under different situations with different processing parameters and inter-electrode gap size. The AR model based on the current signals indicates that the order of the AR model is obviously different relating to the different processing co.ditions and the inter-electrode gap size; Moreover, it is different about the stability of the dynamic system, i.e. the white noise response of the Green＇s function of the dynamic system is diverse. In addition, power spectrum method is used in the analysis of the dynamic time series about the current signals with different inter-electrode gap size, the results show that there exists a strongest power spectrum peak, characteristic power spectrum（CPS）, to the current signals related to the different inter-electrode gap size in the range of 0～5 kHz. Therefore, the CPS of current signals can implement the identification of the inter-electrode gap.

关键词： Electrochemical machining Inter-electrode gap Autoregressive(AR) model Power spectrum

Degradation characteristics of insulation near aluminium foil edges inside dry-type bushing co.es under electrothermal co.pound stress

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High Voltage 2022年第6期7卷 1153-1164页

作者： Ming Chen Xuandong Liu Yuhang Shao Gaoyi Shang Qiaogen Zhang Hao Tang Libao Liu State Key Laboratory of electrical Insulation and Power equipment School of Electrical EngineeringXi'an Jiaotong UniversityXi'anChina China Electric Power Research Institute BeijingChina Nanjing Electric High Voltage Bushing co. NanjingChina

Insulation breakdown of dry-type valve-side bushing co.es under electrothermal co.pound stress has beco.e a key factor limiting the safe and stable operation of the co.verter *** on slices of the real bushing co.e,it is observed for the first time that fold,peeling off,and fracture defects exist near the aluminium(Al)foil edge,acco.panied by many metal spikes with a curvature radiuselectrical tree model is designed to simulate insulation defects near aluminium foil edges inside dry-type bushing co.es,whose insulation degradation characteristics under electrothermal co.pound stress are investigated *** results show that high temperature significantly increases the dielectric loss heat energy density and Joule heat energy density,accelerating the insulation degradation near Al foil *** parallel crepe paper interface significantly accelerates the growth of electrical trees under AC-superimposed positive DC voltage,while this effect is not significant under AC *** the crepe paper co.sists of wooden fibres of 10μm diameter,the electrical trees tend to grow along interfaces between fibres and epoxy resin to form“feathery”electrical trees in epoxy resinimpregnated paper samples.

关键词： stress insulation co.pound

Development of an oscillating grinding machine tool based on error analysis

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Science China(Technological Sciences) 2020年第6期63卷 912-922页

作者： WANG LiPing WANG Dong WANG Bo LI WeiHua Institute of Manufacturing Engineering Department of Mechanical EngineeringTsinghua UniversityBeijing 100084China Beier Machine Tool Works co. LTDBeijing 102444China

Oscillating grinding machine tool is the co.e equipment when machining crankshaft pin journal,which directly determines the final *** paper describes the development of an oscillating grinding machine tool based on error ***,the error analysis of oscillating grinding for crankshaft pin journal is carried out,including the effect on machining accuracy caused by each error and co.responding error *** results show that the tracking error of X-axis has the greatest influence on the grinding accuracy of pin journal,thus,the grinding carriage feed system is the critical co.ponent of an oscillating grinding machine tool,which should be given priority during the development ***,the development of an oscillating grinding machine tool is *** whole structure is given,and the grinding carriage feed system is emphatically presented involving drive mode and assembly *** co.ponents of the oscillating grinding machine tool are also ***,some grinding experiments are performed on the prototype,and the results show that all workpieces are qualified under different co.ditions,which verify the performance of the developed oscillating grinding machine tool.

关键词： oscillating grinding machine tool error analysis crankshaft pin journal grinding carriage feed system

Interfacial Bonding Mechanism and mechanical Performance of co.tinuous Fiber Reinforced co.posites in Additive Manufacturing

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Chinese Journal of mechanical Engineering 2021年第1期34卷 131-141页

作者： co.gze Fan Zhongde Shan Guisheng Zou Li Zhan Dongdong Yan State Key Laboratory of Advanced Forming Technology and equipment Beijing 100044China Department of mechanical Engineering Tsinghua UniversityBeijing 100084China Nanjing University of Aeronautics and Astron autics Nanjing 210016China China Academy of Mach inery Science&Technology Group co. Ltd.Beijing 100044China

The additive manufacturing of co.tinuous fiber co.posites has the advantage of a high-precision and efficient forming process,which can realize the lightweight and integrated manufacturing of co.plex ***,many void defects exist between layers in the printing process of additive manufacturing;co.sequently,the bonding performance between layers is *** bonding neck is co.sidered a key parameter for representing the quality of interfacial *** this study,the formation mechanism of the bonding neck was co.prehensively ***,the influence of the nozzle and basement temperatures on the printing performance and bonding neck size was ***,CT scanning was used to realize the quantitative characterization of bonding neck parameters,and the reason behind the deviation of actual measurements from theoretical calculations was *** the nozzle temperature increased from 180 to 220℃,CT measurement showed that the bonding neck diameter increased from 0.29 to 0.34 mm,and the cross-sectional porosity reduced from 5.48%to 3.22%.Finally,the fracture mechanism was studied,and the influence of the interfacial bonding quality on the destruction process of the materials was *** co.clusion,this study can assist in optimizing the process parameters,which improves the precision of the printing parts and performance between the layers.

关键词： 3D printing Thermoplastic resin co.tinuous fiber Additive manufacturing

Nonlinear impedance co.trol with trajectory adaptation for co.laborative robotic grinding

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Science China(Technological Sciences) 2023年第7期66卷 1928-1936页

作者： HAN FengTao TAM SikYuen CAO ZhiHong ZHAO XingWei TAO Bo DING Han State Key Laboratory of Intelligent Manufacturing equipment and Technology School of Mechanical Science and EngineeringHuazhong University of Science and TechnologyWuhan 430074China State Key Laboratory of Intelligent Manufacturing System Technology for co.plex Products Beijing Institute of Electronic System EngineeringBeijing 100854China ROKAE(beijing)Technology co. Ltd.Beijing 100193China

Stiffness adjustment is an important feature of human arm *** adaptive variable impedance co.trol can adapt to the robotic stiffness,but may result in a large *** this paper,nonlinear impedance co.trol is proposed for co.laborative robotic grinding,where nonlinear force feedback is designed to co.pensate for the nonlinear stiffness of the ***,the interaction system can be linearization to ensure the system ***,a target trajectory adaptation strategy is studied to ensure the force tracking ***,switching law between trajectory tracking and force tracking is proposed when the robot performs a co.plex grinding *** stability of the switch co.trol as well as the trajectory adaptation law is *** are co.ducted in a robotic grinding test rig,where the robot is used to grind a turbine *** results show that the nonlinear impedance co.trol can obtain stable grinding force,and have better grinding quality than the linear impedance co.trol.

关键词： impedance co.trol robotic grinding trajectory adaptation force tracking

Experimental Study on Oxy-Fuel co.bustion and NO Emission in a Spouted-Fluidized Bed with under Bed Feeding

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Journal of Thermal Science 2021年第4期30卷 1132-1140页

作者： XU Mingxin WU Yachang WU Haibo OUYANG Haodong ZHENG Shu LU Qiang National Engineering Laboratory for Biomass Power Generation equipment North China Electric Power UniversityBeijing 102206China Shenhua Guohua Electric Power Research Institute(beijing)co. Ltd.Beijing 100025China

The spouted-fluidized bed is modified from the classical fluidized bed device,which co.bines the features of spouted and fluidized *** the present work,the performance of oxy-fuel spouted-fluidized bed co.bustion with under bed feeding and its effect on NO emission were systematically *** results revealed that it was feasible to use a spouted-fluidized bed co.bustor for oxy-fuel co.bustion with real flue gas *** transition from air co.bustion to oxy-fuel co.bustion was smooth and the co.centration of co.(2) in the flue gas co.ld be as high as 90%steadily(dry base).Increasing the reaction temperature exhibited a negative effect on NO *** with that under the shallow bed,the co.centration of NO in the flue gas was lower under the deep bed ***,the utilization of crush particles was favorable for suppressing NO emission because of the promoted mixing between co.l particles and solid bed ***,the addition of limestone was proven to undesirably increase the NO emission during oxy-fuel spouted-fluidized bed co.bustion.

关键词： spouted-fluidized bed oxy-fuel co.bustion transition NO emission bed materials limestone

Digital twin model of gas turbine and its application in warning of performance fault

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Chinese Journal of Aeronautics 2023年第3期36卷 449-470页

作者： Minghui HU Ya HE Xinzhi LIN Ziyuan LU Zhinong JIANG Bo MA Key Lab of Engine Health Monitoring-co.trol and Networking of Ministry of Education Beijing University of Chemical TechnologyBeijing 100029China beijing Key Laboratory of High-end mechanical equipment Health Monitoring and Self-Reco.ery Beijing University of Chemical TechnologyBeijing 100029China Capital Aerospace Machinery co.poration Limited Beijing 100076China Hangli(Group)Industrial co. LtdChengdu 611936China

The digital twin-driven performance model provides an attractive option for the warn gas-path faults of the gas ***,three technical difficulties need to be solved:(1)low modeling precision caused by individual differences between gas turbines,(2)poor solution efficiency due to excessive iterations,and(3)the false alarm and missing alarm brought by the traditional fixed threshold *** paper proposes a digital twin model-based early warning method for gas-path faults that breaks through the above obstacles from three ***,a novel performance modeling strategy is proposed to make the simulation effect close to the actual gas turbine by fusing the mechanism model and measurement ***,the idea of co.trolling the relative accuracy of model parameters is *** introduction of an error module to the existing model can greatly shorten the modeling *** third solution focuses on the early warning based on the digital twin model,which self-learns the alarm threshold of the warning feature of gas-path parameters using the kernel density *** proposed method is utilized to analyze actual measured data of LM2500+,and the results verify that the new-built digital model has higher accuracy and better *** co.parisons show that the proposed method shows evident superiority in early warning of performance faults for gas turbines over other methods.

关键词： Gas turbine Digital twin model Gas-path fault warning Deviation degree analysis Performance simulation