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Defence technology（防务技术） 2021年第3期17卷 884-897页

作者： Zi-xuan Li Guo-lai Yang Feng-jie Xu Li-qun Wang school of mechanical engineering Nanjing University of Science and TechnologyNanjingPR China

Aiming at the problems of demagnetization effect of electromagnetic buffer(EMB)caused by high velocity under intensive impact load and the difficulty and error of machining composite thin-walled long tube,a segmented EMB is *** inner tube and air-gap are divided into initial segments and the traversing *** theoretical analysis,impact test and simulation,it can be found that the RRF curve has two ***,in order to reduce the resultant resistance force(RRF)peaks,the sensitivity analysis based on optimal Latin hypercube design(OLHD)and polynomial regression was *** results show that the smallest contribution ratio to the dynamic response is the seventh and ninth segments of the inner tube,which are less than 1%.Then,fully considering the uncertain factors,important parameters are selected for uncertain optimization after sensitivity *** interval order and interval probability degree methods are used to establish interval uncertain optimization model of the RRF considering *** model was solved using an interval nested optimization method based on radial basis function(RBF)neural ***,the Pareto front is obtained and numerical simulation is performed to verify the optimal *** indicates that the two kinds of RRF peak is obviously reduced,and the optimization object and strategy are effective.

关键词： EMB Intensive impact load Segmented Sensitivity analysis Interval uncertain Optimization

Design,modeling and experiments of broadband tristable galloping piezoelectric energy harvester

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Acta Mechanica Sinica 2020年第3期36卷 592-605页

作者： Junlei Wang Linfeng Geng Shengxi Zhou Zhien Zhang Zhihui lai Daniil Yurchenko engineering Research Center of Energy Saving technology and Equipment of Thermal Energy System Ministry of EducationZhengzhou 450000China school of Aeronautics Northwestern Polytechnical UniversityXi'an 710072China William G.Lowrie Department of Chemical and Biomolecular engineering The Ohio State UniversityColumbusOH 43210USA Guangdong Provincial Key Laboratory of Micro/Nano Optomechatronics engineering College of Mechatronics and Control EngineeringShenzhen UniversityShenzhen 518060China Institute of mechanical Process&Energy EngineeringHeriot-Watt UniversityEdinburgh EH 144ASUK

Galloping based piezoelectric energy harvester is a kind of micro-environmental energy harvesting device based on flowinduced vibrations.A novel tristable galloping-based piezoelectric energy harvester is constructed by introducing a nonlinear magnetic force on the traditional galloping-based piezoelectric energy *** on Euler-Bernoulli beam theory and Kirchhoff’s law,the corresponding aero-electromechanical model is proposed and validated by a series of wind tunnel *** parametric study is performed to analyse the response of the tristable galloping-based piezoelectric energy *** results show that comparing with the galloping-based piezoelectric energy harvester,the mechanism of the tristable galloping-based piezoelectric energy harvester is more *** the increase of a wind speed,the vibration of the bluff body passes through three branches:intra-well oscillations,chaotic oscillations,and inter-well *** threshold wind speed of the presented harvester for efficiently harvesting energy is 1.0 m/s,which is decreased by 33% compared with the galloping-based piezoelectric energy *** maximum output power of the presented harvester is 0.73 mW at 7.0 m/s wind speed,which is increased by 35.3%.Compared with the traditional galloping-based piezoelectric energy harvester,the presented tristable galloping-based piezoelectric energy harvester has a better energy harvesting performance from flow-induced vibrations.

关键词： Energy harvesting Galloping Tristable Flow induced vibrations

Irreversible demagnetization mechanism of permanent magnets during electromagnetic buffering

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Defence technology（防务技术） 2021年第3期17卷 763-774页

作者： Zi-xuan Li Guo-lai Yang Yu-meng Fan Jia-hao Li school of mechanical engineering Nanjing University of Science and TechnologyNanjingPR China

The permanent magnets will be irreversibly demagnetized under high temperature and high velocity during the electromagnetic *** this study,the magnetic field induced by eddy currents and the self-demagnetizing field of permanent magnet are taken into consideration together for demagnetization *** magnetic Reynolds number is used to express the eddy currents *** correction coefficient being expressed as the index of the air-gap width,the inner cylinder thickness,iron pole axial length and the permanent magnet demagnetization coefficient is introduced by magnetic path analysis to represent the self-demagnetization effect and the demagnetization *** electromagnetic buffer(EMB)prototype is tested under intensive impact loads of different strengths at room *** accuracy of the nonlinear irreversible demagnetization finite element model is verified by demagnetization on damping force,velocity and ***,high-velocity demagnetization and high-temperature demagnetization are analysed in order to obtain the distribution law of irreversible demagnetization.

关键词： EMB Irreversibly demagnetization Magnetic Reynolds number Correction coefficient

A Novel Observer for Nonlinear Descriptor Jumping Systems with Communication time delay

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A Novel Observer for Nonlinear Descriptor Jumping Systems wi...

Uncertainty Optimization Design of a Vehicle Body Structure Considering Random Deviations

第36届中国控制会议

作者： lai Yongbo LU Guoping school of mechanical and engineering Jiangsu College of Information Technology

ISBN: (纸本)9781538629185

Observing and estimating system’s states are the conditions to realize the effective control in the control and communication engineering field. In this paper for nonlinear descriptor jumping systems, proposed a novel observer, considered the nonlinear perturbation and network communication time-varying delay. A novel full-order delay dependent observer design method is developed by using system stability theorem and linear matrix inequalities（LMIs） techniques. The observer guarantees the estimated descriptor error jumping systems to be regular, impulse free and robustly mean-square exponentially stable. The proposed novel observer is more generality than those of last results in practice. Finally, two numerical examples are provided to simulate and show the validity of the proposed method.

关键词： Nonlinear descriptor system Jumping system Observer Communication time delay LMIs

来源： cnki会议评论

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Automotive Innovation 2018年第4期1卷 342-351页

作者： Jianhua Zhou Fengchong Lan Jiqing Chen Fanjie lai school of mechanical and Automotive engineering South China University of TechnologyGuangzhou 510640China Guangdong Provincial Key Laboratory of Automotive engineering Guangzhou 510640China

In vehicle body manufacturing,there are small differences between the actual value and design value of,for example,plate thickness and material *** is caused by the processing technology,environment and other uncertain ***,the performance of the vehicle body processed according to the deterministic optimization solution *** fluctuations may make structural performance fail to meet the design ***,in this study,an optimization design is executed with 6σrobustness criteria and a Monte Carlo simulation single-loop optimization strategy based on the radial basis function neural network approximate model considering deviations in plate thickness,elastic modulus,and welding spot diameter,which is called the uncertainty optimization design *** an example,considering the bending stiffness,torsion stiffness,and first-order frequency as constraints,the method is applied to the lightweight design of a car body structure,and the reliability of deterministic optimization design and uncertainty optimization design is *** results demonstrate that the uncertainty optimization design solution is effective and feasible without lowering the static stiffness and modal performance,and the weight is reduced.

关键词： Body structure Lightweight Approximate models 6σrobustness criteria MCS single-loop optimization strategy

Axis-coupled trajectory generation for chains of integrators through smoothing splines

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Control Theory and technology 2019年第1期17卷 48-61页

作者： Shupeng lai Menglu LAN Kehong GONG Ben M. CHEN Department of Electrical and Computer engineering National University of Singapore Singapore 777583 Graduate school for Integrative science & engineering National University of Singapore Singapore 119077 Department of mechanical and Automation engineering The Chinese University of Hong Kong Shatin N.T. Hong Kong China

Integrator based model is used to describe a wide range of systems in robotics. In this paper, we present an axis-coupled trajectory generation algorithm for chains of integrators with an arbitrary order. Special notice has been given to problems with pre-existing nominal plans, which are common in robotic applications. It also handles various type of constraints that can be satisfied on an entire time interval, including non-convex ones which can be transformed into a series of convex constraints through time segmentation. The proposed approach results in a linearly constrained quadratic programming problem, which can be solved effectively with off-the-shelf solvers. A closed-form solution is achievable with only the boundary constraints considered. Finally, the proposed method is tested in real experiments using quadrotors which represent high-order integrator systems.

关键词： B-spline trajectory generation chains of integrators

Relationship of particle stimulated nucleation,recrystallization and mechanical properties responding to Fe and Si contents in hot-extruded 7055 aluminum alloys

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Journal of Materials science & technology 2019年第11期35卷 2570-2581页

作者： Huan She Da Shu Anping Dong Jun Wang Baode Sun Hongchang lai Department of Implant Dentistry Shanghai Ninth People's HospitalCollege of StomatologyShanghai Jiao Tong University School of MedicineShanghai 200011China Shanghai Key Lab of Advanced High-temperature Materials and Precision Forming School of Materials Science and EngineeringShanghai Jiao Tong UniversityShanghai 200240China State Key Lab of Metal Matrix Composites Shanghai Jiao Tong UniversityShanghai 200240China

The variations of coarse intermetallic particles in hot-extruded 7055 aluminum alloys with 0.041 wt%Fe and 0.024 wt%Si increasing to 0.272 wt%Fe and 0.134 wt%Si were *** particle stimulated nucleation(PSN)behaviors for different kind of coarse particles were detailly analyzed by ***,the effect of PSN responding to Fe and Si contents on recrystallization and tensile properties of 7055 alloys was *** increasing Fe and Si contents,the size and number density of coarseη/S particles are reduced,while the number densities of coarse Al7Cu2 Fe and Mg2Si particles are both increased and the coarse Al7Cu2 Fe particles transform from rod-like to *** PSN recrystallized grains with predominant orientations deviated from the extruded fiber textures are stimulated by the irregular Al7Cu2 Fe and Mg2Si particles,because a higher degree of local non-uniform deformation is *** rod-like Al7Cu2 Fe particles cause the greatest degree of local non-uniform deformation owing to the largest aspect ratio,but the shape also restricts the area of particle deformation zone(PDZ)resulting in fewer PSN recrystallized *** irregularη/S particles give rise to the lowest degree of local non-uniform deformation and fewest PSN recrystallized grains with the major orientations close to the extruded fiber ***,despite the number and size of coarseη/S particles are reduced,the proportion of high angle grain boundaries(HAGBs)is increased and the extruded fiber textures are weakened with Fe and Si contents increasing,because of the increased Al7Cu2 Fe and Mg2Si *** strength is slightly declined by the weakened//ED(extrusion direction)fiber texture,while the elongation is reduced for a larger number of coarse particles and more HAGBs with higher Fe and Si contents.

关键词： 7055 aluminum alloy Particles Recrystallization Texture mechanical properties

Fabrication of NiTi Shape Memory Alloys with Graded Porosity to Imitate Human Long-bone Structure

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Journal of Bionic engineering 2015年第4期12卷 575-582页

作者： Dan Zhou Yan Gao Ming lai Hao Li Bin Yuan Min Zhu school of Materials science and engineering South China University of Technology Guangzhou 510641 China

Replacement of damaged long bones is still a significant challenge in surgery. In the present study, a NiTi Shape Memory Alloy （SMA） constructed with graded porosity imitating human long bone structure was fabricated via a dedicated moulding procedure. The outer layer （porosity 14 %） and inner layer （porosity 52 %） of the bone-like graded NiTi alloy were found to be co-axial very well with the interface with a good metallurgical bonding. Moreover, the compression strength and elastic modulus of the graded-porosity NiTi SMAs were found to be 360.6 MPa and 6.7 GPa, respectively, which have been improved by its coaxiality compared with the one with poor coaxiality. The graded-porosity NiTi SMAs exhibit resembling mechanical performance as human long-bones, and are considered to be better implant candidates for long bone replacement.

关键词： NiTi SMA graded porosity long bone structure compressive strength recoverable strain

Interfacial Structure and Formation Mechanism of Ultrasonic-assisted Brazed Joint of SiC Ceramics with Al—12Si Filler Metals in Air

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Journal of Materials science & technology 2017年第5期33卷 492-498页

作者： Xiaoguang Chen Ruishan Xie Zhiwei lai Lei Liu Jiuchun Yan Guisheng Zou State Key Laboratory of Advanced Welding and Joining School of Materials Science and Engineering Harbin Institute of Technology Department of mechanical engineering Key Laboratory for Advanced Manufacturing by Materials Processing Technology Tsinghua University College of Material science and engineering Taiyuan University of Technology

Ultrasonic-assisted brazing of SiC ceramics was performed by filling with an Al-12Si alloy at a low tem- perature of 620 ℃ in air. The interracial characteristics and formation mechanism were investigated. The joint shear strength reached 84-94 MPa using the ultrasonic time of 2-16 s. The fracture morphology showed that the fracture path initiated and propagated in the joint alloy. The thin film of amorphous SiO2 that formed on the SiC surface was non-uniformly decomposed and diffused into the liquid Al-12Si alloy under the cavitation erosion effect of ultrasound. Abnormal isolated blocks of A12SiO5 compounds formed at the interface between Al-12Si and a thicker SiO2 layer formed during the thermal oxidation treatment of the SiC ceramic. The SiO2 layer on the SiC ceramic did not hinder or impair the wetting and bonding process, and a stronger bond could form between Al-12Si and SiO2 or SiC in ultrasonic- assisted brazing.

关键词： Ultrasonic Brazing Ceramic Interface Cavitation erosion

Effects of heat treatment on the microstructures and mechanical properties of a new type of nitrogen-containing die steel

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International Journal of Minerals,Metallurgy and Materials 2012年第6期19卷 511-517页

作者： Jing-yuan Li Peng Zhao Jun Yanagimoto Sumio Sugiyama Yu-lai Chen school of Materials science and engineering University of Science and Technology Beijing Beijing 100083 China Institute of Radar and Avionics Aviation Industry Corporation of China Suzhou 215151 China Institute of Industrial science the University of Tokyo Tokyo 153-8505 Japan engineering Research Institute University of Science and Technology Beijing Beijing 100083 China

Nitrogen can increase the strength of steels without weakening the toughness and improve the corrosion resistance at the same time. Compared with conventional nitrogen-free die steels, a new type of nitrogen-containing die steel was developed with many superior properties, such as high strength, high hardness, and good toughness. This paper focused on the effects of heat treatment on the microstruc- tures and mechanical properties of the new type of nitrogen-containing die steel, which were investigated by the optimized deformation process and heat treatment. Isothermal spheroidal annealing and high-temperature quenching as well as high-temperature tempering were ap- plied in the experiment by means of an orthogonal method after the steel was multiply forged. The mechanical properties of nitro- gen-containing die steel forgings are better than the standard of NADCA #207-2003.

关键词： die steels nitrogen heat treatment microstructure mechanical properties forgings