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Defect suppression mechanism of ultrasonic vibration-assisted drilling carbon fiber/bismaleimide composite

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Chinese Journal of Aeronautics 2023年第8期36卷 366-380页

作者： Shengguo ZHANG Wenhu WANG Yifeng xiong bo HUANG Ruisong JIANG Key Laboratory of High Performance Manufacturing for Aero Engine Ministry of Industry and Information TechnologySchool of Mechanical EngineeringNorthwestern Polytechnical UniversityXi’an 710072China Engineering Research Center of Advanced Manufacturing Technology for Aero Engine Ministry of EducationSchool of Mechanical EngineeringNorthwestern Polytechnical UniversityXi’an 710072China School of Mechanical Engineering Sichuan UniversityChengdu 610207China

Ultrasonic vibration-assisted drilling(UVAD)has recently been successfully applied in the drilling of carbon fiber reinforced polymer/plastic(CFRP)due to its high *** defects have been observed in the CFRP drilling process which negatively affects the quality of the *** carbon fiber/bismaleimide(BMI)composites is an advanced kind of CFRPs with greater strength and heat resistance,having been rapidly applied in lightweight and high temperature resistant structures in the aerospace *** suppress the defect during the drilling of carbon fiber/BMI composites,it is necessary to comprehensively understand the defect formation and suppression mechanism at different *** this study,the defects formation in both conventional drilling(CD)and UVAD were observed and *** variation trend in the defect factor and thrust force with the spindle speed and feed rate were *** results revealed that the UVAD could significantly enhance the hole’s quality with no delamination and ***,the defect suppression mechanism and thrust force in UVAD were analyzed and verified,where the method of rod chip removal affected the exit defect *** summary,UVAD can be considered a promising and competitive technique for drilling carbon fiber/BMI composites.

关键词： CFRP Defect suppression Rod chip Thrust force UVAD

Neutronic analysis of silicon carbide cladding accident-tolerant fuel assemblies in pressurized water reactors

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Nuclear Science and Techniques 2019年第3期30卷 105-113页

作者： Zhi-xiong Tan Jie-jin Cai School of Electric Power South China University of Technology

In resonance with the Fukushima Daiichi Nuclear Power Plant accident lesson, a novel fuel design to enhance safety regarding severe accident scenarios has become increasingly appreciated in the nuclear power industry. This research focuses on analysis of the neutronic properties of a silicon carbide(SiC) cladding fuel assembly, which provides a greater safety margin as a type of accident-tolerant fuel for pressurized water reactors. The general physical performance of SiC cladding is explored to ascertain its neutronic performance. The neutron spectrum, accumulation of ^(239)Pu, physical characteristics,temperature reactivity coefficient, and power distribution are analyzed. Furthermore, the influences of a burnable poison rod and enrichment are explored. SiC cladding assemblies show a softer neutron spectrum and flatter power distribution than conventional Zr alloy cladding fuel assemblies. Lower enrichment fuel is required when SiC cladding is adopted. However, the positive reactivity coefficient associated with the SiC material remains to be offset. The results reveal that SiC cladding assemblies show broad agreement with the neutronic performance of conventional Zr alloy cladding fuel. In the meantime, its unique physical characteristics can lead to improved safety and economy.

关键词： Accident-tolerant fuels Silicon carbide cladding Neutronic characteristics Pressurized water reactor

Abrasive wear behavior of PTFE for seal applications under abrasive-atmosphere sliding condition

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Friction 2020年第4期8卷 755-767页

作者： Mingxue SHEN bo LI Zhinan ZHANG Longzhi ZHAO Guangyao xiong School of Mechanical Engineering Shanghai Jiao Tong UniversityShanghai 200240China College of Materials Science&Engineering East China Jiaotong UniversityNanchang 330013China

Abrasive wear is a common failure phenomenon that often limits the service life of sealing elements. Evaluation and comparison of the abrasion resistance of polytetrafluoroethylene (PTFE) were conducted using Al2O3particleswithsizesintherange5to200 μmonapin-on-flattribo-testerunderdryreciprocatingsliding conditions at room temperature. Based on the examined worn surface characteristics of both PTFE and 316L stainless steel (as a counterpart) and the analyzed coefficient of friction (COF) evolutions, the wear mechanism and particle size effect have been explored in detail. The results demonstrate that the abrasive size is the main contributing factor, which can drastically impact the wear mechanism and tribological properties of tribo-pairs. The COF exhibits different evolution characteristics (trends) for different abrasive sizes. For moderate particle sizes, the COF trends become more complicated and the most evident wear of the metallic counterpart is evident. The activity behaviors of abrasives are dominated by the particle size. Particles can becomes embedded in one of the tribo-pair materials to plough-cut the counterpart, thus causing two-body abrasive wear. The abrasives can also behave as free rolling bodies, which play the role of third body to realize three-body "PTFE-abrasive-316L"abrasion. When abrasives are involved in the wear process, both the wear rate and COF of the metallic counterpart increase, but the material removal rate of the PTFE is reduced. The results obtained can offer guidelines regarding the design and protection of seals.

关键词： PTFE seals three-body abrasion wear mechanism abrasive particle size

Combining field-modulating electroosmotic vortex and insulating post to manipulate particles based on dielectrophoresis

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Applied Mathematics and Mechanics(English Edition) 2021年第3期42卷 371-386页

作者： Bing YAN bo CHEN Fanyun LIU Jiankang WU Yongliang xiong School of Civil Engineering and Mechanics Huazhong University of Science and TechnologyWuhan 430074China

The dielectrophoretic technology has been one of the most frequently applied microfluidic technologies to manipulate *** way of a combination of controlled electroosmotic micro-vortices and dielectrophoresis to manipulate particles of different sizes was proposed in our previous ***,the thickness of the modulating electrode is *** practice,when the thickness of the modulating electrode increases,the channel flux increases,while the ability of the vortex to capture the particles *** this study,a new method combining the field-modulating electroosmotic vortex and the insulating post is proposed to improve the manipulating capability of the field-modulated electroosmotic vortex to *** results indicate that there are three great advantages as the insulating post is placed on the channel wall on the same side of the modulating ***,the capturing ability of the vortex to particles is greater due to the reduction of channel flux and the squeezing ***,the range of regulating channel flux to achieve the optimal separation is ***,the separation efficiency improves since the perfect separation can be achieved at a higher flow ***,the effects of the location and the size of the insulating post on particle separation are analyzed in *** present work could provide the reference for the application of the DEP technology.

关键词： electroosmotic vortex dielectrophoresis(DEP) insulating post particle separation

Chaos for Subshifts of Finite Type

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Acta Mathematica Sinica,English Series 2005年第6期21卷 1407-1414页

作者： Huo Yun WANGD jin Cheng xiong epartment of Mathematics Guangzhou University Guangzhou 510405 P. R. China Department of Mathematics South China Normal University Guangzhou 510631 P. R. China

This paper deals with chaos for subshifts of finite type. We show that for any subshift of finite type determined by an irreducible and aperiodic matrix, there is a finitely chaotic set with full Hausdorff dimension. Moreover, for any subshift of finite type determined by a matrix, we point out that the cases including positive topological entropy, distributional chaos, chaos and Devaney chaos are mutually equivalent.

关键词： Subshift Chaos Hausdorff dimension Symbolic space

Liquid exfoliating CdS and MoS_(2) to construct 2D/2D MoS_(2)/CdS heterojunctions with significantly boosted photocatalytic H2 evolution activity

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Journal of Materials Science & Technology 2020年第21期56卷 179-188页

作者： Minghui xiong Juntao Yan bo Chai Guozhi Fan Guangsen Song School of Chemical and Environmental Engineering Wuhan Polytechnic UniversityWuhan 430023China

Fabrication of 2D/2D heterojunction photocatalysts have attracted more attentions due to their inherent merits involving the large contact interface,short charge migration distance and plentiful active sites,which are beneficial for the enhancement of photocatalytic ***,a series of 2D/2D MoS_(2)/Cd S type-I heterojunctions were prepared by incorporation the exfoliating of bulk CdS and MoS_(2) with postsintering *** characteristic techniques were employed to corroborate the formation of *** optimizing the 2D MoS_(2) amounts in the heterojunction,the 7 wt.%2D/2D MoS_(2)/CdS heterojunction displayed the maximal photocatalytic H2 evolution rate of 18.43 mmol h^(-1) g^(-1) under visible light irradiation in the presence of lactic acid as the sacrificial reagent,which was 6 times higher than that of pristine 2D *** on the photoelectrochemical and photoluminescence spectra tests,it could be deduced that the charge separation and transfer of 2D/2D MoS_(2)/CdS heterojunction was tremendously improved,and the recombination of photoinduced electron-hole pairs was effectively ***,the 2D MoS_(2) was used as a cocatalyst to provide the abundant active sites and lower the overpotential for H_(2) generation *** current work would offer an insight to fabricate the 2D/2D heterojunction photocatalysts for splitting H_(2)O into H_(2).

关键词： 2D/2D heterojunctions Photocatalytic H_(2)evolution Cocatalysts Charge separation and transfer

Finite element method for coupled diffusion-deformation theory in polymeric gel based on slip-link model

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Applied Mathematics and Mechanics(English Edition) 2018年第4期39卷 581-596页

作者： Hengdi SU Huixian YAN bo jin School of Aerospace Engineering and Applied Mechanics Tongji University School of Mechanical and Electrical Engineering Sanming University

A polymeric gel is an aggregate of polymers and solvent molecules, which can retain its shape after a large deformation. The deformation behavior of polymeric gels was often described based on the Flory-Rehner free energy function without considering the influence of chain entanglements on the mechanical behavior of gels. In this paper,a new hybrid free energy function for gels is formulated by combining the EdwardsVilgis slip-link model and the Flory-Huggins mixing model to quantify the time-dependent concurrent process of large deformation and mass transport. The finite element method is developed to analyze examples of swelling-induced deformation. Simulation results are compared with available experimental data and show good agreement. The influence of entanglements on the time-dependent deformation behavior of gels is also *** study of large deformation kinetics of polymeric gel is useful for diverse applications.

关键词： polymeric gel finite element method slip-link model large deformation mass transport kinetics

Growing actin networks regulated by obstacle size and shape

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Acta Mechanica Sinica 2017年第2期33卷 222-233页

作者： bo Gong Ji Lin jin Qian Department of Engineering Mechanics Key Laboratory of Soft Machines and Smart Devices of Zhejiang Province Zhejiang University Hangzhou 310027 China

Growing actin networks provide the driving force for the motility of cells and intracellular pathogens. Based on the molecular-level processes of actin polymerization, branching, capping, and depolymerization, we have developed a modeling framework to simulate the stochastic and cooperative behaviors of growing actin networks in propelling obstacles, with an emphasis on the size and shape effects on work capacity and filament orientation in the growing process. Our results show that the characteristic size of obstacles changes the protrusion power per unit length, without influencing the orientation distribution of actin filaments in growing networks. In contrast, the geometry of obstacles has a profound effect on filament patterning, which influences the orientation of filaments differently when the drag coefficient of environment is small, intermediate, or large. We also discuss the role of various parameters, such as the aspect ratio of obstacles, branching rate, and capping rate, in affecting the protrusion power of network growth.

关键词： Actin network Growth dynamics Monte Carlo simulation Size effect Shape effect

PREDICTION OF PODDED PROPELLER CAVITATION USING AN UNSTEADY SURFACE PANEL METHOD

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Journal of Hydrodynamics 2008年第6期20卷 790-796页

作者： YE jin-ming xiong Ying College of Naval Architecture and Power Naval University of Engineering Wuhan 430033 China

The unsteady sheet cavitation of podded propeller was predicted by using a surface panel method. The interaction between propeller and pod was treated with the iterative calculation of induced velocity potential, and the method of induced velocity potential can save a great deal of storage and computation time compared to the method of induced velocity. The induced velocity potential of unit singularity on every pod panel to every key blade panel and of unit singularity on every key blade panel and its wake panel to every pod panel were calculated when the key blade is at every angle position. Based on the wake model of the conventional single propeller, a new wake model of podded propeller was constructed. The propeller is analyzed only on the key blade in order to save computation time and memory space. The method can be used to calculate the hydrodynamics performance and cavitation of propeller in uniform and non-uniform inflows. It can give the unsteady force and cavitation shape of propeller. The propeller cavitation range determined by the present method agrees with the observation results of cavity image given in cavitation tunnel well, and this proves the practicability of the method.

关键词： pod propeller unsteady performance cavitation surface panel method