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Origin and evolution of false brinelling and fretting co.rosion under rolling co.ditions

Friction 2024年第4期12卷 618-631页

作者： Xin JIA Lu HUANG Miao SUN Wenbin LI National Institute of Metrology Beijing 100029China Yantai Tiancheng machinery co. Ltd.Yantai 264006China

Rolling bearings working in oscillating applications often suffer from false brinelling and fretting co.rosion that limit their service life.At present,the study of oscillation-induced failures is primarily dominated by a large number of sliding and bench tests.However,most of the previous work are not able to fully describe the two closely related but different failure mechanisms.In this study,the origin and evolution of the two failures are thoroughly investigated under strictly co.trolled oscillating rolling co.ditions.The results show that failure evolves from false brinelling to fretting co.rosion under dry friction co.ditions regardless of the oscillation amplitude.This process is acco.panied by a large area peeling and serious oxidation,and the oxygen co.tent increases from 2.50 wt%to 21.22 wt%.Oxidation is a crucial factor in the evolution of false brinelling into fretting co.rosion.However,the distribution of microwear and oxygen co.tent depend on the oscillation amplitude.Under lubrication co.ditions,the friction co.fficient(co.)is smaller in the initial stage and led to local slip or transient instability of rolling elements.Therefore,the size of the wear marks and co. increased and appeared to be larger than those under a dry friction co.dition.However,grease can separate the co.tact surfaces,only surface deformation owing to false brinelling and slight damage at the roughness level occurred.The evolution of false brinelling and fretting co.rosion is also closely related to residual stress.False brinelling often occurrs with residual stress acco.ulation,meanwhile,the residual stress increases from 120 to 300 MPa.When peeling occurs,residual stress is released.The failure pattern transformed from false brinelling to fretting co.rosion and is acco.panied by oxidation.So far,none of investigation is able to show satisfactory evolution of oscillating-induced failures,this study may co.tribute to more scientific understanding of rolling bearings against long-run reciprocating oscillating wear.

关键词： oscillating false brinelling fretting co.rosion wear residual stress

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Enhancing capacitive deionization performance and cyclic stability of nitrogen-doped activated carbon by the electro-oxidation of anode materials

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Chinese Journal of Chemical Engineering 2024年第5期69卷 23-33页

作者： Xiaona Liu Baohua Zhao Yanyun Hu Luyue Huang Jingxiang Ma Shuqiao Xu Zhonglin Xia Xiaoying Ma Shuangchen Ma School of Environmental Science and Engineering North China Electric Power UniversityBaoding 071003China Huadian Zhengzhou machinery Design and Research Institute co. LtdZhengzhou 450002China Huadian Inner Mongolia Energy co. Ltd.Baotou Power Generation BranchBaotou 014013China

Electrode materials with high desalination capacity and long-term cyclic stability are the focus of capacitive deionization(CDI) co.munity. Understanding the causes of performance decay in traditional carbons is crucial to design a high-performance material. Based on this, here, nitrogen-doped activated carbon(NAC) was prepared by pyrolyzing the blend of activated carbon powder(ACP) and melamine for the positive electrode of asymmetric CDI. By co.paring the indicators changes such as co.ductivity, salt adsorption capacity, pH, and charge efficiency of the symmetrical ACP-ACP device to the asymmetric ACP-NAC device under different CDI cycles, as well as the changes of the electrochemical properties of anode and cathode materials after long-term operation, the reasons for the decline of the stability of the CDI performance were revealed. It was found that the carboxyl functional groups generated by the electro-oxidation of anode carbon materials make the anode zero-charge potential(E_(pzc)) shift positively,which results in the uneven distribution of potential windows of CDI units and affects the adsorption capacity. Furthermore, by understanding the electron density on C atoms surrounding the N atoms, we attribute the increased cyclic stability to the enhanced negativity of the charge of carbon atoms adjacent to quaternary-N and pyridinic-oxide-N.

关键词： Anodic oxidation Capacitive deionization Cyclic stability N-doping

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Three-dimensional parametric co.tact analysis of planetary roller screw mechanism and its application in grouping for selective assembly

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Frontiers of Mechanical Engineering 2024年第1期19卷 53-72页

作者： Huilin HE Peitang WEI Huaiju LIU Xuesong DU Rui HU Genshen LIU Yajun WU State Key Laboratory of Mechanical Transmission for Advanced Equipment Chongqing UniversityChongqing 400044China Taiyuan Heavy machinery Group co. Ltd.Taiyuan 030024China

The planetary roller screw mechanism(PRSM)is a novel precision transmission mechanism that realizes the co.version between linear and rotary motions.The co.tact characteristics of helical surfaces directly determine PRSM’s performance in load-carrying capacity and transmission accuracy.Therefore,studying the co.tact characteristics of PRSM forms the fundamental basis for enhancing its transmission performance.In this study,a three-dimensional parametric analysis method of co.tact characteristics is proposed based on the PRSM meshing principle and PyVista(a high-level API to the Visualization Toolkit).The proposed method co.siders the influence of machining errors among various thread teeth.The effects of key machining errors on co.tact positions and axial clearance,as well as their sensitivities,are analyzed.With excellent solution accuracy,this method exhibits higher calculation efficiency and stronger robustness than the analytical and numerical meshing models.The influence of nominal diameter and pitch errors of the screw,roller,and nut on the axial clearance follows a linear relationship,whereas flank angle errors have negligible effects on the axial clearance.The co.responding influence co.fficients for these three machining errors on the axial clearance are 0.623,0.341,and 0.036.The variations in co.tact positions caused by individual errors are axisymmetric.Flank angle errors and roller diameter errors result in linear displacements of the co.tact points,whereas pitch errors cause the co.tact points to move along the arc of the roller diameter.Based on the proposed threedimensional parametric co.tact characteristics analysis method,the Fuzzy C-Means clustering algorithm co.sidering error sensitivity is utilized to establish a co.ponent grouping technique in the selective assembly of critical PRSM co.ponents,ensuring the rational and co.sistent clearances based on the given co.ponent’s machining errors.This study provides effective guidance for analyzing co.tact characteristics and grouping in selective ass

关键词： planetary roller screw mechanism(PRSM) co.tact position axial clearance machining error grouping for selective assembly

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Design method of extractant for liquideliquid extraction based on elements and chemical bonds

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Chinese Journal of Chemical Engineering 2024年第4期68卷 193-202页

作者： Yuwen Wei Chunling Zhang Yue Zhang Lili Wang Li Xia Xiaoyan Sun Shuguang Xiang Institute of Process System Engineering College of Chemical EngineeringQingdao University of Science and TechnologyQingdao 266042China Yantai Guobang Chemical machinery Technology co. Ltd.Yantai 264002China

In the petrochemical industry process,the relative volatility between the co.ponents to be separated is close to one or the azeotrope that systems are difficult to separate.Liquideliquid extraction is a co.mon and effective separation method,and selecting an extraction agent is the key to extraction technology research.In this paper,a design method of extractants based on elements and chemical bonds was proposed.A knowledge-based molecular design method was adopted to pre-select elements and chemical bond groups.The molecules were automatically synthesized acco.ding to specific co.bination rules to avoid the problem of“co.bination explosion”of molecules.The target properties of the extractant were set,and the extractant meeting the requirements was selected by predicting the co.relation physical properties of the generated molecules.Based on the separation performance of the extractant in liquideliquid extraction and the relative importance of each index,the fuzzy co.prehensive evaluation membership function was established,the analytic hierarchy process determined the mass ratio of each index,and the co.sistency test results were passed.The results of case study based on quantum chemical analysis demonstrated that effective determination of extractants for the analysis of benzeneecyclohexane systems.The results unanimously prove that the method has important theoretical significance and application value.

关键词： Molecular design Element and chemical bonds Molecular simulation Thermodynamics Solvent extraction

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Preparation and property of seal co.ting for gas turbine co.pressor

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China Welding 2024年第1期33卷 60-64页

作者：余沛坰刘中华郑健生徐伏根陈千宝 Zhejiang Ranco. Turbine machinery co. Ltd.Hangzhou 310020China Hangzhou Steam Turbine Power Group co. Ltd.Hangzhou 310020China

Double-layer structure of seal co.ting which co.sisted of a Ni5Al bond co.ting and a Ni25 graphite top co.ting were prepared on steel substrate of gas turbine co.pressor cylinder block.Bond co.ting was prepared by atmospheric plasma spraying and top co.ting was prepared by flame spraying.The microstructure,mechanical properties and abradability of the co.ting were characterized by scanning elec-tron microsco.e(SEM),hardness tester,universal testing machine,thermal shock testing machine and abradability testing machine.The res-ults show that the overall spraying structure of the seal co.ting is uniform,the nickel metal phase is the skeleton supporting the entire co.t-ing,and the co.ting is well bonded without separation.The seal co.ting has a bonding strength of not less than 7.7 MPa,excellent thermal stability,and thermal shock resistance cycle numbers at 500℃more than 50;the scratch length,deepest invasion depth and wear amount of the co.ting increase with rise of test temperature,with almost no co.ting adhesion,indicating that the seal co.ting has excellent abradability.

关键词： gas turbine co.pressor seal co.ting microstructure mechanical property abradability

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Floating plants reduced methane fluxes from wetlands by creating a habitat co.ducive to methane oxidation

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Journal of Environmental Sciences 2024年第1期135卷 149-160页

作者： Fuwei Wang Songhe Zhang Xiuren Hu Xin Lv Min Liu Yu Ma Benjamin Manirakiza Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes Ministry of EducationHohai UniversityNanjing 210098China co.lege of Environment Hohai UniversityNanjing 210098China China machinery International Engineering Desigh and Research Institute co. Ltd.East China Regional CenterNanjing 210008China

Wetlands are one of the important natural sources of atmospheric methane (CH_4),as an important part of wetlands,floating plants can be expected to affect methane release.However,the effects of floating plants on methane release are limited.In this study,methane fluxes,physiochemical properties of the overlying water,methane oxidation potential and rhizospheric bacterial co.munity were investigated in simulated wetlands with floating plants Eichhornia crassipes,Hydrocharis dubia,and Trapa natans.We found that E.crassipes,H.dubia,and T.natans plants co.ld inhibit 84.31%-97.31%,4.98%-88.91%and 43.62%-92.51%of methane fluxes at interface of water-atmosphere co.pared to co.trol,respectively.Methane fluxes were negatively related to nutrients co.centration in water co.umn but positively related to the aerenchyma proportions of roots,stems,and leaves.At the same biomass,root of E.crassipes (36.44%) had the highest methane oxidation potential,followed by H.dubia (12.99%) and T.natans (11.23%).Forty-five bacterial phyla in total were identified on roots of three plants and 7 bacterial genera (2.10%-3.33%) were known methanotrophs.Type I methanotrophs acco.nted for 95.07%of total methanotrophs.The pmoA gene abundances ranged from 1.90×10^(16)to 2.30×10^(18)co.ies/g fresh weight of root biofilms.Abundances of pmoA gene was significantly positively co.related with environmental parameters.Methylotrophy (5.40%) and methanotrophy (3.75%) function were closely related to methane oxidation.This study highlights that floating plant restoration can purify water and promote carbon neutrality partially by reducing methane fluxes through methane oxidation in wetlands.

关键词： Floating plants Methane fluxes Aerenchyma Methanotrophs

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co.mand filtered integrated estimation guidance and co.trol for strapdown missiles with circular field of view

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Defence Technology（防务技术） 2024年第5期35卷 211-221页

作者： Wei Wang Jiaqi Liu Shiyao Lin Baokui Geng Zhongjiao Shi School of Aerospace Engineering Beijing Institute of TechnologyBeijing 10081China China Research and Development Academy of machinery Equipment Beijing 100089China Northwest Industries Group co. Ltd.Xi'an 710043China

In this paper,an integrated estimation guidance and co.trol(IEGC)system is designed based on the co.mand filtered backstepping approach for circular field-of-view(FOV)strapdown missiles.The threedimensional integrated estimation guidance and co.trol nonlinear model with limited actuator deflection angle is established co.sidering the seeker's FOV co.straint.The boundary time-varying integral barrier Lyapunov function(IBLF)is employed in backstepping design to co.strain the body line-of-sight(BLOS)in IEGC system to fit a circular FOV.Then,the nonlinear adaptive co.troller is designed to estimate the changing aerodynamic parameters.The generalized extended state observer(GESO)is designed to estimate the acceleration of the maneuvering targets and the unmatched time-varying disturbances for improving tracking accuracy.Furthermore,the co.mand filters are used to solve the"differential expansion"problem during the backstepping design.The Lyapunov theory is used to prove the stability of the overall closed-loop IEGC system.Finally,the simulation results validate the integrated system's effectiveness,achieving high accuracy strikes against maneuvering targets.

关键词： Integrated estimation guidance and co.trol Circular field-of-view Time-varying integral barrier Lyapunov function co.mand filtered backstepping co.trol Nonlinear adaptive co.trol Extended state observer

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I-DCGAN and TOPSIS-IFP:A simulation generation model for radiographic flaw detection images in light alloy castings and an algorithm for quality evaluation of generated images

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China Foundry 2024年第3期21卷 239-247页

作者： Ming-jun Hou Hao Dong Xiao-yuan Ji Wen-bing Zou Xiang-sheng Xia Meng Li Ya-jun Yin Bao-hui Li Qiang Chen Jian-xin Zhou State Key Laboratory of Materials Processing and Die&Mould Technology Huazhong University of Science and TechnologyWuhan 430074China Xinjiang Technology(Jiangsu)co. Ltd.Nantong 226100JiangsuChina Southwest Technique and Engineering Research Institute Chongqing 400039China Shanghai Spaceflight Precision machinery Institute Shanghai 201600China

The intelligent detection technology driven by X-ray images and deep learning represents the forefront of advanced techniques and development trends in flaw detection and automated evaluation of light alloy castings.However,the efficacy of deep learning models hinges upon a substantial abundance of flaw samples.The existing research on X-ray image augmentation for flaw detection suffers from shortco.ings such as poor diversity of flaw samples and low reliability of quality evaluation.To this end,a novel approach was put forward,which involves the creation of the Interpolation-Deep co.volutional Generative Adversarial Network(I-DCGAN)for flaw detection image generation and a co.prehensive evaluation algorithm named TOPSIS-IFP.I-DCGAN enables the generation of high-resolution,diverse simulated images with multiple appearances,achieving an improvement in sample diversity and quality while maintaining a relatively lower co.putational co.plexity.TOPSIS-IFP facilitates multi-dimensional quality evaluation,including aspects such as diversity,authenticity,image distribution difference,and image distortion degree.The results indicate that the X-ray radiographic images of magnesium and aluminum alloy castings achieve optimal performance when trained up to the 800th and 600th epochs,respectively.The TOPSIS-IFP value reaches 78.7%and 73.8%similarity to the ideal solution,respectively.co.pared to single index evaluation,the TOPSIS-IFP algorithm achieves higher-quality simulated images at the optimal training epoch.This approach successfully mitigates the issue of unreliable quality associated with single index evaluation.The image generation and co.prehensive quality evaluation method developed in this paper provides a novel approach for image augmentation in flaw reco.nition,holding significant importance for enhancing the robustness of subsequent flaw reco.nition networks.

关键词： light alloy casting flaw detection image generator discriminator co.prehensive evaluation index

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Fracture geometry and breakdown pressure of radial borehole fracturing in multiple layers

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Petroleum Science 2024年第1期21卷 430-444页

作者： Yu-Ning Yong Zhao-Quan Guo Shou-Ceng Tian Lu-Yao Ma Tian-Yu Wang Mao Sheng National Key Laboratory of Petroleum Resources and Engineering China University of Petroleum(Beijing)Beijing102249China Beijing Petroleum machinery co.pany Limited CNPC Engineering Technology R&D Company LimitedBeijing102206China Smart Energy co. LtdChina Xiongan GroupXiong’an New Area071000HebeiChina

Radial borehole fracturing that co.bines radial boreholes with hydraulic fracturing is anticipated to improve the output of tight oil and gas reservoirs.This paper aims to investigate fracture propagation and pressure characteristics of radial borehole fracturing in multiple layers.A series of laboratory experiments with artificial rock samples(395 mm×395 mm×395 mm)was co.ducted using a true triaxial fracturing device.Three crucial factors co.responding to the vertical distance of adjacent radial borehole layers(vertical distance),the azimuth and diameter of the radial borehole are examined.Experimental results show that radial borehole fracturing in multiple layers generates diverse fracture geometries.Four types of fractures are identified based on the co.nectivity between hydraulic fractures and radial boreholes.The vertical distance significantly influences fracture propagation perpendicular to the radial borehole axis.An increase in the vertical distance impedes fracture co.nection across multiple radial borehole layers and reduces the fracture propagation distance along the radial borehole axis.The azimuth also influences fracture propagation along the radial borehole axis.Increasing the azimuth reduces the guiding ability of radial boreholes,which makes the fracture quickly curve to the maximum horizontal stress direction.The breakdown pressure co.relates with diverse fracture geometries observed.When the fractures co.nect multi-layer radial boreholes,increasing the vertical distance decreases the breakdown pressure.Decreasing the azimuth and increasing the diameter also decrease the breakdown pressure.The extrusion force exists between the adjacent fractures generated in radial boreholes in multiple rows,which plays a crucial role in enhancing the guiding ability of radial boreholes and results in higher breakdown pressure.The research provides valuable theoretical insights for the field application of radial borehole fracturing technology in tight oil and gas reservoirs.

关键词： Multi-layer radial boreholes Hydraulic fracturing Fracture propagation Pressure characteristic

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co.parison of co.bustion Characteristics of Tars Produced with Tobacco.Stem Biomass Gasification

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Journal of Renewable Materials 2024年第1期12卷 119-129页

作者： Bo Chen Mingjun Wang Bo Liu Chunping Lu Guohai Jia Yong Chao Chao Zhong School of Mechanical Engineering Hunan Institute of EngineeringXiangtan411104China School of Automotive Engineering Xiangtan Institute of TechnologyXiangtan411100China School of Electrical and Information Engineering Hunan Institute of EngineeringXiangtan411104China China Metallurgic Jingcheng(Xiangtan)Heavy Industry Equipment co. Ltd.Xiangtan411100China Hunan Shuanghuan Fiber Molding machinery co. Ltd.Xiangtan411100China

In order to study the co.bustion characteristics of tar in biomass gasifier inner wall and gasification gas,“tobacco.stem semi-tar inside furnace”,“tobacco.stem tar inside furnace”and“tobacco.stem tar out-of-furnace”were subjected to thermogravimetric experiments,and the co.bustion characteristics and kinetic characteristics were analyzed.The result shows that“tobacco.stem semi-tar inside furnace”has the highest value and“tobacco.stem tar out-of-furnace”is has the lowest value on ignition characteristics,co.bustion characteristics and co.bustible stability;“tobacco.stem semi-tar inside furnace”has the lowest value and“tobacco.stem tar outside furnace”has the highest value on burnout characteristics;“tobacco.stem tar outside furnace”has the highest value and“tobacco.stem tar inside furnace”has the lowest value on integrated co.bustion characteristics.

关键词： Tobacco.stem tar gasifier co.bustion characteristics

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