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| 1 | Numerical Calculation and Experimental Research on Residual Stresses in Precipitation-hardening Layer of NAK80 Steel for Shot Peening显示文摘Shot peening can improve fatigue strength of materials by creating compressive residual stress field in their surface layers,and offers a protection against crack initiation and propagation,corrosion,etc.And fatigue fracture and stress corrosion cracking of NAK80 steel parts are improved effectively.Currently there lacks in-depth research in which the beneficial effect of the residual stress may be offset by the surface damage associated with shot peening,especially in terms of the research on the effective control of shot peening intensity.In order to obtain the surface residual stress field of NAK80 steel after shot peening,the samples are shot peened by pneumatic shot peening machine with different rules.The residual stress in the precipitation-hardening layer of NAK80 steel is measured before and after a shot peening treatment by X-ray diffraction method.In order to obtain true residual stress field,integral compensation method is used to correct results.By setting up analytical model of the residual stress in the process of shot peening,the surface residual stress is calculated after shot peening,and mentioning the reason of errors occurred between calculated and experimental residual stresses,which is mainly caused by the measurement error of the shoot arc height.At the same time,micro hardness,microstructure and roughness in the precipitation-hardening layer of NAK80 steel before and after shot peening were measured and surveyed in order to obtain the relation between shot peening strength and surface quality in the precipitation-hardening layer.The results show that the surface quality of NAK80 steel is significantly improved by shot peening process.The over peening effect is produced when the shot peening intensity is too high,it is disadvantageous to improve sample's surface integrity,and leading to reduce the fatigue life.When arc high value of optimal shot peening is 0.40 mm,the surface quality is the best,and the depth of residual stress in the precipitation-hardening layer reaches to about 450 μm.Numerical calculation is very useful to define the process parameters when a specific residual stress profile is intended,either to quantify the benefits on a specific property like fatigue life or to help on modeling a forming process like shot peen forming.In particular,the proposed parameter optimization in the progress of shot peening and effective control of the surface texture provide new rules for the quantitative evaluations of shot peening surface modification of NAK80 steel. | MIAO Hong ZUO Dunwen WANG Min ZHANG Ruihong WANG Hongfeng | 2011 | Chinese Journal of Mechanical Engineering2011，24，3： | 17 |
| 2 | New Iron-based SiC Spherical Composite Magnetic Abrasive for Magnetic Abrasive Finishing显示文摘SiC magnetic abrasive is used to polish surfaces of precise, complex parts which are hard, brittle and highly corrosion-resistant in magnetic abrasive finishing(MAF). Various techniques are employed to produce this magnetic abrasive, but few can meet production demands because they are usually time-consuming, complex with high cost, and the magnetic abrasives made by these techniques have irregular shape and low bonding strength that result in low processing efficiency and shorter service life. Therefore, an attempt is made by combining gas atomization and rapid solidification to fabricate a new iron-based SiC spherical composite magnetic abrasive. The experimental system to prepare this new magnetic abrasive is constructed according to the characteristics of gas atomization and rapid solidification process and the performance requirements of magnetic abrasive. The new iron-based SiC spherical composite magnetic abrasive is prepared successfully when the machining parameters and the composition proportion of the raw materials are controlled properly. Its morphology, microstructure, phase composition are characterized by scanning electron microscope(SEM) and X-ray diffraction(XRD) analysis. The MAF tests on plate of mold steel S136 are carried out without grinding lubricant to assess the finishing performance and service life of this new SiC magnetic abrasive. The surface roughness(Ra) of the plate worked is rapidly reduced to 0.051 μm from an initial value of 0.372 μm within 5 min. The MAF test is carried on to find that the service life of this new SiC magnetic abrasive reaches to 155 min. The results indicate that this process presented is feasible to prepare the new SiC magnetic abrasive; and compared with previous magnetic abrasives, the new SiC spherical composite magnetic abrasive has excellent finishing performance, high processing efficiency and longer service life. The presented method to fabricate magnetic abrasive through gas atomization and rapid solidification presented can significantly improve the finishing performance and service life of magnetic abrasive, and provide a more practical approach for large-scale industrial production of magnetic abrasive. | ZHANG Guixiang ZHAO Yugang ZHAO Dongbiao ZUO Dunwen YIN Fengshi | 2013 | Chinese Journal of Mechanical Engineering2013，26，2： | 12 |
| 3 | Microstructure and Oxidation Behaviors of Nano-particles Strengthened NiCoCrAlY Cladded Coatings on Superalloys显示文摘Nano-particles which can largely improve the microstructure and oxidation resistance of materials are often used as a strengthening component in metal matrix composites. However, few studies were reported on its application in the bond coat of duplex structure thermal barrier coating(TBC). Three kinds of NiCoCrAlY coatings strengthened by different nano-particles with the same addition (1%, mass fraction) were prepared by the laser cladding technique on Ni-based superalloy substrates, aiming to study the effects of the nano-particles on microstructure and oxidation resistance of NiCoCrAlY coatings (the bond coat of the duplex structure thermal barrier coatings). Scanning electron microscope (SEM), X-ray diffractometer(XRD) and thermogravimetry were employed to investigate their morphologies, phases and cyclic oxidation behaviors in atmosphere at 1 050℃, compared with the coating without nano-particles. With the addition of nano-particles, the growth pattern of the grains at the interface changed from epitaxial growth to non-epitaxial growth or part-epitaxial growth; slender dendrites were broken and cellularized; cracks and pores were restrained; and the oxidation weight-gain and the stripping resistance of the oxide scale were improved as well. Among the three kinds of nano-particles, the SiC nano-particles showed the most improvement on microstructure, while the CeO2 nano-particles were insufficient, but its effects on the oxidation resistance are the same as those of the SiC nano-particles. Based on the discussions of the influence mechanism, it is believed that CeO2 nano-particles would show better improvement than SiC nano-particles if the proper amount is added and the proper preparation technique of micro-nanometer composite powders is adopted, with the synergistic action of nanometer effect and reactive element effect. | WANG Hongyu ZUO Dunwen CHEN Xinfeng YU Shouxin GU Yuanzhi | 2010 | Chinese Journal of Mechanical Engineering2010，23，3： | 11 |
| 4 | Low Cycle Fatigue and Strengthening Mechanism of Cold Extruded Large Diameter Internal Thread of Q460 Steel显示文摘高张力钢(LDITHSS ) 的内部线由传统的方法生产了的大直径总是有低精确性和短生活的问题。与传统的方法相比,冷挤出过程是一个有效工具认识到更高的精确性和长寿。LDITHSS 的低周期的疲劳性质被实验获得,并且疲劳裂缝的开始和繁殖被扫描电子显微镜(SEM ) 观察。基于机械性质,表面微观结构和剩余应力,冷渗出的大直径的加强的机制内部线(LDIT ) 被讨论。结果证明新谷物或亚谷物能在冷挤出期间由于谷物分割和谷物精炼在 LDIT 的表面上被形成。含纤维的结构是伸长并且在渗出的表面上沿着导致剩余的牙齿表面的正常方向优化了压缩应力出现。在冷挤出以后的 LDIT 的最大的紧张压力被发现是 192.55 kN。在低应力骑车下面,线上的收益压力增加,裂缝还原剂的繁殖率,吗疲劳生活因此与减少的表面谷物直径和生活增加到 45.539 的平均疲劳显著地被改进???蟳?寪螥??????蟳??鲢駻?媣??鯣???????????廩?仙哠??????矙璣???吗??????????????????蟳龢駻???????辧????????鲥?????焀?焘?焘?? | MIAO Hong MEI Qing YUAN Jingyun ZHENG Zaixiang JIN Yifu ZUO Dunwen | 2016 | Chinese Journal of Mechanical Engineering2016，29，3： | 7 |
| 5 | Numerical Analysis of Nd:YAG Pulsed Laser Polishing CVD Self-standing Diamond Film显示文摘Chemical vapor deposited(CVD) diamond film has broad application foreground in high-tech fields.But polycrystalline CVD self-standing diamond thick film has rough surface and non-uniform thickness that adversely affect its extensive applications.Laser polishing is a useful method to smooth self-standing diamond film.At present,attentions have been focused on experimental research on laser polishing,but the revealing of theoretical model and the forecast of polishing process are vacant.The paper presents a finite element model to simulate and analyze the mechanism of laser polishing diamond based on laser thermal conduction theory.The experimental investigation is also carried out on Nd:YAG pulsed laser smoothing diamond thick film.The simulation results have good accordance with the results of experimental results.The temperature and thermal stress fields are investigated at different incidence angles and parameters of Nd:YAG pulsed laser.The pyramidal-like roughness of diamond thick film leads to the non-homogeneous temperature fields.The temperature at the peak of diamond film is much higher than that in the valley,which leads to the smoothing of diamond thick film.The effect of laser parameters on the surface roughness and thickness of graphite transition layer is also carried out.The results show that high power density laser makes the diamond surface rapid heating,evaporation and sublimation after its graphitization.It is also found that the good polish quality of diamond thick film can be obtained by a combination of large incident angle,moderate laser pulsed energy,large repetition rate and moderate laser pulse width.The results obtained here provide the theoretical basis for laser polishing diamond film with high efficiency and high quality. | XU Feng HU Haifeng ZUO Dunwen XU Chun QING Zhenghua WANG Min | 2013 | Chinese Journal of Mechanical Engineering2013，26，1： | 6 |
| 6 | A review of friction stir joining of SiCp/Al composites显示文摘SiCp/Al composites have excellent comprehensive properties and have been widely used in aerospace,automotive industry and other fields.Due to the huge difference in performance between SiC particles and matrix alloys,traditional fusion welding methods are difficult to meet the join requirements of SiCp/Al composites.Friction stir joining(friction stir welding),as a solid phase joining process,has been proved to be a new technology with fine prospect in joining SiCp/Al composites compared with fusion welding process.Although some progress has been made in recent years,there are still full of challenges.In this paper,the research status of friction stir joining of SiCp/Al composites in recent years is expatiated,including the weldability of SiCp/Al composites,the macrostructure and the microstructure of joints,mechanical properties of joints,and tool wear and monitoring.Furthermore,the existing challenges of friction stir joining of SiCp/Al composites are summarized and the future development directions are prospected. | Lisheng ZUO Xianrui ZHAO Zeyang LI Dunwen ZUO Hongfeng WANG | 2020 | Chinese Journal of Aeronautics2020，33，3： | 6 |
| 7 | Modeling cascading failures and mitigation strategies in PMU based cyber-physical power systems显示文摘This paper presents a model of cascading failures in cyber-physical power systems(CPPSs) based on an improved percolation theory, and then proposes failure mitigation strategies. In this model, the dynamic development of cascading failures is divided into several iteration stages. The power flow in the power grid, along with the data transmission and delay in the cyber layer, is considered in the improved percolation theory. The interaction mechanism between two layers is interpreted as the observability and controllability analysis and data update analysis influencing the node state transformation and security command execution. The resilience indices of the failures reflect the influence of cascading failures on both topological integrity and operational state. The efficacy of the proposed mitigation strategies is validated, including strategies to convert some cyber layer nodes into autonomous nodes and embed unified power flow controller(UPFC) into the physical layer. The results obtained from simulations of cascading failures in a CPPS with increasing initial failure sizes are compared for various scenarios.Dynamic cascading failures can be separated into rapid and slow processes. The interdependencies and gap between the observable and controllable parts of the physical layer with the actual physical network are two fundamental reasons for first-order transition failures. Due to the complexity of the coupled topological and operational relations between the two layers, mitigation strategies should be simultaneously applied in both layers. | Yuqi HAN Chuangxin GUO Shiying MA Dunwen SONG | 2018 | Journal of Modern Power Systems and Clean Energy2018，6，5： | 5 |
| 8 | Optimization of Polishing Parameters with Taguchi Method for LBO Crystal in CMP显示文摘Chemical mechanical polishing(CMP)was used to polish Lithium triborate(LiB3O5 or LBO)crystal.Taguchi method was applied for optimization of the polishing parameters.Material removal rate(MRR)and surface roughness are considered as criteria for the optimization.The polishing pressure,the abrasive concentration and the table velocity are important parameters which influence MRR and surface roughness in CMP of LBO crystal.Experiment results indicate that for MRR the polishing pressure is the most significant polishing parameter followed by table velocity;while for the surface roughness,the abrasive concentration is the most important one.For high MRR in CMP of LBO crystal the optimal conditions are:pressure 620 g/cm2, concentration 5.0 wt pct,and velocity 60 r/min,respectively.For the best surface roughness the optimal conditions are:pressure 416 g/cm2,concentration 5.0 wt pct,and velocity 40 r/min,respectively.The contributions of individual parameters for MRR and surface roughness were obtained. | Jun Li Yongwei Zhu Dunwen Zuo Yong Zhu Chuangtian Chen | 2009 | Journal of Materials Science & Technology2009，25，5： | 4 |
| 9 | Identification of Critical Hidden Failure Line Based on State-failure-network显示文摘The hidden failures generally exist in power systems and could give rise to cascading failures.Identification of hidden failures is challenging due to very low occurrence probabilities.This paper proposes a state-failure-network(SF-network)method to overcome the difficulty.The SF-network is formed by searching the failures and states guided by risk estimation indices,in which only the failures and states contributing to the blackout risks are searched and duplicated searches are avoided.Therefore,sufficient hidden failures can be obtained with acceptable computations.Based on the state and failure value calculations in the SF-network,the hidden failure critical component indices can be obtained to quantify the criticalities of the lines.The proposed SF-network method is superior to common sampling based methods in risk estimation accuracy.Besides,the state and failure value calculations in the SF-network used to re-estimate the risks after deployment of measures against hidden failures need shorter time in comparison with other risk re-estimation methods.The IEEE 14-bus and 118-bus systems are used to validate the method. | Linzhi Li Lu Liu Hao Wu Yonghua Song Dunwen Song Yi Liu | 2022 | Journal of Modern Power Systems and Clean Energy2022，10，1： | 2 |
| 10 | Numerical simulation of the machining distortion of aircraft aluminum part caused by redistribution of residual stress 显示文摘 | Hun Guo Zuo Dunwen Tang Guoxing | 2010 | Advanced Materials Research2010，10，： | 1 |
| 11 | Genetic optimization of hot filament parameters in HFCVD system显示文摘 | Song Shengli Zuo Dunwen Wang Min | 2003 | Transactions of Nanjing University of Aeronautics & Astronautics2003，20，4： | 1 |
| 12 | Sur- face Characteristics of 10Ni3MnCuA1 Steel by Shot Peening显示文摘 | Miao Hong Zuo Dunwen Wang Hongjun | 2010 | Transactions of Nanjing University of Aeronautics & Astronautics2010，26，3： | 1 |
| 13 | Smoothing of Thick Diamond Film Prepared by Electron-Assisted CVD显示文摘 | Zuo Dunwen Li Xiangfeng Xu Feng | 2004 | Key Engineering Materials2004，，： | 1 |
| 14 | Microstructure of nanometer Al2O3 dispersion strengthened Ni-based high-tem-perature protective coatings by laser cladding显示文摘 | Wang Hongyu Zuo Dunwen Sun Yuli | 2009 | Transactions of Nonferrous Metals Society of China2009，19，： | 1 |
| 15 | Hot corrosion behaviour of low Al NiCoCrAlY cladded coatings reinforced by nano-particles on a Ni-base super alloy显示文摘 | Hongyu Wang Dunwen Zuo Gang Chen Guifang Sun Xiangfeng Li Xu Cheng | 2010 | Corrosion Science2010，，10： | 1 |
| 16 | Effect of surface topography on stress distribution of vacuum plate glass for different aluminum alloy braced pillars 显示文摘 | Miao Hong Zuo Dunwen Zhang Ruihong | 2009 | Key Engineering Materials2009，，： | 1 |
| 17 | Fuzzy-entropy theory comprehensive evaluation method and its application in building construction safety显示文摘 | Liu Dunwen Yu Lei Li Bo | 2012 | Procedia Engineering2012，43，： | 1 |
| 18 | Forces and Stresses During Friction Stir Joining of 2024 Aluminum Alloy显示文摘An attempt is made to measure three direction forces using octagonal ring dynamometer in the 2024 aluminum alloy friction stir joining(FSJ)process.A test is made to measure the specific area stress and stress distributions in the specific area of the workpiece are obtained.The workpiece stresses in the FSJ process are analyzed by numerical simulation method.It is found that,in the downward stage of the process,feed force and lateral force in the tool are small,almost zero,and the maximum axial force can reach 12.5kN.In the stable joining stage,the forces acting on the tool become stabilized.Compared with the low speed,high feed speed results in small feed force and small lateral force,but large feed force in the stable joining stage.The stresses in three directions of feed direction,direction that perpendicular to butt face and direction perpendicular to the surface are obtained.The simulation stress value of measure point is obtained.Test and numerical simulation can authenticate each other.Both experimental stress values and numerical simulation stress values are credible. | Deng Yongfang Zuo Dunwen Song Bo | 2016 | Transactions of Nanjing University of Aeronautics and Astronautics2016，33，2： | 1 |
| 19 | Joining Force of Heterogeneous Titanium Alloy in Linear Friction Welding Process显示文摘A dynamometer was designed and manufactured to measure the joining force in the linear friction welding process.The error percentages of the dynamometer in the upset(x)and vibration(y)directions were 0.9% and 0.75%,respectively.The cross-sensitivity range of the dynamometer was 1.2%—3.3% in the two directions.The precision level satisfies the requirements of the dynamometer test.The joining force of the TC17 and TC11 heterogeneous titanium alloys in the linear friction welding process was used to test the manufactured dynamometer.The test results showed that the upset force was large,but the vibration force showed a smaller change in TC11 during the linear friction welding process.In addition,the upset and vibration forces of the linear friction welding were greater with a short welding time than those with a long welding time. | Wang Hongfeng Zuo Dunwen Wang Jianli Song Weiwei | 2016 | Transactions of Nanjing University of Aeronautics and Astronautics2016，33，3： | 1 |
| 20 | 显示文摘 | Li Duosheng Zuo Dunwen Lu Wenzhuang | 2008 | Solid State Ionics2008，179，： | 1 |
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