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Surface Integrity of Ultrasonically-Assisted Milled Ti6Al4V Alloy Manufactured by Selective Laser Melting

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Chinese Journal of Mechanical Engineering 2021年第4期34卷 42-55页

作者： Sai Guo Wei Du Qinghong Jiang zhigang dong Bi Zhang Department of Mechanical and Energy Engineering Southern University of Science and TechnologyShenzhen 518055China School of Mechanical Engineering Dalian University of TechnologyDalian 116024China Key Laboratory for Precision and Non-Traditional Machining Technology of Ministry of Education Dalian University of TechnologyDalian 116024China

The Ti6Al4V parts produced by the existing selective laser melting(SLM)are mainly confronted with poor surface finish and inevitable interior defects,which substantially deteriorates the mechanical properties and performances of the *** this regard,ultrasonically-assisted machining(UAM)technique is commonly introduced to improve the machining quality due to its merits in increasing tool life and reducing cutting ***,most of the previous studies focus on the performance of UAM with ultrasonic vibrations applied in the tangential and feed directions,whereas few of them on the impact of ultrasonic vibration along the vertical *** this study,the effects of feed rate on surface integrity in ultrasonically-assisted vertical milling(UAVM)of the Ti6Al4V alloy manufactured by SLM were systemically investigated compared with the conventional machining(CM)*** results revealed that the milling forces in UAVM showed a lower amplitude than that in CM due to the intermittent cutting *** surface roughness values of the parts produced by UAVM were generally greater than that by CM owing to the extra sinusoidal vibration textures induced by the milling ***,the extra vertical ultrasonic vibration in UAVM was beneficial to suppressing machining *** feed rate increased,surface microhardness and thickness of the plastic deformation zone in CM raised due to more intensive plastic deformation,while these two material properties in UAVM were reduced owing to the mitigated impact effect by the high-frequency vibration of the milling ***,the improved surface microhardness and reduced thickness of the subsurface deformation layer in UAVM were ascribed to the vertical high-frequency impact of the milling cutter in *** general,the results of this study provided an in-depth understanding in UAVM of Ti6Al4V parts manufactured by SLM.

关键词： Ultrasonically-assisted vertical milling Surface integrity Ti6Al4V Selective laser melting

Effects of inclination angles of disc cutter on machining quality of Nomex honeycomb core in ultrasonic cutting

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Frontiers of Mechanical Engineering 2021年第2期16卷 285-297页

作者： Yidan WANG Renke KANG Yan QIN Qian MENG zhigang dong Key Laboratory for Precision and Non-traditional Machining Technology of Ministry of Education Dalian University of TechnologyDalian 116024China

Ultrasonic cutting with a disc cutter is an advanced machining method for the high-quality processing of Nomex honeycomb *** machining quality is influenced by ultrasonic cutting parameters,as well as tool orientations,which are determined by the multi-axis machining requirements and the angle control of the cutting ***,in existing research,the effect of the disc cutter orientation on the machining quality has not been studied in depth,and practical guidance for the use of disc cutters is *** this work,the inclined ultrasonic cutting process with a disc cutter was analyzed,and cutting experiments with different inclination angles were *** theoretical residual height models of the honeycomb core,as a result of the lead and tilt angles,were established and verified with the results obtained by a linear laser displacement *** shows that the residual height of the honeycomb core,as a result of the tilt angle,is much larger than that as a result of the lead ***,the tearing of the cell wall on the machined surface was observed,and the effects of the ultrasonic vibration,lead angle,and tilt angle on the tear rate and tear length of the cell wall were *** results revealed that ultrasonic vibration can effectively decrease the tearing of the cell wall and improve the machining *** in the tilt angle have less effect than changes in the lead angle on the tearing of the cell *** determination of inclination angles should consider the actual processing requirements for the residual height and the machining quality of the cell *** study investigates the influence of the inclination angles of a disc cutter on the machining quality of Nomex honeycomb core in ultrasonic cutting and provides guidelines for machining.

关键词： Nomex honeycomb core disc cutter inclined ultrasonic cutting machining quality

Effects of taping on grinding quality of silicon wafers in backgrinding

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Frontiers of Mechanical Engineering 2021年第3期16卷 559-569页

作者： zhigang dong Qian ZHANG Renke KANG Shang GAO Haijun LIU Key Laboratory for Precision and Non-traditional Machining Technology of Ministry of Education Dalian University of TechnologyDalian 116024China CIMS Institute School of Mechanical EngineeringHefei University of TechnologyHefei 230009China

Taping is often used to protect patterned wafers and reduce fragmentation during backgrinding of silicon *** experiments using coarse and fine resinbond diamond grinding wheels were performed on silicon wafers with tapes of different thicknesses to investigate the effects of taping on peak-to-valley(PV),surface roughness,and subsurface damage of silicon wafers after *** showed that taping in backgrinding could provide effective protection for ground wafers from ***,the PV value,surface roughness,and subsurface damage of silicon wafers with taping deteriorated compared with those without taping although the deterioration extents were very *** PV value of silicon wafers with taping decreased with increasing mesh size of the grinding wheel and the final *** surface roughness and subsurface damage of silicon wafers with taping decreased with increasing mesh size of grinding wheel but was not affected by removal *** hope the experimental finding could help fully understand the role of taping in backgrinding.

关键词： taping silicon wafer backgrinding subsurface damage surface roughness

Fronts and surface zonal geostrophic current along 115°E in the southern Indian Ocean

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Acta Oceanologica Sinica 2010年第5期29卷 1-9页

作者： HE zhigang dong Zhaoqian South China Sea Institute of Oceanology Guangzhou 510301 Polar Research Institute of China Shanghai 200136

Altimeter and in situ data are used to estimate the mean surface zonal geostrophic current in the section along 115°E in the southern Indian Ocean,and the variation of strong currents in relation to the major fronts is *** results show that,in average,the flow in the core of Antarctic Circumpolar Current（ACC） along the section is composed of two parts,one corresponds to the jet of Subantarctic Front（SAF） and the other is the flow in the Polar Front Zone（PFZ）,with a westward flow between *** mean surface zonal geostrophic current corresponding to the SAF is up to 49 cm · s^-1 at 46°S,which is the maximal velocity in the *** eastward flow in the PFZ has a width of about 4.3 degrees in *** mean surface zonal geostrophic current corresponding to the Southern Antarctic Circumpolar Current Front（SACCF） is located at 59.7 °S with velocity less than 20 cm · s^-*** location of zonal geostrophic jet corresponding to the SAF is quite stable during the study *** contrast,the eastward jets in the PFZ exhibit various patterns,i.e.,the primary Polar Front（PF1） shows its strong meridional shift and the secondary Polar Front（PF2） does not always coincide with *** surface zonal geostrophic current corresponding to SAF has the significant periods of annual,semi-annual and *** geostrophic current of the PFZ also shows significant periods of semi-annual and four-month,but is out of phase with the periods of the SAF,which results in no notable semi-annual and fourmonth periods in the surface zonal geostrophic current in the core of the *** terms of annual cycle,the mean surface zonal geostrophic current in the core of the ACC shows its maximal velocity in June.

关键词： southern Indian Ocean Antarctic Circumpolar Current zonal geostrophic current front

Postprocessor development for ultrasonic cutting of honeycomb core curved surface with a straight blade

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Frontiers of Mechanical Engineering 2023年第1期18卷 147-162页

作者： Heng LUO zhigang dong Renke KANG Yidan WANG Jiansong SUN Zhaocheng WEI Key Laboratory for Precision and Non-traditional Machining Technology of Ministry of Education Dalian University of TechnologyDalian 116024China

When ultrasonically cutting honeycomb core curved parts,the tool face of the straight blade must be along the curved surface’s tangent direction at all times to ensure high-quality machining of the curved ***,given that the straight blade is a nonstandard tool,the existing computer-aided manufacturing technology cannot directly realize the above action *** solve this problem,this paper proposed an algorithm for extracting a straight blade real-time tool face vector from a 5-axis milling automatically programmed tool location file,which can realize the tool location point and tool axis vector conversion from the flat end mill to the straight *** the same time,for the multi-solution problem of the rotation axis,the dependent axis rotation minimization algorithm was introduced,and the spindle rotation algorithm was proposed for the tool edge orientation problem when the straight blade is used to machine the curved ***,on the basis of the MATLAB platform,the dependent axis rotation minimization algorithm and spindle rotation algorithm were integrated and compiled,and the straight blade ultrasonic cutting honeycomb core postprocessor was then *** model of the machine tool and the definition of the straight blade were conducted in the VERICUT simulation software,and the simulation machining of the equivalent entity of the honeycomb core can then be *** correctness of the numerical control program generated by the postprocessor was verified by machining and accuracy testing of the two designed *** and analysis of the simulation and experiment indicate that the tool pose is the same under each working condition,and the workpieces obtained by machining also meet the corresponding accuracy ***,the postprocessor developed in this paper can be well adapted to the honeycomb core ultrasonic cutting machine tool and realize high-quality and high-efficient machining of honeycomb core composi

关键词： honeycomb core straight blade ultrasonic cutting tool pose postprocessor

Hole quality in longitudinal–torsional coupled ultrasonic vibration assisted drilling of carbon fiber reinforced plastics

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Frontiers of Mechanical Engineering 2020年第4期15卷 538-546页

作者： Guofeng MA Renke KANG zhigang dong Sen YIN Yan BAO dongming GUO Key Laboratory for Precision and Non-Traditional Machining of Ministry of Education Dalian University of TechnologyDalian 116024China

Carbon fiber reinforced plastic (CFRP) composites are extremely attractive in the manufacturing of structural and functional components in the aircraft manufacturing field due to their outstanding properties, such as good fatigue resistance, high specific stiffness/strength, and good shock absorption. However, because of their inherent anisotropy, low interlamination strength, and abrasive characteristics, CFRP composites are considered difficult-to-cut materials and are prone to generating serious hole defects, such as delamination, tearing, and burrs. The advanced longitudinal–torsional coupled ultrasonic vibration assisted drilling (LTC-UAD) method has a potential application for drilling CFRP composites. At present, LTC-UAD is mainly adopted for drilling metal materials and rarely for CFRP. Therefore, this study analyzes the kinematic characteristics and the influence of feed rate on the drilling performance of LTC-UAD. Experimental results indicate that LTC-UAD can reduce the thrust force by 39% compared to conventional drilling. Furthermore, LTC-UAD can decrease the delamination and burr factors and improve the surface quality of the hole wall. Thus, LTC-UAD is an applicable process method for drilling components made with CFRP composites.

关键词： longitudinal–torsional coupled ultrasonically drilling CFRP thrust force hole quality

Cl- ions accelerating interface charge transfer in a Si/In2S3 Faradaic junction photocathode for solar seawater splitting

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Science China Chemistry 2024年第9期67卷 2923-2929页

作者： Jun Luo Ruotong Bao Hongzheng dong Ye Fu dongjian Jiang Bo Wang Yuzhan Zheng Qiong Wang Wenjun Luo zhigang Zou Eco-materials and Renewable Energy Research Center (ERERC) Jiangsu Key Laboratory for Nano Technology National Laboratory of Solid State Microstructures College of Engineering and Applied Sciences Nanjing University National Laboratory of Solid State Microstructures and Department of Physics Nanjing University

Photoelectrocatalytic seawater splitting is a promising low-cost method to produce green hydrogen in a large scale. The effects of Cl-ions in seawater on the performance of a photoanode have been reported in previous studies. However, few researches have been done on the roles of Cl-ions in a photocathode. Herein, for the first time, we find that Cl-ions in the electrolyte improve the photocurrent of a Si/In2S3photocathode by 50% at-0.6 VRHE. An in-situ X-ray photoelectron spectroscopy（XPS） characterization combined with the time-of-flight secondary-ion mass spectrometry by simulating photoelectrochemical conditions was used to investigate the interface charge transfer mechanism. The results suggest that there is an In2+3S3–x（OH）2xlayer on the surface of In2S3in the phosphate buffer solution（PBS） electrolyte, which plays a role as an interface charge transfer mediator in the Si/In2S3photocathode. The In2+3S3–x（OH）2xsurface layer becomes In2+3S3–x（Cl）2xin the PBS electrolyte with NaCl and accelerates the charge transfer rate at the In2S3/electrolyte interface. These results offer a new concept of regulating interface charge transfer mediator to enhance the performance of photoelectrocatalytic seawater splitting for hydrogen production.

关键词： solar hydrogen production interface charge transfer mechanism coupled electron and ion transfer in-situ XPS characterization In2+3S3–x(OH)2x surface layer

鲜食葡萄杂交种子萌发率与亲本及亲本组合的关系分析

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果树资源学报 2024年第2期5卷 1-6页

作者：谭敏李晓梅贺晋瑜刘政海董志刚黄丽萍荀志丽王敏马小河赵旗峰山西农业大学果树研究所山西太原030031

【目的】常规杂交育种是葡萄新品种选育的重要方法,通过对15年的鲜食葡萄育种资料进行整理汇总,分析研究不同倍性亲本选择及不同亲本杂交组合配置与杂交种子萌芽率之间的关系,为鲜食葡萄育种实践工作提供参考和借鉴。【方法】以山西农... 详细信息

【目的】常规杂交育种是葡萄新品种选育的重要方法,通过对15年的鲜食葡萄育种资料进行整理汇总,分析研究不同倍性亲本选择及不同亲本杂交组合配置与杂交种子萌芽率之间的关系,为鲜食葡萄育种实践工作提供参考和借鉴。【方法】以山西农业大学果树研究所2003—2018年间进行常规杂交的45个鲜食葡萄组合为研究对象,对其亲本选择、杂交组合配置和杂交种子萌发率等进行分析。【结果】1)不同倍性亲本选择及不同亲本组合配置,杂交种子萌发率不同。2)以‘瑰宝’作为父本时,杂交种子的萌发率高。3)45个杂交组合中,不同年份、相同父母本杂交种子萌发率不同。4)45个杂交组合中,玫瑰香和红地球是良好的母本材料;瑰宝是良好的父本材料;美人指不是理想的亲本材料。【结论】选择二倍体品种做母本与四倍体品种杂交比用四倍体品种做母本与二倍体品种杂交时更容易获得种子;以四倍体为父母本时,很难得到杂交后代。

关键词：鲜食葡萄亲本组合杂交种子萌发率

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Resonance mechanism of flapping wing based on fluid structure interaction simulation

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Chinese Journal of Aeronautics 2024年第5期37卷 243-262页

作者： Yueyang GUO Wenqing YANG Yuanbo dong dong XUE National Key Laboratory of Science and Technology on Aerodynamic Design and Research School of AeronauticsNorthwestern Polytechnical UniversityXi'an 710072China Research&Development Institute of Northwestern Polytechnical University in Shenzhen Shenzhen 518063China Yangtze River Delta Research Institute of Northwestern Polytechnical University Taicang 215400China

Certain insect species have been observed to exploit the resonance mechanism of their *** order to achieve resonance and optimize aerodynamic performance,the conventional approach is to set the flapping frequency of flexible wings based on the Traditional Structural Modal(TSM)***,there exists controversy among researchers regarding the relationship between frequency and aerodynamic *** that the structural response of wings can be influenced by the surrounding air vibrations,an analysis known as Acoustic Structure Interaction Modal(ASIM)is introduced to calculate the resonant *** this study,Fluid Structure Interaction(FSI)simulations are employed to investigate the aerodynamic performance of flapping wings at modal frequencies derived from both TSM and ASIM *** performance is evaluated for various mass ratios and frequency ratios,and the findings indicate that the deformation and changes in vortex structure exhibit similarities at mass ratios that yield the highest aerodynamic ***,the flapping frequency associated with the maximum time-averaged vertical force coefficient at each mass ratio closely aligns with the ASIM frequency,as does the frequency corresponding to maximum ***,the ASIM analysis can provide an effective means for predicting the optimal flapping frequency for flexible ***,it enables the prediction that flexible wings with varying mass ratios will exhibit similar deformation and vortex structure *** paper offers a fresh perspective on the ongoing debate concerning the resonance mechanism of Flexible Flapping Wings(FFWs)and proposes an effective methodology for predicting their aerodynamic performance.

关键词： Flexible Flapping Wing(FFW) Acoustic Structure Interaction Modal(ASIM) Fluid Structure Interaction(FSI) Resonance mechanism Aerodynamic performance