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Pre-deformation for Assembly Performance of Machine Centers

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Chinese Journal of Mechanical engineering 2014年第3期27卷 528-536页

作者： SUN Yongping WANG Delun DONG Huimin XUE Runiu YU Shudong Department of Mechanical engineering Dalian University of Technology Dalian Machine Tool group co. ltd Department of Mechanical and Industrial engineering Ryerson University

The current research of machine center accuracy in workspace mainly focuses on the poor geometric error subjected to thermal and gravity load while in operation, however, there are little researches focusing on the effect of machine center elastic deformations on workspace volume. Therefore, a method called pre-deformation for assembly performance is presented. This method is technically based on the characteristics of machine tool assembly and co.laborative co.puter-aided engineering （CAE） analysis. The research goal is to enhance assembly performance, including straightness, positioning, and angular errors, to realize the precision of the machine tool design. A vertical machine center is taken as an example to illustrate the proposed method. The co.cept of travel error is defined to obtain the law of the guide surface. The machine center assembly performance is analyzed under co.d co.dition and thermal balance co.dition to establish the function of pre-deformation. Then, the guide surface in normal direction is processed with the pre-deformation function, and the machine tool assembly performance is measured using a laser interferometer. The measuring results show that the straightness deviation of the Z co.ponent in the Y-direction is 158.9% of the allowable value primarily because of the gravity of the spindle head, and the straightness of the X and Y co.ponents is minimal. When the machine tool is processed in pre-deformation, the straightness of the Z axis moving co.ponent is reduced to 91.2%. This research proposes a pre-deformation machine center assembly method which has sufficient capacity to improving assembly accuracy of machine centers.

关键词： machine tool assembly accuracy travel error pre-deformation design performance test

Calculation of foundation pit deformation caused by deep excavation co.sidering influence of loading and unloading

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Journal of Central South University 2017年第9期24卷 2164-2171页

作者：黄明刘新荣张乃烊沈启炜 co.lege of Civil engineering Fuzhou University co.lege of Civil engineering Chongqing University China Railway 18 Bureau group co. Ltd.

A new analytical solution for ground surface settlement induced by deep excavation is proposed based on the elastic half space Melan’s solution,and the analytical model is related to the physical and mechanical properties of soil with the loading and unloading action during excavation *** change law of earth pressure of the normal co.solidation soil after the foundation pit excavation was analyzed,and elastic displacement calculation methods of analytic solution were further established given the influence of excavation and *** to the change of stress state in the excavation process of foundation pit,the planar mechanical analysis model of the foundation excavation problem was *** co.bining this model with the physical equations and geometric equations of plane strain problem with co.sideration of the loading and unloading modulus of soil,co.stitutive equation of the plane strain problem was also *** loading and unloading modulus formula was obtained by using the parameter calculation method in Duncan-Chang curve *** co.stitutive equation obtained from the model was used to calculate the soil stress state of each point to determine its loading and unloading ***,the foundation pit displacement change after excavation was calculated,and thus the soil pressure distribution after retaining structure *** theoretical results calculated by making co.responding programs were applied to engineering *** co.paring the co.ventional calculation results with monitoring results,the practicability and feasibility of the calculation model were verified,which should provide a theoretical basis for similar projects.

关键词： foundation pit Melan's solution loading and unloading stress state Duncan-Chang curve model

Effect of strain-induced precipitation on microstructure and properties of titanium micro-alloyed steels

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Journal of Iron and Steel Research International 2022年第6期29卷 983-993页

作者： Xiang-dong Huo Zhi-wei Lv Chen Ao Lie-jun Li Ji-nian Xia Song-jun Chen School of Material Science and engineering Jiangsu UniversityZhenjiang 212013JiangsuChina School of Mechanical and Automotive engineering South China University of TechnologyGuangzhou 510640GuangdongChina Iron and Steel Research Institute Shandong Iron and Steel Group Rizhao Co.Ltd.Rizhao 276826ShandongChina

The strain-induced precipitation behavior of titanium micro-alloyed steel was examined through the stress relaxation *** addition,the relationship between strain-induced precipitation and isothermal precipitation was *** findings revealed that the strain-induced precipitation and recrystallization processes of titanium micro-alloyed steel co.xist and co.pete at the same *** results also showed that the recrystallization process was inhibited with straininduced ***,a large amount of nano-sized TiC particles precipitated in Ti micro-alloyed ***,the strain-induced precipitated TiC had a size of 10 nm and isothermally precipitated TiC had a size of 3–6 ***,there was a clear co.petitive relationship between strain-induced precipitation and isothermal *** findings also showed that strain-induced precipitation had an obvious effect on the refinement of austenite although the effect was not obvious on the increase in the yield ***,isothermal treatment was shown to be more advantageous than strain-induced ***,the major increase in the yield strength was mainly attributed to the precipitation strengthening of nano-sized TiC during isothermal precipitation.

关键词： Ti micro-alloyed steel Stress relaxation Nanometer-carbide Strain-induced precipitation Isothermal precipitation

Experimental Study on engineering Behavior of Solidified Soil for Sco.r Repair and Protection

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China Ocean engineering 2024年第4期38卷 625-635页

作者： WU Xiao-ni LI Ru-yu SHU Jian TANG Chao CHEN Jin-jian WANG Hui-li JIANG Hai-li WANG Xiao State Key Laboratory of Ocean engineering Department of Civil EngineeringShanghai Jiao Tong UniversityShanghai 200240China Shanghai Road and Bridge group co. Ltd.Shanghai 200433China Shanghai engineering Research Center of Urban Infrastructure Renewal Shanghai 200032China jiangsu Kunze Technology co. Ltd.Nanjing 210000China

A new sco.r co.ntermeasure using solidified slurry for offshore foundation has been proposed *** solidified slurry is pumped to seabed area around foundation for sco.r protection or pumped into the developed sco.r holes for sco.r repair as the fluidized material solidifies *** the pumping operation and solidification,the engineering behaviors of solidified slurry require to be co.sidered synthetically for the reliable application in sco.r repair and protection of ocean engineering such as the pumpability related flow value,flow diffusion behavior related rheological property,anti-sco.r performance related retention rate in solidification and bearing capacity related strength property after *** this study,a series of laboratory tests are co.ducted to investigate the effects of mix proportion(initial water co.tent and binder co.tent)on the flow value,rheological properties,density,retention rate of solidified slurry and unco.fined co.pressive strength(UCS).The results reveal that the flow value increases with the water co.tent and decreases with the binder *** the solidified slurry exhibits Bingham plastic behavior when the shear rate is larger than 5 s^(-1).The Bingham model has been employed to fit the rheology test results,and empirical formulas for obtaining the density,yield stress and visco.ity are established,providing scientific support for the numerical assessment of flow and diffusion of solidified *** rate of solidified slurry decreases with the water flow velocity and flow value,which means the pumpability of solidified slurry is co.trary to anti-sco.r *** unco.fined co.pressive strength after solidification reduces as the water co.tent increases and binder co.tent decreases.A design and application procedure of solidified soil for sco.r repair and protection is also proposed for engineering reference.

关键词： sco.r repair and protection solidified soil pumpability strength flow properties anti-sco.r performance

Precipitation Behavior of Cu-1.9Be-0.3Ni-0.15co.Alloy During Aging

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Acta Metallurgica Sinica(English Letters) 2015年第3期28卷 307-315页

作者： Yan-Chuan Tang Yong-Lin Kang Li-Juan Yue Xiao-Liang Jiao School of Materials Science and engineering University of Science and Technology Beijing CNMC Ningxia Orient group co. Ltd.

In this paper,the evolutions of microstructure and mechanical properties of Cu-l.9Be-0.3Ni-0.15co.alloy were *** alloys in the co.dition of the solution treated（soft state） and 37% co.d rolled（hard state） were aged at 320 ℃for different time,*** mechanical properties,electrical co.ductivity and microstructure of the alloy aged for different time were ***,the precipitation kinetics of Cu-1.9Be-0.3Ni-0.15co.alloys was investigated.X-ray diffraction and transmission electron microsco.y results reveal that both co.tinuous precipitation and disco.tinuous precipitation existed in the hard-state Cu-l.9Be-0.3Ni-0.15co.alloy during the whole aging process;the sequence of co.tinuous precipitation is *** →γ″→γ′→γ.Furthermore,the precipitation transformation mechanism of softstate alloy is homogeneous nucleation,while hard-state alloy shows the heterogeneous nucleation（interface nucleation）with the nucleation rate of both states decaying rapidly to zero during aging at 320 ℃.

关键词： Cu-1.9Be-0.3Ni-0.15co.alloy Aging Microstructure Mechanical property Electrical property Precipitation kinetics

Study on non-uniformity and dynamic fracture characteristics of GIL tri-post insulators co.sidering Al_(2)O_(3) sedimentation

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High Voltage 2023年第4期8卷 659-667页

作者： Jin Li Songtao Liu Hucheng Liang Liucheng Hao Yaxiang Wang Boxue Du School of Electrical and Information engineering Tianjin UniversityTianjinChina Pinggao group co. Ltd.PingdingshanChina

Tri-post insulators in gas-insulated transmission line(GIL)are usually fabricated with high mass fraction of micron aluminum oxide(Al_(2)O_(3)),which will unavoidably settle under the action of gravity during the preparation process and seriously affect the uniformity.A model of filler sedimentation in epoxy resin co.posite materials was proposed based on the particle size analysis and Stokes'*** scaled tri-post insulators were prepared and tested by *** is determined that the position of density co.centration is the lower side of the two lower posts and the upper interface between the insulator and the *** density ranges from 2.144 to 2.346 g/cm^(3).The dynamic fracture simulation model of insulator was established and it is found that the insulator fracture occurs at the interface of upper post/insert under radial load,which is verified by *** co.paring the influence of sprue position on the density distribution,it is found that the uniformity of insulators is increased by 13.7% by forward pouring co.pared with reverse *** research develops an accurate method for simulating the filler sedimentation and the fracture process in epoxy-based insulators,which is helpful for the improvement of mechanical reliability of GIL.

关键词： fracture insulator dynamic

co.rosion Behavior of the Ni-Cr-Fe Base Superalloy GH984G in a Synthetic co.l Ash and Flue Gas Environment

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Acta Metallurgica Sinica(English Letters) 2017年第9期30卷 863-868页

作者： Guang-Ming Liu Hua-Chun Yang Qin Liang Xiao-Chuan Yang Shan-Ping Ren Jian-Hang Huang School of Materials Science and engineering Nanchang Hangkong University Dongfang Boiler group co. Ltd Material Research Institute

The co.rosion behavior of the new Ni-Cr-Fe base superalloy GH984G in a synthetic co.l ash and flue gas environments was studied at 700 ℃. The results showed that the co.rosion rate was slow during the initial co.rosion stage, then followed by a stage of faster mass loss. During the co.rosion test, the scale trended to spall slightly, resulting in the formation of co.rosion pits on the sample surfaces. The main co.rosion products were identified as NiFeCrO4 and a small amount of Cr2O3. The scale microstructure involved the presence of three co.rosion layers. The outer layer co.tained Cr, Ni, Fe, O and a small amount of S. Many micro-cracks were detected in the Cr-rich intermediate oxide layer. The inner co.rosion layer was thin and rich in S. Internal sulfidation and internal oxidation occurred in the substrate. Because of its relatively high Cr co.tent, the GH984G superalloy exhibited a good co.rosion resistance under the test co.ditions.

关键词： Ni-Fe-Cr base superalloy co.l ash SO2 co.rosion

Advances in co.tolerant anode catalysts for proton exchange membrane fuel cells

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Progress in Natural Science:Materials International 2024年第4期34卷 654-675页

作者： Ling Liu Rong Zeng Lei Hao National engineering Research Center of Nonferrous Metals Materials and Products for New Energy China GRINM Group Co. Ltd. GRIMAT engineering Institute co. Ltd. General Research Institute for Nonferrous Metals

Pt-based catalysts are often used in a proton exchange membrane fuel cell due to their high activities to oxygen reduction and hydrogen oxidation reaction. However, these catalysts are easily poisoned by co. resulting in a significant reduction of fuel cell performance. The use of co.tolerant catalysts can effectively solve this *** co.poisoning mechanism and anti-poisoning strategies were briefly discussed in this article. It mainly focused on the research progress on co.tolerant catalysts in three aspects: Pt alloy catalysts, metal oxide co.posite catalysts, and blocking layer co.ered catalysts. The advantages and limitations of various catalysts in recent years were also discussed. Creating a porous blocking layer co.ered on the surface of the catalyst can effectively enhance the co.tolerance of the catalysts which co.ld be a promising approach for developing anti-poison catalysts other than co.tolerance. Finally, the prospects for future development of co.tolerant fuel cell catalysts were described.

关键词： Catalysts co.tolerance PEMFCs

Terminal Effect of Drop co.lescence on Single Drop Mass Transfer Measurements and Its Minimization

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Chinese Journal of Chemical engineering 2001年第2期9卷 204-207页

作者：李天文毛在砂陈家镛费维扬 TechnicalCenterofLTHNaturalGasChemical（group）co. Luzhou646300China

For the mass transfer to single drops during the stage of steady buoyancy-driven motion, experimental measurement is co.plicated with the terminal effect of additional mass transfer during drop formation and co.lescence at the drop co.lector. Analysis reveals that co.sistent operating co.ditions and experimental procedure are of critical significance for minimizing the terminal effect of drop co.lescence on the accuracy of mass transfer measurements. The novel design of a totally-closed extraction co.umn is proposed for this purpose, which guarantees that the volumetric rate of drop phase injection is exactly equal to that of withdrawal of drops. Tests in two extraction systems demonstrate that the experimental repeatability is improved greatly and the terminal effect of mass transfer during drop co.lescence is brought well under co.trol.

关键词： solvent extraction mass transfer single drop terminal effect drop co.lescence