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Grain refinement impact on the mechanical properties and wear behavior of Mg-9Gd-3Y-2Zn-0.5Zr alloy after decreasing temperature reciprocating upsetting-extrusion

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Journal of Magnesium and Alloys 2022年第12期10卷 3506-3519页

作者： Wenlong Xu Jianmin Yu Leichen Jia Chang Gao Zhan Miao Guoqin Wu Guojun Li Zhimin Zhang School of Material Science and Engineering North University of ChinaTaiyuan 030051China

Based on the deforming technique of severe plastic deformation(SPD), the grain refinement of a Mg-9Gd-3Y-2Zn-0.5Zr alloy treated with decreasing temperature reciprocating upsetting-extrusion(RUE) and its influence on the mechanical properties and wear behavior of the alloy were studied. The RUE process was carried out for 4 passes in total, starting at 0 ℃ and decreasing by 10 ℃ for each pass. The results showed that as the number of RUE passes increased, the grain refinement effect was obvious, and the second phase in the alloy was evenly distributed. Room temperature tensile properties of the alloy and the deepening of the RUE degree showed a positive correlation trend, which was due to the grain refinement, uniform distribution of the second phase and texture weakening. And the microhardness of the alloy showed that the microhardness of RUE is the largest in 2 passes. The change in microhardness was the result of dynamic competition between the softening effect of DRX and the work hardening effect. In addition, the wear resistance of the alloy showed a positive correlation with the degree of RUE under low load conditions. When the applied load was higher, the wear resistance of the alloy treated with RUE decreased compared to the initial state alloy. This phenomenon was mainly due to the presence of oxidative wear on the surface of the alloy, which could balance the positive contribution of severe plastic deformation to wear resistance to a certain extent.

关键词： Mg-9Gd-3Y-2Zn-0.5Zr alloy Reciprocating upsetting-extrusion Grain refinement Texture Mechanical properties Wear behavior

Optimization Design of Vibration Characteristics of Ship Composite Brace with Rigid Vibration Isolation Mass

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Journal of Marine Science and Application 2011年第2期10卷 215-219页

作者：王强勇姚熊亮于丹竹庞福振 Wuhan Second Ship Design and Research Institute College of Shipbuilding Engineering Harbin Engineering University

In considering the theory of structural dynamic optimization design, a design method of the structural style of ship composite brace with rigid vibration isolation mass was studied. Two kinds of structural dynamic optimization formulations minimizing the vibration acceleration of the non-pressure hull on the restraining condition of the gross weight of the ship cabin were established: 1) dynamic optimization of the sectional dimensions of the rigid vibration isolation mass in the composite brace; 2) dynamic optimization of the arranging position of the rigid vibration isolation mass. Through the optimization results, sectional dimensions and the arranging position of the rigid vibration isolation mass with better performance in reducing vibration were gained, and some reference was provided for practical engineering designs as well as enrichment of the design method of a novel ship vibration-isolation brace.

关键词： rigid vibration isolation mass composite brace impedance mismatch optimization design vibration and noise reduction

Numerical simulation research on multiphase flow of aviation centrifugal pump based on OpenFOAM

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Chinese Journal of Aeronautics 2024年第4期37卷 256-275页

作者： Xianwei LIU Jiangfeng FU Junjie YANG Dewen YIN Zhenhua ZHOU Huacong LI College of Power and Energy Northwestern Polytechnical UniversityXi’an 710072China Norinco Group Testing and Research Institute Huayin 714200China AECC Xi’an Engine Control technology Co.Ltd. Xi’an 710077China AECC Guizhou Honglin Aero Engine Control technology Co.Ltd. Guiyang 550009China

This paper aims to tackle the calculation efficiency problem raised in the cavitation-flow simulation of the aviation centrifugal pump due to the fading-away interface resulting from the dissipation of numerics used in the phase-change control equation for unstructured-grid multiphase flow,and due to the limitation of flow time-step in whole flow regimes,the control equation of vapor–liquid two-phase flow considering cavitation mass transport is established firstly,modifying the momentum equation by introducing the surface tension,and adding the artificial convective flow to the phase equation to solve the numerical dissipation ***,in consideration of the local time step principle and based on the multi-dimensional general limiter algorithm with explicit solutions under the OpenFOAM platform,a solution method of steady-state VOF (Volume of Fluid) model considering cavitation two-phase change is constructed,and the feasibility of this method is verified by NACA hydrofoil and NASA flat plate ***,based on the platform developed,the cavitation performance of an aviation centrifugal pump inducer is *** research results show that the error of the calculated cavitation pressure distribution for NACA hydrofoil between the simulation test and the experimental-test is less than 5%,and the maximum error of calculated cavitation number at pump head dropping for NASA high-speed flat plate inducer between the simulation test and the experimental-test is 2.1%.The cavitation area observed in the simulation test is the same as that obtained in the high-speed photography *** on the OpenFOAM simulation method,the position of pump head dropping of the fuel centrifugal pump can be accurately *** error of the calculated cavitation number at pump head dropping between the simulation test and the experimental test is about 3.7%,showing high calculation accuracy.

关键词： Aero engine Fuel centrifugal pump Multiphase flow OpenFOAM Volume of fluid

Reference information time delay estimation and compensation in transfer alignment

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Journal of Southeast University(English Edition) 2011年第1期27卷 52-55页

作者：陆源程向红东南大学仪器科学与工程学院南京210096 东南大学微惯性仪表与先进导航技术教育部重点实验室南京210096

To reduce the error in transfer alignment caused by reference information delay,a time delay estimation method is developed based on least-squares curve fitting of the angular rate ***,the gyro sensor measurements of the main strapdown inertial navigation system（M-SINS） and the slave strapdown inertial navigation system（S-SINS） are recorded for a few seconds and the integration of the data is ***,the possible maximum range of the delay value is defined and the points of the curve at different intervals are *** square of the differences between the corresponding points are ***,the delay estimation can be acquired by the least-squares curve fitting of the M-SINS and the S-SINS.A delay compensation method by local data shifting is also *** simulation results demonstrate the effectiveness of delay estimation and indicate that the estimation accuracy is independent of the delay *** the local data shifting compensation method can effectively reduce the errors of the transfer alignment caused by the reference information delay.

关键词： transfer alignment delay estimation compensation synchronization least squares curve fitting

Effect of temperature on soil-water characteristics and hysteresis of compacted Gaomiaozi bentonite

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Journal of Central South University 2009年第5期16卷 821-826页

作者：叶为民万敏陈宝陈永贵崔玉军王驹 Key Laboratory of Geotechnical and Underground Engineering Ministry of EducationTongji University United Research Center for Urban Environment and Sustainable Development Ministry of Education Ecole des Ponts Paries Tech Beijing Research Institute of Uranium Geology

Laboratory tests under different constraint conditions were carried out to obtain the soil-water retention curves(SWRCs) of highly-compacted confined/unconfined Gaomiaozi(GMZ) bentonite at 20,40 and 80 ℃,respectively. The effect of temperature on the soil-water characteristics of the highly-compacted GMZ bentonite was analyzed. The results show that the water retention capacity of the highly-compacted GMZ bentonite decreases as the temperature increases under unconfined and confined conditions. At a certain temperature,the constraint conditions have little influence on the water retention capacity of the compacted bentonite at high suction,but the water retention capacity of the confined specimen is lower than that of the unconfined specimen at low suction. Under unconfined conditions,the hysteretic behaviour of the compacted bentonite decreases with increasing temperature. At high suction(>4 MPa) ,the hysteretic behaviour of the unconfined bentonite tends to increase with the decrease of the suction. In summary,the hysteretic behaviour of the compacted bentonite is not significant.

关键词： Gaomiaoz bentonite soil-water characteristic hysteretic behavior nuclear waste repository water retention capacity temperature

Numerical Analysis of a Blocking Mass Attenuating Wave Propagation

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Journal of Marine Science and Application 2011年第4期10卷 490-494页

作者：王献忠姚熊亮王强勇吕帅 School of Shipbuilding Engineering Harbin Engineering University Wuhan Second Ship Design and Research Institute

Based on wave theory, blocking mass impeding propagation of flexural waves was analyzed with force excitation applied on a ship pedestal. The analysis model of a complex structure was developed by combining statistical energy analysis and the finite element method. Based on the hybrid FE-SEA method, the vibro-acoustic response of a complex structure was solved. Then, the sound radiation of a cylindrical shell model influenced by blocking mass was calculated in mid/high frequency. The result shows that blocking mass has an obvious effect on impeding propagation. The study provides a theoretical and experimental basis for application of the blocking mass to structure-borne sound propagation control.

关键词： blocking mass deterministic method statistical energy method hybrid method

Preparation and tribological performances of Ni-P-multi-walled carbon nanotubes composite coatings

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Transactions of Nonferrous Metals Society of China 2012年第11期22卷 2719-2725页

作者：孟振强李溪滨熊拥军湛菁中南大学粉末冶金国家重点实验室长沙410083

Multi-walled carbon nanotubes （MWNTs） were wet-milled in the presence of ammonia and cationic surfactant and then used as reinforcements to prepare Ni-P-MWNTs composite coatings by electroless plating. The tribological performances of the composite coatings under dry condition were investigated in comparison with 45 steel and conventional Ni-P coating, Micrographs show that short MWNTs with uniform length and open tips were obtained through the wet-milling process. The results of wear test reveal that the Ni-P-MWNTs composite coatings posses much better friction reduction and anti-wear performances when compared with 45 steel and Ni-P coating. Within the MWNTs content range of 0.74%-1.97%, the friction coefficient and the volume wear rate of the composite coatings decrease gradually and reach the minimum values of 0.08 and 6.22x10-15 m3/（N.m）, respectively. The excellent tribological performances of the composite coatings can be attributed to the introduction of MWNTs, which play both roles of reinforcements and solid lubricant during the wear process.

关键词： Ni-P coating carbon nanotubes composite coating ball milling electroless plating self-lubrication tribologicalperformance friction coefficient volume wear rate

Dynamic Response of Phragmites australis and Suaeda salsa to Climate Change in the Liaohe Delta Wetland

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Journal of Meteorological Research 2021年第1期35卷 157-171页

作者： Yushu ZHANG Wenying YU Ruipeng JI Yijun ZHAO Rui FENG Qingyu JIA Jinwen WU Institute of Atmospheric Environment China Meteorological AdministrationShenyang 110166 Key Laboratory of Agrometeorological Disasters of Liaoning Province Shenyang 110166 Panjin Meteorological Service Center Liaoning Meteorological BureauPanjin 124010

Because of its unique geographical location and ecological function, the Liaohe Delta Wetland is important in maintaining regional ecological balance and security. Monitoring and evaluating changes in the wetland are therefore of great importance. We used medium-and high-resolution satellite data, meteorological station data, and site measurement data to analyze changes in the area and spatial distribution of Phragmites australis and Suaeda salsa in the Liaohe Delta Wetland from 1998 to 2017, as well as their growth response to the climate change. The results showed that during 1998–2017, the areas of both P. australis and S. salsa wetlands alternated through periods of decreasing,increasing, and then decreasing trends. The annual change in the area and spatial distribution range of S. salsa fluctuated more than that of P. australis. The annual variation of normalized difference vegetation index(NDVI) in P. australis wetland showed an upward trend from 1998 to 2017. The area of P. australis cover that was improved, unchanged, and decreased accounted for 81.8%, 12.3%, and 5.9%, respectively, of the total area;evaporation and wind speed were the main meteorological factors affecting the NDVI;and contribution rates of the climate change and human activities to the NDVI were 73.2% and 26.8%, respectively. The area with vegetation cover being mainly *** that was improved, unchanged, and decreased accounted for 63.3%, 18.3%, and 18.4%, respectively, of the total area;and no meteorological factors significantly affected the NDVI of S. salsa in the region. The interaction between vegetation growth and meteorological factors may help to explain the increasing trend in vegetation *** improvement in wetland vegetation also led to carbon sequestration and an increase in sequestration capacity.

关键词： Liaohe Delta wetland Phragmites australis Suaeda salsa climate change

Study on the Impediment to Vibration Wave Propagation from Rigid Vibration Isolation Mass

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Journal of Marine Science and Application 2011年第1期10卷 63-69页

作者：王强勇卢友敏王献忠姚熊亮 Wuhan Second Ship Design and Research Institute College of Shipbuilding Engineering Harbin Engineering University

Based on the principle of impedance mismatching,the performance of rigid vibration isolation mass in impeding vibration wave propagation was discussed from the perspective of wave *** on FEM,the influence of its weight as well as the cross-section shape parameters on the isolation performance of rigid vibration isolation mass was studied through numerical *** results show that rigid vibration isolation mass can effectively impede the propagation of the medium and high frequency vibration waves,and the heavier the vibration isolation mass,the better the isolation *** low frequency waves,the vibration isolation effect is not so obvious;for a rectangular vibration isolation mass,the isolation performance could be effectively improved by increasing the cross-section height and reducing the cross-section width.A useful reference was provided for the application of rigid vibration isolation masses to the vibration isolation and noise reduction of ship structure.

关键词： rigid vibration isolation mass principle of impedance mismatching vibration wave propagationcharacteristics vibration isolation and noise reduction