Based on the physical meaning of sensitivity,a new finite element(FE) model updating method was proposed. In this method,a three-dimensional FE model of the Nanjing Yangtze River Bridge(NYRB) with ANSYS program was es...Based on the physical meaning of sensitivity,a new finite element(FE) model updating method was proposed. In this method,a three-dimensional FE model of the Nanjing Yangtze River Bridge(NYRB) with ANSYS program was established and updated by modifying some design parameters. To further validate the updated FE model,the analytical stress-time histories responses of main members induced by a moving train were compared with the measured ones. The results show that the relative error of maximum stress is 2.49% and the minimum relative coefficient of analytical stress-time histories responses is 0.793. The updated model has a good agreement between the calculated data and the tested data,and provides a current baseline FE model for long-term health monitoring and condition assessment of the NYRB. At the same time,the model is validated by stress-time histories responses to be feasible and practical for railway steel bridge model updating.展开更多
The evolution of microstructure on aging of an （α＋β） titanium alloy （Ti-5A1-5Mo-5V-1Cr-1Fe） in the β and （α＋β） solution-treated and quenched conditions was investigated, The presence of very fine to phase...The evolution of microstructure on aging of an （α＋β） titanium alloy （Ti-5A1-5Mo-5V-1Cr-1Fe） in the β and （α＋β） solution-treated and quenched conditions was investigated, The presence of very fine to phase was detected by electron diffraction for samples aged below 400 ℃. The fine a aggregates are uniformly formed within fl grains by nucleating at the to particles or β/ω interfaces. At higher temperature, the formation of to phase is avoided and the a lamellae are precipitated at the preferred site of grain boundary and then within the matrix. The highest hardness values are found when the alloys are aged at 450 ℃ for fl condition and 350 ℃ for （α＋β） condition.展开更多
Ni-based alloy coating on 21-4-N heat-resistant steel was prepared using CO2 laser, and the high-temperature abrasion wear was tested. The microstructure of this cladding layer and its abrasion wear behavior at high t...Ni-based alloy coating on 21-4-N heat-resistant steel was prepared using CO2 laser, and the high-temperature abrasion wear was tested. The microstructure of this cladding layer and its abrasion wear behavior at high temperature by changing compositions and temperatures were investigated by means of optical microscope and scanning electron microscope. Among the three compositions of cladding layer, i.e. Ni21+20%WC+0.5%CeO2, Ni25+20%WC+0.5%CeO2 and Ni60+20%WC+0.5%CeO2, the experimental results show that Ni21+20%WC+ 0.5%CeO2 cladding layer is made up of finer grains, and presents the best abrasion wear behavior at high temperature. The wear pattern of laser cladding layer is mainly grain abrasion at lower temperature, and it would be changed to adhesive abrasion and oxide abrasion at higher temperature.展开更多
The exploration of stable and highly efficient alkaline hydrogen evolution reaction(HER)electrocatalysts is imperative for alkaline water splitting.Herein,Se-doped NiCoP with hierarchical nanoarray structures directly...The exploration of stable and highly efficient alkaline hydrogen evolution reaction(HER)electrocatalysts is imperative for alkaline water splitting.Herein,Se-doped NiCoP with hierarchical nanoarray structures directly grown on carbon cloth(Se-NiCoP/CC)was prepared by hydrothermal reaction and phosphorization/selenization process.The experimental results reveal that Se doping could increase the electrochemical active sites and alter the electronic structure of NiCoP.The optimized Se-NiCoP/CC electrode exhibits outstanding HER activity in alkaline electrolyte,which only needs a low overpotential of 79 mV at the current density of 10 mA/cm^(2).When serving as anode and cathode electrode simultaneously,the Se-NiCoP/CC electrodes achieve current density of 50 mA/cm^(2) at a low voltage of only 1.62 V.This work provides a feasible way to rationally design high active HER electrocatalysts.展开更多
基金Project(2001G025) supported by the Foundation of the Science and Technology Section of Ministry of Railway of ChinaProject(2006FJ4233) supported by Hunan Postdoctoral Scientific Program of ChinaProject(2006) supported by the Postdoctoral Foundation of Central South University,China
文摘Based on the physical meaning of sensitivity,a new finite element(FE) model updating method was proposed. In this method,a three-dimensional FE model of the Nanjing Yangtze River Bridge(NYRB) with ANSYS program was established and updated by modifying some design parameters. To further validate the updated FE model,the analytical stress-time histories responses of main members induced by a moving train were compared with the measured ones. The results show that the relative error of maximum stress is 2.49% and the minimum relative coefficient of analytical stress-time histories responses is 0.793. The updated model has a good agreement between the calculated data and the tested data,and provides a current baseline FE model for long-term health monitoring and condition assessment of the NYRB. At the same time,the model is validated by stress-time histories responses to be feasible and practical for railway steel bridge model updating.
基金Project (50634030) supported by the National Natural Science Foundation of ChinaProject (2007DS04014) supported by the Program of Science and Technology of Shandong Province,ChinaProject supported by the Open Research Fund from the State Key Laboratory of Rolling and Automation,Northeastern University, China
文摘The evolution of microstructure on aging of an （α＋β） titanium alloy （Ti-5A1-5Mo-5V-1Cr-1Fe） in the β and （α＋β） solution-treated and quenched conditions was investigated, The presence of very fine to phase was detected by electron diffraction for samples aged below 400 ℃. The fine a aggregates are uniformly formed within fl grains by nucleating at the to particles or β/ω interfaces. At higher temperature, the formation of to phase is avoided and the a lamellae are precipitated at the preferred site of grain boundary and then within the matrix. The highest hardness values are found when the alloys are aged at 450 ℃ for fl condition and 350 ℃ for （α＋β） condition.
文摘Ni-based alloy coating on 21-4-N heat-resistant steel was prepared using CO2 laser, and the high-temperature abrasion wear was tested. The microstructure of this cladding layer and its abrasion wear behavior at high temperature by changing compositions and temperatures were investigated by means of optical microscope and scanning electron microscope. Among the three compositions of cladding layer, i.e. Ni21+20%WC+0.5%CeO2, Ni25+20%WC+0.5%CeO2 and Ni60+20%WC+0.5%CeO2, the experimental results show that Ni21+20%WC+ 0.5%CeO2 cladding layer is made up of finer grains, and presents the best abrasion wear behavior at high temperature. The wear pattern of laser cladding layer is mainly grain abrasion at lower temperature, and it would be changed to adhesive abrasion and oxide abrasion at higher temperature.
基金Projects(51772086,51872087,51971089)supported by the National Natural Science Foundation of ChinaProject(2018TP1037-202102)supported by Open Fund of Hunan Provincial Key Laboratory of Advanced Materials for New Energy Storage and Conversion,China+1 种基金Project supported by Student National SIT Innovation Program,ChinaProject(2020CB1007)supported by Hunan Joint International Laboratory of Advanced Materials and Technology for Clean Energy,China。
文摘The exploration of stable and highly efficient alkaline hydrogen evolution reaction(HER)electrocatalysts is imperative for alkaline water splitting.Herein,Se-doped NiCoP with hierarchical nanoarray structures directly grown on carbon cloth(Se-NiCoP/CC)was prepared by hydrothermal reaction and phosphorization/selenization process.The experimental results reveal that Se doping could increase the electrochemical active sites and alter the electronic structure of NiCoP.The optimized Se-NiCoP/CC electrode exhibits outstanding HER activity in alkaline electrolyte,which only needs a low overpotential of 79 mV at the current density of 10 mA/cm^(2).When serving as anode and cathode electrode simultaneously,the Se-NiCoP/CC electrodes achieve current density of 50 mA/cm^(2) at a low voltage of only 1.62 V.This work provides a feasible way to rationally design high active HER electrocatalysts.
