The natural dynamic characteristics of a circular cylindrical tube made of three-directional(3 D)functional graded material(FGM)based on the Timoshenko beam theory are investigated.Hamilton’s principle is utilized to...The natural dynamic characteristics of a circular cylindrical tube made of three-directional(3 D)functional graded material(FGM)based on the Timoshenko beam theory are investigated.Hamilton’s principle is utilized to derive the novel motion equations of the tube,considering the interactions among the longitudinal,transverse,and rotation deformations.By dint of the differential quadrature method(DQM),the governing equations are discretized to conduct the analysis of natural dynamic characteristics.The Ritz method,in conjunction with the finite element method(FEM),is introduced to verify the present results.It is found that the asymmetric modes in the tube are controlled by the 3 D FGM,which exhibit more complicated shapes compared with the unidirectional(1 D)and bi-directional(2 D)FGM cases.Numerical examples illustrate the effects of the axial,radial,and circumferential FGM indexes as well as the supported edges on the natural dynamic characteristics in detail.It is notable that the obtained results are beneficial for accurate design of smart structures composed from multi-directional FGM.展开更多
Seism is one of the main triggering mechanisms of forming fluxoturbidite in front of delta. The forming process of fluxoturbidite in front of delta under seismism was experimentally simulated in lab. The results show ...Seism is one of the main triggering mechanisms of forming fluxoturbidite in front of delta. The forming process of fluxoturbidite in front of delta under seismism was experimentally simulated in lab. The results show that there are two kinds of slumping and three kinds of fluxoturbidites in front of delta under seismism. The liquefied fluxo- turbidite and secondary overlapped turbidite move by their own gravity, and develop mainly on the base of foreslope and the frontal bed slope. They have a small sedimentary scale and can’t move too far. On the contrary, the faulted fluxoturbidites have a larger scale and can move a long distance. The collision- power from hinder overlapped sand body is also the motivity of the faulted fluxoturbidite’s migration besides its own gravity. They mostly develop in the deep sag in front of delta, and are the favorable room to accumulate petroleum. Finally, according to the demonstration and inversion of similarity, at least 7.35 M of earthquake had happened in middle- Shasan period of Paleogene, which induced the slumping of delta front. So the tectonic action of northern steep slope is the main reason to induce earth- quake.展开更多
Donald V.Helmberger was an unparalleled observational seismologist,and theoretician.His pioneering work in seismic waveform modeling,and the numerical methods he developed to simulate seismograms to study the structur...Donald V.Helmberger was an unparalleled observational seismologist,and theoretician.His pioneering work in seismic waveform modeling,and the numerical methods he developed to simulate seismograms to study the structure of the Earth and the nature of earthquake sources have become techniques that are now commonplace.展开更多
This paper"Detecting gravitational wave with an interferometric seismometer array on lunar nearside"[1]was published in SCIENCE CHINA Physics,Mechanics&Astronomy(66,109513(2023),doi:10.1007/s11433-023-21...This paper"Detecting gravitational wave with an interferometric seismometer array on lunar nearside"[1]was published in SCIENCE CHINA Physics,Mechanics&Astronomy(66,109513(2023),doi:10.1007/s11433-023-2179-9).Due to an oversight on our part,some errors were made in the originally published paper.We apologize for these errors and offer the corresponding explanations and corrections for the readers.展开更多
基金Project supported by the National Natural Science Foundation of China(Nos.11902001 and12072221)the China Postdoctoral Science Foundation(No.2018M641643)the Anhui Provincial Natural Science Foundation of China(Nos.1908085QA13 and 1808085ME128)。
文摘The natural dynamic characteristics of a circular cylindrical tube made of three-directional(3 D)functional graded material(FGM)based on the Timoshenko beam theory are investigated.Hamilton’s principle is utilized to derive the novel motion equations of the tube,considering the interactions among the longitudinal,transverse,and rotation deformations.By dint of the differential quadrature method(DQM),the governing equations are discretized to conduct the analysis of natural dynamic characteristics.The Ritz method,in conjunction with the finite element method(FEM),is introduced to verify the present results.It is found that the asymmetric modes in the tube are controlled by the 3 D FGM,which exhibit more complicated shapes compared with the unidirectional(1 D)and bi-directional(2 D)FGM cases.Numerical examples illustrate the effects of the axial,radial,and circumferential FGM indexes as well as the supported edges on the natural dynamic characteristics in detail.It is notable that the obtained results are beneficial for accurate design of smart structures composed from multi-directional FGM.
基金Project 2001BA605A09 supported by national key project of the tenth Five- Year Plan
文摘Seism is one of the main triggering mechanisms of forming fluxoturbidite in front of delta. The forming process of fluxoturbidite in front of delta under seismism was experimentally simulated in lab. The results show that there are two kinds of slumping and three kinds of fluxoturbidites in front of delta under seismism. The liquefied fluxo- turbidite and secondary overlapped turbidite move by their own gravity, and develop mainly on the base of foreslope and the frontal bed slope. They have a small sedimentary scale and can’t move too far. On the contrary, the faulted fluxoturbidites have a larger scale and can move a long distance. The collision- power from hinder overlapped sand body is also the motivity of the faulted fluxoturbidite’s migration besides its own gravity. They mostly develop in the deep sag in front of delta, and are the favorable room to accumulate petroleum. Finally, according to the demonstration and inversion of similarity, at least 7.35 M of earthquake had happened in middle- Shasan period of Paleogene, which induced the slumping of delta front. So the tectonic action of northern steep slope is the main reason to induce earth- quake.
文摘Donald V.Helmberger was an unparalleled observational seismologist,and theoretician.His pioneering work in seismic waveform modeling,and the numerical methods he developed to simulate seismograms to study the structure of the Earth and the nature of earthquake sources have become techniques that are now commonplace.
文摘This paper"Detecting gravitational wave with an interferometric seismometer array on lunar nearside"[1]was published in SCIENCE CHINA Physics,Mechanics&Astronomy(66,109513(2023),doi:10.1007/s11433-023-2179-9).Due to an oversight on our part,some errors were made in the originally published paper.We apologize for these errors and offer the corresponding explanations and corrections for the readers.
