Under sustained strong stochastic impact loads,floating-supported friction plates are susceptible to the formation of fatigue cracks that propagate along the rim.The nonlinearity and randomness introduced by the crack...Under sustained strong stochastic impact loads,floating-supported friction plates are susceptible to the formation of fatigue cracks that propagate along the rim.The nonlinearity and randomness introduced by the cracked teeth participating in the impacts significantly influence the service life and reliability of the transmission system.In this paper,an improved stiffness excitation modeling method is developed for friction plate teeth with rim cracks.It overcomes the limitations of traditional approaches that fail to accurately assess the narrow-band,large-diameter friction plate teeth with rim cracks due to constraints imposed by boundary conditions.Then,an original dynamic impact model for the floating-supported friction plate and inner hub system is proposed,incorporating the effects of bending-torsional-axial-tilting coupled motions on tooth mesh excitations and dynamic responses.This model addresses the limitations of conventional models that only consider bending-torsion coupling,thereby providing a more comprehensive representation of the system's multi-dimensional dynamic behavior.The effects of the crack propagation depth and the number of cracked teeth on the stochastic impact characteristics and vibration responses of the system are investigated.Furthermore,finite element simulations and experimental tests are conducted to validate the cracked tooth stiffness excitations and dynamic impact responses,respectively.The proposed model is anticipated to provide both a theoretical foundation and practical guidance for fault diagnosis and reliability assessment of clutch friction plates.展开更多
Brachinite is a group of primitive achondrites that enables investigating the evolution of asteroids not fully diff erentiated in the early stage of the solar system.Kumtag 061 is a new meteorite sample collected on O...Brachinite is a group of primitive achondrites that enables investigating the evolution of asteroids not fully diff erentiated in the early stage of the solar system.Kumtag 061 is a new meteorite sample collected on October 27,2019,in Kumtag Desert,Xinjiang Province,China.The oxygen isotope composition(δ^(18)O=5.086‰,δ^(17)O=2.396‰,Δ’^(17)O=-0.298‰)and petrologic and mineralogic analysis suggest Kumtag 061 is a heavy-impacted brachinite(S4-S5).The geochemical composition suggests Kumtag 061 represents a partial melting residue of the brachinite parent body.Based on the noble gas composition,the cosmic ray exposure age of Kumtag 061 is 60.9±9.0 Ma.Combined with the gas retention ages,they indicate a(series of)thermal events on the parent body of brachinites before Kumtag 061 was ejected into space.展开更多
The North Atlantic Treaty Organization(NATO) has made two major strate-gic readjustments in the post-Cold War years to shake off the awkward posi-tion when its raison d’etre was called into doubt. At the 1991 Rome Su...The North Atlantic Treaty Organization(NATO) has made two major strate-gic readjustments in the post-Cold War years to shake off the awkward posi-tion when its raison d’etre was called into doubt. At the 1991 Rome Summit, an"All-dimensional defense strategy" was put forth with conflict prevention andcrisis management as its core mission. Preparations for the second strategic read-justment began in 1997 and the concept of a 21st century-oriented new strategywas declared at the Washington Summit last April.展开更多
The admittance features representing the physical attributes are used as the in termediates to extract the materialattributesrelated impact sound features of ribbed plates. Firstly, the admittance feature representati...The admittance features representing the physical attributes are used as the in termediates to extract the materialattributesrelated impact sound features of ribbed plates. Firstly, the admittance feature representations of metal ribbed plates attributes are obtained and the relationship between the admittance features and the impact sound features are established via correlation analysis method. Then, materialattributesrelated impact sound features are obtained indirectly. Finally, the performances of different sound features for the material recognition of ribbedmetal plates are verified through the Support Vector Machine classifier. The results indicate that the obtained four sets of features can effectively identify the materials of the metal ribbed plates, while the accuracy of a single feature depends on the separable degree of the corresponding material attribute. And the features extracted based on admittance functions have higher average accuracy than that of timbre features. Therefore, the proposed sound feature extraction method based on admittance features is valid, and the extracted sound features can effectively reflect the physical attributes.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.52505101,52475087,52475089,52365010)the Early-Career Young Scientists and Technologists Project of Jiangxi Province(Grant No.20252BEJ730175)。
文摘Under sustained strong stochastic impact loads,floating-supported friction plates are susceptible to the formation of fatigue cracks that propagate along the rim.The nonlinearity and randomness introduced by the cracked teeth participating in the impacts significantly influence the service life and reliability of the transmission system.In this paper,an improved stiffness excitation modeling method is developed for friction plate teeth with rim cracks.It overcomes the limitations of traditional approaches that fail to accurately assess the narrow-band,large-diameter friction plate teeth with rim cracks due to constraints imposed by boundary conditions.Then,an original dynamic impact model for the floating-supported friction plate and inner hub system is proposed,incorporating the effects of bending-torsional-axial-tilting coupled motions on tooth mesh excitations and dynamic responses.This model addresses the limitations of conventional models that only consider bending-torsion coupling,thereby providing a more comprehensive representation of the system's multi-dimensional dynamic behavior.The effects of the crack propagation depth and the number of cracked teeth on the stochastic impact characteristics and vibration responses of the system are investigated.Furthermore,finite element simulations and experimental tests are conducted to validate the cracked tooth stiffness excitations and dynamic impact responses,respectively.The proposed model is anticipated to provide both a theoretical foundation and practical guidance for fault diagnosis and reliability assessment of clutch friction plates.
基金supported by the Project of Highlevel Innovative Talents of Guizhou Province(GCC[2022]017-1)the National Natural Science Foundation of China(grant no.42173046)。
文摘Brachinite is a group of primitive achondrites that enables investigating the evolution of asteroids not fully diff erentiated in the early stage of the solar system.Kumtag 061 is a new meteorite sample collected on October 27,2019,in Kumtag Desert,Xinjiang Province,China.The oxygen isotope composition(δ^(18)O=5.086‰,δ^(17)O=2.396‰,Δ’^(17)O=-0.298‰)and petrologic and mineralogic analysis suggest Kumtag 061 is a heavy-impacted brachinite(S4-S5).The geochemical composition suggests Kumtag 061 represents a partial melting residue of the brachinite parent body.Based on the noble gas composition,the cosmic ray exposure age of Kumtag 061 is 60.9±9.0 Ma.Combined with the gas retention ages,they indicate a(series of)thermal events on the parent body of brachinites before Kumtag 061 was ejected into space.
文摘The North Atlantic Treaty Organization(NATO) has made two major strate-gic readjustments in the post-Cold War years to shake off the awkward posi-tion when its raison d’etre was called into doubt. At the 1991 Rome Summit, an"All-dimensional defense strategy" was put forth with conflict prevention andcrisis management as its core mission. Preparations for the second strategic read-justment began in 1997 and the concept of a 21st century-oriented new strategywas declared at the Washington Summit last April.
基金supported by the National Natural Science Foundation of China(11574249)the Aeronautical Science Foundation of China(20131553018)
文摘The admittance features representing the physical attributes are used as the in termediates to extract the materialattributesrelated impact sound features of ribbed plates. Firstly, the admittance feature representations of metal ribbed plates attributes are obtained and the relationship between the admittance features and the impact sound features are established via correlation analysis method. Then, materialattributesrelated impact sound features are obtained indirectly. Finally, the performances of different sound features for the material recognition of ribbedmetal plates are verified through the Support Vector Machine classifier. The results indicate that the obtained four sets of features can effectively identify the materials of the metal ribbed plates, while the accuracy of a single feature depends on the separable degree of the corresponding material attribute. And the features extracted based on admittance functions have higher average accuracy than that of timbre features. Therefore, the proposed sound feature extraction method based on admittance features is valid, and the extracted sound features can effectively reflect the physical attributes.
