To determine the relationship between slabbing failure and the specimen height-to-width(H/W)ratio and to analyze the conditions,characteristics,and mechanism of slabbing failure in the laboratory,uniaxial compression ...To determine the relationship between slabbing failure and the specimen height-to-width(H/W)ratio and to analyze the conditions,characteristics,and mechanism of slabbing failure in the laboratory,uniaxial compression tests were conducted using six groups of granite specimens.The entire failure process was recorded using strain gauges and high-speed cameras.The initiation and propagation of fractures in specimens were identified by analyzing the monitoring results of stress,strain,and acoustic emission.The experimental results show that changes in the specimen H/W ratio can transform the macro failure mode.When the H/W ratio is reduced to 0.5,the macro failure mode is dominated by slabbing.Low load-bearing ability is observed in specimens with slabbing failure,and the slabbing fractures are approximately parallel to the loading direction.Moreover,the fracture propagation characteristics and acoustic emission signals of slabbing failure specimens show typical tensile failure characteristics,indicating that slabbing failure is essentially a special tensile failure.展开更多
Experimental and numerical investigations have suggested the existence of a strong correlation between the passage of coherent structures and events of bursting and intermittency. However, a detailed cause-and-effect ...Experimental and numerical investigations have suggested the existence of a strong correlation between the passage of coherent structures and events of bursting and intermittency. However, a detailed cause-and-effect study on the subject is rarely found in the literature due to the complexity and the nonlinear multiscale nature of turbulent flows. The primary goal of this research is to explore the motion and evolution of coherent structures during late transition, whose structure is much more ordered than that of fully developed turbulence, and their relationship with events of bursting and intermittency based on a verified high-order direct numerical simulation(DNS). The computation was carried out on a flat plate at Reynolds number 1000(based on the inflow displacement thickness) with an inflow Mach number 0.5. It is concluded that bursting and intermittency detected by stationary sensors in a transitional boundary layer actually result from the passage and development of vortical structures, and it would be more rational to design transitional turbulence models based on modelling the moving vortical structures rather than the statistical features and experimental experiences.展开更多
基金the National Natural Science Foundation of China(Nos.11972378,51904335,51927808)the Fundamental Research Funds for the Central Universities of Central South University,China(No.2021zzts0282).
文摘To determine the relationship between slabbing failure and the specimen height-to-width(H/W)ratio and to analyze the conditions,characteristics,and mechanism of slabbing failure in the laboratory,uniaxial compression tests were conducted using six groups of granite specimens.The entire failure process was recorded using strain gauges and high-speed cameras.The initiation and propagation of fractures in specimens were identified by analyzing the monitoring results of stress,strain,and acoustic emission.The experimental results show that changes in the specimen H/W ratio can transform the macro failure mode.When the H/W ratio is reduced to 0.5,the macro failure mode is dominated by slabbing.Low load-bearing ability is observed in specimens with slabbing failure,and the slabbing fractures are approximately parallel to the loading direction.Moreover,the fracture propagation characteristics and acoustic emission signals of slabbing failure specimens show typical tensile failure characteristics,indicating that slabbing failure is essentially a special tensile failure.
基金supported by the Department of Mathematics at University of Texas at Arlington
文摘Experimental and numerical investigations have suggested the existence of a strong correlation between the passage of coherent structures and events of bursting and intermittency. However, a detailed cause-and-effect study on the subject is rarely found in the literature due to the complexity and the nonlinear multiscale nature of turbulent flows. The primary goal of this research is to explore the motion and evolution of coherent structures during late transition, whose structure is much more ordered than that of fully developed turbulence, and their relationship with events of bursting and intermittency based on a verified high-order direct numerical simulation(DNS). The computation was carried out on a flat plate at Reynolds number 1000(based on the inflow displacement thickness) with an inflow Mach number 0.5. It is concluded that bursting and intermittency detected by stationary sensors in a transitional boundary layer actually result from the passage and development of vortical structures, and it would be more rational to design transitional turbulence models based on modelling the moving vortical structures rather than the statistical features and experimental experiences.
