In order to constitute engineering design methods of the flat ribbon wound explosion containment vessels, the dynamic response of such vessels subjected to internal explosion loading is simulated using LS-DYNA3D. Thre...In order to constitute engineering design methods of the flat ribbon wound explosion containment vessels, the dynamic response of such vessels subjected to internal explosion loading is simulated using LS-DYNA3D. Three winding angles, 10°, 15°and 20°, are considered. It is shown that among ribbon vessels investigated, the center displacement of outermost ribbons of the vessel with 10°winding angle is the smallest under the same blast loading. The response of vessels loaded in inner core is local. From the center of the cylindrical shell to the bottom cover, the maximum strain gradually decreases. The ribbons are subjected to tension in the length direction and compression in the width direction. Blasting shock energy concentrates on where is close to center section of blasting. For comparison, numerical simulation of a monobloc thick-walled explosion containment vessel is also investigated. It can be found that the biggest deformation of the flat ribbon wound explosion containment vessels is bigger than that of the monobloc thick-walled explosion containment vessel in the center section of blasting under the same TNT. Numerical results are approximately in agreement with experimental ones. It is proved that the ribbon vessels have the valuable properties of ' leak before burst at worst' compared with the monobloc vessels through numerical simulation.展开更多
In vitro cell loading experiments are used to investigate stimulation of strain to cellular proliferation. As the flowing conditions of culture fluid in loading systems has been little known, strictly people can not d...In vitro cell loading experiments are used to investigate stimulation of strain to cellular proliferation. As the flowing conditions of culture fluid in loading systems has been little known, strictly people can not detect the influence of strain to cellular proliferation exactly because shear flow can enhance cell proliferation either. Based on the working principle and cyclic loading parameters, we simplify Navier-Stokes equation to describe the flow of culture fluid on substrates of uniaxial and equi-biaxial flat tensile loading systems and four point bending system. With approximate solutions, the distributions of velocity field and wall shear flow to cells are gained. Results show: shear flows are zero in the middle (or fixed point or line) of substrate for all systems, and they get larger proportionally to distance from middle and substrate elongate; the shear flow on the substrate of four point bending system is much greater than those of others. This shear flow in four point bending system, confirmed by Owan, I., et al with OPN mRNA increase in their experiment, could cause more influence to osteoblast-like cells than that caused by strain. We estimate the average magnitude of shear stress in Owan’s device, the results are consistent with other experimental data about shear flow. In conclusion our study makes it possible to differentiate the influence of strain on cellular proliferation to that of shear flow in loading experiments with the devices mentioned above quantitatively.展开更多
A numerical wave load model based on two-phase(water-air) Reynolds-Averaged Navier Stokes(RANS) type equations is used to evaluate hydrodynamic forces exerted on flatted-bottom seafloor mining tool during its entering...A numerical wave load model based on two-phase(water-air) Reynolds-Averaged Navier Stokes(RANS) type equations is used to evaluate hydrodynamic forces exerted on flatted-bottom seafloor mining tool during its entering ocean waves of deploying process.The discretization of the RANS equations is achieved by a finite volume approach(FV).The volume of fluid method(VOF) is employed to track the complicated free surface.A numerical wave tank is built to generate the ocean waves which are suitable for deploying seafloor mining tool.A typical deploying condition is employed to reflect the process of flatted-bottom body impacting with waves,and the pressure distribution of bottom is also presented.Four different lowering velocities are applied to obtain the time histories of maximum pressure of bottom,and it can be concluded that the pressure coefficient decreases with water velocity increasing,which is similar with ordinary water entry case.The numerical results clearly demonstrate the characteristics of flatted-bottom body entering ocean waves.展开更多
基金Supported by National Natural Science Foundation of China(No. 10372091)
文摘In order to constitute engineering design methods of the flat ribbon wound explosion containment vessels, the dynamic response of such vessels subjected to internal explosion loading is simulated using LS-DYNA3D. Three winding angles, 10°, 15°and 20°, are considered. It is shown that among ribbon vessels investigated, the center displacement of outermost ribbons of the vessel with 10°winding angle is the smallest under the same blast loading. The response of vessels loaded in inner core is local. From the center of the cylindrical shell to the bottom cover, the maximum strain gradually decreases. The ribbons are subjected to tension in the length direction and compression in the width direction. Blasting shock energy concentrates on where is close to center section of blasting. For comparison, numerical simulation of a monobloc thick-walled explosion containment vessel is also investigated. It can be found that the biggest deformation of the flat ribbon wound explosion containment vessels is bigger than that of the monobloc thick-walled explosion containment vessel in the center section of blasting under the same TNT. Numerical results are approximately in agreement with experimental ones. It is proved that the ribbon vessels have the valuable properties of ' leak before burst at worst' compared with the monobloc vessels through numerical simulation.
文摘In vitro cell loading experiments are used to investigate stimulation of strain to cellular proliferation. As the flowing conditions of culture fluid in loading systems has been little known, strictly people can not detect the influence of strain to cellular proliferation exactly because shear flow can enhance cell proliferation either. Based on the working principle and cyclic loading parameters, we simplify Navier-Stokes equation to describe the flow of culture fluid on substrates of uniaxial and equi-biaxial flat tensile loading systems and four point bending system. With approximate solutions, the distributions of velocity field and wall shear flow to cells are gained. Results show: shear flows are zero in the middle (or fixed point or line) of substrate for all systems, and they get larger proportionally to distance from middle and substrate elongate; the shear flow on the substrate of four point bending system is much greater than those of others. This shear flow in four point bending system, confirmed by Owan, I., et al with OPN mRNA increase in their experiment, could cause more influence to osteoblast-like cells than that caused by strain. We estimate the average magnitude of shear stress in Owan’s device, the results are consistent with other experimental data about shear flow. In conclusion our study makes it possible to differentiate the influence of strain on cellular proliferation to that of shear flow in loading experiments with the devices mentioned above quantitatively.
基金Project(51305463)supported by National Natural Science Foundation of ChinaProject(2012QNZT01601005125)supported by Free Exploration Plan of Central South University,ChinaProject supported by Postdoctoral Foundation of Central South university,China
文摘A numerical wave load model based on two-phase(water-air) Reynolds-Averaged Navier Stokes(RANS) type equations is used to evaluate hydrodynamic forces exerted on flatted-bottom seafloor mining tool during its entering ocean waves of deploying process.The discretization of the RANS equations is achieved by a finite volume approach(FV).The volume of fluid method(VOF) is employed to track the complicated free surface.A numerical wave tank is built to generate the ocean waves which are suitable for deploying seafloor mining tool.A typical deploying condition is employed to reflect the process of flatted-bottom body impacting with waves,and the pressure distribution of bottom is also presented.Four different lowering velocities are applied to obtain the time histories of maximum pressure of bottom,and it can be concluded that the pressure coefficient decreases with water velocity increasing,which is similar with ordinary water entry case.The numerical results clearly demonstrate the characteristics of flatted-bottom body entering ocean waves.
