Field reversed configuration(FRC)is widely considered as an ideal target plasma for magnetoinertial fusion.However,its confinement and stability,both proportional to the radius,will deteriorate inevitably during radia...Field reversed configuration(FRC)is widely considered as an ideal target plasma for magnetoinertial fusion.However,its confinement and stability,both proportional to the radius,will deteriorate inevitably during radial compression.Hence,we propose a new fusion approach based on axial compression of a large-sized FRC.The axial compression can be made by plasma jets or plasmoids converging onto the axial ends of the FRC.The parameter space that can reach the ignition condition while preserving the FRC's overall quality is studied using a numerical model based on different FRC confinement scalings.It is found that ignition is possible for a large FRC that can be achieved with the current FRC formation techniques if compression ratio is greater than 50.A more realistic compression is to combine axial with moderate radial compression,which is also presented and calculated in this work.展开更多
A stiffened cylindrical shell is normally used in refuge chambers of a coal mine. Based on the method of application and shape characteristics of a refuge chamber, we simplified its shell as an orthotropic cylinder. T...A stiffened cylindrical shell is normally used in refuge chambers of a coal mine. Based on the method of application and shape characteristics of a refuge chamber, we simplified its shell as an orthotropic cylinder. The basic buckling equation of the stiffened cylindrical shell under uniform axial compression was deduced by using a Donnell function. The factors affecting its buckling capacity were studied by theoretical analysis and numerical calculations. The results reveal that the torsional rigidity of the longitudinal stiffener had little effect on the buckling capacity of the shell and that the critical load of an externally stiffened cylindrical shell is higher than that of an internally stiffened cylindrical shell.展开更多
To find out the local buckling behaviors of glass fiber reinforced plastic(GFRP)-foam sandwich pipe suffering axial loading,a series of quasi-static axial compression tests are carried out in the laboratory.Comparing ...To find out the local buckling behaviors of glass fiber reinforced plastic(GFRP)-foam sandwich pipe suffering axial loading,a series of quasi-static axial compression tests are carried out in the laboratory.Comparing with the test data,systematic numerical analysis on the local buckling behavior of this sandwich pipe is also conducted,and the buckling failure mechanism is revealed.The influences of the key parameters on bearing capacity of the sandwich structure are discussed.Test and numerical results show that the local buckling failure of the GFRPfoam sandwich pipe is dominated basically by two typical modes,i.e.,the conjoint buckling and the layered buckling.Local buckling at the end,shear failure at the end and interface peeling failure are less efficient than the local buckling failure at the middle height,and ought to be restrained by appropriate structural measures.The local buckling bearing capacity increases linearly with the core density of the sandwich pipe structure.When the core density is relatively high(higher than 0.05 g/cm3),the effect of increasing the core density on improving the bearing efficiency is less on the specimens with a large ratio of the wall thickness to the radius than on those with a small one.Local layered buckling is another failure mode with lower bearing efficiency than the local conjoint buckling,and it can be restrained by increasing the core density to ensure the cooperation of the inner and the outer GFRP surface layer.The bearing capacity of the GFRP-foam sandwich pipe increases with the height-diameter ratio;however,the bearing efficiency decreases with this parameter.展开更多
Bamboo is a unique fiber-reinforced bio-composite with fibers embedded into a parenchyma cell matrix.We conducted axial compression tests on bamboo blocks prepared from bottom to top,and from inner to outer portions o...Bamboo is a unique fiber-reinforced bio-composite with fibers embedded into a parenchyma cell matrix.We conducted axial compression tests on bamboo blocks prepared from bottom to top,and from inner to outer portions of the culm.The apparent Young’s modulus and compressive strength of whole thickness bamboo blocks exhibited slight increases with increasing height along the culm,due to slight increases of fiber volume fraction(Vf)from 28.4 to 30.4%.Other blocks showed a significant increase in apparent Young’s modulus and strength from the inner to outer part of the culm wall,mainly owing to a sharp increase of Vf from 17.1 to 59.8%.With a decrease of fiber fraction volume there was a transition from relatively brittle behavior to very ductile behavior in bamboo blocks.Results indicated that stiffness and strength of bamboo was primarily due to fiber in compression,and ductility of bamboo was provided by the parenchyma cell matrix acting as a natural fiber-reinforced composite.展开更多
基金supported by National Natural Science Foundation of China(No.12175226)。
文摘Field reversed configuration(FRC)is widely considered as an ideal target plasma for magnetoinertial fusion.However,its confinement and stability,both proportional to the radius,will deteriorate inevitably during radial compression.Hence,we propose a new fusion approach based on axial compression of a large-sized FRC.The axial compression can be made by plasma jets or plasmoids converging onto the axial ends of the FRC.The parameter space that can reach the ignition condition while preserving the FRC's overall quality is studied using a numerical model based on different FRC confinement scalings.It is found that ignition is possible for a large FRC that can be achieved with the current FRC formation techniques if compression ratio is greater than 50.A more realistic compression is to combine axial with moderate radial compression,which is also presented and calculated in this work.
基金Financial support from the National Hi-tech Research and Development Program of China is much appreciated
文摘A stiffened cylindrical shell is normally used in refuge chambers of a coal mine. Based on the method of application and shape characteristics of a refuge chamber, we simplified its shell as an orthotropic cylinder. The basic buckling equation of the stiffened cylindrical shell under uniform axial compression was deduced by using a Donnell function. The factors affecting its buckling capacity were studied by theoretical analysis and numerical calculations. The results reveal that the torsional rigidity of the longitudinal stiffener had little effect on the buckling capacity of the shell and that the critical load of an externally stiffened cylindrical shell is higher than that of an internally stiffened cylindrical shell.
基金supported by the National Key R&D Program of China(No.2017YFC0405103)the Natural Science Foundation of China(No. 51978166)the Construction System Science and Technology Guidance Project of Jiangsu(Nos.2017ZD131,2017ZD132).
文摘To find out the local buckling behaviors of glass fiber reinforced plastic(GFRP)-foam sandwich pipe suffering axial loading,a series of quasi-static axial compression tests are carried out in the laboratory.Comparing with the test data,systematic numerical analysis on the local buckling behavior of this sandwich pipe is also conducted,and the buckling failure mechanism is revealed.The influences of the key parameters on bearing capacity of the sandwich structure are discussed.Test and numerical results show that the local buckling failure of the GFRPfoam sandwich pipe is dominated basically by two typical modes,i.e.,the conjoint buckling and the layered buckling.Local buckling at the end,shear failure at the end and interface peeling failure are less efficient than the local buckling failure at the middle height,and ought to be restrained by appropriate structural measures.The local buckling bearing capacity increases linearly with the core density of the sandwich pipe structure.When the core density is relatively high(higher than 0.05 g/cm3),the effect of increasing the core density on improving the bearing efficiency is less on the specimens with a large ratio of the wall thickness to the radius than on those with a small one.Local layered buckling is another failure mode with lower bearing efficiency than the local conjoint buckling,and it can be restrained by increasing the core density to ensure the cooperation of the inner and the outer GFRP surface layer.The bearing capacity of the GFRP-foam sandwich pipe increases with the height-diameter ratio;however,the bearing efficiency decreases with this parameter.
基金supported by Basic Scientific Research Funds of International Center for Bamboo and Rattan(1632016007)the National Science Foundation of China(31400519)
文摘Bamboo is a unique fiber-reinforced bio-composite with fibers embedded into a parenchyma cell matrix.We conducted axial compression tests on bamboo blocks prepared from bottom to top,and from inner to outer portions of the culm.The apparent Young’s modulus and compressive strength of whole thickness bamboo blocks exhibited slight increases with increasing height along the culm,due to slight increases of fiber volume fraction(Vf)from 28.4 to 30.4%.Other blocks showed a significant increase in apparent Young’s modulus and strength from the inner to outer part of the culm wall,mainly owing to a sharp increase of Vf from 17.1 to 59.8%.With a decrease of fiber fraction volume there was a transition from relatively brittle behavior to very ductile behavior in bamboo blocks.Results indicated that stiffness and strength of bamboo was primarily due to fiber in compression,and ductility of bamboo was provided by the parenchyma cell matrix acting as a natural fiber-reinforced composite.
