An approximate method for describing the plastic hardening-softening behaviour of circular pipes subjected to pure bending is presented. Theoretical estimation based on the uniform ovalization model and local collapse...An approximate method for describing the plastic hardening-softening behaviour of circular pipes subjected to pure bending is presented. Theoretical estimation based on the uniform ovalization model and local collapse model proposed in the paper is incorporated to give several simple formulations with reasonable accuracy for determining the relationship between bending moment (M) and curvature (kappa) in the purely bended pipes. Attention is focused on the critical curvature associated with maximum resistant moment and the maximum change in the original diameter before the end of uniform ovalization stage as well as the local collapse behaviour. Some comparisons between analytical results and experimental results are made in order to examine the theory.展开更多
The hollow spherical joints welded with circular pipes applied to the National Swimming Center of China are subjected to large bending moments, but the influence of bending moments is not considered in the design equa...The hollow spherical joints welded with circular pipes applied to the National Swimming Center of China are subjected to large bending moments, but the influence of bending moments is not considered in the design equations in Technical Specification for Latticed Shells. Based on the von Mises yield criterion, multilinear isotropic hardening rule and associated flow rule, the elasto-plastic finite element model is put forward to analyze the behavior of the joints, and a calculation method for the joints under bending moments or eccentric loads is proposed. It is shown by the analytical results of joint that the stiffening rib can improve the ultimate bearing capacity by 10% for joints under axial tensile load, by 40% for joints under axial compressive load, and by 50% for joints under bending moment. The unified calculation equations for joints with or without stiffening rib are put forward, which can be applied to calculating the ultimate bearing capacity of the hollow spherical joints with circular pipes under eccentric loads.展开更多
In this paper we use the Green function method to solve the problem of steady one dimensional flow of an incompressible viscous, electrically conducting fluid through a pipe with partial circular ring cross sec- tion ...In this paper we use the Green function method to solve the problem of steady one dimensional flow of an incompressible viscous, electrically conducting fluid through a pipe with partial circular ring cross sec- tion and one with annular cross section, in the presence of an applied transverse uniform magnetic field, We ob- tain analytic solutions and carry out some numerical calculations of the velocity distribution and induced magnet- ic field.展开更多
Based on the Hamilton' s principle for elastic systems of changing mass, a differential equation of motion for viscoelastic curved pipes conveying fluid was derived using variational method, and the complex charac...Based on the Hamilton' s principle for elastic systems of changing mass, a differential equation of motion for viscoelastic curved pipes conveying fluid was derived using variational method, and the complex characteristic equation for the viscoelastic circular pipe conveying fluid was obtained by normalized power series method. The effects of dimensionless delay time on the variation relationship between dimensionless complex frequency of the clamped-clamped viscoelastic circular pipe conveying fluid with the Kelvin-Voigt model and dimensionless flow velocity were analyzed. For greater dimensionless delay time, the behavior of the viscoelastic pipe is that the first, second and third mode does not couple, while the pipe behaves divergent instability in the first and second order mode, then single-mode flutter takes place in the first order mode.展开更多
This paper investigate some important works done on numerical analysis and modeling of laminar flow in pipes. This review is focused on some methods of approach and the analytical tools used in analyzing of the import...This paper investigate some important works done on numerical analysis and modeling of laminar flow in pipes. This review is focused on some methods of approach and the analytical tools used in analyzing of the important parameters to be considered in laminar flow;such as frictional losses, heat transfer etc. in laminar flow in pipes of different shapes, and the importance of laminar flow in its areas of applications. Prominent researchers have approached this from different perspectives. Some carried out analysis on the pressure drop as a function of permeability, some worked on friction factor analysis, some discussed heat transfer effects of laminar flow in the entrance region, while some discussed its applications in various industries. Some of these works were done considering a given form of pipe configuration or shape which is circular pipes. Only a few, of the literature reviewed have related their considerations to different forms of pipes. Most consider pipes to be majorly circular in shape, but in industries today some circular pipes have become elliptical in shape due to long time usage of the pipes, which would have contributed to increase in some different forms of losses in the industries. In engineering, efficiency and effectiveness improvement is the major goal, if a research work has been done, considering the important parameters in laminar flow showing their effects on different forms of pipe configuration as a result of pipe deformation due to usage, huge amount of money will be saved. This will show clearly how the efficiency of a given circular pipe has seriously been affected due to deformation, and the level of loss this has resulted to.展开更多
Flat plate pulsating heat pipe is useful for hot spot heat spreader. Two kinds of flat plate spreader of pulsating heat pipe are designed, fabricated and experimented. For the embedded circular capillary type, the tra...Flat plate pulsating heat pipe is useful for hot spot heat spreader. Two kinds of flat plate spreader of pulsating heat pipe are designed, fabricated and experimented. For the embedded circular capillary type, the transferred heat flux could reach 32 W/cm2, the smallest thermal resistance for acetone, methanol and FC-72 were respectively 0.50, 0.57 and 0.40℃/W. While for the square capillary type, the transferred heat flux could reach 26 W/cm2, the equivalent thermal conductivity could reach 3211 W/（m. ℃）. There are ranges of optimal transferred power and filling ratio for different working liquid. If the transferred power is constant, changing the heating area and the place has little effects on the performance.展开更多
文摘An approximate method for describing the plastic hardening-softening behaviour of circular pipes subjected to pure bending is presented. Theoretical estimation based on the uniform ovalization model and local collapse model proposed in the paper is incorporated to give several simple formulations with reasonable accuracy for determining the relationship between bending moment (M) and curvature (kappa) in the purely bended pipes. Attention is focused on the critical curvature associated with maximum resistant moment and the maximum change in the original diameter before the end of uniform ovalization stage as well as the local collapse behaviour. Some comparisons between analytical results and experimental results are made in order to examine the theory.
基金National Natural Science Foundation of China (No 50608054)
文摘The hollow spherical joints welded with circular pipes applied to the National Swimming Center of China are subjected to large bending moments, but the influence of bending moments is not considered in the design equations in Technical Specification for Latticed Shells. Based on the von Mises yield criterion, multilinear isotropic hardening rule and associated flow rule, the elasto-plastic finite element model is put forward to analyze the behavior of the joints, and a calculation method for the joints under bending moments or eccentric loads is proposed. It is shown by the analytical results of joint that the stiffening rib can improve the ultimate bearing capacity by 10% for joints under axial tensile load, by 40% for joints under axial compressive load, and by 50% for joints under bending moment. The unified calculation equations for joints with or without stiffening rib are put forward, which can be applied to calculating the ultimate bearing capacity of the hollow spherical joints with circular pipes under eccentric loads.
文摘In this paper we use the Green function method to solve the problem of steady one dimensional flow of an incompressible viscous, electrically conducting fluid through a pipe with partial circular ring cross sec- tion and one with annular cross section, in the presence of an applied transverse uniform magnetic field, We ob- tain analytic solutions and carry out some numerical calculations of the velocity distribution and induced magnet- ic field.
基金Project supported by the Science Foundation of Shaanxi Provincial Commission of Education (No.03JK069)
文摘Based on the Hamilton' s principle for elastic systems of changing mass, a differential equation of motion for viscoelastic curved pipes conveying fluid was derived using variational method, and the complex characteristic equation for the viscoelastic circular pipe conveying fluid was obtained by normalized power series method. The effects of dimensionless delay time on the variation relationship between dimensionless complex frequency of the clamped-clamped viscoelastic circular pipe conveying fluid with the Kelvin-Voigt model and dimensionless flow velocity were analyzed. For greater dimensionless delay time, the behavior of the viscoelastic pipe is that the first, second and third mode does not couple, while the pipe behaves divergent instability in the first and second order mode, then single-mode flutter takes place in the first order mode.
文摘This paper investigate some important works done on numerical analysis and modeling of laminar flow in pipes. This review is focused on some methods of approach and the analytical tools used in analyzing of the important parameters to be considered in laminar flow;such as frictional losses, heat transfer etc. in laminar flow in pipes of different shapes, and the importance of laminar flow in its areas of applications. Prominent researchers have approached this from different perspectives. Some carried out analysis on the pressure drop as a function of permeability, some worked on friction factor analysis, some discussed heat transfer effects of laminar flow in the entrance region, while some discussed its applications in various industries. Some of these works were done considering a given form of pipe configuration or shape which is circular pipes. Only a few, of the literature reviewed have related their considerations to different forms of pipes. Most consider pipes to be majorly circular in shape, but in industries today some circular pipes have become elliptical in shape due to long time usage of the pipes, which would have contributed to increase in some different forms of losses in the industries. In engineering, efficiency and effectiveness improvement is the major goal, if a research work has been done, considering the important parameters in laminar flow showing their effects on different forms of pipe configuration as a result of pipe deformation due to usage, huge amount of money will be saved. This will show clearly how the efficiency of a given circular pipe has seriously been affected due to deformation, and the level of loss this has resulted to.
文摘Flat plate pulsating heat pipe is useful for hot spot heat spreader. Two kinds of flat plate spreader of pulsating heat pipe are designed, fabricated and experimented. For the embedded circular capillary type, the transferred heat flux could reach 32 W/cm2, the smallest thermal resistance for acetone, methanol and FC-72 were respectively 0.50, 0.57 and 0.40℃/W. While for the square capillary type, the transferred heat flux could reach 26 W/cm2, the equivalent thermal conductivity could reach 3211 W/（m. ℃）. There are ranges of optimal transferred power and filling ratio for different working liquid. If the transferred power is constant, changing the heating area and the place has little effects on the performance.
