The aerodynamic unstable critical wind velocity for three-dimensional open cable-membrane structures is investigated. The geometric nonlinearity is introduced into the dynamic equilibrium equations of structures. The ...The aerodynamic unstable critical wind velocity for three-dimensional open cable-membrane structures is investigated. The geometric nonlinearity is introduced into the dynamic equilibrium equations of structures. The disturbances on the structural surface caused by the air flow are simulated by a vortex layer with infinite thickness in the structures. The unsteady Bernoulli equation and the circulation theorem are applied in order to express the aerodynamic pressure as the function of the vortex density. The vortex density is then obtained with the vortex lattice method considering the coupling boundary condition. From the analytical expressions of the unstable critical wind velocities, numerical results and some useful conclusions are obtained. It is found that the initial curvature of open cable-membrane structures has clear influence on the critical wind velocities of the structures.展开更多
To solve the problems of divergence,low accuracy and project application of membrane wrinkling analysis,an analysis method of zero shear modulus and equivalent stiffness was proposed.This method is an improvement to t...To solve the problems of divergence,low accuracy and project application of membrane wrinkling analysis,an analysis method of zero shear modulus and equivalent stiffness was proposed.This method is an improvement to the previous method (Method I) of local coordinate transposition and stiffness equivalence.The new method is derived and the feasibility is theoretically proved.A small-scale membrane structure is analyzed by the two methods,and the results show that the computational efficiency of the new method (Method II) is approximately 23 times that of Method I.When Method II is applied to a large-scale membrane stadium structure,it is found that this new method can quickly make the second principal stress of one way wrinkled elements zero,and make the two principal stresses of two-way wrinkled elements zero as well.It could attain the correct load responses right after the appearance of wrinkled elements,which indicates that Method II can be applied to wrinkling analysis of large-scale membrane structures.展开更多
On the basis of choosing the basic element as the bar and choosing the basic mesh as the triangle as well as supposing the conditions of the element, the membrane states of an antenna reflector were researched by the ...On the basis of choosing the basic element as the bar and choosing the basic mesh as the triangle as well as supposing the conditions of the element, the membrane states of an antenna reflector were researched by the analogue method, because the membrane effect was not omitted during the ending deployment process of the radial rib antenna. The expressions of the bar element’s section area and density were obtained, while the expression of the stress state during the ending deployment process of antenna was attained. During the establishment process of the analogue method, the analysis method of the net shell structure was employed. Moreover, during the backward deduction of membrane stress, the continuation method was adopted. Because the expression of the membrane stress state can realize the analysis on the antenna membrane state, this research has great significance of theoretical direction to the normal operation of the space deployable antenna.展开更多
The determination of stress distribution is important for the safe use of membrane structures in practical engineering,which is difficult to be obtained by existing measurement methods and analysis methods.This paper ...The determination of stress distribution is important for the safe use of membrane structures in practical engineering,which is difficult to be obtained by existing measurement methods and analysis methods.This paper proposes a rigid-membrane method to determine the stress distribution of the membrane,which expands the stiffness of the membrane,applies the load of the membrane in equilibrium to the membrane shape of the equilibrium state,and performs nonlinear finite element analysis.The rigid-membrane method inversely acquires the stress distribution of the membrane based only on the shape and load distribution in equilibrium obtained from the numerical simulation of a membrane structure under water loads,and determines the modulus magnitude and mesh size required to rigidize the membrane.The accuracy of the rigid-membrane method is verified by the small differences between the stress distributions obtained from the proposed method and numerical simulations.The equilibrium membrane shape in the actual project can be scanned and reconstructed by the laser scanner system without any pre-processing,and the load is determined by the water level,internal pressure,etc.Based on the actual membrane shape and water load distribution,the rigid-membrane method determines the real stress distribution of the membrane in the test of flat membrane subjected to ponding water,which verifies that the rigid-membrane method is a practical method to determine the stress distribution only by the membrane shape and external load distribution.展开更多
It is very important for gas-structure interaction between compressible ideal gas and elastic structure of space folded membrane booms during the inflatable deployment. In order to study this gas-structure interaction...It is very important for gas-structure interaction between compressible ideal gas and elastic structure of space folded membrane booms during the inflatable deployment. In order to study this gas-structure interaction problem, Arbitrary Lagrangian-Eulerian （ALE） finite element method was employed. Gas-structure interaction equation was built based on equilibrium integration relationship, and solved by operator split method. In addition, numerical analysis of V-shape folded membrane booms inflated by gas was given, the variation of inner pressure as well as deployment velocities of inflatable boom at different stage were simulated. Moreover, these results are consistent with the experiment of the same boom~ which shows that both ALE method and operator split method are feasible and reliable methods to study gas-structure interaction problem.展开更多
基金supported by the Natural Science Foundation of Guangdong Province of China (No. 020904)
文摘The aerodynamic unstable critical wind velocity for three-dimensional open cable-membrane structures is investigated. The geometric nonlinearity is introduced into the dynamic equilibrium equations of structures. The disturbances on the structural surface caused by the air flow are simulated by a vortex layer with infinite thickness in the structures. The unsteady Bernoulli equation and the circulation theorem are applied in order to express the aerodynamic pressure as the function of the vortex density. The vortex density is then obtained with the vortex lattice method considering the coupling boundary condition. From the analytical expressions of the unstable critical wind velocities, numerical results and some useful conclusions are obtained. It is found that the initial curvature of open cable-membrane structures has clear influence on the critical wind velocities of the structures.
基金Project(020940) supported by the Natural Science Foundation of Guangdong Province,China
文摘To solve the problems of divergence,low accuracy and project application of membrane wrinkling analysis,an analysis method of zero shear modulus and equivalent stiffness was proposed.This method is an improvement to the previous method (Method I) of local coordinate transposition and stiffness equivalence.The new method is derived and the feasibility is theoretically proved.A small-scale membrane structure is analyzed by the two methods,and the results show that the computational efficiency of the new method (Method II) is approximately 23 times that of Method I.When Method II is applied to a large-scale membrane stadium structure,it is found that this new method can quickly make the second principal stress of one way wrinkled elements zero,and make the two principal stresses of two-way wrinkled elements zero as well.It could attain the correct load responses right after the appearance of wrinkled elements,which indicates that Method II can be applied to wrinkling analysis of large-scale membrane structures.
基金Sponsored by the National Natural Science Foundation of China(Grant No.19682003)
文摘On the basis of choosing the basic element as the bar and choosing the basic mesh as the triangle as well as supposing the conditions of the element, the membrane states of an antenna reflector were researched by the analogue method, because the membrane effect was not omitted during the ending deployment process of the radial rib antenna. The expressions of the bar element’s section area and density were obtained, while the expression of the stress state during the ending deployment process of antenna was attained. During the establishment process of the analogue method, the analysis method of the net shell structure was employed. Moreover, during the backward deduction of membrane stress, the continuation method was adopted. Because the expression of the membrane stress state can realize the analysis on the antenna membrane state, this research has great significance of theoretical direction to the normal operation of the space deployable antenna.
基金the National Natural Science Foundation of China(No.51978395)。
文摘The determination of stress distribution is important for the safe use of membrane structures in practical engineering,which is difficult to be obtained by existing measurement methods and analysis methods.This paper proposes a rigid-membrane method to determine the stress distribution of the membrane,which expands the stiffness of the membrane,applies the load of the membrane in equilibrium to the membrane shape of the equilibrium state,and performs nonlinear finite element analysis.The rigid-membrane method inversely acquires the stress distribution of the membrane based only on the shape and load distribution in equilibrium obtained from the numerical simulation of a membrane structure under water loads,and determines the modulus magnitude and mesh size required to rigidize the membrane.The accuracy of the rigid-membrane method is verified by the small differences between the stress distributions obtained from the proposed method and numerical simulations.The equilibrium membrane shape in the actual project can be scanned and reconstructed by the laser scanner system without any pre-processing,and the load is determined by the water level,internal pressure,etc.Based on the actual membrane shape and water load distribution,the rigid-membrane method determines the real stress distribution of the membrane in the test of flat membrane subjected to ponding water,which verifies that the rigid-membrane method is a practical method to determine the stress distribution only by the membrane shape and external load distribution.
基金supported by the National Natural Science Foundation of China (10902032)the National Key Laboratory Opening Funding of Advanced Composites in Special Environments (HIT.KLOF.2009035)
文摘It is very important for gas-structure interaction between compressible ideal gas and elastic structure of space folded membrane booms during the inflatable deployment. In order to study this gas-structure interaction problem, Arbitrary Lagrangian-Eulerian （ALE） finite element method was employed. Gas-structure interaction equation was built based on equilibrium integration relationship, and solved by operator split method. In addition, numerical analysis of V-shape folded membrane booms inflated by gas was given, the variation of inner pressure as well as deployment velocities of inflatable boom at different stage were simulated. Moreover, these results are consistent with the experiment of the same boom~ which shows that both ALE method and operator split method are feasible and reliable methods to study gas-structure interaction problem.
