Structural stabilization by a pressurized fluid is very common in nature, however hardly found in technology. Car tires, hot air balloons, airships and airhouses are among the few technical exceptions, which are stab...Structural stabilization by a pressurized fluid is very common in nature, however hardly found in technology. Car tires, hot air balloons, airships and airhouses are among the few technical exceptions, which are stabilized by a compressed medium, typically air. Restricted by simple geometries and a very limited load bearing capacity these pneumatic structures could succeed only in very specialized applications. Nevertheless, prospective concepts ag has systematically investigated pneumatic structures during the last few years. As a major result, it was demonstrated that almost any shape can be made with pneumatic structures and that astonishing structures such as the pneumatic airplane Stingray can be realized even with low air pressure. On top of that, Airlight Ltd. in close collaboration with prospective concepts ag has recently developed the fundamental new structural concept Tensairity. The synergetic combination of an inflated structure with conventional structural elements such as cables and struts yields pneumatic light-weight structures with the load bearing capacity of steel girders. Thus, complex forms and high strength open up many new opportunities for pressure induced stability in technology. An overview of these recent developments is presented and the close relationship of pneumatic structures with biology is outlined.展开更多
Plants possess many structural and functional properties that have a high potential to serve as concept generators for the production of biomimetic technical materials and structures. We present data on two features...Plants possess many structural and functional properties that have a high potential to serve as concept generators for the production of biomimetic technical materials and structures. We present data on two features of plants (variable stiffness due to pressure changes in cellular structures and rapid self-repair functions) that may be used as models for biomimetic projects.展开更多
The whole analysis process of pneumatic stressed membrane structure contains nine states and seven analysis processes.The zero-stress state is the corner-stone of analysis and design of pneumatic stressed structure,an...The whole analysis process of pneumatic stressed membrane structure contains nine states and seven analysis processes.The zero-stress state is the corner-stone of analysis and design of pneumatic stressed structure,and has significant impact on the pre-stressed state and load state.According to the logical model of the whole numerical analysis process of pneumatic stressed structure,a numerical analysis method to solve the zero-stress state from the elasticized equilibrium state was firstly proposed,called linear compatibility matrix M-P inverse method.Firstly,the pneumatic membrane stressed structure was transferred into grid structure by using membrane link to simulate membrane surface.Secondly,on the basis of equilibrium matrix theory of pin joint structure and small deformation assumption,compatibility equation of system was established.Thirdly,the unstressed length and elongation of links were calculated from the tension and material parameters of elasticized equilibrium state.Finally,using compatibility matrix M-P inverse,the nodal displacement was calculated by solving compatibility equation,the configuration of zero-stress state could be obtained through reverse superposition,and the stress was released.According to the algorithm,the program was coded with MATLAB.The correctness and efficiency of this method were verified by several numerical examples,and it could be found that one elasticized equilibrium state corresponded to one configuration of the zero-stress state.The work has theoretical significance and practical guidance value for pneumatic membrane structural design.展开更多
Inflatable membrane antennas have been extensively applied in space missions;however,the simulation methods are not perfect,and many simulation methods still have many difficulties in accuracy,efficiency,and stability...Inflatable membrane antennas have been extensively applied in space missions;however,the simulation methods are not perfect,and many simulation methods still have many difficulties in accuracy,efficiency,and stability.Therefore,the extended position-based dynamics(XPBD)method is employed and improved for the simulation of folded inflatable structures in this paper.To overcome the problem that the original XPBD method with only geometric constraints does not contain any mechanical information and cannot reflect the mechanical characteristics of the structure,we improve the XPBD method by introducing the strain energy constraint.Due to the complicated nonlinear characteristics of the membrane structures,the results with the traditional finite element method(Abaqus)cannot converge,while the tension field theory(TFT)can,but some pretreatments are needed.Compared with them,the method in this paper is simple and has better stability to accurately predict the displacement,stress,and wrinkle region of the membrane structure.In addition,the present method is also compared with the experiment in the reference to verify the feasibility of the folded tube simulation.Finally,the present method is applied to simulate inflatable membrane antennas and analyze the deployable driving force and deployable process sequence of each component.展开更多
文摘Structural stabilization by a pressurized fluid is very common in nature, however hardly found in technology. Car tires, hot air balloons, airships and airhouses are among the few technical exceptions, which are stabilized by a compressed medium, typically air. Restricted by simple geometries and a very limited load bearing capacity these pneumatic structures could succeed only in very specialized applications. Nevertheless, prospective concepts ag has systematically investigated pneumatic structures during the last few years. As a major result, it was demonstrated that almost any shape can be made with pneumatic structures and that astonishing structures such as the pneumatic airplane Stingray can be realized even with low air pressure. On top of that, Airlight Ltd. in close collaboration with prospective concepts ag has recently developed the fundamental new structural concept Tensairity. The synergetic combination of an inflated structure with conventional structural elements such as cables and struts yields pneumatic light-weight structures with the load bearing capacity of steel girders. Thus, complex forms and high strength open up many new opportunities for pressure induced stability in technology. An overview of these recent developments is presented and the close relationship of pneumatic structures with biology is outlined.
文摘Plants possess many structural and functional properties that have a high potential to serve as concept generators for the production of biomimetic technical materials and structures. We present data on two features of plants (variable stiffness due to pressure changes in cellular structures and rapid self-repair functions) that may be used as models for biomimetic projects.
基金supported by the National Natural Science Foundation of China (Grant Nos. 50878128, 50808122)
文摘The whole analysis process of pneumatic stressed membrane structure contains nine states and seven analysis processes.The zero-stress state is the corner-stone of analysis and design of pneumatic stressed structure,and has significant impact on the pre-stressed state and load state.According to the logical model of the whole numerical analysis process of pneumatic stressed structure,a numerical analysis method to solve the zero-stress state from the elasticized equilibrium state was firstly proposed,called linear compatibility matrix M-P inverse method.Firstly,the pneumatic membrane stressed structure was transferred into grid structure by using membrane link to simulate membrane surface.Secondly,on the basis of equilibrium matrix theory of pin joint structure and small deformation assumption,compatibility equation of system was established.Thirdly,the unstressed length and elongation of links were calculated from the tension and material parameters of elasticized equilibrium state.Finally,using compatibility matrix M-P inverse,the nodal displacement was calculated by solving compatibility equation,the configuration of zero-stress state could be obtained through reverse superposition,and the stress was released.According to the algorithm,the program was coded with MATLAB.The correctness and efficiency of this method were verified by several numerical examples,and it could be found that one elasticized equilibrium state corresponded to one configuration of the zero-stress state.The work has theoretical significance and practical guidance value for pneumatic membrane structural design.
基金supported by the National Natural Science Foundation of China(Grant Nos.11922203 and 11772074).
文摘Inflatable membrane antennas have been extensively applied in space missions;however,the simulation methods are not perfect,and many simulation methods still have many difficulties in accuracy,efficiency,and stability.Therefore,the extended position-based dynamics(XPBD)method is employed and improved for the simulation of folded inflatable structures in this paper.To overcome the problem that the original XPBD method with only geometric constraints does not contain any mechanical information and cannot reflect the mechanical characteristics of the structure,we improve the XPBD method by introducing the strain energy constraint.Due to the complicated nonlinear characteristics of the membrane structures,the results with the traditional finite element method(Abaqus)cannot converge,while the tension field theory(TFT)can,but some pretreatments are needed.Compared with them,the method in this paper is simple and has better stability to accurately predict the displacement,stress,and wrinkle region of the membrane structure.In addition,the present method is also compared with the experiment in the reference to verify the feasibility of the folded tube simulation.Finally,the present method is applied to simulate inflatable membrane antennas and analyze the deployable driving force and deployable process sequence of each component.
