Study On The Interaction Between Inner Air And Enveloping Membrane Of Inflated Membrane Tubes

Inflatable membrane tubes are widely applied in aerospace engineering and other fields due to their advantages of light weight,small folding volume and fast forming.The inflatable membrane tube is composed of inner air and outer membrane,and the air-membrane interaction is generated between the two,which has a significant effect on the mechanical properties of the inflatable membrane tube.In the static aspect,the air-membrane interaction is mainly reflected in the deformation under the action of load,which will cause the change of inner pressure and stiffness.In the dynamic aspect,the additional mass effect of internal air is mainly reflected.In this paper,the air-membrane interaction of the inflatable membrane tube is studied,so as to have a deeper understanding of its mechanical properties,which is helpful to design and analyze it more accurately.This paper studies the effect of air-membrane interaction on the static and dynamic characteristics of inflatable membrane tubes,and explores how the effect of air-membrane interaction with the influencing factors.The main research contents of this paper are as follows:(1)In this paper,according to the experiment boundary conditions and the precision of requirements,the experiment device was independently designed and manufactured,vertical load and transverse load are applied with weights,displacement and inner pressure are measured with laser displacement sensor and barometer,through the precision control of the processing,loading,and measurement of the experiment device,ensure the accuracy of the experiment results.(2)The commercial finite element software ADINA was used to establish the static and dynamic finite element model of the inflatable membrane tubes.In the static finite element models,the inner air is equivalent to the static boundary condition and the potential fluid;In the dynamic finite element models,the inner air is equivalent to the potential fluid,the additional mass on the membrane surface,and the static boundary condition,studying the influence of air-membrane interaction by comparison.The correctness and accuracy of the finite element models established in this paper are verified by comparison with the corresponding results in experiments and literatures.(3)Static analysis of inflatable membrane tubes.Through the comparison between the case where the constant inner air mass and constant inner pressure,this paper quantitatively explores how the air-membrane interaction with the initial inner pressure,slenderness ratio,constraint type and axial force,further explores the effect of air-membrane interaction on the critical wrinkling load and ultimate bearing capacity,and its variation with influencing factors.(4)Analysis of the natural vibration characteristics of the inflatable membrane tubes.By comparing the three different finite element models of the inner air equivalent to potential fluid,additional mass on the membrane surface and static boundary conditions,the influence of air-membrane interaction on its natural vibration characteristics is studied and further researched the influence of air-membrane interaction varies with the initial inner pressure,slenderness ratio,constraint type,and membrane thickness.The results show that under load,the air-membrane interaction decreases with the increase of the initial inner pressure,the slenderness ratio and the enhancement of the constraint strength,With the increase of axial load,the air-membrane interaction is non-monotone,which is first strengthened and then weakened.The influence of air-membrane interaction on the first frequency of inflatable membrane tubes decreases with the increase of the initial inner pressure and slenderness ratio,while the influence on other frequencies increases.With the increase of membrane thickness,the influence of air-membrane interaction on natural vibration frequency decreases.Under the condition of one end fixed and the other simply-supported,the influence of air-membrane interaction is the strongest.