充气薄膜管气-膜耦合作用的有限元分析

FINITE ELEMENT ANALYSIS OF AIR-MEMBRANE INTERACTION IN INFLATED MEMBRANE TUBES

充气薄膜管通过内充气压获得刚度和承载力。荷载作用下的变形会导致内充气压改变,进而引起结构刚度的变化,体现为内充气体与外围薄膜耦合作用。该文采用有限元方法对充气薄膜管的气-膜耦合作用及其随影响因素的变化规律进行数值分析。通过将内充气体等效为小扰动线性有势流体以考虑内充气体与外围薄膜的耦合作用;通过将有限元分析结果与相应的试验结果进行对比,验证考虑气-膜耦合作用有限元模型的正确性和精确性;通过将分析结果与内充气体被等效为外围薄膜静力边界条件情况下的计算结果进行对比,研究气-膜耦合作用对充气薄膜管褶皱临界荷载和极限承载力的影响及其随初始内压、长细比、端部约束类型以及轴向荷载的变化情况。研究结果表明,气-膜耦合作用对褶皱临界荷载和极限承载力具有重要影响,且呈现非单调变化的特点,在影响因素的变化范围内,出现极大值或(和)极小值。该文的研究成果揭示了充气薄膜管的气-膜耦合作用规律,有助于深入认识充气薄膜管的力学行为,确保空间充气薄膜结构设计计算的可靠性。

Inflated membrane tubes are supported by inflating air from which their stiffness and bearing capacities originate.The deformation of an inflated membrane tube under external loads induces a change in the inner pressure and can therefore affect the stiffness of the tube.This phenomenon features the interaction between the inner air and enveloping membrane.The authors,using the finite element method,numerically analyze the airmembrane interaction in inflated membrane tubes and its variation with the influencing factors.The air-membrane interaction is considered by regarding the inner air as a kind of linear potential flow and the numerical solutions are compared with the corresponding experimental results to verify the validity and accuracy of the finite element model developed herein.Then the inflated membrane tubes are numerically analyzed with the verified model to study the air-membrane interaction and its variation with the initial inner pressure,slenderness ratio,end constraint type and axial compression by comparing the results with those of the tubes in which the inner air is treated as the static boundary conditions of the enveloping membrane.The results indicate that the air-membrane interaction has an important effect on the critical wrinkling load and ultimate bearing capacity and the influence varies non-monotonically,reaching maxima or(and)minima within the ranges of the studied parameters.The present research reveals the air-membrane interaction and is helpful to the understanding of the mechanical behavior of inflated membrane tubes for the reliable design of spatial inflated membrane structures.