拱形气肋结构干、湿模态分析及附加质量简化公式研究

Dry and wet modal analysis of air-inflated arch structure and simplified formula study for additional mass

为研究拱形气肋结构的模态特征和外部流场附加质量,基于流固耦合势流理论,建立薄膜充气管流固耦合模态有限元模型,以充气管和内充气体共同作用理论模型对薄膜充气管进行干模态分析,并考虑外部空气三者共同作用理论模型对薄膜充气管进行湿模态分析,根据ETFE充气管试验结果对有限元模拟方法进行验证。对拱形气肋结构进行干模态、湿模态参数分析,考虑拱形气肋结构的跨度、直径、充气内压、矢跨比对模态的影响。结果表明:随着气肋跨度和矢跨比的增加,模态频率随之减小;随着气肋直径和充气内压的增加,模态频率随之增加。在模态分析的基础上,进一步分析得到拱形气肋结构前五阶模态附加质量,并提出前五阶模态附加质量的简化公式。

In order to analyze the modal characteristics of air-inflated arch structure and the additional mass of external flow field, a finite element simulation model for fluid structure interaction modal of pneumatic membrane tube was presented based on the FSI(fluid structure interaction) theory and potential flow theory. And the dry modal analysis of pneumatic membrane tube was carried out by the theoretical model of the interaction between the inflatable tube and the inner inflatable body. And the wet modal analysis of pneumatic membrane tube was carried out by the theoretical model of the interaction between the air flow field and the inflatable tube. The finite element simulation method was verified by the ETFE inflatable tube test results. Then, the dry and wet modal parameters of air-inflated arch structure were analyzed, considering the influence of the span, diameter, inflation internal pressure and rise-span ratio of air-inflated arch structure on the mode. The results show that the modal frequency decreases with the increase of air-inflated span and rise-span ratio, and increases with the increase of air-inflated diameter and air pressure. Based on the modal analysis, the additional mass of the first five modes of the air-inflated structure was obtained by further analysis, and the simplified formulas of the additional mass of the first five modes were put forward.