充液贮箱液固耦合振动模态与阻尼比研究

对于液体运载火箭纵向振动的稳定性分析，在建立贮箱内液体的振动模型时，不仅需要考虑结构的弹性特性，还需要考虑液体晃动时的阻尼特性。由于模态阻尼比与一个振动周期内阻尼力做功、平均机械能及模态固有频率相关。因此可以先通过结构与液体的耦合振动分析确定其模态，进而分别计算液体与结构接触面、自由面以及液体内部阻尼力做功，同时计算平均机械能，从而得到模态阻尼比。在计算模态阻尼比时，对耦合振动的模态分析、液体内部流场计算均采用等效比拟的方法，为充分利用通用程序计算创造了条件。此方法不仅能够提高效率，同时也便于工程上的应用。

A research of liquid filled container fluid-structure coupling vibration modal and damping ratio

When conducting stability analysis to the longitudinal vibration of liquid rocket and establishing the vibration model of liquid inside of the tank, we need to consider the elastic characteristic of structure, as well as the damping character of liquid shaking. Due to the fact that the modal damping ratio is correlated to the work of damping force per vibration period, mean mechanical energy, and the modal nature frequency, we can first get the modal via analyzing the coupled vibrations of structure and liquid, and then calculate the work of the contact surface between liquid and structure, free surface and inner damping force, as well as mechanical energy, so as to achieve the modal damping ratio. The heat flux analogy method, which is adapted in the modal analyze of coupled vibration and the calculation of liquid inner fluid area, enables us to take full advantage of general program in calculation, which not only improves efficiency, but facilitates engineering application as well.