航天刚-弹-液耦合系统的弹-液耦合研究

航天刚-弹-液耦合动力学中的弹-液耦合问题是关系到航天刚-弹-液耦合系统液固耦合机理研究和大规模液固耦合建模计算研究的重要课题。通过分析刚-弹-液耦合动力学拟变分原理的泛函，说明刚-弹-液耦合中的刚-弹耦合、刚-液耦合和弹-液耦合的特点。应用Lagrange乘子法，将无际边界条件纳入泛函中，通过识别Lagrange乘子，逐步说明弹-液耦合的机理。通过对泛函求驻值发现，无际边界条件由原来的先决条件转化为驻值条件，实现了从协调元到杂交元的过渡。通过分析泛函识别Lagrange乘子前后的驻值条件，明确了识别Lagrange乘子可以有效地减少计算自由度。 

Elastic-liquid coupling in aerospace rigid-elastic-liquid coupling system

This paper focuses on the elastic-liquid coupling problem in the rigid-elastic-liquid coupling dynamics. It is an important topic related to researches on mechanism and large-scale modeling and calculation of liquid-solid coupling in the aerospace rigid-elastic-liquid coupling system. Based on the analysis of the function of the quasi-variational principles for the rigid-elastic-liquid coupling dynamics, characteristics for rigid-elastic coupling, rigid-liquid coupling and elastic-liquid coupling in the rigid-elastic-liquid coupling system were illustrated. Inter-element boundary conditions were plugged into the function by Lagrange multiplier method and the mechanization of the elastic-liquid coupling was illustrated step by step through the identification of Lagrange multipliers. Solving stationary values of function shows that inter-element boundary conditions convert from preconditions to stationary value conditions. It realizes the transition from compatible element model to the hybrid element model. Through analysis on stationary value conditions before and after identification of Lagrange multipliers, it is shown that the identified Lagrange multipliers can effectively reduce the degree of freedom for calculation.