Nonlinear Dynamics Research On The Liquid-Solid Coupled Sloshing System In The Space Vehicle

It is worthiness to deal with liquid-solid coupled problems, which is widely relyon industrial engineering problems,particularly in space vehicles which filled with high heat value fuel. The liquid-solid coupled sloshing research has practical significance. In this paper, using the dynamic stability theory, perturbation method, C-L method and Melnikov method, the coupled system combined by rigid and elastic cylindrical storage tank and liquid fuel was studied. Specific research contents and key findings are as follows.1. Based on the basic theory of elastic mechanics and fluid mechanics, the basic equations of the elastic tank and liquid fuel are established respectively, which equivalence is proved by variation principle as well. By using modal expansion method, the nonlinear equations of the rigid coupled system and elastic coupled system are established respectively.2. Given the system parameter, the stability conditions of rigid tank-liquid coupled system in aircraft are studied. For further analysis, whether or not in case of internal resonance, the bifurcation diagrams of the coupled system are gained respectively. By contrast, under the condition of internal resonance, the chaotic road is changed from almost periodic to paroxysmal, and a new phenomenon called"Chaos Synchronism"is found under the condition of internal resonance.3. By means of multiple scales and C-L method, the bifurcation behaviors of elastic tank-liquid coupled system with harmonic excitation in the case of combination resonance are studied, so that abundant nonlinear dynamical characteristics of the coupled system are obtained, which can make a further explanation of the relationship between physic parameters and bifurcation solutions. The result shows that: The case of linear systems happened when the unfolding parameter is zero, then the calculation of turning point is possible; furthermore, On one hand,when the fill ratio is less than 0.43, the system elastic performance turns to hard features; On the other hand, when the fill ratio greater than 0.43, the feature of the system become soft.4. By applying Melnikov method, the global dynamic behaviors of the sloshing equations in aircraft filled with liquid under multi-frequency excitied model are studied. Consequently, threshold values of heteroclinic bifurcation and subhamonic bifurcation are obtained, and mechanism of chaotic motion is determined. Meanwhile, the switch point which is highly noteworthiness is detected.5. General nonlinear dynamical systems contain the complicated dynamical phenomenon mostly, such as bifurcation, chaos and so on. First of all, the effect of the self-excited vibration of piecewise-smooth nonlinear system caused by dry friction was taken into consideration. Concurrently, a new method which is used to decide the subsection integral limits of the system is highlighted. Second, resonance solution to a suspension system with two degrees of freedom is investigated with the C-L method. Based on the relationship between parameters and the topological bifurcation solutions, motion characteristics with deferent parameters are obtained. The result provides a theoretical basis for the optimal control of vehicle suspension system parameters.