Analysis Methods Research Of Liquid Sloshing In Tank Under Dynamic Loads

For the fuel tank of aircraft under dynamic load,the fluid-structure interaction between fluid and solid could produce impact loads,which seriously threaten the safety of the structure.It makes the liquid sloshing of the fuel tank becomes a key problem for aircraft structure design.However,as the obvious nonlinear unsteady characteristics accompanied by fluid-solid coupling and the complexity of composite mechanical properties,the calculation efficiency and safety assessment accuracy of the liquid sloshing problem for fuel tanks under dynamic load is limited.Therefore,research on the analysis method of liquid sloshing in the tank under dynamic load is significant for the structural design of aircraft.Aiming at this problem,the main research work is as follows:First,research on the time-domain analysis methods is carried out.The effectiveness of Smoothed Particle Hydrodynamic(SPH)method and Coupled Eularian-Lagrangian(CEL)methods is analyzed by studying the liquid sloshing in a rectangular tank under harmonic loads.The influence of the grid size on solution efficiency and accuracy on SPH method is studied.The research results show that both SPH and CEL achieve high computational accuracy.Compared to CEL,the SPH could capture the large-scale nonlinear liquid sloshing phenomenon with higher efficiency.The smooth length of fluid particles is the key factor for the calculation efficiency of SPH.Secondly,research on the frequency-domain analysis methods is carried out.The wet modal of the solid structure and the internal liquid under the fluid-solid coupling state is simulated based on the acoustical boundary element method and added mass method,respectively.Simulation results show that the acoustical boundary element method can effectively simulate the wet mode characteristics of the fluid.The sloshing frequencies increase with increasing fluid height.The wet mode of the structure obtained by the added mass method can be further applied to frequency-domain dynamic response analysis.The dynamic response in the time-domain matches well with the predicted dynamic response in the frequency-domain.Finally,the liquid sloshing analysis of a composite fuel tank under impact loads is investigated.The influence of liquid weight and laminate angles on structural strength and reliability is studied.Research results indicate that liquid sloshing is the main impact source to the structure.The hydrodynamic pressure on the wall and failure indicator increase significantly with increasing fuel weight.The most likely failure mode is fiber fracture.